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
mitosis - anaphase
- centromere splits - chromatids separate - spindle fibres shorten - pulls identical chromatids to opposite poles with centromere leading
26
mitosis - telophase
- chromosomes uncoil - nuclear envelope reforms - spindle fibres break down
27
mitosis vs meiosis
- 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
28
cell division and budding in yeast cells
- nucleus divides by mitosis - bulge in surface of cell - nucleus moves into bulge - bulge nips/ pinches off - leaves uneven distribution of cytoplasm
29
red blood cell differentiation
- 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
30
root hair cell differentiation
- 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
31
neutrophil ( phagocytes ) differentiation
- 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
32
Sperm differentiation
- 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
33
Protein structure
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
34
how does DNA structure determine specific shape of proteins
- 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
properties of collagen for function
- high tensile strength - not elastic - flexible - insoluble
36
role of fats in organisms
- 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
amylose
- 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
amylopectin
- 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
glycogen
- 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
cellulose
- 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
Haemoglobin
- 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
Collagen
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
Tryglyceride
- 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
Phospholipid
- 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
cholesterol
- 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
Compare the structures of collagen and haemoglobin
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
compare glycogen and collagen
- 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
compare glycogen and cellulose
- 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
compare phospholipids and triglycerides
- 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
why is glycogen a good storage molecule
- 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
water
HYDROGEN BONDING
52
water and temperature stability
- 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
water and ice floating
- 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
water as a solvent
- 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
water as a transport medium
- 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
water as transparent
- transparent to light | - plants can photosynthesise under water
57
water in plants
- forms long unbroken columns of water - in xylem for transpiration - due to cohesion - reactant in photosynthesis - role in hydrolysis reactions
58
water and cooling
- high latent heat of vaporisation - lots of energy needed for molecules to escape - evaporation has cooling effect - sweating, panting, transpiration
59
water as a surface
- can use as habitat - due to high surface tension - water boatmen, pond skaters, water lily pads
60
**protein test- what is it
- add biuret | - blue to lilac
61
**reducing sugar test (what is it)
- add benedicts reagent and heat | - blue to red precipitate ( yellow/orange/green)
62
non-reducing sugar test
- boil with HCl to hydrolyse and free up OH groups - neutralise with sodium hydrogencarbonate - add benedicts and heat - blue to red precipitate
63
starch test
- add iodine | - orange to blue/black
64
lipid test
- add alcohol then mix with water | - white emulsion
65
quantitative food test for sugar- determining conc of unknown solution
- 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
structure of a DNA nucleotide
- one phosphate group - one nitrogenous base (ATCG) - both joined to deoxyribose pentose sugar - with a covalent bond
67
structure of an RNA nucleotide
- one phosphate group - one nitrogenous base ( AUGC) - both joined to ribose pentose sugar - with a covalent bond
68
difference between DNA and RNA
- rna has ribose instead of deoxyribose - rna has uracil instead of thymine - rna single stranded not double - rna smaller
69
Structure of nucleotide chain
- 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
how 2 nucleotide chains bonded
- 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
DNA replication
- 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
why DNA replication is semi conservative
-2 identical molecules made, each with 1 strand from the original molecule (conserved strand and template) and 1 new strand
73
Enzyme wording
- globular proteins - specific - active sites - substrate complimentary to active site - Enzyme substrate complexes - Lock and key/ induced fit
74
Why enzymes are specific
-shape of active site is complimentary to correct substrate and will form ESC, any other substrate will not
75
Induced fit hypothesis
- 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
Temperate and enzyme activity
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
enzyme activity and pH
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
Increasing Enzyme concentration
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
Substrate concentration on enzyme activity
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
Competitive inhibitors
- 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
non-competitive inhibitors
- 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
competitive inhibitor conc on rate
- 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
non competitive inhibitor conc on rate
- 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