biology unit 1

a compacted version of unit 1 

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A micro-organism that causes disease.

Gain entry,

Colonise tissue,

resist defences,

causes damage

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Micro Organism into body & Defences

Gas exchange system

Diestive system 

Mucous layer


Stomach Acids

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Pathogens cause disease

Damage host cells

Producing toxins

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Lifestyle Choices




physical activity


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CHD lifestyle factorsa nd redusing the risks

smoking, high blood pressure, blood cholesterol levels, obesity, diet, physical activity

giving up smokeing not starting, avoid obesity, reduce salt intake, reduse cholesterol, more sat. fats in diet, regular aerobic exercise, alcohol intake low, increase dietery fibre & anti oxidents

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Major parts of the digestive system

Oesopagus- transport, thick muscular wall

Stomach- muscular sac, produces enzymes and mucous

small intestine- long muscular tube, S.A increased (micro)villi 

large intestine- absorbs water, faeces, egestion

salivary gland- amylase, starch into maltose

pancreas- large gland, protease-proteins, lipase-lipids, amylase-starch 

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2 types of digestion

Physical- large molecules to small molecules, by means of structures like teetha nd stomach muscles, increases surface area for chemical digestion, 

Chemical- large insoluable molecules into smaller soluable ones, carried out by enzymes functioning by hydrolysis, (adding water to break up bonds molecules)


Carbohydrase- carbohydrates into monosaccharides

Lipase- lipids into glycerol and fatty acids

Protease- proteins into amino acids

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Carbon molecules

readily form bonds with other carbon atoms, organic compounds formed, 

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Monosaccharides & Reducing sugars

sweet tasting, soluble, general formular (CH2)0 n, 3<n<7

Glucose is a monosacchride, 6 carbons, 

Redusing sugars:-

Benedicts test

benedicts reagent is an alkaline solutions of copper (II) sulphate, when redusing sugars are heated you get red precipitate, copper oxide

blue-none, green-very low, yellow- low, orange- medium, red- high

Non- reducing sugars you have to boil then it will go orange-brown

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Disaccharides and Polysaccharides

Glucose + Glucose -> Maltose

Glucose + Fructose -> Sucrose

Glucose + Galactose -> Lactose

When monosaccharides are are formed through condensation a water molecule is given out, forming a gylcosidic bond

breaking them is called hydrolysis, addition of a water molecule. 

-OH  HO-  -------->  -O- +H2O

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Starch Digestion

food into mouth chewed, smaller pieces, larger surface area

salvia, mixed with food, salviary amylase startd hydrolysing any starch, to maltose, neutral pH

into stomach, amylase denatured by pH, bacteria killed

small intestine, mixes with pacreatic juices containing pancreatic amylase, starch into maltose, pH neutral again

then maltase is produced breaking maltose into alpha-glucose

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Amino Acids (primary, secondary, tertiary, quatern

amino group (-NH2)
r group- (-variety of different chemical groups)
hydrogen atoms- (-H)
carboxyl group- (-COOH)

Primary- monomers joined together through polymerisation, produces polypeptide, determines ultimate shape and function

secondary- (-NH) has +tive charge (-O) had -tive charge, alpha helix or beta pleated sheet, made by H bonds, 3D shape

tertiary- twisted on itself, disulphide bonds -> strong, ionic bonds -> carboxyl groups and amino groups weaker effectd by pH, H bonds -> numerous easily broken.

Quaternary structure- groups or tertiary structure linked together, haemoglobin (haem group)

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Fibrous and Globular

Fibrous- structural functions

unbranched polypeptide chain
polypeptide chain tightly wounded, compact
twisted second helix
3 polypeptide chains wound like rope

Globular- metabolic functions, haemoglobin, enzymes.

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Lock and Key, Induced Fit Model

Lock and Key-

Advs- specific shape (active site), substrate complementary.
Disadvs- rigid structure, applying pressure to substrate.

Induced Fit-

Advs- slightly flexible, moulds to substate like glove to hand, applying pressure to break substrate, molecules affect enzyme activity, activation is lowered.
Diadvs- not so complementary to substrate.

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Effect on enzyme activity

Temp- more kinetic energy, move more rapidily, more collision more often, more enzyme-substrate complexes.

pH- alters charges on amino acid and carboxyl groups that make up active site, not complementary, less enzyme-substrate complexes, breaks bonds creating the tertiary structure, 

Substrate Conc.- rate of reaction increases as conc. increases, more substrates to bind with and break, will plateau because enzyme becomes a limiting factor.

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(Non-)Competitive inhibitors

Competitive- in active site,  substrate cannto bond with enzyme, compete for active sites, if enzyme conc. increases the effect of the inhibitor is reduced.

Non-Competitive- they attached at other site not active site, affects the shape of active site, enyme not complementary, less enzyme-substrate complexes, an increase in substrate conc. does not effect the effect of the inhibitor.

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magnefication=size of image/size of object

size of object= size of image/magnefication

resolution- min. dstance apart 2 things must be to be seen as seperate objects, clarity, light mocroscope, 0.2 micrometres, electron microscope 0.1 nanometres

electron microscope-2 types TEM, SEM 
advs- electron beam is very short wavelength good resolution, beam can be focused ( -tively charged)

TEM- in vacuum, dead specimins, complex staining process, black white image, specimin extremely thin, can contain artefacts

SEM- all of TEM except specimins can be thicker, build up 3D image.

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Cell Fractionation

cold- to reduce enzyme activity
isotonic- to stop osmosis
buffered- control pH


cells broken up, relaease organelles from cell, filtered to remove any complete cells or large debris. 


placed in centrifuge and spung low speed
heavy organelle at bottom form sediment/pellet
fluid at top removed spun faster 
supernatant is removed leaving sediment 
nucleus, mitochrondira, endoplasmic reticulum

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Structure of an Epithelial Cell (Nucleus)

Nucleus-control cell, retain genetic materials, manufacture RNA & ribosomes

nuclear envelope- double membraned, had ribosomes on it, controls entry and exit, contains reactions

nuclear pores- allows passage of large molecules 

nucleoplasm- granular, jelly like, material makes up most of nuclus

Chromatin- DNA within nucleus this is diffuse form that chromosomes make up when cell is not dividing

Nucleolus- small spheric body withing nucleoplasm, manufactures RNA

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Structure of an Epithelial Cell (Mitochondria)

Mitochondria- rod shaped RESPIRATION
double membrane- outer controls what goes in/out, inner folded to form extension known as cristae

Cristae- shelf like extensions, large S.A, 

Matrix- semi rigid, contains proteins, lipids, traces of DNA

responsible for making the energy-carrier molecule, ATP from carbohydrates
epithelial cells use lost of energy, active transport, need lots of ATP  

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Structure of an Epithelial Cell (Endoplasmic retic

Endoplasmic reticulum- elaborate, 3D system 

rough RER- ribosomes present on surface membrane 
large surface area, pathway for transport of materials espec. proteins

smooth SER- lack of ribosomes on surface, more tubular,
synthesis, store and transport lipids and carbohydrates.

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Structure of an Epithelial Cell (Golgi Apparatus)

Golgi apparatus- similar structure to SER, more compact, modifies proteins, adds non protein components, 'labels' them, send to correct destinations, transported in vesicles


add carbs to proteins to make gylcoproteins

produce enzymes

secrete carbs 

transport, modify, and store lipids

form lysosomes

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Structure of an Epithelial Cell (Lysosomes)

Lysosomes- contain potentially harmful enzymes, suicide cells, gets rid of enzymes outside of cells or in phagocytic cells, 


break down materials ingested by phagocytic cells such as white blood cells

release enzymes to outside cell to destroy outside cells 

digest worn out organelles

completely break down cells after they have died

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Structure of an Epithelial Cell (Ribosomes/Microvi

Ribosomes- PROTEIN SYNTHESIS   small cytoplasmic granules, associated with RER or cytoplasm, 2 types 

80s- eukaryotic cells, bigger

70s- prokaryotic cells, smaller

2 sub units, one big, one small, each contain RNA and protein, 

Microvilli- finger-like projections, increase S.A, allow efficient absorption, 

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contain carbon, hydrogen, oxygen
proportions are smaller then in carbs
insoluble in H2O
soluble in organic solvents such as alcohol
solid room temp 

Main group- triglycerides (condensation reaction (+H2O), phospholipids, waxes

energy source                               double bond- unsaturated
waterproofing                                  single bonds- saturated

Phospholipids- Polar, test for them by the emulsion test (ethanol)
hydrophilic 'head'- interacts with water not fat
hydrophobic 'tail'- moves away from water but mixes with fats. 

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