ALL OF BIOLOGY explained in 17 Minutes
Summary
TLDRThis script takes a fascinating journey through the origins of Earth and the fundamentals of biology. It explains the transformation from a fiery ball to a habitable planet, the emergence of life from hydrothermal vents, and the basic building blocks of life, including cells, enzymes, and genetic material. It delves into the complexity of genetics, the process of evolution, and the human body's intricate systems, highlighting the importance of understanding our biological makeup.
Takeaways
- đ The Earth began as a ball of flaming rocks bombarded by space debris, which contributed water that turned into steam as the planet cooled.
- đ§ Hydrothermal vents played a crucial role in early Earth, providing heat and chemicals necessary for the emergence of life's building blocks.
- đŹ Biology is essentially chemistry in action, with life forms being complex arrangements of molecules capable of metabolism, growth, reproduction, and response to stimuli.
- đż Enzymes are special proteins that act as catalysts to speed up chemical reactions, essential for life processes.
- đŹ Eukaryotic and prokaryotic cells differ in their structure, with eukaryotes having membrane-bound organelles and prokaryotes lacking these features.
- đŹ The classification of life forms into kingdoms is based on taxonomic ranks that reflect the relationships among different species.
- đŹ Homeostasis is the process by which organisms maintain stable internal conditions, essential for the proper functioning of enzymes and cellular processes.
- đ° The cell membrane's selective permeability allows for the regulation of what enters and exits the cell, maintaining necessary chemical balances.
- đ ATP, or Adenosine Triphosphate, is the energy currency of the cell, derived from the chemical bonds between phosphate groups.
- đ± Plants, as autotrophs, produce their own glucose through photosynthesis, while humans, as heterotrophs, consume food to obtain glucose.
- 𧏠DNA stores genetic information through the sequence of its nitrogenous bases, which is transcribed into RNA and then translated into proteins.
Q & A
How did the Earth initially form according to the script?
-The Earth initially formed as a big ball of flaming rocks about 4.5 billion years ago, constantly bombarded by more rocks from space, which likely contained water that turned into steam.
What is the role of hydrothermal vents in the early Earth?
-Hydrothermal vents played a significant role as they were piping hot and filled with chemicals that could create interesting substances, contributing to the early chemical processes on Earth.
What is the basic unit of life according to the script?
-The basic unit of life is the cell, which can be classified into two main categories: Eukaryotes and Prokaryotes.
How do Eukaryotes and Prokaryotes differ in terms of their cellular structure?
-Eukaryotes have organelles bound by membranes, including a nucleus containing DNA, while Prokaryotes lack these organelles and have DNA that floats freely within the cell.
What is the function of enzymes in living organisms?
-Enzymes are special proteins that act as catalysts to speed up chemical reactions by breaking down or combining specific substances, enabling life processes to occur more efficiently.
How does the cell maintain homeostasis?
-Cells maintain homeostasis by keeping certain conditions, such as pH levels and chemical concentrations, in check to ensure that enzymes and other cellular processes function properly.
What is the role of the cell membrane in maintaining the cell's internal environment?
-The cell membrane, being a semipermeable phospholipid bilayer, controls what substances enter and exit the cell, allowing small molecules to pass through while requiring larger particles like ions to use specific channels.
What is the process by which cells balance out gradients known as?
-The process by which cells balance out gradients is known as 'diffusion,' which can occur passively or actively with the use of energy from ATP.
How do plants produce their own glucose?
-Plants produce their own glucose through a process called photosynthesis, where chlorophyll in chloroplasts absorbs light energy to split water and carbon dioxide into glucose and oxygen.
What is the genetic material of an organism and how is it replicated?
-The genetic material of an organism is DNA, which consists of two strands of nucleotides. It is replicated when an enzyme called DNA polymerase synthesizes a new strand using each original strand as a template.
What is the process of transcription and translation in genetics?
-Transcription is the process where the information in a gene is copied onto mRNA. Translation is the process where the mRNA is used to build proteins by assembling a chain of amino acids, with the help of ribosomes and tRNA.
How do mutations in DNA affect organisms and can they be beneficial?
-Mutations in DNA can change the protein coded by a gene, potentially affecting the organism's traits. While many mutations are neutral or harmful, some can be beneficial, leading to increased fitness and natural selection.
What is the difference between bacteria and viruses?
-Bacteria are prokaryotic single-cell organisms that can reproduce on their own and are treated with antibiotics. Viruses are non-cellular entities that require a host to reproduce and cannot be treated with antibiotics, relying on the host's immune system.
How do neurons transmit signals in the nervous system?
-Neurons transmit signals as electrical impulses called action potentials, which travel along the axon. These signals can be modulated in strength and frequency to convey different types of information to the brain.
What is the function of neurotransmitters in the nervous system?
-Neurotransmitters are signaling molecules that dock onto ion channels on the axon, causing ions to flow and change the electric potential, which can either block or trigger further action potentials in the connected neuron.
Outlines
đ Earth's Formation and Early Biology
This paragraph delves into the origins of Earth, starting as a fiery mass bombarded by space rocks that contributed to the planet's water through steam. It highlights the cooling process that led to Earth's first rain and subsequent flooding, creating environments like hydrothermal vents. The script introduces the concept of biology as chemistry in action, with a focus on the molecular composition of living beings, including carbohydrates, lipids, proteins, and nucleic acids. Enzymes are described as biological catalysts that facilitate life-sustaining chemical reactions. The distinction between living organisms and non-living matter is explored, emphasizing the characteristics that define life, such as metabolism, growth, reproduction, and response to stimuli. The paragraph concludes with a discussion on the cellular structure of life, differentiating between eukaryotes and prokaryotes, and introduces the taxonomic classification of organisms.
𧏠DNA, Genetics, and Cellular Life
The second paragraph explores the intricacies of DNA, the genetic material that carries the code for life. It explains the structure of DNA, including its four nucleotide bases and how they pair up through hydrogen bonds. The concept of genes as sections of DNA that code for specific traits is introduced, along with the role of proteins in performing various biological functions. The paragraph discusses the process of transcription, where DNA information is copied into mRNA, and translation, where this information is used to build proteins. It also touches on the vastness of the human genome, the presence of non-coding DNA, and the idea of genetic dominance and recessiveness in determining traits. The discussion on cell division includes mitosis for growth and repair, and meiosis for gamete production, highlighting the importance of genetic diversity and the formation of zygotes.
đŹ Cellular Functions and Genetic Inheritance
This section delves deeper into the mechanisms of cellular function and genetic inheritance. It starts by explaining the cell cycle, including interphase and the various checkpoints that ensure cellular health. The paragraph discusses apoptosis as a self-destruction mechanism for unhealthy cells and introduces the concept of cancer as uncontrolled cell replication due to gene mutations. Mutations are further explored as potential drivers of evolution, with both negative and positive outcomes for species survival. The distinction between bacteria and viruses is clarified, with an emphasis on their different treatment methods. The paragraph also examines the symbiotic relationship between humans and beneficial gut bacteria, and concludes with an overview of the human body's complex organ systems, particularly the nervous system, and how electrical signals are transmitted through neurons.
đ Neurotransmission and Educational Resources
The final paragraph focuses on the process of neurotransmission, detailing how neurons communicate through electrical signals and neurotransmitters. It describes the resting state of a neuron, the initiation of action potentials, and the propagation of these signals along the axon. The role of the myelin sheath in speeding up signal transmission is highlighted, as well as the synaptic cleft and the release of neurotransmitters for inter-neuronal communication. The paragraph concludes with a promotional mention of Brilliant, an educational platform offering interactive lessons in various subjects, including math and its applications in biology. The offer includes a free trial period and a discount on an annual premium subscription for viewers interested in enhancing their scientific understanding.
Mindmap
Keywords
đĄBiology
đĄEnzymes
đĄEukaryotes
đĄProkaryotes
đĄHomeostasis
đĄCell Membrane
đĄATP (Adenosine Triphosphate)
đĄPhotosynthesis
đĄDNA (Deoxyribonucleic Acid)
đĄRNA (Ribonucleic Acid)
đĄMutation
đĄNatural Selection
đĄNervous System
đĄNeurons
Highlights
Earth's formation began 4.5 billion years ago as a ball of flaming rocks, with water-bearing rocks contributing to early steam.
The emergence of hydrothermal vents during Earth's cooling phase created environments rich in chemicals, crucial for early biological processes.
Biology is essentially chemistry, with organisms being complex molecules capable of metabolism, growth, reproduction, and environmental response.
Enzymes, as biological catalysts, are essential for speeding up life-sustaining chemical reactions by breaking down or combining specific substances.
Life is differentiated from non-living matter by its ability to metabolize energy, grow, reproduce, and maintain homeostasis.
Cells, the basic units of life, are categorized into Eukaryotes with membrane-bound organelles and Prokaryotes lacking such organelles.
Eukaryotes form complex organisms like animals and plants, while Prokaryotes are limited to single-celled life forms.
Taxonomic ranks, such as 'kingdoms,' classify and relate different species based on shared characteristics.
Each species has a unique scientific name composed of genus and species, aiding in precise identification.
Homeostasis is vital for life, maintaining stable internal conditions for enzymes and cellular functions.
The cell membrane's phospholipid bilayer selectively controls the passage of molecules, maintaining internal balance.
Diffusion and active transport are mechanisms by which cells manage the movement of molecules across the cell membrane.
ATP, derived from glucose through cellular respiration, is the energy currency for biological processes.
Plants, as autotrophs, perform photosynthesis to convert light energy into chemical energy stored in glucose.
DNA, composed of nucleotides, carries genetic information through base pairs of Adenine-Thymine and Cytosine-Guanine.
Genes, sections of DNA, code for traits by specifying sequences of amino acids in proteins through the process of transcription and translation.
RNA plays a crucial role in protein synthesis, transferring genetic information from DNA to ribosomes for translation.
Mutations, alterations in DNA sequences, can lead to changes in protein structure and function, potentially impacting an organism's survival and evolution.
Natural selection favors beneficial mutations, driving evolution as better-adapted species pass on advantageous traits.
The human body's complex organ systems work in concert to maintain life, with the nervous system facilitating rapid communication through electrical signals.
Neurons transmit information via action potentials, which are electrical signals modulated by ion flow across the neuron's membrane.
The myelin sheath in some neurons accelerates signal transmission, contributing to faster and more efficient nervous system responses.
Neurotransmitters are key in intercellular communication, bridging the gap between neurons and modulating subsequent neuronal activity.
Transcripts
Hi. Youâre on a rock, floating in space. Have did we get here?Â
Well, about 4.5 billion years ago, the earth was big ball of flaming rocks, constantly Â
bombarded by even more rocks from space. Fun fact! Those rocks probably had some water Â
inside them, which has now turned into steam. Breaking news! The earth is cooling down. Oh yeah, Â
did I mention tha- [itâs raining.] Whoops, everythingâs flooded, but hey, Â
at least thereâs some cool stuff at the bottom, like hydrothermal vents, which are piping hot Â
and filled with a bunch of chemicals, that can make some very interesting stuff. Wait a minute, Â
what the heck is going on here? [Biology]Â
Biology is the study of life, but really, itâs just chemistry in disguise. I mean Â
you and I are basically just a big ball of molecules that can make funny sounds.Â
Carbohydrates give you quick energy, lipids store long term energy and make membranes, proteins make Â
up tissues and nucleic acids make DNA. Also, to make all the chemical reactions possible, living Â
beings, have inside of them a bunch of enzymes. Theyâre special proteins that act as catalysts, Â
which just means they help chemical reactions speed up by either breaking down or combining Â
one specific thing. For example, lactase breaks down lactose, the sugar found in milk.Â
Ok, so enzymes make life possible by speeding up chemical reactions, Â
but what even isâŠlife? Scientists donât really seem to agree, but obviously a cat is different Â
from a rock. The cat can produce energy by metabolizing food, it can grow and develop, Â
reproduce, and it responds to the environment, whereas the rock does not.Â
Also, unlike rocks, every living thing on earth is made of cells, of which thereâs Â
two main categories: Eukaryotes and prokaryotes. Eukaryotes have fancy organelles which are bound Â
by membranes, like the nucleus, inside of which is DNA. Prokaryotes, have none of those organelles, Â
and the DNA is just kind of chilling there, like freely floating around.Â
This is why Prokaryotes are just single cell organisms like bacteria Â
and archea whereas eukaryotes can form complex organisms like protists, fungi, Â
plants and animals. These are whatâs known as âkingdomsâ, which is a taxonomic rank, Â
so basically, how we classify different living things and how theyâre related to one another.Â
Because there are quite a few species of life on this planet, and naming them cat, Â
dangerous cat and water cat wouldnât really be all that helpful, we also give every species Â
a unique and unambiguous scientific name consisting of the genus and the species.Â
One thing every species has in common is homeostasis, aka, Â
keeping certain conditions in check, so ya donât die. If you feel warm, your body will sweat, Â
if youâre cold, your body will shiver. A cell does kind of the same thing just Â
that it balances out concentrations of certain chemicals. You see, enzymes for example, only Â
work in a very specific environment, letâs say at some specific pH value. If this changes too much, Â
the enzymes will denature and wonât work anymore. To counter this, the cell needs to constantly keep Â
up this specific pH value, which is controlled by the concentration of acid and base molecules.Â
Ok. But like, how does the cell do that? The secret lies in the cell membrane. You see, Â
itâs a semipermeable phospholipid bilayer, okay thatâs way too many words, all it is, Â
is two layers of these funky looking molecules with a polar head and a nonpolar tail.Â
This allows small molecules like water and oxygen to slip right through, Â
whereas larger particles like ions need special channels that can be opened or closed, which Â
gives the cell control of what goes in and out. Naturally, particles move with the gradient, Â
so from a place of high concentration to a place of low concentration. Or, Â
in the case of water, it can also move to a place of high solute concentration, so for example salt.Â
Welcome to Biology Pro Tips Season 1, tip of the day: do not drink too much saltwater. Â
Thereâs a bunch of salt in saltwater, in fact, more salt than inside of a cell, Â
which means it will draw water from your cells and dehydrate you. Yeah thatâs it have a great day.Â
The process of balancing out gradients is known as âdiffusionâ and happens automatically, but, Â
by using a little bit of energy, particles can actively be moved against the gradient.Â
The energy comes from Adenosine Triphosphate or ATP. To be exact, Â
the highly energetic chemical bonds between the phosphate groups can be broken to obtain energy.Â
This is kind of important, as in, every organism and every cell Â
needs to make ATP for example, through cellular respiration which happens in the mitochondria:Â
Together with oxygen, glucose, so sugar, is turned into water, carbon dioxide and ATP.Â
This is nice, but it only works if you already have glucose. Humans are âheterotrophsâ. They Â
eat food, inside of which is sugar, which is then broken down into glucose.Â
Plants on the other hand are âautotrophsâ. Simply put, they said âscrew food, Iâll just Â
make my own glucose by staring at the sunâ. You see, plant cells have small organelles called Â
âchloroplastsâ inside of which is chlorophyll, which absorbs red and blue light but reflects Â
green light, which is why most plants look green. The absorbed energy from light is used to split Â
water and make a special form of carbon dioxide which can then be turned into glucose and oxygen. Â
Okay quick recap, once you have glucose, either from food or photosynthesis, you can do cellular Â
respiration, to get energy in the form of ATP. Chemically, ATP is whatâs known as a nucleotide. Â
It has a phosphate group, a five carbon sugar and a nitrogenous base. You know what else is made of Â
nucleotides? Deoxyribonucleic acid, or DNA. It consists of two strands of nucleotides, Â
with the sugar and phosphate groups, but the actually important part is the nitrogenous base, Â
which comes in four flavours: Adenine, Thymine, Cytosine and Guanine.Â
These bases can form base pairs through hydrogen bonds, where Adenine goes with Thymine, Â
and Cytosine goes with Guanine. These bonds are what holds the two strands of DNA together.Â
Okay, but, how the heck does that store genetic information? Iâm glad you ask!Â
A âgeneâ is a section of this DNA that codes for a special trait, Â
by carrying a certain sequence of base pairs, which is like a recipe for making a protein.Â
Why proteins? Because theyâre like really important, they transport molecules, Â
act as enzymes and determine the way you look. For example, the difference between brown and Â
blue eyes is the amount of a pigment called âmelaninâ in the cells of the iris. The OCA2 Â
Gene codes for âP-Proteinâ which we believe controls the amount of melanin in cells, Â
meaning that the proteins made from this gene, could be what determines your eye colour.Â
Cool! Thereâs just one issue: Your DNA and its information is in the nucleus, Â
but proteins are made in organelles called the ribosomes. How do we get the Â
information from A to B? The answer is RNA. Itâs kind of like DNA, just that itâs most Â
often a single strand, it uses a ribose instead of deoxyribose and instead of Thymine it uses Uracil, Â
which makes it less stable, but thatâs besides the point, hereâs what RNA actually does:Â
Letâs say you want to make the protein coded for by this gene. An enzyme called Â
âRNA polymeraseâ will split the DNA and make a strand of RNA with the complementary bases, Â
essentially copying the information from the DNA to the RNA. This is called âtranscriptionâ.Â
The new strand is called messenger RNA or mRNA, because it carries this Â
message out of the nucleus to a ribosome. Remember how I said that a gene is like a Â
recipe for a protein? Well, on the mRNA, which carries the same base sequence as that gene, Â
every group of three bases, which is called a âcodonâ, codes for a specific amino acid, Â
which are the building blocks for proteins. Welcome to Biology Pro Tips Season 1, if you want Â
to decode a sequence of RNA, there is actually a chart for that! Yeah thatâs all have a great day.Â
These amino acids are carried by special molecules called transfer RNA or tRNA, Â
which have a unique anticodon that can only attach to its matching codon on the mRNA.Â
The job of the ribosome is to read over codons on the mRNA and attach the matching tRNA molecules, Â
which then leave behind their amino acid. As the ribosome moves along the mRNA and attaches more Â
tRNA, which happens a couple thousand times, the amino acids combine into a âpolypeptide chainâ, Â
which is just a really long chain of amino acids, that can be bunched up, Â
creased, smacked and folded into a protein. Okay, letâs recap: A gene is copied onto mRNA, Â
which is then used to build proteins by assembling a chain of amino acids. Â
Aka transcription and translation. Hey, this genetics stuff is pretty Â
cool, can we learn more? Absolutely. Oh yeah did I mention that you have, like, Â
a bunch of DNA? You have about 20000 protein coding genes, each thousands to millions of Â
bases long, and that only makes up around 1% of your entire DNA, the rest is just non-coding.Â
PLUS, almost every cell in your body contains your entire genetic code, but genes can be turned on or Â
off depending on the cell, which is good, because otherwise your brain cells might just start Â
making stomach acid, which would not be good. FUN FACT! If you were to stretch out all the Â
DNA of just one single cell, it would be about 2 meters long.Â
Wait a minute, how does that fit into a microscopic cell? Well, if you were to look inside Â
the nucleus, you wouldnât find the DNA floating around like this or even this, no, you would Â
actually find lots of these worm looking things. To be exact, DNA is coiled up around Proteins Â
called âHistonesâ, which are then condensed into strands of Chromatin, which are then coiled up Â
even more to make tightly packed units of DNA called âChromosomesâ, which kinda look like Â
worms. Different sections on a chromosome carry different genes, and the entire human genome is Â
split amongst 23 different chromosomes, although every body cell has 2 copies of every chromosome, Â
one from the mother and one from the father. For most chromosomes, the two copies are Â
said to be homologous, meaning that they carry the same genes in the same location. However, Â
the two versions of a gene can be different, so the motherâs gene could code for brown eyes, Â
while the fatherâs gene codes for blue eyes. These different versions of a gene are called âallelesâ.Â
For most of your genes, you have 2 alleles, one on each chromosome from either parent. These alleles Â
can be dominant or recessive, which determines which of them is expressed. For example, Â
brown eye color is a dominant trait, which is shown by an uppercase B, whereas blue Â
is recessive, which is shown by a lowercase b. All this means, is that if you have the dominant Â
brown allele, you will have brown eyes, no matter what the second allele is. Only when there are Â
two recessive alleles will it be expressed. With this knowledge, we can predict the future!Â
Letâs look at how this trait is inherited from parents to children:Â
Both of these parents have brown eyes, but also have a recessive blue allele in their Â
genotype. Every child receives one allele from each parent randomly, so these are the Â
possible combinations for the children. Most combinations contain the dominant Â
brown allele, so the child will have brown eyes. But, there is a small chance that a child gets Â
two recessive alleles and has blue eyes, even though both parents had brown eyes! You see, Â
itâs whatâs on the inside that counts. Alright, thatâs cool, but reality is not always Â
so simple. Some genes are not fully dominant, but not fully recessive either, which means that the Â
phenotype, so the appearance, appears to mix. Crossing a red and a white snapdragon, where Â
red is âdominantâ and white is ârecessiveâ gives you a pink phenotype which is somewhere inbetween, Â
aka intermediate inheritance. Or, crossing a brown and a white cow where both colours Â
are dominant could give you spotted cow, so both phenotypes are expressed equally, aka codominance.Â
Hey remember how I said almost all chromosomes are homologous? Well, Â
thereâs one exception: the sex chromosomes. Females have two big X chromosomes, whereas Â
males have one X and one smaller Y chromosome. These are partially homologous at the top, Â
but since the Y chromosome is so small, itâs missing genes that are present Â
on the lower part of the X chromosome. These genes are called âX-linked genesâ.Â
If one of these genes is a recessive trait like colour blindness, males are stuck with that trait, Â
whereas females probably have another dominant allele, to override it. This Â
is why most colourblind people are male. Now, for genes to even be passed on, Â
the body has to make new cells which can inherit the genes. Thereâs two main mechanisms:Â
Mitosis, which is how the body makes identical copies of body cells to grow and repair tissues, Â
and Meiosis, which is how the body makes gametes, so sperm and egg cells.Â
Mitosis starts with a diploid cell, so a cell with two sets of chromosomes. These chromosomes consist Â
of one chromatid, which has to be replicated for the new cell. After replication is when Â
you see the familiar X shape consisting of two identical sister chromatids. These are Â
split into two identical diploid cells, with two sets of chromosomes consisting of one chromatid.Â
Meiosis also starts with a diploid cell, but after replication, the chromosomes comingle Â
and exchange genetic information in a process called âcrossing overâ. The cell is then split Â
into two non-identical haploid cells. These have one set of chromosomes, but they still Â
consist of 2 sister chromatids. These cells split again into 4 genetically different haploid cells, Â
where each chromosomes has one chromatid. Meiosis produces haploid cells, so that when two Â
gametes combine into a fertilized egg or âzygoteâ, it again has the correct number of chromosomes.Â
This is cool, but, cell division is only a tiny part of a cellâs entire life cycle. Most of its Â
time is actually spent in interphase, aka just chilling. All it does here, is grow and replicate Â
all of its DNA, so that it actually has enough genetic material and size to divide in M-Phase.Â
Thereâs multiple checkpoints in the cell cycle which are controlled by proteins Â
like p53 or cyclin to check if the cell is healthy and ready to reproduce. If a cell Â
is not quite right, itâs either fixed or it destroys itself, which is called Â
âapoptosisââŠor at least, thatâs what it should do. Normal cells replicate until thereâs no need to, Â
but some cells just keep going. This is because they donât respond correctly to these checkpoints Â
and end up replicating out of control and functioning wrong, which is also known as cancer.Â
This damaging behaviour is often a result of a gene mutation, which is a change somewhere in the Â
base sequence of a gene. This can happen during DNA replication, when a single base is changed, Â
left out or inserted into the original sequence. This often changes the protein coded for by that Â
gene and letâs just say that change is often not optimal.Â
Another type of mutation happens in chromosomes, where entire sections of DNA could be duplicated, Â
deleted, flipped around or transferred between chromosomes. The most famous chromosomal mutation Â
is probably when the 21st pair of chromosomes has an additional copy, so that thereâs 3 Â
instead of 2. The result? Down syndrome. Mutations might seem like a bad thing, Â
but actually, they can also be neutral or even beneficial. For example, Â
a species of yellow grasshoppers might mutate and become green, which makes them Â
blend in with the grass and get eaten less. Over time, you can expect to see more and Â
more green grasshoppers, as their fitness has increased. Not that kind of fitness, Â
fitness as in, they can have more offspring, because they get eaten less.Â
This is natural selection and the driving factor behind evolution, as the poorly adapted Â
species gets selected against and the fittest species, which has adapted to the environment, Â
survives and and has the most offspring, passing down the trait that made them survive.Â
If you think adaptation is cool, yes, but also it kind of sucks. You see, Â
humans can get sick from bacteria or viruses, but nowadays, we have medicine that works. Good!Â
However, what if the bacteria mutates and suddenly, the medicine doesnât work anymore? Well, Â
thatâs kind of exactly what is happening, aaand we have no clue how to fix it. So, yeah.Â
Oh yeah by the way, one thing many people confuse is bacteria and viruses, and NO, theyâre not the Â
same. Bacteria are prokaryotes, so they consist of a single cell which can reproduce on its own, Â
and we treat bacterial infections such as strep throat and tetanus with antibiotics.Â
Viruses are not made of cells, in fact, weâre not even sure theyâre alive. They Â
share some signs of life, but they can only reproduce inside a host, and they donât grow, Â
so itâs not really alive, but itâs not dead either, itâs more of non-living kind of thing. Â
Also, you cannot treat viral infections with antibiotics, most of the time you just have to Â
chill out and let your immune system do its thing. Now you might think bacteria are a bad thing, but Â
actually, you have millions good bacteria inside your gut. The live in symbiosis with you, so you Â
give them food, and they help you digest it. Speaking of digestion, your body is made of Â
many complex organ systems that work together to make sure you donât die, Â
and I know what youâre thinking. Actually I donât, but I know how youâre thinking.Â
The nervous system, consisting of nerves, which connect to the spinal cord and lead Â
to your brain, is made of cells called âneuronsâ which can conduct electricity Â
along this long tube called the âaxonâ. Anything you see, think and feel, itâs Â
all just electrical signals going to your brain, and your brain telling your body how to respond.Â
To be exact, the signals are called âaction potentialsâ and happen at the same strength Â
and the same speed every time, so the only difference between âhey, Â
Iâm a little coldâ and âOMG I AM ON FIREâ is where it happens and how frequent the signals are.Â
When a neuron is just chilling, the axon is more negative on the inside than on the outside, Â
because thereâs an unbalanced amount ions. This causes an electric potential of about -70mV.Â
When there is a stimulus, signalling molecules called neurotransmitters dock onto ion channels on Â
the axon and open them, letting the ions flow and changing the electric potential around that area.Â
Now, action potentials are all or nothing. A small stimulus wonât really do anything, Â
but, if the potential exceeds about -55 mV, boom, action potential.Â
Ion channels around the stimulus open and ions rush into the cell.Â
This causes the charge distribution in that section of the axon to reverse for a split second, Â
which is called âdepolarisationâ. The ion channels that are next to Â
this area are influenced by this and open as well, Â
which causes a chain reaction and sends the signal all the way down the axon.Â
Some neurons have a myelin sheath made of Schwann cells, which insulate the Â
axon and only leave tiny gaps called nodes of ranvier. If thereâs a stimulus, the charges Â
can âjumpâ across the nodes which transmits the signal way faster than a normal neuron.Â
But either way, at the bottom, the electric signal reaches a terminal button, which connects the Â
current neuron to the dendrites of the next. If you zoom in, youâd notice that the two cells donât Â
even touch, there is actually a small gap. This is once again where neurotransmitters come in:Â
Once the button is depolarized, tiny packages of neurotransmitters get released, and bind Â
to receptors of following dendrite, either blocking it from doing anything or causing Â
another action potential, which repeats the cycle. Hmmm. Something in my brainâs telling me that you Â
should definitely subscribe, and also, if you want to stimulate your neurons and find out Â
how math is used in Biology, a resource I canât recommend enough is Brilliant, which has thousands Â
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