Core principles - BIOLOGY UNIT 1 - What you should know! Watch

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This should cover most of what you should know for AS Biology Unit 1 AQA, had it in my folder and though I'd share

Lifestyle, correlation and causal relationships, can you:
1) state what is 'risk'?
2) list the lifestyle factors that increase the risk of getting cancer and coronary heart disease?
3) list the lifestyle changes that can reduce the risk of getting cancer and coronary heart disease?
4) state what is correlation and how is it different from a causal relationship

Enzymes and the digestive system, can you:
1) show how two amino acids join to form a dipeptide?
2) state the difference between hydrolysis and condensation?
3) define the primary, secondary, tertiary and quaternary structure of a protein?
4) describe the biuret test

Cells and microscopes, can you:
1) state the main function of the following: cell-surface membrane, mitochondria, lysosome, ribosome, RER, SER and nucleus?
2) state the difference between magnification and resolution?
3) state and explain why an electron microscope has better resolution that a light microscope?
4) state differences between SEM and TEM?

Fractionation and centrifugation, can you:
1) state what is cell fractionation?
2) outline the main steps involved in cell fractionation?
4) state explain what conditions are needed for cell fractionation?

Plasma membranes and lipids, can you:
1) describe the structure of the plasma membrane?
2) show how 3 fatty acids and glycerol join to form a triglyceride?
3) state what the difference between a saturated and non-saturated fat is?
4) describe the emulsion test?
5) state three functions of the proteins in cell membranes?
6) state the difference between a phospholipid and a triglyceride?

Diffusion, osmosis and active transport, can you:
1) define diffusion, facilitated diffusion, osmosis and active transport?
2) write out Ficks law?
3) state how osmosis, diffusion, facilitated diffusion and active transport are similar and different?

Enzymes, can you:
1) define activation energy?
2) state how enzymes speed up chemical reactions?
3) sketch graphs for enzyme activity (substrate concentration, pH, temperature)?
4) state and explain the differences between a competitive and non-competitive inhibitor?
5) explain why a denatured enzyme doesn't work?

Carbohydrates, can you:
1) state what is digestion and why is it necessary?
2) explain what is the process of and end product of starch digestion?
3) explain what is lactose intolerance and what it's symptoms are
4) list adaptations of the small intestine for efficient absorption of digestion
4) explain the two main transport processes involved in the absorption of glucose

Heart structure and heart disease, can you:
1) list; the four chambers of the heart, the 4 main vessels bringing blood back to and taking blood out of the heart and name heart valves?
2) explain what causes certain valves to open?
3) how the heart is myogenic and explain the process?
4) calculate cardiac output?
5) explain what, atheroma, aneurysm and thrombosis are and what causes them?
6) what is mycardial infarction and what causes it

Lung function and lung disease, can you:
1) describe what is the gas exchange surface of a mammal?
2) describe how mammals ventilate - the mechanism of breathing?
3) calculate pulmonary ventilation?
4) list features of the gas exchange system that makes diffusion of oxygen fast?
5) list the symptoms of, explain the transmission and course of TB?
6) explain pulmonary fibrosis, symptoms and what effects it has on lung function?
7) explain what causes asthma, symptoms and effects on lung function?
8) explain what causes emphysema, symptoms and effects on lung function?
9) name risk factors associated with lung disease

Immunology and disease, can you:
1) state what is a pathogen?
2) name two interfaces in the human body that serve as common entry points for pathogens?
3) state the two main ways pathogens cause disease?
4) give three examples of natural defence mechanisms that prevent entry of pathogens?
5) list the main differences between eukaryotic and prokaryotic?
6) explain what causes cholera, how it's transmitted and its symptoms?
7) describe the process of phagocytosis?
8) describe the general structure of an antibody?
9) describe how an antibody-antigen complex is formed?
10) explain what is cell-mediated immunity?
11) explain what is humoral immunity?
12) explain what is the role of plasma cells and antibodies in the primary immune response?
13) explain what is the role of memory cells in the secondary response and how do they respond to a second encounter of the same antigen?
14) state what is antigenic variability?
15) define vaccine?
16) explain the differences between passive and active immunity?
17) state what are monoclonal antibodies and how are they made?
18) list three useful functions of monoclonal antibodies

Sorry if there are any spelling mistakes, had to write this up pretty quickly, hope this helps, use it as a check list to make sure you know your stuff!

If there is anything I've missed of please do tell me so I can add it to the list
Good luck for the exam!

BELOW ARE SOME CONDENSED NOTES I WROTE UP ON THE EXAM THREAD AS PEOPLE REQUESTED THEM BUT AS IT'S HARD TO FIND IN THERE ILL REPOST THEM HERE, if you have any requests for any notes feel free to ask:
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Protein structure: Proteins are polymers of amino acids, amino acids join in a condensation reaction to form a dipeptide, many condensed together form a polypeptide.

Primary:
The number and sequence of amino acids in the polypeptide chain, the only bond is peptide bond

Secondary:
This is the coiling and folding of the polypeptide chain, two most common arrangements are the a-helix and b-pleated sheet.
The bonds are peptide bond and hydrogen bond
Note: the hydrogen bonds hold the chain in the a-helix and b-pleated sheet

Tertiary:
This is the extensive coiling and folding in the polypeptide chain into a compact 3D shape. This creares a specific shape it needs to carry out its function.
The bonds are peptide bonds, hydrogen bonds, ionic bonds and disulphide bridges (bonds)


Quaternary:
This is a protein that consists of more than one polypeptide chain, the chains are help together by the same bonds found in the tertiary structure.
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T-Cells and cell-mediated immunity:

T-cells mature in the thymus gland, each t-cell has only one type of receptor.
T-cells become activated when antigens being displayed on an antigen-presenting cell (usually a macrophage that has carried out phagocytosis)
The T-cell with complementary shape to the displayed antigen divides by mitosis to form a clone of genetically identical cells, these include:
  • T-killer cells - these destroy infected body cells that are showing the antigen on their surface
  • T-memory cells - for the secondary response if the same antigen is encountered again
  • T-helper cells - help to stimulate the B-cells that produce antibodies
  • T-suppressor cells - stop the immune response when the antigen has been removed
NOTE: T-CELLS DO NOT PRODUCE ANTIBODIES!




B-Cells and humoral immunity:

B-cells mature in the bone marrow, each one has one type of receptor on its surface. You have many B-cells in your body one of which, hopefully, has complementary shape to the antigen being presented on the antigen-presenting cell.
The B-cells with complementary shape become activated and divide by mitosis to form genetically identical cells, these include:
  • plasma cells - these rapidly secrete antibodies, antibodies can bind to the antigen forming the antibody-antigen complex and destroying the pathogen
  • memory cells - these DO NOT produce antibodies, but remain in the blood for the secondary response, if the same antigen is encountered again they rapidly divide into plasma cells that release antibodies.
Antigenic variability:

Some pathogens have many strains, the antigens are constantly changing, this is known as antigenic variability. The antibodies in the body will NOT be of complementary shape to these new antigens and so will not bind, you can only overcome this new infection by going through the primary response again.
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Cholera:

Caused by a bacterium (prokaryotes)

1)produces a toxin which causes chloride ions to be secreted into the lumen

2)this makes the water potential of the lumen more negative (lower) than normal causing water to move in by osmosis from surrounding cells from a region of less negative (higher) to a region of more negative (lower) water potential

3)this loss of water into the lumen causes diarrhoea

Note: The toxin is a protein that only binds to specific carbohydrate receptors found on the intestinal epithelium cells that's why it only affects that part of the body, this isn't specifically in the specification but it good background knowledge to know.

Oral rehydration therapy - ORS

Contains glucose and ions for example sodium ions that reverses the osmotic effect of cholera.

Sodium ions help with the co-transport of glucose back into the epithelial cells via a protein carrier, so less water lost in gut and less lost by cells, water moves from lumen into epithelial cells by osmosis.

The glucose provides the patient with a source of energy.
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Non competitive inhibitor:
Have a different shape to the substrate
bind to a site other than the active site
causes the active site to change shape
correct substrate cannot bind, rate of reaction is reduced

Competitive inhibitor:
Have a shape similar to the correct substrate
can bind to the complementary shaped active site of the enzyme and block it
correct substrate cannot bind and has to wait until active site is unoccupied, rate of reaction is reduced.


Lock and Key:
-The tertiary structure of the active site of the enzyme is of complementary shape to the substrate
-so the substrate can bind to the active site
-enzyme-substrate complex can form

Induced fit:
-The tertiary structure of the active site is not of exact complementary shape
-the substrate will bind to the active site
-the active site will change shape and mould around the substrate
-enzyme-substrate complex will form
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As someone requested these are really condensed notes on enzyme activity and what effects it:

Enzyme activity

Temperature:
A rise in temperature increases kinetic energy of molecules so there are more frequent collisions, optimum temperature will be at the peak of a curve. However a further increase in temperature will permanently denature the active site causing it to change shape, as hydrogen and other bonds in the tertiary structure are broken


pH:

Optimum pH is at the peak, when pH is changed two things are mainly affected-
  • Charges, on amino acids that make up the active sit so enzyme-substrate complex will not form as substrate cannot bind to the active site

  • bonds, in the tertiary structure, pH changes case them to break, mainly affecting ionic bonds, and can change the shape of the active site so substrate cannot bind.
Substrate concentration:

As substrate is added the rate of reaction increases as there is increased chance of collision therefore the substrate is the limiting factor, until all of the active sites are occupied, further addition of substrate will have no effect of the rate of reaction ,the graph remains constant, after this the enzyme concentration is the limited factor.
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Lung disease

Pulmonary tuberculosis:

Transmission:
through droplets of mucus containing the bacteria which are inhaled.

Course of infection:
  1. The bacteria multiply in the lungs inside the alveoli, the immune system responds and the bacteria are engulfed by phagocytes which encase them in a granuloma
  2. inside the granuloma some bacteria are killed others remain dormant as they are unable to replicate
  3. When the immune system is weakened e.g. by stress the bacteria become active and are able to multiply again
  4. the bacteria destroy the alveoli and capillary walls which can lead to scars & fibrous tissue forming, this reduces the surface area and increases the length of diffusion pathway of oxygen into the blood
  5. the damage can allow bacteria to enter the blood system and spread to other organs
Emphysema:
  1. The alveoli walls are broken down leading to fewer larger alveoli which reduces the available surface area for diffusion
  2. the alveolar epithelium becomes thicker so there is increased length of diffusion pathway
  3. elastic tissue of the lungs is reduced so ventilation, particular breathing out, is difficult so this reduces the concentration gradient of oxygen between alveoli and blood
  4. there is a lower rate of respiration
Astma:
  1. The attack narrows the airways so less air containing oxygen can reach the alveoli
  2. as a result concentration gradient between alveoli and blood is reduced so lower rate of diffusion of oxygen
  3. more mucus is secreted so airflow is further restricted
Pulmonary fibrosis:
  1. alveolar epithelium becomes thicker so increasing the length of diffusion pathway
  2. elasticity of the lungs is reduced therefore cannot inflate or deflate as much reducing the concentration gradient between alveoli and blood
  3. these are caused by scar and fibrous tissue forming on the lungs
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Vaccination - a preparation of antigen from the pathogen which stimulates the production of antibodies and memory cells


Passive:
Vaccine containing antigens stimulates primary response producing antibodies and memory cells, so if same antigen is encountered again the secondary response is stimulated


Active:
contains antibodies therefore there is no primary response so no memory cells are produced, this does not last very long as the antibodies are destroyed by the body's defence mechanism, if the same antigen is encountered again the body has to go through the primary response, an example of active would be mothers breast milk, the mother passes some antibodies to the child in this way.
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Cardiac cycle notes based on a typical graph e.g. the one in the AQA textbook page 93


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Monoclonal antibodies are one type of antibody produced from a clone of hybridoma cells

A hybridoma cell is made up of:
  1. Tumour/cancer/myeloma cell as it has the ability to grow and divide rapidly in lab conditions
  2. B-cell and this produces the one type of antibody needed
The hybridoma cell has both properties and can keep dividing to produce large numbers of genetically identical cells producing one type of antibody

Uses:
  • large numbers of a desired antibody can be produced for the production of a vaccine
  • as a 'magic bullet' - a drug can be attached to the antibody and as the antibody will bind only to the complementary shaped antigen the drug will be carried directly to the pathogen on which the drug is to work (e.g. cancer treatment)
  • in transplant surgery the monoclonal antibodies can be used to 'knock out' specific T-cells causing a reduced chance of rejection of the organ

Hope this helps
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Heart disease


Atheroma:
Build up of fatty material e.g. cholesterol and lipoproteins in the lining (endothelium) of the artery wall, the lumen of the artery narrows and there is reduced blood flow through it.


Thrombosis:
Can occur when the atheroma breaks through the artery wall making the lining of the artery rough. This can lead to the formation of blood clots which can be carried away and block other arteries e.g. coronary artery

Aneurysm:
Can form when the artery wall is damaged or weakened due to the atheroma. It is a blood filled balloon-like swelling of the artery wall, if this aneurysm bursts there is severe blood loss to the part of the body the artery supplies blood to.

Coronary heart disease (CHD):
This affects the coronary arteries specifically They supply the heart muscles with glucose and oxygen, if a person has CHD it means their heart cells are receiving an inadequate amount of blood

Myocardial infarction (heart attack):
This is the death of the heart muscle cells as the blood supply to the heart in the coronary arteries is reduced. The heart cells do not receive enough glucose and oxygen, they cannot respire and die.


Risk factors:
  • diet e.g. high salt intake
  • blood cholestrol e.g. LDL's
  • cigarette smoking
  • high BP
Hope this helps!
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Microscopes

Magnification - the number of times the lens makes the image bigger than the object

Resolution - the ability to see two points that are close together, It is the degree of detail visible in the image


TEM:

  • higher resolution can be achieved so smaller structures e.g. organelles can be seen
  • higher magnification can be achieved
SEM:
  • 3d images can be produced
  • can view surface of specimen
  • thin sections do not need to be cut
Limitations to electron microscopes (SEM & TEM):
  • artefacts may be created that are seen in the image but were not present on the natural specimen
  • the images are black and white so the natural colour cannot be seen
  • must be in a vacuum so living material cannot be observed
REMEMBER: Magnification = enlarged image / actual size
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