all12- Flashcards
What are the three ways a pathogen can damage hosts cells?
1) rupturing them to release nutrients inside them
2) breaking down nutrients inside the cell for their own use. This starves and eventually kills the cell.
3) replicating inside the cells and bursting them when they’re released
What are the two ways pathogens cause disease?
1) production of toxins
2) cell damage
What are the lifestyle factors that can affect your chances of getting cancer?
1) smoking
2) excessive exposure to sunlight
3) excessive alcohol intake
What are the three surfaces of contact- where pathogens enter our body? and how do they get in?
1) gas-exchange system = if you breathe in air that contains pathogens, most of them will be trapped in mucus lining the lung epithelium. Some pathogens are able to reach the alveoli where they can invade cells and cause damage.
2) Skin = if you damage your skin, pathogens on the surface can enter your bloodstream. blood clots prevent pathogens from entering.
3) Digestive system = if you eat or drink food that contains pathogens. Some will survive from the acidic conditions of the stomach, and invade cells of the gut wall and cause disease.
Explain the process of phagocytosis.
1) A phagocyte recognises the antigens on a pathogene
2) The cytoplasm of the phagocyte moves round the pathogen, engulfing it.
3) The pathogen is now contained in a vacuole or a vesicle in the cytoplasm of the phagocyte.
4) A lysosome fuses with the phagocytic vacuole and the lytic enzymes break down with the pathogen
5) The phagocyte presents the pathogens antigens, it sticks the antigens on its surface to activate other immune system cells.
What is the cellular and humoral response?
Cellular = The T-cells and other immune system cells that they interact with e.g phagocytes , form the cellular response
Humoral - B cells and the production of antibodies form the humoral response.
Explain what is meant by a primary response.
The primary response is slow because there aren’t many B-cells that can make the antibody needed to bind to it.
The infected person will show symptoms of the disease while the body produces enough of the right antibody to overcome the infection.
T-cells and B-cells produce memory cells. Memory T-cells remember the specific antigen and will recognise it second time round. Memory B-cells record the specific antibodies needed to bind the antigen.
The body is now immune.
Explain what is meant by the secondary response.
If the same pathogen enters the body again, the immune system will produce a quicker, stronger immune response.
Memory B-cells divide into plasma cells that produce the right antibody to the antigen. Memory T-cells divide into the correct type of T cells to kill the cell carrying the antigen.
The secondary response often gets rid of the pathogen before you begin to show any symptoms.
Explain how monoclonal antibodies target cancer
1) Cancer cells have antigens called tumour markers that are not found on body cells.
2) Monoclonal antibodies can be made that will bind to the tumour markers.
3) You can also attach anti-cancer drugs to the antibodies
4) Antibodies come into contact with the cancer cells and bind to the tumour markers
5) This means the drug will acuumulate in the body where there are cancer cells.
6) side effects of an antibody based drug are lower than other drugs because they accumulate near specific cells
how do monoclonal cells work in pregnancy tests?
1) The application area contains antibodies for hCG bound to a coloured bead
2) when urine is applied to the application area any hCG will bind to the antibody on the beads, forming an antigen-antibody complex.
3) the urine moves up the stick to the test strip, carrying any beads with it
4) the test strip contains antibodies to hCG that are stuck in place.
5) if there is hCG present the test strip turns blue because the immobilised antibody binds to any hCG. if no hCG is present, the beads will pass through the test area without binding to anything so it won’t go blue.
How do vaccines protect individuals and populations against disease?
Vaccines contain antigens that cause your body to produce memory cells against a particular pathogen, without the pathogen causing disease. This means you become immune without getting the symptoms.
Vaccines protect individuals because they reduce the occurance of the disease. Those not vaccinated are less likely to catch the diease because there are fewer people to catch it from - this is called herd immunity.
Explain the primary, secondary, tertiary and quaternary structure of a protein.
Primary structure = A sequence of amino acids in the polypeptide chain
Secondary structure = Hydrogen bonds form between the amino acids. This makes it coil or fold.
Tertiary structure = The coiled or folded chain is coiled or folded furthur. More bonds form between different parts of the polypeptide chain. For proteins made from a single polypeptide chain, It forms their final 3D structure
Quaternary structure = the way the polypeptide chains are assembled together. Several different polypeptide chains held together by bonds. For proteins made from more than one polypeptide chain this is their final 3D structure
Describe the test for proteins.
1) add sodium hydroxide solution
2) add a few drops of copper (II) sulfate solution
3) if theres protein = it will go purple
if theres no protein = it will stay blue
Describe three functions of proteins.
three from:
Enzymes = break down large food molecules or help to synthesise large molecules
Antibodies = involved in the immune response, they have variable regions.
Transport proteins = transport ions and molecules across membranes
Structural proteins = physically strong. They consist of long polypeptide chains lying parallel to each other with cross links between them.
Describe the cause and symptoms of lactose intolerance
When you don’t have enough of the enzyme lactase, you can’t break down lactose in milk properly.
undigested lactose is fermented by bacteria and can cause a whole host of intestinal complaints such as stomach cramps, excessive flatulence and diarrhoea
Describe the test for reducing sugars
Add benedicts and heat
if the sample contains reducing sugars = will turn red
Describe the test for non-reducing sugars
1) boil with hydrocholric acid and neutralise with sodium hydrogencarbonate.
2) carry out the benedicts test as if you would for the reducing sugars test.
Describe the test for starch
1) Add iodine dissolved in potassium iodide solution
2) if there is starch = will turn a blue-black colour
Explain the effect of temperature on enzymes.
1) The rise in temperature makes the enzymes molecules vibrate more
2) If the temperature goes above a certain level, this vibration breaks some of the bonds that hold the enzyme in shape
3) The active site changes shape and the enzyme and subtrate no longer fit together
4) At this point, the enzyme in denatured
Explain the effect of PH on enzymes
1) All enzymes have an optimum PH value
2) Above and below the optimum PH, the H + and OH - ions can mess up the ionic and hydrogen bonds that hold the enzymes tertiary structure in place.
3) The active site changes shape, so the enzyme is denatured
Explain the effect of substrate concentration on enzymes.
1) the higher the substrate concentration, the faster the reaction.
2) More substrate molecules means a collision between substrate and enzyme is more likely
3) This only happens until the saturation point, when there are too many substrates, all active sites are full and adding more makes no difference
Explain What a competitive inhibitor is
1) Competitive inhibitors compete with the substrate to bind to the active site but no reaction takes place.
2) Instead they block the active site so that no subtrate molecule can fit in it
3) If theres a high concentration of the inhibitor, it’ll take up nearly all the active sites and hardly any of the substrate will get to the enzyme.
Explain what a non-competitive inhibitor is.
1) non-competitive inhibitor molecules bind to the enzyme away from its active site
2) This causes the active site to change shape so the substrate molecules can no longer bind to it.
3) They dont compete with the substrate molecules to bind to the active site because they are a different shape.
4) increasing the concentration wont make any difference - enzyme activity will still be inhibited.
Explain the function of the:
1) plasma membrane
2) nucleus
3) lysosome
4) ribosome
1) regulates the movement of substances in and out of the cell
2) The pores allow substances to move between the nucleus and cytoplasm, the nucleolus makes ribosomes.
3) Contains digestive enzymes. These are kept seperate from the cytoplasm by the surrounding membrane and can be used to digest invading cells or to break down worn out components of cell.
4) The site where proteins are made.
Explain the functions of:
1) endoplasmic recticlum
2) golgi apparatus
3) microvilli
4) mitochondrion
1) synthesises and processes lipids
2) Processes and packages lipids and proteins. it also makes lysosomes
3) They increase the surface area of the plasma membrane - found on cells involved in processes such as absorption
4) the site of aerobic respiration
Explain the process of cell fractionation
1) homogenisation = breaking up the cells = by vibrating the cells or grinding the cells, this breaks up the plasma membrane and releases the organelles into solution
2) filtration = getting rid of the big bits = by filtering through a gauze to seperate any large debris or tissue debris.
3) ultracentrifuguation = seperating the organelles = to seperate a particular organelle from all the others.
Explain the process of ultracentrifugation.
1) Cell fragments are poured into a tube. The tube is put in a centrifuge and is spun at low speed. The heaviest organelles get flung to the bottom of the tube by the centrifuge.
2) the supernatent (fluid above sediment) is drained off, poured into another tube and spun in the centrifuge at a higher speed. the heaviest organelles form a pellet at the bottom, the supernatant is drained and spun at a higher speed.
3) The process in repeated at higher speeds until all the organelles are seperated.
Explain what order organelles are seperated in ultracentrifugation
1) nuclei
2) mitochondria
3) lysosome
4) endoplasmic recticulum
5) ribosomes
Explain the two types of microscope - light and electron
light =
they have a lower resolution than electron microscopes
they use light
Electron microscopes =
They use electrons
they have a higher resolution so give a more detailed image
Explain the strengths and weaknesses of the transmission scanning microscope and the scanning electron microscope
TEM = good because they give high resolution images, but bad because they can only use thin specimens
SEM = good because they can be used on thick specimens but bad because they give a lower resolution
Explain what an aneurysm is
Aneurysm is a balloon-like swelling of the artery. Atheroma plaques damage and weaken arteries, they narrow arteries increasing blood pressure.
When blood travels through a weakened artery at high pressure, it may push inner layers through the outer elastic layer to form an aneurysm.
This may burst - causing a haemorrahage
Explain what thrombosis is.
Thrombosis is a formation of a blood clot.
An atheroma plaque can rupture the endothelium damaging the artery wall and leaving a rough surface
platelets and fibrin accumulate at the site of damage and form a blood clot
This blood clot can cause a complete blockage of the artery or it can become dislodged and block a blood vessel elsewhere in the body.
Debris from the rupture can cause another blood clot to form furthur down the artery.
Explain what atheroma is.
If damage occurs to the endothelium, white blood cells and lipids clump together to form fatty streaks.
over time, white blood cells, lipds and connective tissue builds up and hardens to form an atheroma - a fibrous plague.
It blocks the lumen of the artery and restricts blood flow, which causes blood pressure to increase.
Explain the process of the cardiac cycle.
1) The sino-atrial node (SAN) sends out impulses across atrial walls
2) This causes the right and left atria to contract at the same time / causes atrial systole
3) impulses can not cross to ventricles due to non conducting tissue
4) Waves of electrical activity are transferred from the SAN to the atrioventricular node (AVN)
5) new impulse travels down bundle of His
6) slight delay before the AVN reacts to make sure ventricles contract after atria empty
7) bundle of His conducts impulses to the purkyne fibres.
8) purkyne fibres carry the impulses to the muscular walls of the right and left ventricles causing ventricles to contract from bottom up.
Describe what happens in inspiration and expiration in the lungs.
inspiration:
1) the intercostal and diaphragm muscles contract.
2) this causes the ribcage to move upwards and downwards and the diaphragm to flatten increasing the volume of the throax
3) As the volume of the throax increases, the lung pressure decreases.
4) This causes air to flow into the lungs. Inspiration requires energy.
Expiration:
1) The intercostal and diaphragm muscles relax
2) the ribcage moves downwards and inwards and the diaphragm becomes curved again
3) the thorax volume decreases, causing the air pressure to increase
4) air is forced out of the lungs. it doesnt require energy.
Explain what happens when someone gets cholera
1) The toxin causes chloride ion protein channels in the plasma membranes of the small intestine epithelial cells to open.
2) chloride ions move into the small intestine lumen. The build up of chloride ions lowers the water potential of the lumen.
3) water moves out of the blood across the epithelial cells and into the small intestine lumen by osmosis.
4) the increase in water secretion in intestine leads to diarrhoea causing the body to become dehydrated.
Monomers
Small basic molecular units
Examples of monomers
monosaccharides, amino acids and nucleotides
Polymers
Large complex molecules composed of long chains of monomers joined together
Examples of polymers
Carbohydrates, proteins and nucleic acids
What are the names of the types of glucose?
Alpha-glucose and beta-glucose
What is a condensation reaction?
reaction?
When 2 molecules join together with the formation of a new chemical bond, releasing a water molecule
What type of chemical bond forms between 2 monosaccharides?
Glycosidic
What is formed when 2 monosaccharides join together?
Disaccharide
Which 2 molecules make maltose?
Alpha glucose and alpha glucose
What is sucrose made from?
Alpha glucose and fructose
Which 2 molecules make lactose?
Which 2 molecules make lactose?
Alpha glucose and galactose
What is a hydrolysis reaction?
When 2 molecules are broken apart using a water molecule
What is broken down by hydrolysis to form monosaccharides?
Carbohydrates
What makes up starch?
Amylose and amylopectin
