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UNIT 1
BIOLOGY
Cells:
Tissue – A group of cells that carry out a job
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System – A group of organs that work together to carry out a job
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Microvilli – Increase surface area
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Pores
allow substances to move between the nucleus and the cytoplasm e
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RNA
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Lysosome – Contains digestive enzymes
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Ribosome – The site where proteins are made
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Rough folds and
processes proteins which have been made at the ribosomes
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It also makes lysosomes
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Produces ATP for active transport
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Smallest distance between
two objects where the microscope can still distinguish the object as separate
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001mm
0
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Solution kept ice cold to reduce enzyme activity
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Prevents
bursting or shrivelling caused by osmosis
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Organelles smaller than debris
so they pass through the gauze
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The tube is placed into a centrifuge and spun at a
low speed
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Spun in the centrifuge at a
higher speed
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Separated by mass: nuclei, mitochondria, lysosomes, endoplasmic reticulum and
then ribosomes
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Ribosomes – site where proteins are made
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Capsule – protects the cell from attack by immune system cells
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Bacterial chromosome – contains genetic material, floats free in the cytoplasm
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Membrane – Regulates movement of substances in and out of the cell
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Phosphate group is highly polar so attracts water
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Arrange into a bilayer
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Plasma membrane:
Fluid mosaic model – mosaic as there are many proteins scattered around the membrane
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Diffusion:
Particles move from an area of high concentration to an area of low concentration down a
concentration gradient
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Rate of diffusion:





Temperature – higher the temperature the more kinetic energy
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Concentration – The greater the difference the faster the rate
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Thin exchange surface – Diffusion only efficient over short distances
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Carrier proteins take particular substances from one side of the membrane to the other by
co-transport, e
...
when an ion such as Na+ is transported alongside glucose
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g
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Osmosis:
The net movement of water molecules from an area of high concentration to an area of low
concentration, across a partially permeable membrane
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Hypertonic – more negative water potential (would cause a cell to shrink)
Isotonic – same water potential
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Active Transport:
Moves molecules against their concentration gradient with the use of ATP
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Biological molecules:
Carbohydrates:
Contain carbon, hydrogen and oxygen
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Glucose molecule:

Disaccharides:
Made by condensation reactions - glucose joining to another monosaccharide
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Monomer – a molecule that can be bonded to other identical molecules to form a polymer
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Starch is made of amylose and amylopectin
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A lot of glucose can be stored in a cell as it is compact
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It
is branched and insoluble
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Cellulose – made by many beta glucose molecules joined together by glycosidic bonds
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It keeps plant cells rigid
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They are polymers of amino acids
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They are joined by peptide bonds
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Amino acid:

Condensation reactions link amino acids together
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Secondary structure – Hydrogen bonds form between the amino acids in the chain
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Tertiary structure – Coiled or folded chain coils or folds further
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For proteins with one polypeptide this is the final 3D shape
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This is
their final 3D shape
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Glycerol molecule:

Fatty acid molecule:

Triglyceride molecule: Formed by condensation reaction and the components are joined
with ester bonds
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(Solid at room temperature)
Unsaturated fatty acids – Have double bonds between carbon atoms which causes the chain
to kink
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Non-reducing sugar – Boil with dilute hydrochloric acid
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Heat with Benedict’s and it will go red/orange
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Proteins (Biuret test) – Add a few drops of sodium hydroxide to make the solution alkaline
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Lipids – Add ethanol and shake for one minute
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Enzymes:
The rate of metabolic reactions are controlled by enzymes
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They are specific: they work on one particular substrate
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They are globular proteins with a precise 3D structure
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Made from one or more chains of amino acids
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Activation energy – the energy that needs to be provided before a reaction can take place
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Lock and key:
The substrate binds to the active site to form an enzyme-substrate complex
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Induced fit hypothesis:
The active site changes shape so that the enzyme moulds itself around the substrate
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It
gives a measure of the speed of enzyme action
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The molecules gain more kinetic energy and move faster which increases the chance of
collisions
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This causes the enzyme to denature
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PH – If PH increases or decreases beyond the optimum the rate of reaction decreases
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The shape of the
enzyme and the active site changes
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Enzyme concentration – Increasing the number of active sites increases the rate of reaction
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Substrate concentration – As it increases the rate of reaction increases as more enzymesubstrate molecules can be formed
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Rate of
reaction then depends on the turnover rate of the enzyme
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Competitive inhibitor – They are similar to the shape of the substrate
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This prevents the substrate from entering the active
site as it is blocked
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They bind to the enzyme
anywhere but the active site
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Digestion:
Mouth – Starts the digestive process
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Saliva is secreted to make food easier to swallow and it contains
enzymes which start to break down food
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) Mucus is secreted from tissue walls to lubricate the foods passage
down
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The entrance and exit are controlled by
sphincter muscles
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Peristalsis of the stomach turns food into chyme
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In the duodenum
bile and pancreatic juice neutralise the acidity of the chyme and break it down into smaller
molecules
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Large intestine – Absorbs water salts and minerals
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Liver – Produces bile
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Gall bladder – Where bile is stored
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Transmission is usually via drinking
contaminated water
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The toxin causes chloride ion protein channels in the epithelial cells to open
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The build-up of chloride ions lowers the water
potential of the lumen
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The big increase in water secretion leads to diarrhoea causing the body to
become extremely dehydrated
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It contains a large amount of
salts (sodium and chloride ions) and sugars (sucrose and glucose) dissolved in water
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The lungs and lung disease:
Inspiration (breathing in) – The intercostal and diaphragm muscles contract
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As thorax pressure increases lung pressure decreases
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This is an active process
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The ribcage moves downwards
and inwards and the diaphragm becomes curved again
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Air is forced out of the lungs
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Alveoli – Made from a thin layer of flat cells called alveolar epithelium
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They have a
large surface area as there are a large numbers of alveoli
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Carbon dioxide diffuses into the alveoli from
the blood and is breathed out
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Tidal volume – volume of air in each breath
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Spirometer – A machine which measures the volume of air breathed in and out
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They form tubercles, infected tissues within the tubercles dies
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Symptoms include a persistent cough, coughing up
blood, chest pain, shortness of breath and fatigue
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Fibrosis – It is the formation of scar tissue in the lungs
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They are less able to expand and so can’t hold as much air as usual, tidal volume is reduced
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This means less respiration takes place so less energy is released
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This causes constriction of the airways
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The body receives less oxygen so the rate of aerobic respiration is reduced
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Emphysema – Foreign particles become trapped in the alveoli which causes inflammation,
this attracts phagocytes to the area
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The loss of elastin means the alveoli can’t recoil to expel air as well
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This reduces rate of gas exchange
and the lack of oxygen leads to fatigue
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The heart and heart disease:
Heart valves – If there is higher pressure behind the valves they are forced open
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Control heart beat –



Myogenic – it can contract and relax without receiving signals from walls
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



Collagen tissue prevents the waves of electrical activity being passed straight to the
ventricles
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They pass the wave to the His bundle
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The
bundle of his conduct the wave to the finer muscle fibres in the ventricle walls –
pukyne fibres
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Cardiac output = stroke volume x heart rate
Heart rate – The number of heart beats per minute
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Cardiac cycle:






Ventricles relax, atria contract – decreases chamber volume, increasing pressure
inside the chamber
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Slight increase in
ventricular pressure and chamber volume as ventricles receive blood from
contacting atria
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Pressure higher in ventricles than atria, forces AV valves to shut
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Ventricles relax, atria relax – Higher pressure in the pulmonary artery and aorta
forces the SL valves closed
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Starts to increase
pressure of the atria
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Blood flows passively into the ventricles
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Atheroma – If damage occurs to the endothelium white blood cells and lipids (fat)
from the blood clump together under the lining to form fatty stacks
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It partially
blocks the lumen of the artery, restricting blood flow and increasing blood pressure
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Atheroma plaque damages and
weakens arteries
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It may
burst causing a haemorrhage
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It
damages the artery wall and leaves a rough surface
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This can cause blockage of the artery or
become dislodged and block a blood vessel elsewhere in the body
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It will receive no
oxygen causing a myocardial infarction
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Coronary heart disease – The coronary arteries have a lot of atheromas in them
which restricts blood flow to the heart
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The order of
amino acids gives it a specific shape
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The cytoplasm of
a phagocyte moves around the pathogen, engulfing it
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A lysosome fuses with the phagocytic vacuole
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The phagocyte presents the
pathogen’s antigens on its surface to activate other cells
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Some release substances to activate B-cells and some attach to antigens
and kill the cell
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Each B-cell has a
different shaped antibody on its membrane (specific
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Antibody production – plasma cells are clones of the original B-cell
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Primary response – when an antigen enters the body for the first time it activates
the immune system
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The infected person will show symptoms of the
disease
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The person is now immune
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Memory B-cells divide
into plasma cells
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It gets rid of the pathogen before you show symptoms
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The spleen cells contain B lymphocytes
that have been stimulated by the antigen and can produce antibodies specific to the
antigen
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They will grow forever in tissue culture if the
nutrients are replaced every few days
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They grow forever and secrete antibodies into the culture medium – monoclonal
antibody
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Each cell is tested to see if it is specific to the antigen
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