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103 Cards in this Set
- Front
- Back
How do pathogens enter the body? |
Gas exchange system Digestive system |
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How do pathogens cause disease |
Damaging host tissues Producing toxins |
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Name the major organs in the digestive system |
Oesophagus Stomach- contains HCl Small intestine- microvilli absorb nutrients Lage intestine - absorb water Rectum |
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What is hydrolysis? |
The breaking down of a molecule by the addition of water |
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Where is amylase produces |
Salivary glands Pancreas |
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Define digestion |
The process in which large molecules are hydrolysed by enzymes to produce smaller molecules that can be absorbed and assimilated |
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What is the general structure of an amino acid |
H NH2-C-C=O R OH |
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How does a peptide bond form |
Condensation reaction between two amino acids |
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What is primary structure |
The sequence of amino acids |
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What is secondary structure |
The shape a polypeptide forms as a result of H bonding. Results in alpha helix or beta pleated sheet |
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What is tertiary structure |
The overall 3D shape |
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What is quaternary structure |
Results from a combination of polypeptides |
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What is the test for proteins |
Add biuret Purple positive Blue negative |
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How do enzymes speed up a reaction |
Lowers activation energy |
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How does the lock and key model differ from the induced fit model |
Lock and key states enzyme and substrate are exact fit whereas induced fit states that the enzyme can slightly change shape and mould itself around a substrate |
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What bonds are in the tertiary structure of proteins, and which are the strongest? |
1.Disulfide 2.Ionic 3.hydrogen |
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How could changing one amino acid affect the function of an enzyme |
Affect primary and tertiary structure Changes the shape of the active site No E/S complexes can form |
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What is the effect of temperature on enzyme controlled reactions |
RoR increases as temperature increases as molecules have more kinetic energy so more frequent successful collisions. After a certain point temperature is too high, which causes bonds in the tertiary structure to break causing the enzymes to denature. The active site has changed shape so no E/S complexes can form |
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What is the effect of pH on enzyme action |
A wrong pH (different for different enzymes) causes bonds in the tertiary structure to break, denatures enzyme Also alters be charge on amino acids so the substrate cannot bind |
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How does competitive inhibition of an enzyme work |
A molecule with a similar shape to a substrate binds to an enzyme instead of the substrate. Therefore there are less active sites available so less E/S complexes form so rate of reaction decreases |
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How does non competitive inhibition of an enzyme work |
A molecule binds to a place on an enzyme that is not the active site. This causes the active site to change shape, so no E/S complexes can form |
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How is starch digested |
Salivary amylase starts to break alternate glycosidic bonds in starch turning it into maltose. In the stomach the amylase then denatures. The pancreas squirts pancreatic amylase to turn the remaining starch into maltose In the small intestine, maltase is produced, which hydrolyses maltose into glucose |
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What causes lactose intolerance |
Some people do not produce enough lactase to break down lactose. As a result microorganisms in the small intestine break it down which causes bloating and gas |
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Glucose +Glucose ---> Glucose + Fructose ---> Glucose + Galactose ---> |
Maltose Sucrose Lactose Formed by a condensation reaction |
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What is the test for reducing sugars |
Add Benedict's and heat Positive brick red precipitate Negative blue |
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Name a non reducing sugar |
Sucrose
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What is the test for non reducing sugars |
Add Benedict's and heat. If negative add HCl and hea Neutralise or make slightly acidic with sodium hydrogencarbonat |
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What is the test for starch |
Add iodine Positive blue black |
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Magnification= |
Image size in um ----------------- Actual size in um |
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What is magnification |
How many times bigger an image is compared to the original object |
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What is resolution |
The minimum distance apart that two objects can be in order for them to be seen as two separate items |
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What are the advantages and disadvantages of a light microscope |
Cheap Easy to use. Doesn't take long to prepare a slide Poor resolution as a result of the relatively long wavelength of light
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What are the advantages and disadvantages of a transmission electron microscope |
High resolution -can see organelles Needs to be in a vacuum Complex process Thin specimen May contain artefacts - a result from the specimin being prepared and not actually there |
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What are the advantages and disadvantages of a scanning electron microscope |
High resolution 3D picture Complex process Expensive Needs to be a thin specimen |
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Why can electron microscopes resolve objects better than light microscopes |
Light has a longer wavelength than a beam of electrons |
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What is the structure of a nucleus |
Nuclear envelope - double membrane that surrounds the nucleus Nuclear pores - allow the passage of late molecules Nucleoplasm- jelly like material Chromatin - DNA within the nucleoplasm Nucleolus- manufacturers ribosomal RNA Functions of the nucleus Control centre of the cellContains DNA and chromosomes |
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Structure and function of mitochondria |
Double membrane Cristae - foldings provide a large SA for enzymes involved in respiration Matrix - the remainder of the mitochondria Function Aerobic respiration Produce ATP
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RER/SER |
RER Synthesis of proteins and glycoproteinsTransport of materials around the cell SER Synthesis and store and transport lipids and carbohydrates |
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Golgi |
Transport and package carbohydrates Form lysosomes |
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Lysosomes |
Contains enzymes to digest |
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Ribosomes |
Synthesise proteins 80S large in eukaryotes 70s smaller in prokaryotes |
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Microvilli |
Increase SA in Small intestine for absorption |
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What conditions are needed for cell fractionation and why |
Cold- reduce enzyme activity that might break down organelles Isotonic- prevent organelles (not cells!) from bursting or shrinking Buffered - maintain a constant pH |
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Steps in cell fractionation |
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What are the heaviest organelles |
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What are the roles of lipids |
An energy source Waterproofing (they are insoluble) Insulation Protection |
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How is a triglyceride formed |
3 fatty acids + glycerol condensation reaction. 3H20 formed |
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How are phospholipids formed |
One fatty acid in a triglyceride is replaced by a phosphate molecule |
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Describe a phosopholipid |
Hydrophilic head which is attracted to water Hydrophobic tail which moves away from water |
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Test for lipids |
Add ethanol and water Positive cloudy white |
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How do fatty acids differ |
They are either saturated unsaturated or polyunsaturated |
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Plasma membrane |
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What is the function of the phosopholipid membrane |
Allows lipid soluble material to enter and exit the cell Prevents water soluble substances entering and leaving the cell Makes the membrane flexible |
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What is the function of the proteins in the plasma membrane |
Provide structural support Transport water soluble materials Allow active transport by forming ion channels Act as receptors for hormones |
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Diffusion is proportional to |
Surface area x difference in concentration ---------------------–--------------------- Length of diffusion pathway |
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How does facilitated diffusion work |
Molecules bind to carrier proteins, causing the proteins to change shape letting the molecules through Alternatively proteins form water filled channels allowing water soluble molecules to pass through |
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Define Osmosis |
The movement of water from a region of high water potential to low water potential through a partially permeable membrane |
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Pure water has a water potential of |
0 kPa |
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An isotonic solution is |
Where the water potential is equal on both sides of a membrane |
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How does glucose co transport work |
1. Na out of epithelial cells into capillaries 2.Na diffuses out of lumen into epithelial 3. Na couples win glucose and moves into epithelial with it 4. Glucose passes into blood through facilitated diffusion |
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What are the differences between pro and eukaryotic cells? |
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Label |
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How does cholera cause diarrhoea |
Cholera produced a toxin that binds specifically to the epithelial cells, which causes ion channels to open. Chloride ions then flood the small intestine, causing the water potential to decrease. Hence water is drawn out of epithelial cells into the lumen of the small intestine by osmosis |
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What does a ORS contain and why |
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Key features of exchange surfaces |
Large SA Very thin Partially permeable Diffusion gradient maintained |
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Describe the passage of oxygen into the blood |
Lungs Alveoli capillary |
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How do we inhale |
Diaphragm contracts Intercostal muscles contract Ribs pulled up and out Decreases pressure in lungs Air moves along a pressure gradient |
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Pulmonary ventilation = |
Tidal volume (dm3) x ventilation rae (min-1) |
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What is the bacteria that causes TB called |
Mycobacterium tuberculosis (or bovis) |
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Label |
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Describe how TB is transmitted |
Through the air by droplets eg coughing, sneezing talking |
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Course of infection of TB |
Primary infection:White blood cells ingest the bacteria Leads to inflammation and enlargement of the lymph nodes Some bacteria remain Secondary infection: Bacteria re emerge in the upper regions of the lungs Bacteria destroy lung tissue Leads to scar tissue Can spread to whole body
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What is pulmonary fibrosis |
Scarring on the lung epithelium causing the lungs to become irreversibly thickened Reduces elasticity of lungs Increases diffusion pathway |
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What causes asthma |
Allergens cause
Lining of airways to become inflamedMore mucas to be secreted Fluid leaving capillariesThe muscle surrounding the bronchioles contracts so constricts the airway
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What causes emphysema |
SmokingElastin permanently stretched Reduces elasticity of lungs Less recoil Air not forced out Alveoli can burst |
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General symptoms of lung disease |
Couching Shortness of breath Fatigue |
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Why does the ventricle have a thick wall |
Muscle to pump blood to the rest of the body |
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Which chamber of he heart is the pressure the greatest in |
Left Ventricle |
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Cardiac output = |
Heart rate (min-1) x stroke volume (dm3) |
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What is diastole |
Relaxation of the heart As the atria fill, the pressure rises, causing the AV valves to open and blood flow to the ventricles The pressure is lower in the ventricles than the aorta so SL valves shut |
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Atrial systole |
Atria contract forcing the remaining blood out |
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Ventricular systole |
Short delay to allow ventricle to fill with blood Ventricles contrac . Shuts AV valves opens SL valves blood flows out |
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How is the cardiac cycle controlled |
A wave of electrical activity from the sinoatrial node, causing atria to contract Non conductive tissue prevents ventricles contracting Short delay before AVN sends out electrical activity along bundle of his Heart beats from apex upwards
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What is an atheroma |
A fatty deposit within the wall of an artery from Low density lipoproteins |
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What is thrombosis |
Atheroma breaks causing the blood to clot |
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What causes an aneurysm |
Atheromas weaken the artery walls. These points swell as they fill with blood. These then burst leading to a haemorrhage. Can move to brain and cause a stroke |
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What causes myocardial infarction |
In conary artery, Atheroma bursts, leads to thrombosis, blood cannot get to heart muscle, so no O2 or nutrients, so muscle dies |
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How does smoking increase risk of heart disease |
Carbon monoxide combines with Hb so heart works harder, increases blood pressure Nicotine stimulates adrenaline whij increases heart rate and blood pressure |
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What are risk factors associated with heart disease |
Smoking High blood pressure Blood cholesterol LDLs Diet- high salt raises bp, high saturated fat increases LDLs |
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Describe phagocytosis |
The phagocyte is attracted to the pathogen by chaemoattractants The phagocyte binds to the pathogen The lysosomes within the phagocyte move towards the engulfed pathogen Forms a phagosome Enzymes released and pathogen digested |
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What is an antigen |
A molecule on the surface of a pathogen that triggers an immune response (antibody production) |
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What is an antibody |
A protein produced by lymphocytes in response to the presence of a foreign antigen |
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Where do B and T lymphocytes mature |
B in Bone marrow T in Thymus gland |
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What is the function of T cells |
Kill infected cells by punching a whole in their membrane |
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What is humoral immunity |
Immunity that involves antibodies |
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Why do antigens have a quaternary structure |
They have more than 1 polypeptide |
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What is the use of monoclonal antibodies |
Targeting specific substances and cells |
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What is the difference between passive and active immunity |
Passive where antibodies are given Active stimulates antibodies by a person's own immune system. Lasts longer |
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Why does vaccination not eliminate a disease |
Fails against people with poor immune systems Pathogen may mutate frequently Not all vaccinated for medical or religious reasons |
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How is the stomach adapted toa) churn food b) prevent enzymes digesting itself |
a) has a muscular wall b) has a mucas lining |