AP Biology Unit 2 Review: Cell Structure and Function

Summary

This educational video script delves into cell biology, contrasting light and electron microscopy for cell study. It explains cell structure and function, emphasizing the plasma membrane's role. The video explores membrane transport, including diffusion and active transport mechanisms. It also covers organelles, highlighting the nucleus, endoplasmic reticulum, Golgi apparatus, and mitochondria. Special attention is given to the endosymbiotic theory of mitochondria and chloroplasts. The script aims to simplify complex biological concepts for better understanding.

Takeaways

• 🔬 Microscopes are essential tools for studying cell structures and functions, with light microscopes magnifying up to a thousand times and electron microscopes offering even greater magnification.
• 🌟 The plasma membrane is crucial for protecting the cell and regulating what enters and exits it, composed of phospholipid bilayers that self-organize to keep hydrophilic heads facing water and hydrophobic tails away from water.
• 🚪 Transport proteins in the cell membrane facilitate the movement of molecules across the membrane, including channels that allow specific molecules to pass and carrier proteins that transport molecules through the membrane.
• 💧 The fluidity of the cell membrane is influenced by factors like temperature, the presence of unsaturated fatty acids which introduce kinks preventing tight packing, and cholesterol which can modulate membrane fluidity.
• 🌀 Diffusion is a passive process where molecules move from an area of high concentration to an area of low concentration, and it plays a key role in the movement of molecules across cell membranes.
• 🔋 Active transport requires energy (ATP) to move molecules against their concentration gradient, typically involving carrier proteins that facilitate the movement of substances into the cell.
• 🌱 Plant cells differ from animal cells in several ways, including the presence of chloroplasts for photosynthesis, a cell wall for structural support, and plasmodesmata for communication between cells.
• 🔑 The endosymbiotic theory explains the origin of organelles like mitochondria and chloroplasts, suggesting they were once free-living organisms that were engulfed by a host cell and eventually became integral parts of the cell's functioning.
• 🧬 The nucleus serves as the control center of the cell, containing the genetic material (DNA) and regulating cellular activities through the process of transcription and translation.
• ⚙️ Organelles such as the endoplasmic reticulum, Golgi apparatus, and mitochondria each have specialized functions in the cell, including protein synthesis, packaging and secretion, and energy production, respectively.

Q & A

What are the two types of microscopes mentioned in the script and how do they differ?

The two types of microscopes mentioned are light microscopes and electron microscopes. Light microscopes use light to magnify specimens up to a thousand times and are used to observe live organisms. Electron microscopes offer much higher magnification, up to 10^6 times, and can see the surface and internal structures of specimens, but they require the specimen to be dead and coated in a heavy metal.

What is the function of the plasma membrane in a cell?

The plasma membrane functions as a protective barrier for the cell, controlling what enters and exits the cell. It is composed of a phospholipid bilayer with embedded proteins and cholesterol, which helps regulate its fluidity and selective permeability.

How do integral proteins, transmembrane proteins, and peripheral proteins differ in their association with the plasma membrane?

Integral proteins are located within the phospholipid bilayer, transmembrane proteins span across the entire membrane, and peripheral proteins are attached to the exterior surface of the membrane but are not embedded within it.

What role do unsaturated fatty acids and cholesterol play in the fluidity of the plasma membrane?

Unsaturated fatty acids introduce kinks in the fatty acid chains, which prevent them from packing closely together, thus increasing the membrane's fluidity. Cholesterol helps to regulate fluidity by preventing the fatty acids from packing too closely at low temperatures and from spreading too far apart at high temperatures.

What is the difference between simple diffusion and facilitated diffusion?

Simple diffusion is the passive movement of molecules from an area of high concentration to an area of low concentration without the assistance of any proteins. Facilitated diffusion also involves the passive movement down a concentration gradient but requires the assistance of transport proteins, such as channels or carriers, to move larger or charged molecules across the membrane.

What is the significance of the endosymbiotic theory in relation to mitochondria and chloroplasts?

The endosymbiotic theory suggests that mitochondria and chloroplasts were once free-living bacteria that were engulfed by a larger cell. Over time, these bacteria became essential organelles within the cell, retaining their own DNA and carrying out vital functions such as energy production in mitochondria and photosynthesis in chloroplasts.

How does the structure of the nucleus relate to its function within the cell?

The nucleus serves as the control center of the cell, containing the genetic material that directs cellular functions. Its structure includes the nuclear envelope with nuclear pores for communication, the nucleolus for ribosome production, and the chromatin where DNA is stored.

What is the primary function of the Golgi apparatus in a cell?

The Golgi apparatus is responsible for the modification, sorting, and packaging of proteins and lipids for transport to other parts of the cell or for secretion outside the cell.

Why are lysosomes considered 'digestive' organelles?

Lysosomes contain enzymes that can break down a wide variety of substances, including cellular debris and foreign particles. They function as the cell's digestive system, breaking down and recycling materials within the cell.

What is the main difference between animal cells and plant cells as depicted in the script?

The main differences include the presence of a cell wall, large central vacuole, and chloroplasts in plant cells, which are absent in animal cells. Additionally, plant cells have plasmodesmata for communication between cells, while animal cells have centrioles which are not present in plant cells.

Outlines

00:00

🔬 Introduction to Microscopy and Cell Structure

The speaker begins by expressing enthusiasm for the topic and quickly dives into the importance of microscopy for understanding cell structure and function. They explain the basics of light microscopy, emphasizing its ability to magnify cellular structures up to a thousand times. The concept of magnification and resolution is introduced, with a focus on how these factors contribute to the clarity of microscopic images. The speaker contrasts light microscopy with electron microscopy, highlighting the superior magnification power of electron microscopes and their capacity to reveal both surface and internal cellular structures. However, they also note the downside of electron microscopy, which is the requirement to kill the organism under study to prepare samples. The speaker concludes this section by encouraging the use of light microscopy for observing live cells.

05:01

🧬 Exploring the Cell Membrane and Its Components

The speaker provides an in-depth look at the cell membrane, starting with its structure composed of phospholipid bilayers. They explain the hydrophilic and hydrophobic properties of phospholipids and how these properties dictate the formation of the membrane. The role of proteins within the membrane is discussed, distinguishing between integral, transmembrane, and peripheral proteins based on their location and function. The impact of unsaturated fatty acids and cholesterol on membrane fluidity is also explored, with the speaker using analogies to help explain these concepts. The paragraph concludes with an overview of how substances move across the plasma membrane, touching on passive transport mechanisms like diffusion and facilitated diffusion.

10:03

🌟 Diving Deeper into Membrane Transport and Osmosis

This section delves into the specifics of how substances are transported across the cell membrane. The speaker explains the concepts of simple diffusion, facilitated diffusion, and active transport, providing examples of each process. They introduce the terms 'hypertonic' and 'hypotonic' to describe solutions relative to the cell's internal environment and explain how osmosis, the movement of water across a membrane, is influenced by these conditions. The speaker also discusses the role of transport proteins, such as channels and carriers, in allowing specific molecules to pass through the membrane, with a special mention of aquaporins, which facilitate the movement of water molecules.

15:04

🌿 Comparing Animal and Plant Cells: Organelles and Functions

The speaker compares animal and plant cells, highlighting the common organelles such as the nucleus, mitochondria, and endoplasmic reticulum, and their functions. They discuss the unique organelles found in plant cells, such as chloroplasts and large central vacuoles, and their roles in photosynthesis and storage, respectively. The speaker also touches on the endosymbiotic theory, which posits that mitochondria and chloroplasts were once independent organisms that became incorporated into larger cells. They briefly mention other organelles like the Golgi apparatus, lysosomes, and centrioles, emphasizing their specific functions and the differences between animal and plant cells. The paragraph ends with a note on the importance of understanding these concepts for subjects like AP Biology.

Keywords

💡Microscope

A microscope is an optical instrument that allows the observation of small objects or details that are not visible to the naked eye. In the context of the video, microscopes are essential tools for studying cell structures and functions. The script mentions both light microscopes and electron microscopes, highlighting their differences in magnification and resolution. Light microscopes are used for general cell observation, while electron microscopes provide much higher magnification, allowing the study of cellular components in greater detail.

💡Cell Structure

Cell structure refers to the organization and arrangement of components within a cell. The video script delves into the various parts of a cell, such as the plasma membrane, nucleus, and organelles. Understanding cell structure is crucial for grasping cellular functions, as each component has a specific role. The script uses the analogy of the nucleus being the 'brain' of the cell, emphasizing its importance in controlling cell function.

💡Phospholipid Bilayer

The phospholipid bilayer is a fundamental component of cell membranes, consisting of two layers of phospholipids. Each phospholipid molecule has a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tails. In the video, the phospholipid bilayer is described as the key structural element of the cell membrane, with the hydrophilic heads facing the aqueous environments inside and outside the cell, and the hydrophobic tails facing each other, forming a barrier.

💡Proteins

Proteins are large biomolecules that play a wide range of roles in cells, including catalyzing reactions, providing structural support, and facilitating transport. The script discusses different types of proteins associated with the cell membrane, such as integral proteins, transmembrane proteins, and peripheral proteins. These proteins are crucial for various cellular processes, including transport across the membrane and signal transduction.

💡Cholesterol

Cholesterol is a lipid molecule that plays a significant role in cell membranes by regulating fluidity. As mentioned in the script, cholesterol can prevent the fatty acid tails of phospholipids from getting too close together, which helps maintain the membrane's fluidity. At low temperatures, cholesterol helps keep the membrane fluid by preventing the fatty acids from packing too closely, while at high temperatures, it helps keep the membrane stable by preventing it from becoming too fluid.

💡Diffusion

Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration. The video script explains diffusion in the context of how molecules pass through the cell membrane, such as small hydrophobic molecules moving through the phospholipid bilayer. This process does not require energy input from the cell and is a fundamental concept in understanding how cells regulate the movement of substances.

💡Active Transport

Active transport is the movement of molecules or ions across a cell membrane against their concentration gradient, requiring energy input, usually in the form of ATP. The script uses active transport as an example of how cells move substances that cannot passively diffuse across the membrane, such as larger molecules or substances moving from an area of lower concentration to an area of higher concentration.

💡Endosymbiotic Theory

The endosymbiotic theory proposes that certain organelles, such as mitochondria and chloroplasts, originated from free-living prokaryotic cells that were engulfed by a larger cell. Over time, these engulfed cells became dependent on their host and evolved into organelles. The video script highlights the mitochondria as an example, explaining that they were once bacteria that became incorporated into a eukaryotic cell, eventually evolving into the energy-producing organelles found in cells today.

💡Osmosis

Osmosis is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. The script explains osmosis in the context of cell biology, describing how water moves in and out of cells in hypertonic and hypotonic solutions. This process is essential for maintaining cell shape and function, as it affects the cell's internal environment.

💡Organelles

Organelles are specialized subunits within cells that perform specific functions. The video script mentions several organelles, such as the nucleus, mitochondria, and Golgi apparatus, each with a unique role. For example, the nucleus houses the cell's genetic material, mitochondria produce energy, and the Golgi apparatus is involved in modifying, sorting, and packaging proteins for secretion or use within the cell. Understanding the function of organelles is key to comprehending cellular processes.

Highlights

Importance of microscopy for studying cell structure and function.

Explanation of how a light microscope works and its magnification capabilities.

Difference between light microscope and electron microscope for cell observation.

Functionality of scanning electron microscopes in studying cell surfaces.

Capability of transmission electron microscopes to observe internal cell structures.

Advantages and limitations of using electron microscopes over light microscopes.

Introduction to cell fractionation as a technique for studying cells.

Basic structure of a cell including the plasma membrane, cytosol, and organelles.

Role of the phospholipid bilayer in forming the plasma membrane.

Types of proteins found in the plasma membrane: integral, transmembrane, and peripheral.

Impact of unsaturated fatty acids and cholesterol on membrane fluidity.

Passive transport mechanisms including diffusion and facilitated diffusion.

Importance of transport proteins like channels and carriers in moving molecules across membranes.

Concept of concentration gradients and their role in passive transport.

Differences between hypertonic and hypotonic solutions and their effects on cells.

Process of osmosis and its significance in water movement across cell membranes.

Active transport mechanisms and their requirement for energy.

Description of the nucleus as the control center of the cell and its components.

Functions of the endoplasmic reticulum, Golgi apparatus, and mitochondria.

Explanation of the endosymbiotic theory relating to the origin of mitochondria and chloroplasts.

Comparison between animal and plant cells highlighting the presence of chloroplasts in plant cells.

Overview of the significance of the surface area to volume ratio in cell biology.

Transcripts

I'm a DAB on video and forever dude and

then I want to send that ap by the 30th

ap kind of small brain now come on par

we're gonna I'm car and today we are

getting back into the bio whip unit 2 of

80 by not considered cell structure and

function is pretty relevant to both

ether Bo and ap bomb because both of

them tested a lot so why don't we just

jump into the cool stuff so because I'm

a campout fan everybody uses a capsule

biology into the biology Bible we're

gonna start exactly where Campbell

biology starts on this topic white

microscopy so basically in order to know

how a cell structures and functions you

gotta have a light microscope right so

basically you got your beautiful

microscope from what the heck fellas

like to know cute but anyway the point

is you know how to know what the parts

of the microscope are what you do not

know is that these are used to study

cells and basically the way it works is

that you shine a light up from here and

go through the sample which is right

here and goes in here it goes in here it

gets refracted around in here it goes

over here and you look at the light over

here

very cool stuff and basically these

light microscopes and magnify things a

thousand times now everybody knows what

magnification is the other measurement

you have to keep track up score a

microscope is resolution right the

technical definition is how far are two

Doc's have to be for you to be tell them

apart but that's not really important

you just gotta know that it's how clear

the image on the microscope is alright

so literally does all you have to know

about white microscope right you can

just take a cell and you fella you want

put it on the light microscope it shines

light up through it it goes to your eyes

and you can see you magnify didn't know

the reason why I'm talking about this is

because in a bottle and you said oh it's

pretty important to know the difference

between light microscope and electron

microscope because light microscopes

have some advantages and electron

microscopes have other advantages so

basically there are two types of

electron microscopes we'll talk about

them first you got the scanning electron

microscope and basically what the

microscope do is you have like a probe

right here you got a sample here and

basically what the probe does it ascends

an electron it bounces off and you have

a scanner that tell where the electrons

bounced off now the thing about scanning

microscopes is because it's going

through the whole sample right into the

bouncing off electrons you could only

tell the service of a sample right

because when the electrons bounce off

they're not going into the sample

they're just hitting off the surface so

the only thing that you can see is a

service the way I like to remember it is

scanning

I'd like to make sense right to scan so

over the things but it also stands for

surface so the one thing you gotta know

about scanning microscope

they're good for telling you detailed

about really tiny surfaces and then

there is tunneling basically what these

do is instead of bouncing the electrons

over it it shoots the electron right

through the sample go through it and

then it checks for how it looks on the

other side and that makes sense right

because tunneling means that it's going

through so basically these are good

because it no longer just looking at the

surface right it goes through and you

can see all the internal mechanisms of

anything you want

now electron microscope seemed really

good right why would we want to use a

light microscope electron microscopy we

do a thousand times more magnification

like 10 to the 6 magnification nonsense

and these got only 1000 X so lame so the

benefits of electron microscopes are

pretty clear right like you can first

off you have to often together see the

surface and really good detail a

thousand times more and you can also

look at the internal working however

four electron microscopes a bad thing is

that you gotta kill the organism this is

so sad we're gonna kill organisms why

today the reason you had to do that

though is because in order to bounce

electrons off of it you have to actually

put it in a heavy metal and that killed

them right so if you want to see live

organisms you have to use a light

microscope no I've seen this kind of

problem so many times on AP bio and use

the boat basically want to ask you is it

like if you have a lime cell and you

just want to see it outside

what type of microscope you dislike

right so you've gotta use a light

microscope so it doesn't know the

difference okay the book goes into a lot

more detail on this mountain I'm not

gonna go into that one detail cuz it's

really boring really useless who care

okay before again the interesting stuff

we first got to talk about one more

technique for studying cells and that's

called cell fractionation and ap bio is

not gonna ask you that much details

about cell fractionation right you

basically the time to know what it does

so obviously you take a cell you

fractionated so basically exactly how it

works then you take a blender perfect

normal kitchen a blender you put in

yourselves you blend it all up and you

throw that into a centrifuge okay and

this centrifuge spins around alright and

basically by spinning this around you

know like how if you jiggle like a sand

tray it separates out the particle is

this exactly in concept it spins it

around so that it separates the particle

based on some so it definitely has a

very end you take out the test tube and

you got like your nuclei you got your

mitochondria you got a bunch of

different layers very cool stuff

essentially the point is you can

basically use just a blender and a

centrifuge to separate a fell into a

different part which is really useful

right like if you wanted to study

mitochondria you just frakkin ate it you

take

we're right here alright and you got

mitochondria epic alright it's finally

time to get into fun stuff we're gonna

talk about cells oh my god what the heck

cell that's crazy

to the basic structure of a cell if you

have a circle and this circle is the

plot in the membrane and then inside of

it you got your cytosol and then inside

of the cytosol you got all your

different parts of the cell you got a

nucleus you got your mitochondria like I

said we'll talk about it later

the first thing you want to talk about

is apply the membrane because that is

the most important organelle of the cell

arguably right you're plotting the

membrane and literally the same with

your skin right Lily protects your cell

right and let's think in and out of your

cell it's really important so let's talk

about that first

so how the heck did this boy structured

basically you got a bunch of these like

phospholipid right I talked about these

guys phospholipids in my unit one video

but the basic idea that you have to know

is that the head is hydrophilic so it

likes water okay

hydrophilic loves water then these guys

are hydrophobic hates water

so essentially no matter where the heck

you put these phospholipids they always

want it so that the head is touching the

water and the tails if not hugging walk

so let's try to make a membrane so to

make a membrane you know that a cell is

like water right the cytosol is like the

jelly ish thing some nasty yucky jelly

you know what I'm saying and then the

outside of a cell used to be cell door

immersed in water right so there's water

over here and there's also water on this

side so what's gonna make a layer right

so we either put a bunch of you guys

next to each other okay so let's say

this extends all the way to the other

time okay so this is fine right like all

the guys who like water or with the

water they're all happy cool stuff but

does it not okay okay we can't let these

tails touch the water they don't like

the water it's like putting a cat in the

shower it's not okay it's morally

incorrect so what we got to do is we got

to figure out how to make these tails

not touch the water and the way we can

do that if we put another molecule right

here and another one right here

and another one right there and we

extend that all the ways to the other

side and her aid we got the head that

likes the water touching the water and

we got the tail to heat the water

successfully protect it from the water

ever so this right here in this whole

thing the double layer is remembered and

because made out of phospholipid into

two layers what do you think is called

that's right phospholipid bilayers all

right very hot stuff now this membrane

is not just a bunch of follow with it

okay we also got someone that stuff in

it so basically one thing that could be

in

or membrane our protein so you got a

protein does just hanging out over here

that's called an integral protein color

inside the plasma membrane then there

are also proteins that span the entire

plasma membrane they go out one way and

they come out the other side like this

these are called transmembrane proteins

oh my god I could not guess if it goes

across the membrane it's a transmembrane

protein holy moly and then there's some

protein that does hang out like all the

way outside itself but they're connected

to the membrane and those are called

peripheral Road and though they're

called / and those are called peripheral

proteins right because they're not

inside the membrane they're on the

periphery of it so three types you gotta

know our integral which are like inside

of the membrane transmembrane across the

membrane and peripheral outside but

connected all righty what else could be

in the bottle lipid bilayer why thank

you yes it is unsaturated fatty acid the

basic PV on these straight fatty acids

those are saturated right they don't

have any kinks in them there's no double

bond and then there are saturated but

what happened to be change this guy to

have a kink in it now this is an

unsaturated fatty acid and basically

this kink over here prevents these guys

are coming too close to each other right

like if you have two of you guys right

next to each other well then one of them

get a kink

so now they can only be so far apart so

basically by adding these kinks or

unsaturated fatty acid you're making the

membrane less stable right call you're

pushing them apart so essentially your

membrane is going to be more fluid the

way I like to think about it and like

the more compact your membrane is the

more sturdy it is right but then as you

push it apart with these unsaturated

fatty acid to become more and more

liquidy because they're less and less

connected now the last thing you got to

know about your membrane is that you can

also put cholesterol in so basically

just like slamming a little cholesterol

right here the way I like to think of

calash well it'll be like a really

sticky stress ball okay so essentially

when the bottle lipids get close

together

it pushes them apart right cuz it's

elastic it just try to push them apart

but then when the fossil wouldn't get

too far apart from it it tried to pull

them back in because it's sticky so it's

like pulling them back in so that

basically means that like let's say

we're at a cold temperature right these

phospholipids are getting close closer

together and more structured because

it's colder right then cholesterol I'm

going to push them out because like on

the last expressible I'm just gonna push

them out and that's why it keeps the

bilayer fluid even at low temperature

however when

you got high temperatures and the fossil

doesn't start at spread out it'll pull

them back in because it's stuck to them

so basically to summarize unsaturated

fatty acid they make the membrane more

fluid right because they have the kinks

and the kinks spread things out and then

you got cholesterol at low temperatures

it pushes them apart from each other so

it keeps it more food but a high

temperature that pull the bottle goes

back in so it keeps the membrane fluid

but at higher temperatures it pulls the

fluid back together so it keeps it

solvent even at higher temperatures okay

builder basically the two things that

affect the fluidity of a polymer

membrane and these are pretty important

so you gotta know B okay let us talk

about how things get through the plasma

membrane now so making meat you got your

membrane and things could pass through

it right but only small and hydrophobic

molecules can go through easily and the

reason for that is small right when

you're small you can easily pass through

the membrane but when you're hydrophobic

like the inside of your plasma membrane

and hydrophobic right so if you want to

pass it as a membrane you've got to be

hydrophobic so that the tails don't like

kick you out of the memory so it's

actually a good thing to know is that

small hydrophobic molecules are easier

to pass to the member but we know that

cell the other thing right they need

soup really neat glucose they need high

fructose corn syrup you know what I'm

saying

but basically the point is not all these

molecules that the need are small right

we look at the massive molecule like how

are you gonna get that three remember it

basically there's something called

transport protein okay and basically

what they do is they let specific

molecule bit and then maybe to type to

the channel which is pretty obvious that

just lets the molecule path to the

channel and then there's the carrier

that like grab a thing over here and

then they flip around and they put it

out over here and here it we got it in

herself now these are the two types

right but the specific one that's

important for channel are aquaporin and

basically what those are are just

channel proteins that let water through

and they're pretty obvious right aqua

porins

water pours very cool stuff now to

understand how things actually get

pushed through the membrane right we're

gonna think about

depute so basically if you have like one

molecule here and like a ton of molecule

right here all the same thing more of

the molecules from the inside are going

to go to the outside because it is more

of them right so if a certain percentage

of them go to the other side more of

them are going to come from this side of

that side then there are from this side

of that fun so essentially if you have

like a ton a ton of time

these guys the net movement of these

particles and basically gonna be from

high concentration to low concentration

so the only thing y'all know about

diffusion is that high concentration low

concentrate it's like a milk you go from

a high hill roll down below here so this

particle was a pass through the membrane

that way so this is called aphelion

right and diffusion is called passive

transport become a cell doesn't have to

do anything to get it through but let's

say that we have like a really big

molecule and it can't just pass it a

member and it goes like well blammo get

bounced off toasted you go you hit it

yourself into a wall get roasted

basically then the cell have to put in

their own protein right

like let's say there's like a ton of

really big molecule on this side and

they all want to get out but they can't

it doesn't like the too big so basically

the cell have to put in a protein with a

channel let these guys to pass through

and now they're still diffusing right

it's still like higher concentration to

lower concentration but now they're

getting help from the stuff so that's

called facilitated diffusion okay very

epic and that's also passive transport

because once it's all puts in this

channel protein it doesn't have to do

anything stuff the molecules themselves

already want to go through the membrane

so it still has a transport and

basically the definition of passive

transport is when molecules move from

there

- the Train and a lower concentration

and that's what's called your

concentration gradient this one

basically does a bawd where you could

throw around to sound cool hey look at

Mike on the tree ingredient I'm so cool

but the actual concept is pretty useless

I mean it's just saying you go from high

to look pretty useless

you've probably heard electrochemical

gradient to write the chemical just

means concentration gradient and an

electro is like let's say if you've

gotten how a plus charge right once it

is like a really strong plus charge

already in the cell then even though the

you guys might be more concentrated on

the outside they won't want to come in

because it's so much less charge already

in there is that even though there's

less of this particular molecule inside

they were getting repulsed by the

electric pore so that's all I got to

know about electrochemical gradient that

is basically your concentration gradient

compared to the actual charge of the

molecule now one thing that a lot of

people get confused about is hypertonic

vs. like hypotonic right so let's say

the cell is here and your outside is

here then hypertonic basically means

hyper means more so it's more than the

cell so if you're selling has like two

of you guys two particles here then the

outside has like way more of the

particle right and let's say that the

membrane did not let the particle pass

in and out but the way the Dafina works

that it wants to equal concentrations so

if the particle themselves can move how

do we equalize the concentration that's

right

we decrease the amount of water that's

up so if you have more particles on the

outside and they can't move into the

cell then the water is going to go to

the particles if the particles can't go

to the water the water goes to the party

so in a hypertonic solution the water

leaves itself and that's why you get

yourself Stribling off in a hypertonic

solution so let's say we had a hypotonic

solution you got two over here you got

like a ton over here then basically the

same concept these guys can't go out to

meet the water until the water from the

outside comes into the cells and hooray

you got blown itself hooray that's so

fun I love blowing itself and basically

this is water diffusing right it's going

from lower concentration to higher

concentration and going from a higher

concentration of water relative to the

particles to lower concentration of

water relative to the particles so when

I have to do with water if called

osmosis that's just the movement of

water diffusion is the more general

thing of Moses is specifically for water

okay last thing for plowing the membrane

we got your membrane and let's say that

we have like a couple of you got here

and a ton of you guys here but if the

cell wants to bring even more into the

cell so naturally these guys are gonna

try to get out right but we want to

bring things in and that's super hard

because they don't want to come in

so essentially what the cell does is

they put in a carrier protein and it

snatches it in and forces it through the

membrane and puts it out over here but

because it's hard it takes energy to do

it so you need some ATP as well

and since the cell is putting in energy

to move it from outside to inside it's

called active transport ok very epic

we're done with plasma membrane stuff

let's move on to the actual organelles

and I'm gonna go through it pretty

quickly because the actual organelle

they're not that complicated and you

probably have like got this ingrained in

your head like 600 million times and

it's not going to be tested that much on

the test so I want to talk about it real

briefly I wanted to focus more on the

more complicated thing that actually

require like conceptual knowledge and

like for example hypertonicity is really

hard to understand so that's why I

talked about that more all right so we

got a beautiful animal cell you got your

nucleus in the center right and

basically the nucleus in the brain of

the cell right you can only see it

doesn't Center on the cell oh my god

it's like a control center and that's

exactly what it does so basically the

nucleus has all the genetic codes that

tells the cell how to function and then

you go to your nuclear pores which let

you communicate between the outside of

the cell and nucleus then you got a

nucleolus which is not actually an

organelle okay it's just like a quantum

DNA's that create ribosome and then

nuclear famine is that the inside of the

new

and then the nuclear envelope is like a

double membrane so there is a by later

but there's only one of it for the

nucleus you got two bilayers it's pretty

cool and basically this is protect the

nucleus

okay and then you got your rough

endoplasmic reticulum all the little box

you could see are just ribosome

basically it's just responsible for

creating a membrane and like doing

metabolism so it like detoxify of toxins

and that kind of thing and smooth

endoplasmic reticulum basically does the

exact same thing the exact difference

between smooth and rough endoplasmic

reticulum is pretty irrelevant so don't

worry about it too much okay we already

talked about cell membranes cilia are

basically just like oars right like if

you have a rowboat you got your or right

there

it made it leave a push liquid so I

could pull it forward or just push the

liquid around so you go your ribosome

they create protein you got your license

tones that does break things down it's

like your stomach except for your cell

in digesting thank you very sentry oh

you guys are kind of confusing basically

they don't play your role in cell

division is not that important so don't

worry about it too much until we get too

seldom in and then it's actually

important such as though my veins mean

you have two centrioles the peroxisome

is such a cool organelle bus and not

really that important for ap bio

basically other got ton of roles for

example in detoxify the alcohol which is

pretty cool but it also does like a ton

of other stuff but another relevant okay

then you got your Golgi apparatus which

is basically for packaging stuff so like

the rough endoplasmic reticulum might

send something to the Golgi apparatus

like a protein or something and then the

Golgi apparatus will send it somewhere

else

what's in line you have secretory

vesicles apical the apparatus right it's

happened is up the vesicles sends them

to where they gotta go time filing we

already talked about mitochondria now

this guy is interesting and yes that's

right it is a powerhouse of the cell not

be sure you know I totally came up with

a definition right on the spot all by

myself did not even okay no whatever

we're good we're good

the powerhouse of the cell and basically

is responsible for generating all the

ATP that Acela me already made a video

on respiration so if you guys want to

walk that you guys can do that but in

the next unit we'll talk more about

exactly how the mitochondria work the

other important thing to know about

mitochondria is a structure right you

basically got your two membranes just

like the nucleus it has two bilayers

right and the inner membrane is actually

like super folding so there's your outer

membrane then your inner membrane and

then the inside of the inner membrane is

called the matrix right it's such a cool

name for a bunch of squiggles

not gonna lie and then these folds are

called Christic that's kind of important

if you want to do it use a bow but for

it's not that important to know the

exact thing okay the other thing you got

to know about mitochondria is the

endosymbiotic theory so basically the

mitochondria are super super cool

because basically they're not into any

other organelle

they have their own DNA they are

basically autonomous they could divide

by themselves and why not give that well

basically they used to be bacteria so

essentially there's a start eerie about

floating around making this on food what

a cool kids and then this other big boy

would like I don't want to make food for

myself get in here so this guy goes in

engulf this guy and right now this guy

starts making food for the bigger guy

and now we got our first mitochondria so

basically what you have to know is that

mitochondria used to be and archaea to

be specific and basically one of the

first you kyrios decided to engulf it

and now it acts as a mitochondria

creating food for it okay epic now let

us talk about the plant cell so you can

see that a lot of the stuff in this

thing you even have mitochondria

one thing I like for some reason did not

know is that plants also need energy so

they also have mitochondria but you

could tell that the new thing is a

chloroplast and basically that's just

for carrying out photosynthesis it has a

bunch of pigments and stuff to capture

light all that good stuff and it's

similar to the mitochondria cuz it's

also an endosymbiotic so essentially

it's an endo so it's inside and a symbol

so it's another organism that was taken

over by a bigger organism which is why

I'm Clara glass also have your own DNA

very cool stuff so you can at least be

destructor from this diagram you got

your double boiler again right then you

got your staffs of stuff so the

individual like little sacs you can see

there are called thylakoids

then Granum are the staffs that you see

you right there like a bunch of these

like long stack right here and there's a

liquid that's surrounding them it's

called the stroma once again not that

important but might be good to know

anything your vacuolar to dust for

storing stuff I don't know why there's a

lysosome here because in Campo it said

that the no license on the plant cells I

was in a camp oh right because that's

basically what the EP by was tested

based on so then no wife's done their

plant so maybe they're just calling like

vacuoles license because some vacuums

and plants have digestive juices in them

okay another thing that's not present is

centrioles so the two organelles that

are not in plants but they are in

animals are centrioles and lysosomes and

then you can see that right here did the

plasmodesmata with this basically does a

way for they can pass between adjacent

time cells and that's basically it

of course they didn't cover everything

cuz

ton of stuff to cover in this unit but I

covered all the important thing that you

asked me out of note and all this stuff

is actually relevant like one thing I

didn't cover is surface area to volume

ratio become Khan you guys got that

under control come on you guys got that

but I'm always if you enjoyed the video

leave a like and subscribe for more help

me out a ton thing guys so much for

watching again and see you guys next

time