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103 Cards in this Set

  • Front
  • Back

How do pathogens enter the body?

Gas exchange system


Digestive system

How do pathogens cause disease

Damaging host tissues


Producing toxins

Name the major organs in the digestive system

Oesophagus


Stomach- contains HCl


Small intestine- microvilli absorb nutrients


Lage intestine - absorb water


Rectum

What is hydrolysis?

The breaking down of a molecule by the addition of water

Where is amylase produces

Salivary glands


Pancreas

Define digestion

The process in which large molecules are hydrolysed by enzymes to produce smaller molecules that can be absorbed and assimilated

What is the general structure of an amino acid

H


NH2-C-C=O


R OH

How does a peptide bond form

Condensation reaction between two amino acids

What is primary structure

The sequence of amino acids

What is secondary structure

The shape a polypeptide forms as a result of H bonding. Results in alpha helix or beta pleated sheet

What is tertiary structure

The overall 3D shape

What is quaternary structure

Results from a combination of polypeptides

What is the test for proteins

Add biuret


Purple positive


Blue negative

How do enzymes speed up a reaction

Lowers activation energy

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

What bonds are in the tertiary structure of proteins, and which are the strongest?

1.Disulfide


2.Ionic


3.hydrogen

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

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

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

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

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

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

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

Glucose +Glucose --->


Glucose + Fructose --->


Glucose + Galactose --->

Maltose


Sucrose


Lactose


Formed by a condensation reaction

What is the test for reducing sugars

Add Benedict's and heat


Positive brick red precipitate


Negative blue

Name a non reducing sugar

Sucrose


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










What is the test for starch

Add iodine


Positive blue black

Magnification=

Image size in um


-----------------


Actual size in um

What is magnification

How many times bigger an image is compared to the original object

What is resolution

The minimum distance apart that two objects can be in order for them to be seen as two separate items

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


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

What are the advantages and disadvantages of a scanning electron microscope

High resolution


3D picture


Complex process


Expensive


Needs to be a thin specimen

Why can electron microscopes resolve objects better than light microscopes

Light has a longer wavelength than a beam of electrons

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

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


RER/SER

RER


Synthesis of proteins and glycoproteinsTransport of materials around the cell


SER


Synthesis and store and transport lipids and carbohydrates

Golgi

Transport and package carbohydrates


Form lysosomes

Lysosomes

Contains enzymes to digest

Ribosomes


Synthesise proteins


80S large in eukaryotes


70s smaller in prokaryotes

Microvilli

Increase SA in Small intestine for absorption

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

Steps in cell fractionation

What are the heaviest organelles

What are the roles of lipids

An energy source


Waterproofing (they are insoluble)


Insulation


Protection

How is a triglyceride formed

3 fatty acids + glycerol condensation reaction. 3H20 formed

How are phospholipids formed

One fatty acid in a triglyceride is replaced by a phosphate molecule

Describe a phosopholipid

Hydrophilic head which is attracted to water


Hydrophobic tail which moves away from water

Test for lipids

Add ethanol and water


Positive cloudy white

How do fatty acids differ

They are either saturated unsaturated or polyunsaturated

Plasma membrane

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

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

Diffusion is proportional to

Surface area x difference in concentration


---------------------–---------------------


Length of diffusion pathway

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

Define Osmosis

The movement of water from a region of high water potential to low water potential through a partially permeable membrane

Pure water has a water potential of

0 kPa

An isotonic solution is

Where the water potential is equal on both sides of a membrane

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

What are the differences between pro and eukaryotic cells?

Label

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

What does a ORS contain and why

Key features of exchange surfaces

Large SA


Very thin


Partially permeable


Diffusion gradient maintained

Describe the passage of oxygen into the blood

Lungs Alveoli capillary

How do we inhale

Diaphragm contracts


Intercostal muscles contract


Ribs pulled up and out


Decreases pressure in lungs


Air moves along a pressure gradient

Pulmonary ventilation =

Tidal volume (dm3) x ventilation rae (min-1)

What is the bacteria that causes TB called

Mycobacterium tuberculosis (or bovis)

Label

Describe how TB is transmitted

Through the air by droplets eg coughing, sneezing talking

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






































































What is pulmonary fibrosis

Scarring on the lung epithelium causing the lungs to become irreversibly thickened


Reduces elasticity of lungs


Increases diffusion pathway

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










































What causes emphysema

SmokingElastin permanently stretched


Reduces elasticity of lungs


Less recoil


Air not forced out


Alveoli can burst

General symptoms of lung disease

Couching


Shortness of breath


Fatigue

Why does the ventricle have a thick wall

Muscle to pump blood to the rest of the body

Which chamber of he heart is the pressure the greatest in

Left Ventricle

Cardiac output =

Heart rate (min-1) x stroke volume (dm3)

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

Atrial systole


Atria contract forcing the remaining blood out

Ventricular systole

Short delay to allow ventricle to fill with blood


Ventricles contrac



















. Shuts AV valves opens SL valves blood flows out












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























A

What is an atheroma

A fatty deposit within the wall of an artery from Low density lipoproteins

What is thrombosis

Atheroma breaks causing the blood to clot

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

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

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

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

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

What is an antigen

A molecule on the surface of a pathogen that triggers an immune response (antibody production)

What is an antibody

A protein produced by lymphocytes in response to the presence of a foreign antigen

Where do B and T lymphocytes mature

B in Bone marrow


T in Thymus gland

What is the function of T cells

Kill infected cells by punching a whole in their membrane

What is humoral immunity

Immunity that involves antibodies

Why do antigens have a quaternary structure

They have more than 1 polypeptide

What is the use of monoclonal antibodies

Targeting specific substances and cells

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

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

How is the stomach adapted toa) churn food


b) prevent enzymes digesting itself

a) has a muscular wall


b) has a mucas lining