Levels of Organization

The level of organization on the human includes: Organelles, Cells, Tissues, Organs, Organ Systems and Organisms.

Organelles are subcellular structures, things that are subcellular are Ribosomes, Mitochondria and the Nucleus.

And combined they make cells, which are all different, skin cells, blood cells, brain cells, these are specialised cells, which the scientific names of these cells are, Muscle cells, Glandular cells, and Epithelial cells. 

Next are tissues, these are groups of cells that work together to carry out functions like scar tissue, which is meant to cover up wounds to help them heal by shielding the wound from external sources, the epithelial cells combine together to make human skin along with the inside of our intestines.

The muscle tissue in our ligaments helps our body to move and flex, allowing us to grip things.

It also helps create chemicals and enzymes, like sweat, to cool our bodies and saliva, to help us digest food.

Next are our Organs. Once again, the tissues combine to make a larger structure, for example, the stomach, which breaks down food into proteins. Other things that tissues make are the lungs, teeth, bones, the digestive system and much more.

The organ's job is to 'carry out functions', which is similar to tissues, but can carry out larger processes compared to cells or tissues. These organs make systems like the Respiratory system, the Cardiovascular system, and the Reproductive system.

Then to make the whole organism, as you would need all of the organism's cells, tissues, organelles, organ systems and organs to make a functioning human body.

 

Specialised Exchange Surfaces

These types of exchange surfaces are parts of an organism that exchange substances with the exterior envorment. 

Our exchange cells in our bodies are the Villi, and the Alveoli.
Its job is to exchange Oxygen and Carbon dioxide in our blood, but the Villi, which are our intestines, help with absorbing glucose and amino acids.

The roots in the bottom of the plant have their root hair cells, which help absorb the water in the surrounding soil, along with the leaves, to help them absorb CO2  in the air.

Something to help with these exchange surfaces is a large surface area, so by having hundreds of millions of Alveoli in our lungs, it makes it a larger surface area, having a large surface area increases the amount of diffusion and can also help with the diffusion rates. 

Another thing about diffusion surfaces is that they are often very thin because it makes the substances diffuse over a short distance, for root hair cells, the water only has to diffuse through a thin cell wall and membrane,
this is known as a 'short diffusion distance', which increased the speed with which the plant can absorb. 

Other types of diffusion surfaces are blood, as the blood has to flow and diffuse throughout the body, so having glucose dissolve into the blood that gets taken away to the intestines to then be replaced by more blood.

Another good thing to keep in mind is a 'good supply of external mediums', a good example of this is keeping a good supply of Oxygen for your lungs, when you breathe the Oxygen mixed with the Alveoli, which helps keep a steady concentration gradient for your bloodstream.

Active Transport

Active transport works in root hair cells in plants, for example, we can use diffusion to compare it.

When we talk about diffusion it is particles going from a region of high concentration to low concentration, this takes no energy from the cell, as it is a passive process.

Active Transport is the movement of molecules that go against to concentration gradient, and that does require energy from the cell, which is ann active process. 
It also always happens across a cell membrane, in which special proteins transfer molecules across the cell membrane.

In a plant, all the energy comes from solar respiration, which happens in the mitochondria which break down glucose to create energy for the plant, and the mitochondria store the energy in things called ATP, which are basically batteries, transporting the energy from the mitochondria and moving it around the plant.

Let's take a plant as an example of active transport, this plant needs energy to function and mineral ions to survive, which it gets from the soil, which they use roots to gather these, there are cells on the roots which are named root hair cells which help absorb all the minerals the plant needs from the surrounding soil. 

The plant needs certain minerals the plant needs mainly nitrates to produce proteins and magnesium for chlorophyll since they need to gather the minerals the plant has to absorb the minerals via active transport going against their concentration gradient, the reason why the plant can't absorb the minerals via diffusion is that there is a higher concentration of magnesium and nitrates in the root cells than the soil, so active transportation is necessary, in the root hair cells are a lot of mitochondria, which help with energy in the cell.

Osmosis

Diffusion is when particles go from a place of high concentration to a low concentration, Osmosis is similar to diffusion but mainly for water.

Water concentration is the amount of other molecules most commonly sugars and salts, and how much is dissolved in the water. 
These molecules that dissolve in the water are named solutes, so if we take two beakers and fill both with water and then put one solute in the left beaker, and put 3 in the right beaker we would have a higher amount of solute concentration.

What matters is the amount of solute that is in the beaker, because that's what dictates the water concentration.

 

Diffusion

When Molecules are left alone, they will want to want to move randomly, the proper term is that the particles will move from a place with high concentration to a place with a lower concentration. 

This can happen in gasses and liquids, for example when you spray perfume it diffuses throughout the air so it is very fragrant, 
or smoke comes out of the car the gasses from the car's exhaust disperse into the air, and if you add food colouring to water.

Diffusion can also occur through materials like cell membranes, usually only really small things can fit through cell membranes, things like water, glucose and amino acids can pass through cell membranes. 

There are three types of diffusion:

Firstly is the Concentration gradient, the larger the concentration gradient the higher the rate of diffusion if we were hypothetically to have two boxes, one on top and one on the bottom, and we put more particles inside the top box and put very little in the bottom one. 

The top one would have a harder time passing through the cell membrane compared to the bottom one since they have a different amount of particles one having much more than others. 

The second is Temperature, the reason is that particles will move faster due to the heat and that the heat gives the particles more energy, a higher temperature helps with the rate of diffusion. 

Lastly is a Surface area, which the higher surface area the higher rate of diffusion, 

Stem Cells in Medicine

 Stem cell medicine can help with Paralysis and Diabetes, but it also comes with its own risks, as it is slightly unethical and dangerous.

Once again stem cells can divide by mitosis and they can also differentiate into different kinds of cells. 
The main types of stem cells are Embryonic stem cells which are found in the early embryos usually from embryos from growing infants to grow into babies, and stem cells found in the bone marrow inside all ages, but the stem cells from the bone marrow can only differentiate into different blood cells.

Lots of medical issues come from damaged or faulty cells, as diabetes is one of them due to the cells in the pancreas not producing insulin, while paralysis is due to damaged nerve cells which can't move, and Sickle cell anaemia is caused by misshaped blood cells this is where the stem cells come into play, as we use the stem cells to replace the faulty cells to help the patent.

The most common way to do this is for scientists to take embryonic stem cells, grow them in a laboratory, and then stimulate them enough to turn them into the specialized cells necessary. 

For example, when scientists want to treat someone with diabetes, they will take some embryonic stem cells, and then stimulate them to turn them into insulin cells, and then inject the cells into the patient pancreas too. 

For paralysis, it is the same thing, first, take some embryonic stem cells, then stimulate them into nerve cells and then inject them into the patient's limbs. 

There are some slight problems about using stem cells in medicine such as embryonic stem cells. It is because we need embryonic stem cells, we need them from embryos and collecting the embryonic cells involves some ethical issues.  

And also a rejection of the stem cells, so the immune system might destroy the carefully obtained cells, although we can give medication to slighty reduce the risk of the immune system thinking it is harmful.

The easier way of getting stem cells is from Adult stem cells, but these cells come with a large caveat as they can only differentiate into blood cells such as red and white cells.

These can combat blood cell disorders like SicklCeliaia, but since these cells cannot be used in other applications like paralysis and diabetes. But new research is finding out that we can implement adult stem cells in other ways than just blood cells basically turning the adult stem cells into embryonic stem cells.

One of the dangers of this is that, where the scientists gather the stem cells also matters if the doctor has a virus of any kind, it might affect the patient and might even cause more problems in the future.

Another problem is that the stem cells might cause tumour development, as the cells can divide via mitosis so quickly, that having the cells form into tumours might be a danger by forming cancer or a tumour.

The ethical part of using stem cells is that you are using embryonic stem cells, since the scientists are using the cells that could be used to foster human life, into something to save a suffering patient.
Some people believe that creating a new human life is much more valuable than saving one who pain or suffering, while others believe that saving an individual who is in pain is better.

But something to keep in mind is that the embryonic cells are from fertility clinics that are unwanted by their hosts and would have been destroyed.
Also, certain governments heavily regulate this form of research, while some ban it entirely due to the ethical part.

Specialized Cells & Differentiation

 Every 'complex' organism, is built out of cells, and these cells are known as specialized cells.
For humans, those would be and there are over 200 times of specialized cells in humans, muscle cells, nerve cells, and sperm cells. While a plant will have Root cells, Phyleom cells, and Xylem cells.

Let's take a Sperm cell, they take generic material to an egg cell, and sperm cells have half the genetic material to make an adult cell.
Because it is meant to combine with the egg cell to make one adult cell, they have a tail named the Flagellum and mitochondria to help the sperm swim through the uterus and the fallopian tubes to reach the egg cell and at the tip is a digestive enzyme to break a hole in the egg. 

Nerve cells and Red blood cells are completely different due to differentiation, as they are used in the body for completely different reasons.

Zygotes are fertilized egg cells, which will duplicate due to mitosis  and then they can differentiate into other cells, like red blood cells, nerve, muscle or skin cells.

Mitosis

Cells in every living being need a new supply of new cells, as when you are growing, repairing or undergoing development you need new cells to replace the old cells, like our skin cells which will always fall off our bodies and need to replace themselves.

Every cell has a "Cell cycle", along the lines of.
Growth, DNA replication, Mitosis and Division(Cytokineses).

Firstly the cell grows in size, and now it has more Mitochondria and Ribosomes, usually when a cell is not trying to reproduce and duplicate its DNA is now a noodle-like substance, but once it is ready to duplicate the DNA condenses into Chromosomes.
These affect things in humans like eye colour, Eukaryotic cells like animal cells have two copies of chromosomes which are named 'pairs' of chromosomes, one chromosome is from their father while the other is from the mother.

Humans have 23 pairs of chromosomes so in total we have 46 chromosomes, but other species of life have different numbers of chromosomes, this is why animals cannot reproduce with other animals with different numbers of chromosomes like if an elephant and a bird were to have offspring they have different numbers of chromosomes so it would not work.

So when a chromosome wants to divide into more chromosomes, it first duplicates the 46 chromosomes, but the duplicate stays attached, so you get these X-shaped chromosomes, you might hear people talk about these chromosomes that have "arms". The right arm has the same amount of DNA as the left arm. Keep in mind this is all happening inside a human cell.

Once the cell is ready to divide, the chromosomes start to move to the centre of the cell, and after fibres or microtubules start slowly pulling the arms of both sides of the chromosomes splitting them in half and pulling them to each side of the cell. Pulling it to the 'poles' of the cell, and this breaks the cells apart, this happens to all 46 chromosomes inside the cell.

After all of that, we are finally able to do Cytokeneis or division, the cell membrane and cytoplasm pull apart making two daughter cells.
With the same DNA and the 46 chromosomes split between them, so each cell has 23 chromosomes, and then they repair, and undergo the same cycle infinitely repeating and duplicating. 

How to convert between nm, um, mm, m and km

 The: nm, um, mm, m and km.

Are all units of measurement, depicting size. Nm for nanometers, um for micrometre, mm for millimetres, m for meters, and km for kilometre. 

Now each of these numbers is either 1000 times bigger or smaller than the previous one.
To convert each number, simply divide or multiply it by 1000, so if you want to convert 2 kilometres into meters, all you have to do is multiply 2 * 1000, and you get 2000 meters. Then if you want to convert it back to km do 2000 meters and do
2000/ 1000, and then you will get 2 kilometres.

Now let's take an example number of 6mm or 6 millimetres.
In order to increase the 6mm in size, you have to divide it by 1000, so if you want to convert the 6mm to meters then it would be 0.006 meters or 6x10^-3 meters, it is still the same number of 6mm but since the unit are larger the number is smaller. 

Now if you want to convert the 6mm to um or micrometers, you would multiply by 1000.
So, 6mm * 1000 = 6000. Or 6000um or micrometres, or 6x10^-3um. 

Now let's put these all into scale, atoms are 0.1 - 0.5 nanometers big, viruses are around 100 nanometers across, bacteria might be a micrometre, and plant and animal cells are around 10-100 micrometre range.
But not even the best eyesight can see past nanometers in size, as the smallest thing we can see is the width of the human hair, light microscopes allow you to see around 500 nanometers, but if you have a selection microscope you can see until 0.1 nanometers which is the size of atoms.

Light & Electron Microscopes

 There is a difference between Light and Electron microscopes, most microscopes we use are light microscopes which are lighter in weight cheaper to purchase and easier to use than electronic ones. But that comes with some drawbacks, as we can only see stuff that is 0.2 micrometres so our resolution can only go to 0.2 micrometres because light has a wavelength of 0.2 micrometres and we use the light to focus on the subject, 
and if we try to zoom in further than 0.2 micrometres it will be unfocused and blurry.

While electron microscopes are heavy, expensive and hard to use, and only really used by scientists, election microscopes use electrons instead of light which enables you to zoom in until 0.1 nanometers, electron microscopes have a nearly 2000x zoom compared to light microscopes.
They are normally used to look at sub-cellular structures, so you can look at the nucleus of cells along with the mitochondria, but they also have no colour and thus are black and white since that there is no light going into the subject. 

Microscopes

Light microscopes are highly important in Biology because they allow you to see the smallest things like cells.

First lets start with the base, which connects to the arm, then there's the "Stage" which is where we put our objects on to examine them. 
Usually there's 3 objective lenses, with different magnification strengths, then there's the lens at the top which is where our eye goes and has a fixed magnification, then the tube which goes from the lens at the top to the lenses at the objective lenses,
then the coarse and fine focusing nobs to focus the lenses on the object on stage.  

Let's get this straight, there are two things that are important when looking through the magnifying glass (there's more but that doesn't matter right now), mainly the "image" and the "object".
When referring to the object you are usually referring to the object or sample you are looking at on the stage. So if we have let's say onion cells on the stage, that would be considered to be the "object" or "sample". 

The term "Image" comes from the image that we see when we look down, we see the individual cells, and what we see in the lens is the image. 

Light Microscopes work by shining or reflecting light onto the subject.
Or by using an adjustable mirror below the stage or by turning on a lamp at the bottom to illuminate the clear stage. 

First, the light shoots up towards and through the sample, then through the objective lenses, then through the tube then into the lens where our eyes are.
This, in turn, is necessary for the light to bounce off objects for our eyes to see, magnification happens when you magnify the object, so an x100 magnification means the object is magnified 100 times. 

Resolution means how detailed the image is, so if an object has a terrible resolution it is very blurry, while a good resolution is good when it is crystal clear and very sharp. 

Types of Life

 Animals, Fungi, Plants, Protocysts, Bacteria and Viruses are all different but they are all different types of Life.

Animals, Fungi, Protists and Plants are Eukaryotes, meaning they are made of Eukaryotic cells DNA is stored in chromosomes and their DNA is found in a Nucleus inside the cell. While Bacteria are Prokaryotes which means they don't have a nucleus their DNA is loose floating around in the cell, like a stand of string floating in water.
Viruses on the other hand do not count as organisms so they don't meet the criteria of being either a Eukaryotic or Prokaryotic cell, they are also 10 to 100 times smaller than prokaryotic cells.

There are to our estimates 5-10 million different species of animals on earth, from fish to insects to birds to humans, but the one thing similar to all is they are Multicellular and they are Heterotrophs.
Most reproduce sexually, and each animal is made out of multiple cells instead of one.
It is thought that an adult human is made out of 40,000,000,000,000 cells or 40 trillion cells, so in order to get energy humans and animals need plants or other animals to gain energy.

Plants on the other hand with around 300,000 species on earth, ranging from tomato plants, to trees to leaves. Like animals, plants, are multicellular and they are Autotrophs instead of Heterotrophs meaning that they get energy from the sun via photosynthesis instead of consuming other organisms. 

Fungus are different from plants, they are mostly multicellular, most forms are mushrooms or fungi growing on sandwiches, but yeast which is used in bread is unicellular which means they are made of one cell. Although they look like plants, the key difference is that they cannot photosynthesis instead they get their energy from other sources like animals so they are Heterotrophs, but that's not fully correct as fungi are Saprotrophs which means that they feed using digestive enzymes outside their body to and wait for the enzymes to break down the food and then digest it by absorbing it into their bodies.
Although some of the multicellular ones have a body known as the Mycelium which is made from small string-like substances called Hyphae.
Although rare some fungi are considered Pathogens which means disease-bringing to humans for example Athlete's foot is a fungus that grows on your foot.

Protoctists/Protoctista/Protists/Protista. Are all basically the same thing, nearly all of them are unicellular meaning they are made of singular cells, cells like Chlorella and Euglena are similar to plant cells due to them having chloroplast, while other cells like Amoeba are similar to animal cells because they have to consume other organisms to survive. Most protoctists have nothing to do with humans although some are considerd pathogens and are harmful to humans like Plasmodium which causes Malaria. 

Bacteria live practically everywhere from skin, to the ground to even food, although some species can photosynthesize bacteria in general don't have chloroplasts, but most feed of other organisms maybe dead leaves or living organisms like humans. 
Scientists speculate that there are more species of bacteria than all the other species of life on this planet combined. Some are harmful like Salmonella which causes food poisoning, but most don't bother with humans, in fact some are even helpful to humans like the bacteria in our intestines that help digest food that we eat.

Viruses are basically small tiny particles, for a sense of scale you can fit around 1 million of them along the width of a single fingernail, all viruses are different but all have similar features like a Protein coat around it.

  

Cell Structure

Let's start with the difference between Animals, Plants, and Bacterial cells.
Cells are the smallest form of life that can replicate independently, unlike plant and animal cells that can replicate and duplicate. 
Bacterial cells are a whole organism, they can also fully reproduce asexually, but animal and plant cells are multicellular which are organisms that contain lots of cells. 

If we take a human and put him under a microscope, we will notice that the human is made out of cells, and the skin is made of skin cells, blood is made from blood cells, in our bodies alone we contain hundreds of different types of cells, an adult human can have up to 40 trillion (40,000,000,000,000) cells.

Plant and animal cells are eukaryotic cells.

Let's take a plant and animal cell to compare each other. 
First, they both have a cell membrane that controls what can go in and out of the cell, like a security gate.

Inside the cell membrane is a Nucleus which has all the DNA of the cell both are filled with cytoplasm a type of gel-like substance, and both are littered with lots of Mitochondria which provide energy from sugars like glucose to make energy for the cell, and both have lots of Ribosomes which protein is synthesised.

Plant cells are slightly different from animal cells, one thing that separates the plant cell from the animal cell is the walls are more rigid and made from cellulose, along with a Permanent Vacuole which is a sort of sac which is a mixture of water, sugars and salts, and finally Chloroplast which is where Photosynthesis is done.
For a rough explanation, photosynthesis is when a plant takes energy from the sun and forms sugars like glucose to help feed the plant. 
And plants that do photosynthesis have a green-coloured substance named Chlorophyll, which gives the plant leaves its green colour. 

Bacterial cells are unicellular which means that they are one cell, they are Prokaryotes which are=.