Organelles of the Cell

Summary

This educational video script delves into the intricate components of a eukaryotic cell, emphasizing the plasma membrane, nucleus, and cytoplasm as the cell's foundational sections. It illustrates the cytoplasm's role as a medium for chemical reactions and the plasma membrane's selective permeability. The nucleus, often dubbed the 'control center,' houses DNA and directs protein synthesis. Ribosomes, ER, and the GOI body collaborate in protein production and modification. Mitochondria, known as the 'powerhouse,' generate energy through cellular respiration. The script also touches on the endosymbiosis theory, suggesting mitochondria and chloroplasts were once independent organisms. Lysosomes handle waste and food breakdown, while vacuoles store materials. The video concludes with a review of these concepts, encouraging viewer engagement.

Takeaways

• 🔬 Organelles are specialized structures within cells that perform specific functions, akin to organs in the body.
• 🌟 The plasma membrane, or cell membrane, is a lipid bilayer that selectively allows substances to pass in and out of the cell.
• 🧬 The nucleus acts as the cell's control center, housing DNA and directing the cell's activities through the production of proteins.
• 🍯 The cytoplasm is a gel-like substance that fills the cell and facilitates chemical reactions, including the dissolution of solutes like carbohydrates and proteins.
• 🏋️‍♂️ Ribosomes are the cellular structures responsible for protein synthesis, translating genetic information into functional proteins.
• 📦 The Golgi apparatus modifies, sorts, and packages proteins for transport within the cell or for secretion outside the cell.
• ⚡ Mitochondria are known as the 'powerhouses' of the cell, generating energy in the form of ATP through cellular respiration.
• 🔁 Endosymbiosis theory suggests that mitochondria and chloroplasts were once free-living organisms that became incorporated into larger cells.
• 🌱 Chloroplasts, found in plant cells, carry out photosynthesis, converting sunlight into glucose and oxygen using chlorophyll.
• 💧 Vacuoles store water, nutrients, waste products, and pigments, and can also regulate the cell's internal environment.

Q & A

What is meant by the term 'organelle' in the context of a eukaryotic cell?

An organelle refers to the small specialized structures within a eukaryotic cell that perform specific functions necessary for the cell's survival and operation.

What are the three basic functions that all cells must perform?

All cells must perform the functions of taking in food, getting rid of waste, and reproducing.

What is the primary role of the plasma membrane, also known as the cell membrane?

The plasma membrane's primary role is to regulate the passage of materials into and out of the cell, acting as a selectively permeable barrier.

What is the cytoplasm and what does it do?

The cytoplasm is a jellylike substance filling the cell, providing a medium for organelles to float within and facilitating various chemical reactions, including the dissolution of solutes like carbohydrates and proteins.

Why is the nucleus often referred to as the 'control center' of the cell?

The nucleus is called the 'control center' because it contains DNA in the form of chromatin, which holds the genetic instructions for making proteins that perform most of the work within the cell.

What is the function of the nucleolus within the nucleus?

The nucleolus is responsible for producing ribosomes, which are essential for protein synthesis within the cell.

How does the rough endoplasmic reticulum differ from the smooth endoplasmic reticulum?

The rough endoplasmic reticulum is covered in ribosomes, which are involved in protein synthesis, while the smooth endoplasmic reticulum lacks ribosomes and is involved in lipid synthesis and toxin breakdown.

What is the role of ribosomes in the cell?

Ribosomes are responsible for protein synthesis by linking amino acids together to form proteins, a process also known as translation.

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

The Golgi apparatus receives proteins from ribosomes, modifies them, sorts, and packages them into vesicles for export from the cell.

What is the significance of the mitochondria being referred to as the 'powerhouse' of the cell?

Mitochondria are called the 'powerhouse' because they generate ATP, the cell's primary energy molecule, through cellular respiration.

What is the endosymbiosis theory and how does it relate to the origin of mitochondria and chloroplasts?

The endosymbiosis theory suggests that mitochondria and chloroplasts were once free-living organisms that were engulfed by a larger cell and eventually became integrated as organelles, surviving and reproducing within the host cell.

What is the primary role of lysosomes within a cell?

Lysosomes contain digestive enzymes that break down various materials, including food particles, pathogens engulfed by immune cells, and even old or damaged cell components.

How do cilia and flagella differ in structure and function within cells?

Cilia are short, hairlike extensions that aid in movement over short distances, while flagella are long, whip-like structures that can propel cells over greater distances, such as in the case of sperm cells.

What is the cell wall and what is its primary function?

The cell wall is a tough, outermost layer found in plant, fungal, and bacterial cells, providing structural support and protection.

What is the role of chloroplasts in plant cells?

Chloroplasts perform photosynthesis, converting sunlight, carbon dioxide, and water into glucose and oxygen, using the green pigment chlorophyll.

What is the function of the vacuole in both plant and animal cells?

The vacuole serves as a storage area for food, water, waste, and pigments. In plant cells, it is often the largest organelle, pushing other structures to the cell's periphery.

Outlines

00:00

🌐 Overview of Eukaryotic Cell Organelles

The paragraph introduces the concept of organelles within eukaryotic cells, comparing them to organs in the body. It outlines the three fundamental sections of a cell: the plasma membrane, the nucleus, and the cytoplasm. The plasma membrane, also known as the cell membrane, is highlighted as a key part of the cell's structure. The nucleus is referred to as the 'control center' due to its role in housing DNA. The cytoplasm is described as a gel-like substance filling the cell, within which most organelles are suspended. The paragraph also mentions the importance of the cytoplasm in facilitating chemical reactions and providing support to the cell structure.

05:01

🧬 The Nucleus: Control Center and DNA Repository

This section delves into the nucleus, emphasizing its role as the 'headquarters' of the cell due to containing DNA. DNA is depicted as the cell's blueprint, with chromatin being the physical form of DNA within the nucleus. The nucleolus, a distinct structure within the nucleus, is introduced as the site of ribosome production. Ribosomes are then explained as the cellular machinery responsible for protein synthesis, which is central to the cell's functions. The paragraph also touches on the endoplasmic reticulum (ER), distinguishing between the rough ER, studded with ribosomes, and the smooth ER, which lacks ribosomes and is involved in lipid synthesis and toxin breakdown.

10:03

🔬 Ribosomes and Protein Synthesis

The focus shifts to ribosomes, which are described as the cellular structures responsible for protein synthesis. Ribosomes are shown to be composed of RNA and proteins, and their function is to link amino acids together to form proteins. The process of protein synthesis is mentioned as translation, a concept to be further explored. The paragraph also discusses the role of the Golgi apparatus in receiving proteins from ribosomes, modifying them, and packaging them into vesicles for export from the cell. This process is visualized through an animation that shows ribosomes moving through the ER and the Golgi apparatus processing and shipping out proteins.

15:03

🏋️‍♂️ Mitochondria: The Powerhouse of the Cell

This paragraph introduces mitochondria as the 'powerhouses' of the cell, responsible for generating ATP, the cell's energy currency, through cellular respiration. The theory of endosymbiosis is introduced to explain the origin of mitochondria as once free-living organisms that became integrated into cells. The paragraph discusses the unique characteristics of mitochondria, such as having their own DNA and ribosomes, allowing them to replicate independently. The historical context of cell theory development is also briefly touched upon, mentioning the contributions of Robert Hooke and his observations of cell walls in cork.

20:03

🌱 Plant Cells and Their Unique Organelles

The paragraph discusses the cell wall, a feature unique to plant, fungal, and bacterial cells, providing structural support and rigidity. It contrasts with animal cells, which lack a cell wall. The role of cellulose in forming the cell wall is highlighted, along with its toughness and indigestibility. Chloroplasts are introduced as the organelles responsible for photosynthesis in plant cells, containing chlorophyll, which converts sunlight, carbon dioxide, and water into glucose and oxygen. The endosymbiotic theory is also applied to chloroplasts, suggesting they were once free-living organisms that became part of plant cells. The paragraph concludes with a brief mention of vacuoles, which store food, water, waste, and pigments, and are often the largest organelle in plant cells.

25:05

🍄 The Role of Vacuoles and Cell Wall in Plant Cells

This final paragraph emphasizes the role of vacuoles in storing various substances within plant cells, including nutrients, water, and waste. It contrasts the large central vacuoles found in plant cells with the smaller, scattered vacuoles in animal cells. The paragraph also reiterates the importance of the cell wall in providing structural support to plant cells, mentioning the historical significance of Robert Hooke's observations of cell walls in cork. The paragraph serves as a conclusion, summarizing the key organelles and their functions within eukaryotic cells.

Keywords

💡Organelle

An organelle is a specialized subunit within cells that performs a specific function. In the context of the video, organelles are the 'small parts' that enable cells to carry out essential life processes. The video discusses various organelles such as mitochondria, chloroplasts, and the Golgi apparatus, each with unique roles in cellular activities.

💡Plasma Membrane

The plasma membrane, also known as the cell membrane, is a biological membrane that separates the cell from its external environment. It is described in the video as a selectively permeable barrier, composed of a lipid bilayer with embedded proteins, which allows certain molecules to pass through while restricting others. This membrane is crucial for the cell's ability to control the movement of substances in and out.

💡Nucleus

The nucleus serves as the control center of the cell, containing the cell's genetic material (DNA). As explained in the video, it is often referred to as the 'headquarters' because it directs cellular activities by housing DNA, which provides the instructions for making proteins. The video also mentions the nucleolus, a structure within the nucleus responsible for producing ribosomes.

💡Cytoplasm

Cytoplasm is the jelly-like substance that fills a cell, in which organelles are suspended. The video describes it as facilitating chemical reactions within the cell and providing support. It also dissolves solutes, such as carbohydrates and proteins, which are essential for cellular functions. The concept of cytoplasmic streaming is introduced, illustrating the movement of organelles within the cytoplasm.

💡Mitochondria

Mitochondria are referred to as the 'powerhouses' of the cell because they generate most of the cell's supply of adenosine triphosphate (ATP), which is used as a source of chemical energy. The video explains that mitochondria carry out cellular respiration and were once free-living organisms, a concept supported by the endosymbiosis theory.

💡Endoplasmic Reticulum (ER)

The endoplasmic reticulum is a network of membranous tubules and sacs within the cell. It is divided into two types: rough ER, which is studded with ribosomes, and smooth ER, which lacks ribosomes. The rough ER's function, as detailed in the video, includes the synthesis of proteins and lipids, while the smooth ER is involved in lipid metabolism and detoxification.

💡Ribosomes

Ribosomes are cellular structures responsible for protein synthesis. The video explains that ribosomes are produced by the nucleolus, travel through the rough ER, and link amino acids together to form proteins. This process is essential for the cell's ability to produce the proteins necessary for its structure and function.

💡Golgi Apparatus

The Golgi apparatus is an organelle responsible for modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles. In the video, it is described as receiving proteins from ribosomes, modifying them, and then packaging them into vesicles for export from the cell, playing a crucial role in the cell's protein production and secretion processes.

💡Cytoskeleton

The cytoskeleton is a network of protein filaments that maintain cell shape, provide structural support, and enable cell movement. The video mentions two types of cytoskeletal structures: cilia, which are short and hair-like, and flagella, which are long and whip-like. These structures are essential for cell motility, such as the movement of sperm cells.

💡Cell Wall

The cell wall is a rigid layer outside the cell membrane in plant, fungal, and bacterial cells. It provides structural support and protection. The video explains that unlike animal cells, plant cells have a cell wall made of cellulose, which is a tough and fibrous material that gives plants their structural integrity.

💡Chloroplasts

Chloroplasts are organelles found in plant cells that carry out photosynthesis, the process by which light energy is converted into chemical energy. The video describes chloroplasts as containing chlorophyll, which absorbs light and carbon dioxide to produce glucose and oxygen. Like mitochondria, chloroplasts are thought to have originated from free-living bacteria through the endosymbiosis theory.

💡Vacuoles

Vacuoles are membrane-bound organelles that store water, nutrients, waste products, and pigments. The video explains that in plant cells, the central vacuole can be quite large and push other organelles to the cell's periphery. In contrast, animal cells have smaller vacuoles scattered throughout the cytoplasm, serving similar storage functions.

Highlights

An organelle is a small part within a cell, akin to how organs are small parts within the body.

Cells have three main sections: the plasma membrane, the nucleus, and the cytoplasm.

The plasma membrane, also known as the cell membrane, regulates the entry and exit of materials.

The nucleus acts as the control center of the cell, containing DNA.

The cytoplasm is a jellylike substance within the cell where organelles float.

Cytoplasmic streaming is the movement of organelles within the cytoplasm.

The cytoplasm facilitates chemical reactions and dissolves particles like carbohydrates and proteins.

The plasma membrane is composed of a bilayer of lipids and proteins, and is selectively permeable.

The nucleus contains chromatin, which is DNA that provides instructions for protein synthesis.

The nucleolus within the nucleus is responsible for producing ribosomes.

Ribosomes, made by the nucleolus, are transported by the rough endoplasmic reticulum to make proteins.

The Golgi apparatus receives, modifies, sorts, and packages proteins for export from the cell.

Mitochondria are known as the powerhouse of the cell, generating energy through cellular respiration.

The theory of endosymbiosis suggests that mitochondria were once free-living organisms that became part of the cell.

Lysosomes contain digestive enzymes to break down food, pathogens, and even old cells through a process called autophagy.

Cilia and flagella are cell parts used for movement, with cilia being short and flagella being long and whip-like.

The cell wall is the outermost layer in plant, fungal, and bacterial cells, providing support and structure.

Chloroplasts, found in plant cells, perform photosynthesis using chlorophyll, a green chemical.

Like mitochondria, chloroplasts are thought to have evolved from free-living bacteria through endosymbiosis.

Vacuoles store food, water, waste, and color pigments, and are often the largest part in plant cells.

Transcripts

okay so in this video we're going to go

over some of the common organel of a

eukaryotic cell now an organel is simply

a word that means small part so just

like the body has small parts called

organs cells have small parts called

organel well there's a lot of them so

let's go ahead and get

started first thing I want to mention

are the three basic sections to the cell

and all cells need to take in food get

rid of waste and reproduce well cells

have three main sections to them and

inside of those three sections are parts

that allow them to take in food get rid

of waste and reproduce so the first

section you can see highlighted by the

flashing black line the plasma membrane

you might also hear the plasma membrane

simply called the cell membrane we'll

talk more about this in a little

bit pulsing in the picture you can see

the second main section the nucleus uh

you often hear the nucleus called the

control center we'll explain why in a

little

bit and lastly we have the cytoplasm now

the arrow in the picture looks like it's

kind of just pointing to empty space

well cells are not filled with empty

space they're filled with a part called

the cytoplasm we'll go into that in more

detail let's actually do the cytoplasm

first here we

go so the cytoplasm the first thing I

want to mention is that it's the

jellylike material on the inside of a

cell you know when you look at diagrams

sometimes in a diagram a cell might look

like it's empty or filled with Hollow

air Hollow air space and that's not true

cells are filled with a jellylike

liquidy material called the cytoplasm

and in that cytoplasm most organel float

within you can see here's a list of a a

few of the organel that are floating

around in the cytoplasm we're going to

go and talk about all of these

throughout this video we'll talk about

what mitochondria is what lomes

are and because the cytoplasm is a jelly

material and things are floating around

inside of it you often under a

microscope can actually see Parts

floating around in this animation here

you can see what's known as cytoplasmic

streaming the green circles that are

drifting around inside of the square

cells the rectangular shaped cells those

green circles are plant cell

chloroplasts you can see in every

rectangular shaped plant cell there's a

few dozen

chloroplasts in in each of these cells

here and this is known as cytoplasmic

streaming okay well what about the job

what does the cytoplasm actually do well

a lot of chemical reactions take place

within the cell and chemical reactions

take place in the cytoplasm so that's

kind of what the job of the cytoplasm is

it helps to facilitate chemical

reactions and it also helps to dissolve

uh solutes uh particles that are in the

cell carbohydrates proteins these are

all dissolved within the actual

cytoplasm of the cell so that's really

what the main function of the cytoplasm

is it also adds support to the cell a a

pressure a support for the

cell so the next part I want to mention

is called the plasma membrane also known

as the cell membrane and first of all

it's composition means what is it made

from it's a by layer of lipids and

proteins earlier in the school year uh

we we learned lipids lipid and this is a

drawing of a very simple lipid here the

round part represents the head two tails

are the fatty acids and what we mean by

a by layer it's not just one layer but

two layers on top of one another this is

a by layer of lipids right here in

between the by layer of lipids are also

proteins I've labeled this protein

Channel and you're going to see its

importance in a moment well the job of

the plasma membrane is to allow

materials to p uh to pass to enter and

exit you know small molecules like water

and oxygen H2O for water O2 for oxygen

small molecules like this can simply

pass through the lipid by layer however

larger molecules larger molecules like

glucose have to pass through these

protein channels and that's what you see

happening in the animation and so that's

really the job of the cell membrane but

the cell membrane is what we call

semi-permeable or selectively permeable

that means that it doesn't allow

everything in and out it only allows um

certain specific molecules and ions and

uh and and charged particles to enter or

exit through the plasma

membrane so when we come back to this

picture we saw earlier here we have the

next part I want to mention you can see

the black Square highlighting the

nucleus let's zoom on in for a closer

look when we zoom on in here we have the

nucleus and you've heard maybe in middle

school that the job of the nucleus is to

control the cell's activity you often

hear it given the nickname of the

headquarters what does that mean well

the reason we call the nucleus the

headquarters is because it contains DNA

and in the picture we see five uh

Twisted strands of what is called

chromatin chromatin are long strands of

DNA and DNA is the instructions the

blueprint the manual on how to make

proteins and this is why we call the

nucleus the control center is because

the chromatin will be sending out

information to make proteins and

proteins do a lot of the work the vast

majority of the work inside of our cells

inside of our bodies are performed by

proteins so this is why the nucleus gets

the nickname of the control

center also inside the nucleus there's a

round object known as the nucleolus and

the job of the nucleis is to make a

another part of a cell another organel

called the MIT excuse me called the

ribosome so the job of the nucleis is to

make ribosomes and we're going to see

what ribosomes do in just a

moment when we look at this picture

right here we can see a nice electron

microscope picture the overall round

object is the nucleus you can see the

dark spot is the nuclea a really nice

picture here of the nucleus and the

nucle

olis so we come back here we have the

box highlighting the rough ER and the

smooth ER let's zoom on in and take a

closer look at the endoplasmic

reticulum okay first of all there's two

kinds of er let's look at the rough ER

first the ER stands for endoplasmic

reticulum the rough ER the reason it's

called rough is that's covered in

ribosomes so we mentioned a moment ago

that the nucleolus makes ribosomes the

ribosomes then exit the nucleus and

travel along this tunnel system known as

the rough ER that's kind of the job of

the rough ER is to receive the ribosomes

and transport and carry around the

ribosomes from one part of the cell to

another as you can see we can uh we

finally see what the job of a ribosome

is protein making ribosomes so so that's

the job of a ribosome is to make a

protein so the rough ER will transport

the ribosomes as the ribosomes are

making a

protein well if we look at this picture

here we have the purple nucleus identify

part A in the nucleus I hope you know

that's the

nucleis the the the lines the purple

lines identified by letter B that's the

DNA I hope you remember the name of the

DNA that's called chromatin and then the

outside of the nucleus in picture C I

never mentioned the name earlier but

that's called the nuclear envelope

notice how the blue is the rough ER and

there's gray dots all over it well look

in the animation you see gray dots

exiting the nucleolus in the animation

and those gray dots are traveling

through the blue rough ER that means

those gray dots have to be the ribosomes

the job of ribosomes are to make

proteins we're going to go into more on

that in just a few moments

so what about the smooth ER well if the

rough ER is covered in ribosomes then a

little Common Sense the smooth ER is not

covered in ribosomes and you can see it

has a different job the job of the

smooth ER is to help make lipids and

fats and to help break down certain

toxins but the reason it gets its name

smooth ER is it's not covered in

ribosomes the rough ER is covered in

ribosomes and that's why it kind of has

a rough appearance to

it so let's talk a few moment a few

extra moments about those things called

ribosomes they're created by the nucleis

remember the nucleis is inside the

nucleus they're transported the

ribosomes are transported by the rough

ER and as the ribosomes are being

transported by the rough ER we now come

to their job their Duty their function

is to make proteins

and so if we highlight a few a few

ribosomes with that flashing Black Box

let's zoom on

into a ribosome that's attached to the

Ruff well here we have a ribosome and

the reason what what I mentioned a

moment ago is its job is to make a

protein and what it does is it will

gather individual amino acids and

earlier in the school year I hope you

learn you remember that amino acids are

the building blocks of protein

and so here we see a ribosome is

gathering and connecting a bunch of

amino acids into a long chain this long

chain of amino acids is what we call a

protein and that's the job of a ribosome

is to gather and build these amino acids

into a larger protein this process by

the way is known as translation we're

going to learn about it later in the

school year

though so if we come back back out here

to our diagram I've highlighted the

flashing box of the GOI body let's zoom

on in to the GOI body you might often

hear it called the GGI apparatus or the

GGI complex it's always going to be

called GOI because it's named after the

scientists with the last name of GOI who

discovered it and so the job of the GOI

body is to receive proteins that

ribosomes made receive proteins from

that ribosomes made modify them sort

them and package them so they can be

exported from the cell and the GOI body

will put the proteins into a protective

little envelope known as a vesicle and

so let's go ahead and review what we've

learned really

quick when we look at the process of

shipping out of protein in our animation

we can see the nucleolus is releasing a

black dot that black dot represents RI a

ribosome so the nucleis makes a ribosome

notice that ribosome then travels

through that rough ER that system of T

tubes and tunnels so the ribosome is

traveling through the rough ER making a

protein let's zoom on in for a closer

look so there's the

ribosome okay now that we can see the

ribosome remember what the job of a

ribosome is it it makes a protein and so

there you see the word protein now it's

spelled p r o t i n but it's not really

put together properly so this protein is

not quite finished even though the

ribosome made it well Watch What Happens

Next remember this is all happening at

the rough ER the protein is going to be

placed inside a of a protective vesicle

and travel away where is it going I hope

you know where it's

going it's going to a GGI body and so

the protein arrives at the gii body what

happens to the vesicle the vesicle fuses

and becomes a part of the gii body

well Watch What Happens the protein

moves through the gii body and is

eventually processed and modified and

ultimately is going to be released so

the GOI body kind of makes the final

changes to the protein well when the GOI

body releases the protein it also will

put it in a protective vesicle so the

vesicle is going to be a protective

little envelope watch this the protein

is put into a protective vesicle and

it's released the vesicle fuses with the

cell membrane and then the protein is

simply released from the cell goes where

it's

needed all right so if we were in class

I would have you turn to your neighbor

and try to work on these review

questions so we've kind of covered a lot

of information let's take a quick moment

you know pause the video pause the video

try to answer these seven questions I'm

going to go over the answers in three 2

one so which organel builds proteins I

hope you know that a ribosome which

organel stores DNA well that's the

that's the control center called the

nucleus which organel produces ribosomes

that's the nucleolus it's found inside

the

nucleus which organel creates fats and

breaks down toxins well that's the

smooth ER which organel number five

packages and releases proteins from a

cell that's the goldi body remember

they're put inside of a protective

vesicle number six which organel allows

material to enter and exit a cell that's

the cell membrane also called the plasma

membrane number seven which organel

links chains of amino acids together

that's the same thing as question number

one question number one and question

number seven it's the same question just

worded a little differently because

amino acids make proteins let's try this

one same thing in class I would have you

work on this with a neighbor for a

minute but pause the video try to put

these four step steps in order what

comes first second third fourth I'm

going to show the answer in 3 2 1

okay so the answer is I hope you chose

step C first the nucleolus makes

ribosomes and then I hope you chose D

ribosomes will exit the nucleus and then

I hope you chose B the ribosomes are

going to travel along the rough ER and

create proteins and then finally I hope

you chose a the gold body will package

and Export the finished protein inside

of a protective vesicle let's move

on so now we're back to our diagram and

I've highlighted the flashing box the

mitochondria let's zoom on in for a

closer look here we have the

mitochondria artist drawing on top

actual picture on the bottom and so the

job of the mitochondria you know in

middle school they give cute little

nicknames to cell parts in Middle School

you may have been told this is the

PowerHouse but you may never have told

why well it's the PowerHouse because its

job is to make an energy molecule by the

name of a Denine

triphosphate ATP so the mitochondria

does a very important process known as

cellular respiration and during the

process of cellular respiration it will

create an an energy molecule by the name

of ATP ATP is a molecule used by your

cells for energy so the analogy is the

mitochondria is kind of like the battery

of your cell

cells what's interesting about the

mitochondria is we're pretty certain the

mitochondria used to be a living

organism it used to be a basically a

bacteria cell but it has become part of

today's modern cells and this theory of

of how we think this happened is called

endosymbiosis I'll go over in more

detail in just a

moment well when we look at some of the

evidence for why we think the

mitochondria used to be its own living

organism is because it has its own DNA

it has its own ribosomes because it has

its own ribosomes it can manufacture its

own proteins and the mitochondria does

something very important to life the

mitochondria can reproduce and replicate

so when you look at this evidence it's

pretty C we're pretty certain the

mitochondria used to be a free living

organism a bacteria species but it's

become part of cells how did that happen

that's what endosymbiosis tries to

explain I hope I can visualize that on

the next

slide okay so I really want to try to

visualize the endosymbiosis Theory here

we have a large Predator cell in Orange

and it's going to devour that red

mitochondria ancestor Watch the watch

this so there it goes it just devoured

the mitochondria ancestor but the way we

think it were it happened is that red

mitochondria survived and divided and

multiplied it's just trapped inside of

the large Predator cell well as the two

go about their lives the large Predator

cell Al eventually is going to multiply

and divide as well and watch this when

cells divide they often grow and then

they split right down the middle and now

you have two Cells Two cells with the

mitochondria ancestors trapped inside of

them and then the process simply

continues so the the mitochondria

ancestors keep multiplying and then the

orange Predator cell divides in half and

over time over millions and millions of

years the two have become so dependent

on one another that they can't survive

without them so this is kind of what the

uh what the Endo symbiosis Theory uh it

tries to explain is how cells became

more complex how did we obtain certain

cell parts and this is the explanation

for how we think the mitochondria was

obtained

okay let's zoom on in Let's uh focus on

the lomes back in our diagram here and

let's zoom on in for a closer look at

the

lomes and so the lomes contain inside of

them very powerful digestive enzymes and

that's what my little animated scissors

here are showing so the blue circle is

the lome with the animated scissors

representing the enzymes

inside and so lomes have various jobs

number one is to break break down food

so here we have a protein molecule

that's being taken into the cell and the

protein is being broken down into

smaller parts I hope you know those

smaller parts are called amino

acids here we have an example of a white

blood cell you probably know white blood

cell's job is to fight off infections

like bacteria and viruses well that's

what we call pathogens things that cause

disease are called pathogens and so here

is a virus or a bacteria and and notice

how it just landed on a white blood cell

well what happens is the white blood

cell will swallow up that pathogen put

it inside of a lome and those powerful

digestive enzymes will destroy it so

that's one way that our immune system

Keeps Us

healthy and then there's the process

called autois where uh it's basically um

an aging cell will destroy itself and so

in our in the middle of our picture here

we have a group of cells and I have the

animated Scissors because what happens

is when cells are dying and aging they

will kind of self-destruct in a process

called autois where the lomes will

release all the digestive enzymes and

kill that cell it leaves behind a gap

but don't worry that Gap will simply be

filled in as cells multiply so you've

heard the expression out with the old in

with the new

another a couple other cell parts I want

to mention are used in movement and

that's the job of cyia and fella now not

all cells move so not all cells have

cyia and fagella but if cells move they

probably have either cyia or

fella so the picture on the left shows

the cyia short hairlike extensions

there's numerous hundreds and thousands

of them per cell way too many to count

very short stubby almost look like

eyelash ashes they're so short and

stubby the picture on the right shows a

sperm cell with a real long fella fella

is actually the plural version fum is

singular and so the difference is really

their length the cyia short stubby fella

are long and whip-like and usually

there's only a few of them maybe only

one flagellum maybe two maybe three

maybe four but not nearly as many as the

cyia

well in that picture on the right we

have a sperm cell about to penetrate a

female egg cell to create a fertilized

egg also known as a zygote let's have a

little fun with

this so after the fertili after the

sperm fertilizes the egg that fertilized

egg is going to grow into a fetus here

we have a nice little ultrasound showing

a child growing inside of a pregnant

woman well eventually 9 months later

that child's going to be born well let's

follow the life of this

child 17 years go by 17 years later hey

it's your first day at high school and

so here you go welcome to high

school and hopefully four years after

that you know you'll be celebrating your

graduation from high school so this all

started because of that flagella that

provided the swimming movement to

fertilize an egg

so we look at the next part I want to

mention is the cell wall and so this is

the outermost layer of plants fungus and

bacteria cells so from left to right we

have plants fungi and bacteria notice

animals like humans do not have a cell

wall well we also mentioned that the

cell wall is the outermost layer so when

we look at this picture we have a yellow

layer and a Green Layer so I hope you

know that yellow layer represents the

plasma membrane or the cell membrane and

the definition in the definition we see

that the outermost layer is the cell

wall so that's represented by the Green

Layer what about its job one of the jobs

of the cell wall is to add support it's

made from a real tough sturdy material

known as cellulose and so this adds some

of the support to plants and fungus and

bacteria cells that have

and so as I just mentioned the cell wall

is made from a real tough material by

the name of cellulose it's very hard to

digest the reason for the picture is

celery has a lot of cellulose in it and

I'm sure you've had bites of celery it's

a very tough very fibrous plant very

hard to digest well that's because

you're having to chew through a lot of

cellulose which is a main ingredient of

the cell

wall and the cell wall really started

our understanding of cells earlier in

another video we learned that Robert

Hook in 1665 again there's there's no

real good pictures of Robert Hook so

here we just have a a glass stained

glass picture in a cathedral Robert Hook

in 1665 examined

Cork and so he used a very primitive

microscope like this one in this picture

here and as I mentioned a moment ago he

examined cork now cork we might be

familiar with cork from you know wine

bottles

but cork is actually tree bark and he

examined a real thin slice of tree bark

called Cork and this is what he

saw in this picture

here is a drawing that he made it's kind

of shocking to believe that this picture

right here is a drawing made by hand but

that's how good of an artist he was and

what you see are hundreds of little tiny

cells but the outline of the cell is all

that's left he did a drawing of the cell

w there was no nucleus Cork and tree

bark is dead there was no nucleus when

he made the drawing there were no

mitochondria no vacul all that's left

and all you can see in the picture is

the drawing of the cell wall the cell

wall is very tough very strong and can

last for years and years after the cells

have

died so uh the next part I want to

mention is called the chloroplasts and

so you might might know the job of the

chloroplast is is to perform

photosynthesis well here are several

dozen plant cells taken with a

microscope let's zoom on in for a closer

look when we zoom on in we can see that

inside of every cell are dozens of those

green round shaped objects called

chloroplasts they're inside every single

cell there's dozens of them per

cell so you know that the job of the

chloroplast is to perform photosynthesis

well inside of the chloroplast is a

chemical A green chemical by the name of

chlorophyll the job of chlorophyll is to

actually perform photosynthesis it will

absorb sunlight absorb carbon dioxide

absorb water and turn those into oxygen

and sugar particularly in the form of

glucose so what photosynthesis does is

it uses three ingredients

water carbon dioxide sunlight and will

release two products oxygen and sugar

sugar called

glucose just like the mitochondria the

chloroplast is thought to have evolved

according and become a cell part

according to the endosymbiosis Theory we

think the chloroplast was also a free

living organism a bacteria in our

animation here we have a pred ether cell

devouring the chloroplast but not really

being digested that chloroplast ancestor

in green multiplies just like we saw a

moment ago with the mitochondria

ancestors and notice how the two are

just living together the green

chloroplast ancestors are just trapped

inside of the larger one well as time

goes by the larger cell divides and

splits into two and as years and go by

these two have become so dependent on

one another that they are now a part of

each other and the evidence to support

this is again the the chloroplasts just

like the mitochondria have their own DNA

and ribosomes they make their own

proteins they can replicate and multiply

and divide these are all real strong

indicators that the chloroplasts were

probably once a free living organism all

by itself but has become taken into the

cell and become part of mod

cells so the final one the last part I

want to mention is called the vacu the

job of the vacu is to store food store

Water waste color pigments and in the

picture here you can see it's the big

blue round object in the middle of the

cell often in plants that is it's often

the largest part of a plant

cell so in Plants it's often the largest

Central meaning in the middle so we

often think of the nucleus being in the

middle of a cell often the vacu is

because it's so big it pushes all the

other parts to the

edges when we look at this little

animation right here again I mentioned

cytoplasm ex streaming earlier here the

green circles represent chloroplasts but

they're all kind of revolving around the

Central vacu and so the central vacu is

often so big it will put the other

organel to the edge of the

cell so in Plants there tends to be a

large Central vacle but it's not like

that with animal cells here's a diagram

a drawing of animal cell of an animal

cell and the vacu are much smaller and

they're usually randomly scattered

throughout the cytoplasm but they still

serve the same purpose they still store

food store water store waste and so

that's really the job of the vacuo right

there well so there you have it I mean

there's a lot of cell parts that we

covered in this video here so try and

pause the video and work through these

questions if you're in my biology class

bring your answers to on a separate

sheet of paper I'd be happy to check

your accuracy either before school or

after school good luck