Module 2 Flashcards

1
Q

Components and functions of cell surface membrane

A
  • phospholipids form bilayer ( hydrophobic tails inwards, hydrophilic tails outwards )
  • provides barrier to large/polar molecules and ions
  • proteins from carrier or channel proteins across membrane
  • for active transport / facilitated diffusion
  • cholesterol molecules fit between phospholipids
  • stabilises membrane structure and regulate fluidity
  • glycoproteins (and glycolipids)
  • receptors for cell communication
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2
Q

roles of membranes within cells

A
  • form edge of organelles within a cell
  • isolation of organelle contents from cytoplasm
  • site for attachment of enzymes and ribosomes (RER)
  • provide selective permeability to control what enters and leaves organelles
  • separates areas of different concentrations to provide gradients
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3
Q

cell signalling- how receptors work

A
  • release of cell signal molecules e.g. hormones by exocytosis into blood
  • proteins/glycoproteins/glycolipids act as receptors (e.g for hormones/ drugs )
  • receptor is specific as the shape of the receptor and hormone are complementary
  • hormone binds to receptor
  • binding causes change in cell and brings about a response
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4
Q

Role of glycoproteins

A
  • cell signalling ( communication to work together )
  • antigens for…
  • cell recognition (self/ non self )
  • receptors found on target cells
  • for hormones/cytokines to trigger responses in cells
  • cell adhesion- hold cells together in tissue ( attaches to base membrane to stabilise tissue )
  • forms bonds with water molecules to stabilise membranes
  • (forms glycocalyx to attract water and dissolved solutes)
  • receptors on transport proteins
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5
Q

substances crossing membranes

A

small non polar molecules
-diffuse through bilayer

large substances

  • use carrier proteins
  • specific to certain molecules
  • protein changes shape to allow molecule through
  • facilitated diffusion/ active transport ( uses ATP against gradient, faster, one way)
  • endo/exocytosis
  • bulk transport

polar substances

  • through channel proteins
  • facilitated diffusion
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6
Q

Active transport

A
  • carrier proteins
  • low to high conc
  • uses ATP
  • one direction
  • faster than diffusion
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7
Q

facilitated diffusion

A
  • carrier/ channel proteins
  • large molecules e.g. glucose
  • ions/polar molecules e.g K+
  • when large/polar/water soluble materials cant pass through bilayer
  • no ATP
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8
Q

diffusion through bilyaer

A

small non polar molecules

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9
Q

compare carrier and channel proteins

A

CARRIER

  • specific to molecule
  • molecules attach to one side
  • protein changes shape
  • releases molecules on other side
  • carries large molecules across in facilitated diffusion
  • carries all molecules in active transport which requires energy

CHANNEL

  • specific to molecule
  • forms pore in centre of protein
  • hydrophilic lining in pore
  • allows charged and polar molecules across membrane in facilitated diffusion
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10
Q

diffusion definition

A

the net movement of molecules from a region of high concentration of that molecule to a region of low concentration of that molecule down a concentration gradient. passive.

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11
Q

facilitated diffusion definition

A

the net movement of molecules from a region of high concentration of that molecule to a region of low concentration of that molecule down a concentration gradient through carrier proteins (large molecules) or channel proteins (charged molecules). passive.

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12
Q

Active transport definition

A

the movement of molecules or ions across a membrane from a region of low low concentration to a region of higher concentration of that molecule, against the concentration gradient. uses ATP to drive protein pumps within the membrane

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13
Q

Osmosis definition

A

the net movement of water molecules from a region of high water potential to a region of low water potential down the water potential gradient across a partially permeable membrane. passive

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14
Q

stages in producing an extracellular protein

A
  • nucleus contains gene which codes for protein
  • transcription produces mRNA
  • ribosomes/ RER are production site
  • protein transported to Golgi
  • Golgi modifies and packages protein into vesicle
  • vesicles move towards the cell surface membrane
  • vesicles fuse with cell surface membrane
  • protein released by exocytosis
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15
Q

stages of exocytosis

A
  • vesicles move towards cell surface membrane
  • along microtubules
  • vesicles fuse with cell surface membrane
  • released by exocytosis
  • movement of vesicles on microtubules and fusion with membrane requires ATP
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16
Q

Stages of endocytosis

A
  • molecule binds to receptor
  • causes cell surface membrane to invaginate (fold in on itself )
  • requires ATP
  • membrane fuses with itself
  • forming a vesicle
  • vesicle moves through cytoplasm to designated organelle
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17
Q

Roles of the cytoskeleton

A
  • cell support and stability to maintain shape
  • movement of cilia
  • movement of flagellum to move cell
  • changing shape of cell (exo/endocytosis)
  • move organelles
  • anchor organelles
  • move chromosomes and mRNA
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18
Q

Microtubules (cytoskeleton)

A
  • hollow tubulin cylinders 25nm
  • maintain cell shape and anchor organelles
  • make up 9+2 flagellum and cilia in eukaryotes
  • move vesicles using microtubule motor proteins ATP
  • spindle fibres move chromosomes
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19
Q

Intermediate filaments (cytoskeleton)

A
  • keratin cables 10nm

- maintains cell shape and anchors organelles

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20
Q

Actin microfilaments (cytoskeleton)

A
  • 2 twisted actin stands 7nm
  • maintains cell shape
  • causes muscle contraction
  • involved in cytokinesis
  • allows pseudopodia
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21
Q

organisation of cells in a multicellular organism

A
  • cells differentiate
  • groups of similar specialised cells work together to perform a common function to form tissues
  • groups of tissues work together to form organs
  • groups of organs work together to form organ systems
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22
Q

Cell Cycle

A

Interphase

  • G1, S, G2
  • G1- cells grow, respiration, proteins made, organelles replicated
  • s- DNA replication, chromosomes become sister chromatids joined by centromere
  • G2- DNA replication checked for mistakes, organelles replicated

Mitosis

  • Prophase- sister chromatids condense and supercoil, nuclear envelope breaks down, centromere replicates, spindle fibres form
  • Metaphase-sister chromatids line up at equator, spindle fibres attach to centromere
  • Anaphase- spindle fibres shorten, pull sister chromatids apart towards opposite poles
  • Telophase- chromosomes uncoil, nuclear envelope reforms

Cytokinesis

  • cytoplasm cleaves down furrow to split cytoplasm
  • produces 2 new genetically identical daughter cells ( and to parent )
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23
Q

Mitosis - prophase

A
  • chromosomes condense and supercoil to shorten and thicken
  • chromosomes consist of sister chromatids joined by centromere
  • now visible under light microscope
  • nuclear envelope breaks down
  • centriole divides in 2, each daughter centriole goes to opposite poles of the cell
  • spindle fibres (microtubules) begin to form
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24
Q

mitosis - metaphase

A
  • chromosomes (sister chromatids) line up along equator

- spindle fibres attach to centromere

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25
Q

mitosis - anaphase

A
  • centromere splits
  • chromatids separate
  • spindle fibres shorten
  • pulls identical chromatids to opposite poles with centromere leading
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26
Q

mitosis - telophase

A
  • chromosomes uncoil
  • nuclear envelope reforms
  • spindle fibres break down
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27
Q

mitosis vs meiosis

A
  • mitosis produces 2 genetically identical diploid daughter cells used for growth and repair. it occurs in all body cells and involves only one division
  • meiosis produces 4 genetically different haploid daughter cells and is used for producing gametes. it occurs only in the ovaries and testes and involves 2 divisions
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28
Q

cell division and budding in yeast cells

A
  • nucleus divides by mitosis
  • bulge in surface of cell
  • nucleus moves into bulge
  • bulge nips/ pinches off
  • leaves uneven distribution of cytoplasm
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29
Q

red blood cell differentiation

A
  • no nucleus or many organelles ( e.g. Golgi, mitochondria, ER) provides maximum space for haemoglobin to increase oxygen carrying capacity
  • also makes it more flexible to fit through capillaries ( well developed cytoskeleton )
  • filled with haemoglobin ( made when immature ) which binds to oxygen forming oxyhaemoglobin to transport it to aerobically respiring cells
  • bioconcave disc shape to provide large surface area and SA:VOL for oxygen exchange for more efficient uptake into red blood cells
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30
Q

root hair cell differentiation

A
  • hair like projection into soil provides large SA for osmosis and active mineral uptake into roots
  • thin wall for short diffusion path
  • many mitochondria provides energy for active transport of minerals
  • many carrier proteins for active transport of minerals
  • many channel proteins for uptake of water via osmosis
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31
Q

neutrophil ( phagocytes ) differentiation

A
  • lots of lysosomes contain lysin enzymes to digest pathogens
  • multi-lobed nucleus to fit between gaps in capillary endothelium to leave blood
  • many mitochondria to move lysosomes and phagosomes through cell along microtubules
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32
Q

Sperm differentiation

A
  • haploid nucleus so zygote from fertilisation is diploid
  • many mitochondria so energy for flagellum movement
  • long and thin for ease of movement
  • enzyme in acrosome to digest egg protective coating so sperm can fertilise it
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33
Q

Protein structure

A

Primary- order of amino acids joined in a polypeptide chain. joined with peptide bonds
Secondary- coiling or folding of chain into alpha helixes or beta pleated sheet. held with H bonds
Tertiary- overall 3D shape
-H bonds
-Ionic bonds between oppositely charged R groups
-Disulphide bridges between sulphurs on different amino acids
-Hydrophobic and hydrophilic interaction - hydrophobic move inside, hydrophilic move outside
Quaternary- more than one polypeptide to make final functional version of the protein

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34
Q

how does DNA structure determine specific shape of proteins

A
  • DNA codes for proteins
  • DNA transcribed then translated into polypeptide chain
  • 3 bases code for 1 amino acid
  • sequence of bases determines sequence of amino acids- primary structure
  • secondary- coiling/folding into alpha helixes or beta pleated sheets with H bonds
  • tertiary- overall 3D shape
  • quaternary- more than one polypeptide chain held to make final functional version
35
Q

properties of collagen for function

A
  • high tensile strength
  • not elastic
  • flexible
  • insoluble
36
Q

role of fats in organisms

A
  • energy source
  • energy store ( adipose cells store lipids )
  • phospholipid bilayers
  • thermal insulation
  • myelin sheath of neurones for electrical insulation
  • steroid hormones
  • waxy cuticle of leaves - prevents drying
37
Q

amylose

A
  • carbohydrate polysaccharide
  • a glucose joined with 1,4 glyosidic bonds
  • coiled, unbranched, compact
  • energy storage in plants
  • insoluble
  • stored in starch grains and reacts with iodine to turn it black
38
Q

amylopectin

A
  • carbohydrate polysaccharide
  • a glucose joined with 14 glycosidic bonds. branches form 1,6 glycosidic bonds
  • compact
  • energy storage in plants
  • insoluble
  • stored in starch grains, branches are hydrolysed to release a glucose for respiration for energy.
  • less branched than glycogen
39
Q

glycogen

A
  • carbohydrate polysaccharide
  • a glucose joined with 1,4 glycosidic bonds. branches form 1,6 glycosidic bonds
  • more compact and more branched than starch
  • energy storage in animals
  • insoluble
  • branches hydrolysed to release a glucose for respiration for energy. more branched than glycogen, more ends for hydrolysis. more energy release
40
Q

cellulose

A
  • carbohydrate polysaccharide
  • cellulose chains: b glucose with 1,4 glycosidic bonds. every other is flipped 180 in relation to last. long and unbranched
  • microfibrils: chains cross link with H bonds ( cross link into macrofibrils )
  • structural, in plant cell walls
  • insoluble
  • strong, pectin glues macrofibrils in cell wall in criss cross for increased strength. lets water through but stops cell from bursting
41
Q

Haemoglobin

A
  • globular protein
  • quaternary, 4 subunits ( 2 a chains, 2 b chains ) each has haem prosthetic group
  • carries oxygen in blood
  • soluble
  • haem group is non protein and contains Fe2+ ion
42
Q

Collagen

A

Collagen chain: every 3rd amino acid is glycine
Collagen molecule: quaternary, £ chains tightly wound, H bonds gives strength
Collagen fibrils: collagen molecules cross linked with covalent bonds
-structural in animals ( artey walls, cartilage, tendons, connective tissue )
-insoluble
-high tensile strength, not elastic, flexible

43
Q

Tryglyceride

A
  • lipid
  • 3 fatty acids joined to glycerol with ester bonds
  • energy store in animals
  • insoluble
  • compact storage in adipose cells, can be broken down more completely than carbs so releases more energy and metabolic water
44
Q

Phospholipid

A
  • lipid
  • 2 fatty acid tails ( bonded with ester bonds ) and a phosphate group head bonded to a glycerol
  • phospholipid bilayer membrane
  • heads soluble, tails not
  • more unsaturated bonds means more fluid membrane, prevents freezing in cooler climates (non homeotherms)
45
Q

cholesterol

A
  • lipid
  • 4 carbon rings
  • steroid hormones, decreases fluidity in membranes
  • insoluble
  • deposited in blood vessel causing atherosclerosis - narrowed vessels, increased bp, risk of myocardial infarction
46
Q

Compare the structures of collagen and haemoglobin

A

SIMILARITIES.
-both proteins made of amino acids
-held together by peptide bonds
-both tertiary structures with H, ionic, disulphide
-both have quaternary structure with more than one polypeptide chain
DIFFERENCES
-haemoglobin is globular, collagen fibrous
-haemoglobin has hydrophobic R on inside and hydrophilic R on outside, collagen does not
-haemoglobin has 4 polypeptide chains, collagen has 3
-haemoglobin has 2 different types of polypeptide chain, collagens are all the same
-haemoglobin has a wider range of amino acids, a third of collagens are glycine.

47
Q

compare glycogen and collagen

A
  • glycogen is a polysaccharide, collagen is a protein
  • monomers in glycogen are alpha glucose, in collagen they are amino acids
  • glycogen has glyosidic bonds between monomers, collagen has peptide bonds
  • glycogen branched, collagen unbranched
  • glycogen non helical, collagen is helical
  • only one chain per molecule in glycogen, 3 in collagen
  • no cross links in glycogen, cross links in collagen
48
Q

compare glycogen and cellulose

A
  • no H bonds In glycogen, H bonds in cellulose between chains
  • glycogen polysaccharide of alpha glucose, cellulose polysaccharide of beta glucose
  • glucose has 1,4 and 1,6 glycosidic bonds in glycogen but only 1,4 in cellulose
  • glycogen branched, cellulose isn’t
  • glycogen has no fibres, cellulose does
  • all glucose molecules same orientation in glycogen, but alternate flipped 180 from last in cellulose
49
Q

compare phospholipids and triglycerides

A
  • 2 fatty acids in phospholipids, 3 in triglycerides
  • 2 ester bonds in phospholipids, 3 in triglycerides
  • phosphate group in phospholipids
  • both have glycerol
  • both have fatty acids
  • both have ester bonds
  • both contain CHO
50
Q

why is glycogen a good storage molecule

A
  • insoluble
  • doesn’t reduce water potential of cell
  • can be hydrolysed easily
  • as lots of branches for enzymes to attach to
  • compact
  • so high energy content for mass
51
Q

water

A

HYDROGEN BONDING

52
Q

water and temperature stability

A
  • many/stable H bonds between molecules
  • lots of energy needed to break hydrogen bonds to break apart and heat molecules
  • high specific heat capacity
  • large amounts of energy must be removed to freeze
  • liquid under normal temperatures
  • slow to change temp so stays fairly constant
  • lakes/oceans/large volumes provide thermally stable environment
  • internal body temp changes minimised for aquatic life so close to enzyme optimum
53
Q

water and ice floating

A
  • water expands from 4 to freezing point
  • ice less dense as molecules spread out
  • max H bonds form, molecules in open lattice
  • ice floats on water
  • insulates water beneath
  • large bodies of water don’t freeze completely
  • organisms don’t freeze and can move and swim
  • causes currents to circulate nutrients
  • support for large organisms on ice (penguins or polar bears)
54
Q

water as a solvent

A
  • solvent for polar or ionic substances, ions attracted to water which cluster
  • gases soluble
  • reactions can take place
  • water plants can obtain nutrients e.g nitrates for proteins
55
Q

water as a transport medium

A
  • transports food particles for water dwelling organisms
  • transports male gametes for external fertilisation and stops them drying out
  • transport medium for blood cells
  • low viscosity aids movement
56
Q

water as transparent

A
  • transparent to light

- plants can photosynthesise under water

57
Q

water in plants

A
  • forms long unbroken columns of water
  • in xylem for transpiration
  • due to cohesion
  • reactant in photosynthesis
  • role in hydrolysis reactions
58
Q

water and cooling

A
  • high latent heat of vaporisation
  • lots of energy needed for molecules to escape
  • evaporation has cooling effect
  • sweating, panting, transpiration
59
Q

water as a surface

A
  • can use as habitat
  • due to high surface tension
  • water boatmen, pond skaters, water lily pads
60
Q

**protein test- what is it

A
  • add biuret

- blue to lilac

61
Q

**reducing sugar test (what is it)

A
  • add benedicts reagent and heat

- blue to red precipitate ( yellow/orange/green)

62
Q

non-reducing sugar test

A
  • boil with HCl to hydrolyse and free up OH groups
  • neutralise with sodium hydrogencarbonate
  • add benedicts and heat
  • blue to red precipitate
63
Q

starch test

A
  • add iodine

- orange to blue/black

64
Q

lipid test

A
  • add alcohol then mix with water

- white emulsion

65
Q

quantitative food test for sugar- determining conc of unknown solution

A
  • get known concentrations of reducing sugar
  • heat with excess benedicts
  • use same volumes of solution each time
  • colour change to red
  • remove precipitate to obtain filtrate
  • calibrate colorimeter with distilled water
  • use red colour filter
  • read transmission/absorbance for each known conc filtrate
  • more transmission/less absorbance = more sugar?
  • draw calibration curve
  • plot transmission / absorbance against sugar conc
  • use reading of transmission/ absorbance of unknown to read of graph to determine concentration
66
Q

structure of a DNA nucleotide

A
  • one phosphate group
  • one nitrogenous base (ATCG)
  • both joined to deoxyribose pentose sugar
  • with a covalent bond
67
Q

structure of an RNA nucleotide

A
  • one phosphate group
  • one nitrogenous base ( AUGC)
  • both joined to ribose pentose sugar
  • with a covalent bond
68
Q

difference between DNA and RNA

A
  • rna has ribose instead of deoxyribose
  • rna has uracil instead of thymine
  • rna single stranded not double
  • rna smaller
69
Q

Structure of nucleotide chain

A
  • 2 nucleotides bonded with 1 covalent bond
  • between phosphate group of one and pentose sugar of other
  • forming sugar phosphate backbone bonded by phosphodiester bonds
70
Q

how 2 nucleotide chains bonded

A
  • H bonds between bases
  • complementary base pairing
  • purine to pyrimidine
  • A to T with 2 H bonds
  • C to G with 3 H bonds
71
Q

DNA replication

A
  • double helix untwisted ( gyrase )
  • DNA unzipped when helicase breaks H bonds between bases
  • both strands act as a template for free DNA nucleotides to align and complementary base pair
  • H bonds reform
  • new strand synthesised in 5’ to 3’ direction by DNA polymerase
  • leading continuously synthesised, lagging in fragments later joined by ligase
  • activated nucleotides extra phosphates hydrolysed to provide energy to form phosphodiester bond
  • molecule twists into double helix
  • now 2 identical DNA molecules
72
Q

why DNA replication is semi conservative

A

-2 identical molecules made, each with 1 strand from the original molecule (conserved strand and template) and 1 new strand

73
Q

Enzyme wording

A
  • globular proteins
  • specific
  • active sites
  • substrate complimentary to active site
  • Enzyme substrate complexes
  • Lock and key/ induced fit
74
Q

Why enzymes are specific

A

-shape of active site is complimentary to correct substrate and will form ESC, any other substrate will not

75
Q

Induced fit hypothesis

A
  • as substrate binds to active site, shape changes slightly
  • active site binds tighter around substrate molecule
  • oppositely charged groups on substrate and active site interact holding the substrate in place in the ESC
  • shape puts strain on bonds in substrate to destabilise it so reaction occurs more easily
  • product formed and is different shape to reactant so is released from the active site
76
Q

Temperate and enzyme activity

A

UP TO AND INC OPTIMUM
-as molecules are heated they gain KE and move faster, results in more frequent collisions and greater force of collisions
-more ESCs form so higher rate and more product
ABOVE OPTIMUM
-molecules have more KE
-enzymes vibrate more, breaking weaker bonds (ionic and H)
-tertiary structure changes as enzyme unfolds
-so active site loses complimentary shape
-no ESCs form as substrate doesn’t fit
-enzymes denatures
-irreversible so reaction stops

77
Q

enzyme activity and pH

A

NOT AT OPTIMUM
-change in pH (H+) alters distribution of charge
-so hydrogen and ionic bonds break
-enzyme loses tertiary structure
-changes shape of active site of enzyme
-substrates not attracted to AS as H+ alter charge
-substrates cant bind as not complimentary
-no ESC=no product= no reaction
-enzymes denatured at pH extremes
OPTIMUM
-H+ concentration gives tertiary structure its best shape with a most complementary active site

78
Q

Increasing Enzyme concentration

A

SUBSTRATE IN EXCESS
-as enzyme concentration increases, rate increases
-more enzymes means more likely successful collisions means more active sites so more ESCs so more product and higher rate
SUBRTATE USED UP
-rate decreases as substrate used up as less product is formed. the substrate is limiting factor

79
Q

Substrate concentration on enzyme activity

A

ENZYME IN EXCESS
-as substrate conc increases, rate increases
-more substrate = more frequent collisions between substrates and active sites so more ESCs form and and more product forms so higher rate
WHEN ALL ACTIVE SITES OCCUPIED
-not possible for more ESCs to form so increasing substrate conc has no effect on rate, it plateaus
-enzyme conc is limiting factor

80
Q

Competitive inhibitors

A
  • similar shape to substrate
  • complementary to active site so bind and block it
  • prevents ESCs forming and slows rate as no product can form
  • don’t bind permanently, reversible
81
Q

non-competitive inhibitors

A
  • fit into allosteric site
  • alters tertiary structure of enzyme and changes active site shape
  • substrate cant fit, no ESCs, rate decreases
  • binds permanently to enzymes- irreversible, enzyme becomes useless
82
Q

competitive inhibitor conc on rate

A
  • rate depends on relative concentrations of substrate/ inhibitor
  • more inhibition is substrate conc low/ lower than inhibitor
  • higher chance of inhibitor entering active site than substrate so less ESC and less product
  • effects reduced by increasing substrate conc
83
Q

non competitive inhibitor conc on rate

A
  • increasing substrate conc has no effect on rate as they bind irreversibly, if all enzymes have inhibitor bound reaction stops
  • changing conc of inhibitor will further reduce the rate, fewer ESCs so less product
  • limits Vmax