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topics 1-4 Flashcards

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1
Q

monomers

A

smaller units from which larger molecules are made

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2
Q

examples of monomers

A

monosaccharides, amino acids, nucleotides

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3
Q

polymers

A

molecules made from a large number of monomers joined together

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4
Q

examples of polymers

A

polysaccharides, proteins, DNA

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5
Q

condensation reaction

A

joins two molecules; removal of a water molecule; forms a chemical bond

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6
Q

hydrolysis reaction

A

separates two molecules; requires the addition of a water molecule; breaks a chemical bond

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7
Q

monosaccharides

A

single sugar molecules (e.g., glucose, fructose, galactose).

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8
Q

disaccharides

A

formed by the condensation of two monosaccharides
(e.g., glucose + glucose = maltose, glucose + fructose = sucrose, glucose + galactose = lactose)

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9
Q

polysaccharides

A

formed by the condensation of many monosaccharides
(e.g., starch, glycogen, cellulose);
releases water;
forms glycosidic bonds

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10
Q

glycogen

A

store of glucose in animals; formed from α-glucose; more branches (1-6 gd bonds) than amylopectin (increases SA and allows enzymes to work simultaneously and hydrolyse it back into glucose); large and compact maximising the amount of energy it can store; insoluble means it will not affect the water potential and cannot diffuse out of cells

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11
Q

starch

A

amylose and amylopectin; store of glucose in plants

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12
Q

amylose

A

formed by a condensation reaction;
long, unbranched helix of alpha-glucose;
forms 1-4 glycosidic bonds;
coils up to form a helix (compact; stores a lot of energy-glucose)

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13
Q

amylopectin

A

formed by condensation reaction;
long, branched chain of alpha-glucose;
more ends for hydrolysis
forms straight chains of 1-4 glycosidic bonds and branches out with 1-6 glycosidic bonds (increases surface area)

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14
Q

cellulose

A

for structural strength of plant cell wall;
formed from β-glucose;
each alternate glucose is inverted;
formed by many condensation reactions and 1-4 gd bonds;
creates a long, straight chain;
the chains line up parallel to each other, held in place by H bonds which are individually weak, but collectively strong (fibril)

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15
Q

triglycerides

A

formed via condensation reactions between glycerol and three fatty acids, forming ester bonds;
used as an energy storage molecules;
properties: high ratio of C-H bonds to C atoms, insoluble in water (forms droplets).

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16
Q

phospholipids

A

formed via condensation reactions between glycerol, two fatty acids, and a phosphate group;
forms phospholipid bilayer in cell membranes;
properties: hydrophilic phosphate heads, hydrophobic fatty acid tails
the centre of the bilayer is hydrophobic so water-soluble molecules can’t easily pass through-the membrane acts as a barrier

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17
Q

saturated and unsaturated fatty acids

A

saturated: no C=C double bonds;
unsaturated: one or more C=C double bonds

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18
Q

emulsion test for lipids

A

add ethanol and shake (dissolves lipids) then add water;
positive result: milky/cloudy white emulsion

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19
Q

biuret test for proteins

A

add biuret solution (sodium hydroxide + copper (II) sulfate)
positive result: purple color (negative result: stays blue)

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20
Q

amino acids

A

monomer of proteins

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21
Q

dipeptide

A

two amino acids joined by a peptide bond

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22
Q

polypeptide

A

many amino acids joined by peptide bonds

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23
Q

primary structure

A

sequence of amino acids in polypeptide chain

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24
Q

secondary structure

A

hydrogen bonding causes folding into alpha-helix or beta-pleated sheet

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25
Q

tertiary structure

A

3D structure held by interactions between side chains (ionic bonds, disulfide bridges, hydrogen bonds)

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26
Q

ionic bonds in tertiary structure

A

form between the carboxyl and amino groups not involved in the peptide bonds;
weaker than disulfide bridge

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27
Q

disulfide bridges in tertiary structure

A

whenever two molecules of cysteine (amino acid) come close together; the S atom in one cysteine bonds to the S atom in the other cysteine

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28
Q

quaternary structure

A

the quaternary structure is the way the polypeptide chains are assembled tg

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29
Q

how do enzymes speed up reactions

A

enzymes lower the activation energy by providing alternative pathway

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30
Q

lock and key model

A

active site is a fixed shape/doesn’t change shape;
it is complementary to one substrate;
after a successful collision, an enzyme-substrate complex forms leading to reaction

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31
Q

induced fit model

A
  1. before reaction, enzyme active site not completely complementary to substrate/ doesn’t fit substrate
  2. active site shape changes as substrate binds and enzyme-substrate complex forms
  3. this stresses / distorts bonds in substrate leading to a reaction
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32
Q

how does enzyme concentration affect the rate of enzyme-controlled reactions

A

there are more active sites for the substrates to bind to
however, its only applicable to a certain extent;
at some point, enzyme activity will plateau because there are too many active sites and not enough substrates

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33
Q

how does temperature affect the rate of enzyme-controlled reactions

A

rate of reaction increases as particles gain more kinetic energy;
leading to more collisions;
if temperature is too high enzymes denature

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34
Q

how does pH affect the rate of enzyme-controlled reactions

A

at very acidic and alkaline pH values the shape of the enzyme is altered so that it is no longer complementary to its specific substrate

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35
Q

competitive inhibitors

A

have a similar shape to substrate;
compete with the substrate molecules to bind to the active site but no reaction takes place

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36
Q

what happens when there’s a higher concentration of competitive inhibitors

A

if there’s a higher conc of inhibitors, it will take up nearly all active sites and hardly any of the substrate will get to the enzyme

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37
Q

what happens when there’s a higher concentration of substrates

A

if there’s a higher conc of substrates, the substrates chance of getting to an active site before the inhibitor increases
increasing substrate conc increases rate of reaction

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38
Q

non-competitive inhibitors

A

they bind to the enzyme away from its active site which causes the active to change shape so the substrate molecules can no longer bind to it

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39
Q

what happens when you increase the substrate concentration when non-competitive inhibitors are present

A

has no effect because non-competitve inhibitors don’t compete with the substrate molecules to bind to the active site because they are a different shape;
inhibits enzyme activity

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40
Q

DNA

A

double-stranded helix, holds genetic information (ACGT)

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41
Q

RNA

A

single-stranded, transfers genetic information from DNA to ribosomes (ACGU)

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42
Q

nucleotide

A

DNA and RNA are polymers of nucleotides
nucleotides are made from: a pentose sugar (sugar with 5 C atoms) and phosphate group (sugar-phosphate backbone and a nitrogen-containing base (ACGT)

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43
Q

polynucleotide structure

A

nucleotides join tg to form polynucleotides via a condensation reaction between phosphate group of one nucleotide and the sugar of another;
form a phosphodiester bond

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44
Q

DNA structure

A

double-helix;
composed of two polynucleotides joined tg by H bonds between complementary bases;
(a+t, c+g)

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45
Q

complementary base pairing

A

adenine pairs with thymine (2 H bonds)
guanine pairs with cytosine (3 H bonds)
equal amounts of A+T and C+G

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46
Q

RNA structure

A

a pentose sugar (sugar with 5 C atoms) and phosphate group (sugar-phosphate backbone and a nitrogen-containing base (ACGU)

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47
Q

difference between DNA and RNA

A
  1. deoxyribose/ribose
  2. thymine/uracil
  3. double strand/single strand
  4. long/short
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48
Q

how does DNA replicate?

A

semi-conservative replication

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49
Q

what does semi-conservative replication mean?

A

half of the strands in the new DNA are from the original DNA molecule;
leads to genetic continuity

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50
Q

semi-conservative replication (process)

A
  1. DNA helicase breaks the H bonds between bases on the two polynucleotide strands (helix unwinds)
  2. each original single strand acts as a template for a new strand; complementary base pairing makes free-floating DNA nucleotides are attracted to their complementary exposed bases from original template strand
  3. condensation reactions join the nucleotides of the new strands together catalysed by DNA polymerase; H bonds form between the bases
  4. each new DNA molecule contains one strand from the original DNA molecule and one new strand
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51
Q

meselson+stahl experiment

A

used 2 isotopes of N to show that DNA replicates using semi-conservative replication
(heavy-15);(light-14)
1. grow 2 samples of bacteria (one in lightN broth and one in heavyN broth)
2. sample of DNA taken from each batch and spun in centrifuge
3. bacteria grown in heavyN broth taken out and put in lightN broth and left for one round of DNA replication
4. DNA settled in the middle, mixture of both heavyN and lightN

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52
Q

ATP

A

adenosine triphosphate;
immediate source of energy for metabolic reactions

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53
Q

what is ATP made up of?

A

one adenine base, ribose sugar and 3 phosphate groups (ATP synthase)

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54
Q

where is the energy in ATP stored?

A

stored in high energy bonds between the phosphate groups and is released via hydrolysis reactions
ATP → ADP + Pi (ATP hydrolase)

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55
Q

properties of water

A

high specific heat capacity: stable temperature for organisms
high latent heat of evaporation: efficient cooling mechanism
cohesion: surface tension, water transport in plants
solvent: dissolves ionic compounds and other substances, medium for metabolic reactions
metabolite: involved in hydrolysis and condensation reactions

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56
Q

phosphate (inorganic ion)

A

DNA/RNA backbone;
energy storage/release in ATP

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57
Q

hydrogen (inorganic ion)

A

pH regulation;
impacts enzyme and haemoglobin function

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58
Q

iron (inorganic ion)

A

transports oxygen with haemoglobin

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59
Q

sodium (inorganic ion)

A

Na+, involved in cotransport of glucose and amino acids

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60
Q

cell surface membrane

A

phospholipid bilayer with embedded proteins; selectively permeable; barrier between internal and external environments

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61
Q

nucleus

A

nuclear envelope (double membrane), nuclear pores, nucleolus, DNA/chromatin;
controls the cells activities through transcription;
nuclear pores allow substances to move between nucleus and cytoplasm(mRNA);
nucleolus makes ribosomes which are made up of proteins and ribosomal RNA

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62
Q

mitochondria

A

double membrane; inner membrane folded to form cristae;
matrix contains small 70s ribosomes, small circular DNA and enzymes involved in glycolysis;
site of aerobic respiration to produce ATP

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63
Q

golgi apparatus

A

modifies proteins to glycoproteins (adds carbs) from RER; packages glycoproteins into vesicles for transport; produces secretory enzymes; transports, modifies and stores lipids, forms lysosomes

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64
Q

lysosomes

A

hydrolyse material injested by phagocytic cells, releases enzymes to the outside of the cell in order to destroy material around the cell, digest worn out organelles so that the useful chemicals they are made of can be reused, completely break down cells after they have died (autolysis)

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65
Q

ribosomes

A

made of RNA and proteins, float free in cytoplasm or bound to RER; not membrane bound; site of translation

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66
Q

RER

A

ribosomes bound to a system of folded membranes; folds polypeptides to secondary/tertiary structure; modifies proteins to glycoproteins; packages to vesicles, transport to the golgi apparatus

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67
Q

SER

A

system of folded membranes; synthesises, stores and transports lipids and carbs, packaged into vesicles

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68
Q

chloroplasts

A

chloroplast envelope is a double plasma membrane that surrounds the organelle (highly selective); thylakoid membranes stacked to form grana which is linked by lamellae (th contains chlorophyll); stroma is a fluid filled matrix where second stage of photosynthesis occurs, contains starch grains

chlorophyll absorbs light for photosynthesis to produce organic substances

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69
Q

cell wall

A

made of cellulose in plants and algae; chitin in fungi;
rigid structure, prevents the cell changing shape and bursting

provides mechanical strength to avoid cell lysis under osmotic pressure

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70
Q

vacuole

A

fluid filled sac bounded by a single membrane; contains cell sap; surrounding membrane is tonoplast;
maintains pressure in the cell
makes cells turgid, sugars and amino acids act as a temporary food store, pigments attract pollinating insects

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71
Q

differences in prokaryotic cells

A

no membrane bound organelles;
no nucleus, circular DNA, not associated with proteins;
cell wall is made of murein;
70s ribosomes;
one or more plasmids

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72
Q

scanning electron microscope

A

uses electrons to form a 2D image;
beam of electrons scan surface;
shorter wavelength so higher resolution; x1500000 magnification

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73
Q

transmission electron microscope

A

uses electrons to form a 3D image; electromagnets focus beam of electrons onto specimen, more dense=more absorbed=darker;
shorter wave,entry of electrons; x1500000 magnification

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74
Q

magnification vs resolution

A

how much bigger the image of a sample is compared to the real size; magnification
how well distinguished an image is between 2 points; resolution

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75
Q

viruses

A

acellular; not made of/cannot divide into cells
non-living; unable to exist/reproduce without a host cell

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76
Q

cell fractionation (describe)

A
  1. homogenisation–>grinding up the cells in a blender
    CONDITIONS:
    >ice cold
    >isotonic (solution has same water potential as cells)
    >have a buffer added
  2. filtration (through a gauze)
  3. ultracentrifugation–>separate organelles by mass-density
    >filtered solution centrifuged at low speed
    >respin supernatant at higher speed
    > process repeated at higher speeds
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77
Q

cell fractionation (explain)

A
  1. homogenisation–> break opens the cells, breaking up the plasma membrane to release the organelles
    > ice cold: reduces enzyme activity, preventing organelles from being broken down
    > isotonic solution: prevents damage to organelles by osmosis (prevents organelle lysis)
    >have a buffer added: maintain pH of a solution to prevent proteins denaturing
  2. filtration–>take out debris e.g. connective tissue and whole cells
  3. ultracentrifugation
    >centrifuge at low speed–separate out heaviest organelles e.g. nuclei
    >respin at higher speed– remove heaviest organelles from supernatant e.g. chloroplast into the pellet
    >process repeated at higher speeds–to remove the heaviest organelles in pellets each time
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78
Q

stages of cell cycle

A

interphase (synthesis; G1; G2), mitosis (PMAT), cytokinesis

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79
Q

interphase

A

> G1: cell enlarges; volume and mass increases (more organelles);
more mitochondria (needed to produce ATP and release energy to allow the spindle fibres to pull the chromosomes to opposite sides of the cell)
S phase: DNA replicates semi-conservatively leading to two sister chromatids
G2: cell keeps growing and protein synthesis increases to make spindle fibres for mitosis

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80
Q

mitosis (meaning)

A

parent cell divides = two genetically identical daughter cells

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81
Q

prophase

A

chromosomes condense, becoming shorter, thicker and more visible; appear as two sister chromatids joined by a centromere
nuclear envelope breaks down and centrioles move to opposite poles forming spindle network

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82
Q

metaphase

A

chromosomes align along equator; spindle fibres attach to chromosomes by centromeres

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83
Q

anaphase

A

spindle fibres contract, pulling sister chromatids to opposite poles of the cell; centromere divides;
chromatids appear v shaped

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84
Q

telophase

A

chromosomes uncoil, becoming longer and thinner;
nuclear envelope reforms = two nuclei;
spindle fibres and centrioles break down

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85
Q

cytokinesis

A

division of the cytoplasm, producing two new cells

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86
Q

importance of mitosis

A

parent cell divides to produce 2 genetically identical daughter cells for…
- growth of multicellular organisms by increasing cell number
- repairing damaged tissues / replacing cells
- asexual reproduction

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87
Q

result of uncontrolled division

A

uncontrolled cell division can lead to the formation of tumours and of cancers
- malignant tumour – cancerous – spreads and affects other tissues / organs
- benign tumour – non-cancerous

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88
Q

binary fission

A

circular DNA and plasmids replicate (circular DNA replicates once, plasmids can be replicated many times);
cytoplasm expands (cell gets bigger) as each DNA molecule moves to opposite poles of the cell;
cytoplasm divides = 2 daughter cells, each with a single copy of DNA and a variable number of plasmids

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89
Q

viral replication

A
  1. attachment protein binds to complementary receptor protein on surface of host cell
  2. inject nucleic acid (DNA/RNA) into host cell
  3. infected host cell replicates the virus particles
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90
Q

fluid mosaic model of cell surface membrane

A

molecules within membrane can move laterally (fluid) e.g. phospholipids;
mixture of phospholipids, proteins, glycoproteins and glycolipids

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91
Q

structure of cell surface membrane

A

phospholipid bilayer;
phosphate heads are hydrophilic so attracted to water;
fatty acid tails are hydrophobic so repelled by water;
embedded proteins;
channel and carrier proteins;
glycolipids (lipids and attached polysaccharide chain) and glycoproteins (proteins with polysaccharide chain attached);
cholesterol (binds to fatty acid tails)

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92
Q

phospholipid bilayer

A

allows movement of non-polar small/lipid-soluble molecules e.g. oxygen or water, down a concentration gradient (simple diffusion);
restricts the movement of larger/polar molecules

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93
Q

channel proteins

A

allows movement of water-soluble/polar molecules / ions, down a concentration gradient (facilitated diffusion)

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94
Q

carrier proteins

A

allows movement of water-soluble/polar molecules / ions, down a concentration gradient (facilitated diffusion);
allows the movement of molecules against a concentration gradient using ATP (active transport)

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95
Q

features of the plasma membrane adapt it for its other functions

A

phospholipid bilayer; maintains a different environment on each side of the cell

phospholipid bilayer is fluid; can bend to take up different shapes for phagocytosis / to form vesicles

surface proteins (glycoproteins / glycolipid) ; used for cell recognition / act as antigens

cholesterol; regulates fluidity / increases stability

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96
Q

role of cholesterol

A

makes the membrane more rigid / stable / less flexible, by restricting lateral movement of molecules making up membrane e.g. phospholipids (binds to fatty acid tails causing them to pack more closely together)

note: not present in bacterial cell membranes

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97
Q

what is ventilation needed for

A

maintains an oxygen concentration gradient
-brings in air containing higher concentration of oxygen
-removed oxygen with lower concentration of oxygen

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98
Q

gas exchange in alveoli (oxygen)

A

oxygen diffuses from alveoli down its concentration gradient;
across the alveolar epithelium;
across the capillary endothelium;
into the blood

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99
Q

gas exchange in alveoli (oxygen)

A

oxygen diffuses from alveoli down its concentration gradient;
across the alveolar epithelium;
across the capillary endothelium;
into the blood

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100
Q

features of alveolar epithelium

A

thin/one cell thick: short dp and fast diffusion;
large SA:V: fast diffusion;
permeable;
good blood supply from capillaries: maintains concentration gradient;
elastic tissue: recoils after expansion

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101
Q

adaptions of lungs

A

many alveoli/capillaries: large SA for fast diffusion;
thin walls (A/C): short dp for fast diffusion;
ventilation: maintains concentration gradient for fast diffusion

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102
Q

inspiration

A

external IM contract, internal IM relax;
ribcage moves up and out;
diaphragm muscles contract/flatten;
increasing volume and decreasing pressure in thoracic cavity;
atmospheric pressure higher than pressure in lungs;
air moves down pressure gradient into lungs;
ACTIVE PROCESS

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103
Q

expiration

A

internal IM contract, external IM relax;
ribcages moves down and in;
diaphragm relaxes and moves upwards;
decreasing volume and increasing pressure in thoracic cavity;
atmospheric pressure lower than pressure in lungs;
air moves down pressure gradient out of lungs;
PASSIVE PROCESS

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104
Q

tidal volume

A

volume of air in each breath

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105
Q

ventilation rate

A

number of breaths per minute

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106
Q

forced expiratory volume (FEV)

A

maximum volume of air that can be breathed out in 1 second

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107
Q

forced vital capacity (FVC)

A

maximum volume of air possible to breathe forcefully out of lungs after a deep breath in

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108
Q

fibrosis

A

scar tissue in lungs; thicker and less elastic;
diffusion distance increased; rate of diffusion decreased; faster ventilation rate to get enough oxygen;
lungs can expand and recoil less (can’t hold as much air);
reduced tidal volume and FVC

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109
Q

asthma

A

inflamed bronchi;
asthma attack= smooth muscle lining bronchioles contracts;
constriction of of airways-narrow diameter; airflow reduced (FEV);
less oxygen enters alveoli/blood;
reduced rate of gas exchange - less oxygen diffuses into the blood - cells receive less oxygen - rate of aerobic respiration - less energy released = fatigue, weakness

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110
Q

digestion

A

large biological molecules are hydrolysed into smaller molecules that can be absorbed

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111
Q

digestion of starch (polysaccharides)

A

amylase hydrolyses starch to maltose;
maltase hydrolyses maltose to glucose;
hydrolysis of glycosidic bond

amylase produced by salivary glands, released into mouth;
amylase produced by pancreas, released into small intestine

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112
Q

digestion of lipids

A

bile salts emulsify lipid to smaller lipid droplets (increases SA to speed up action of lipases);
lipase hydrolyses lipids to monoglycerides and fatty acids;
breaking ester bond;
monoglycerides, fatty acids and bile salts stick together to form micelles

bile salts produced by the liver;
lipase made in the pancreas, released to small intestine

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113
Q

digestion of proteins

A

endopeptidases;
-hydrolyses peptide bonds between amino acids in the central region; breaking protein into two two or more smaller peptides
exopeptidases;
-hydrolyse peptide bonds at the ends of protein molecules; removing a single amino acid
dipeptidases;
-hydrolyses peptide bond between a dipeptide

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114
Q

circulatory system

A

general pattern of blood circulation;
involves lungs, pulmonary artery/vein, aorta, vena cava, hepatic artery/vein, renal vein/artery, coronary arteries

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115
Q

double circulatory system

A

blood passes through heart twice for each complete circulation of body

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116
Q

pulmonary circulation

A

deoxygenated blood in right side of heart pumped to lungs; oxygenated blood returns to left side of the heart

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117
Q

systematic circulation

A

oxygenated blood in left side of heart pumped to tissues/ organs of body; deoxygenated blood returns to the right side

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118
Q

why is a double circulatory system important

A

prevents mixing of oxygenated and deoxygenated blood; ensures full oxygen saturation of blood going to the body for respiration

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119
Q

coronary arteries

A

deliver oxygenated blood to cardiac muscle

120
Q

aorta

A

takes oxygenated blood from heart to respiring tissue

121
Q

vena cava

A

takes deoxygenated blood from respiring tissues to heart

122
Q

pulmonary artery

A

takes deoxygenated blood from the heart to lungs

123
Q

pulmonary vein

A

takes oxygenated blood from the lungs to heart

124
Q

renal arteries

A

takes oxygenated blood to kidneys

125
Q

renal veins

A

take deoxygenated blood from the kidneys to the vena cava

126
Q

structure of the heart related to its function

A

atrioventricular valves
-prevent backflow of blood from ventricles to atria
semi lunar valves
-prevent backflow of blood from arteries to ventricles
left ventricle has thicker muscular wall
-generates higher blood pressure
-oxygenated blood has to travel greater distance around the body
right has thinner muscular wall
-generates lower blood pressure (high pressure would damage alveoli)
-deoxygenated blood travels a smaller distance to the lungs

127
Q

structure of arteries in relation to their function

A

carries blood from heart to rest of body at high pressure
-thick, smooth muscle layer; contracts pushing blood along; controls blood flow/pressure
elastic tissue layer
-stretch as ventricle contracts and recoils as ventricle relaxes; reduces pressure surges
thick wall
-withstands high pressure and prevents artery bursting
smooth, thin endothelium
-reduces friction
narrow lumen
-increases and maintains high blood pressure

128
Q

arterioles

A

division of arteries to smaller vessels which can direct blood to specific capillaries/ areas

129
Q

structure of arterioles in relation to its function

A

thicker muscle layer than arteries
-constricts to reduce blood flow by narrowing lumen; dilates to increase blood flow by enlarging lumen
thinner elastic layer for lower pressure surges

130
Q

structure of veins in relation to in function

A

wider lumen than arteries; very little elastic and muscle tissues; valves to prevent backflow of blood; contraction of skeletal muscles squeezes veins, maintaining blood flow

131
Q

structure of capillaries and capillary beds

A

capillaries allow the efficient exchange of gases and nutrients between blood and tissue fluid;
capillary wall is a thin layer of squamous endothelial cells; short dp for rapid diffusion;
capillary bed is made a large network of branched capillaries; increase SA:V for rapid diffusion;
narrow lumen; reduces flow rate so more diffusion/exchange;
capillaries permeate tissues; short dp;
pores in walls between cells; allows substances to escape

132
Q

atrial systole

A

atria contract; decreasing volume and increasing pressure inside atria;
AV valves forced open;
blood pushed into ventricles

133
Q

ventricular systole

A

ventricles contracts from the bottom up; decreasing volume and increasing volume;
SL valves forced forced upon;
AV valves shut;
blood pushed out of heart through arteries

134
Q

diastole

A

atria and ventricles relax; increasing volume and decreasing pressure inside the chambers;
blood from veins fills atria and flows passively to ventricles;
AV valves open;
SL valves shut

135
Q

cardiac output

A

amount of blood pumped out of the heart per minute

stroke volume x heart rate

136
Q

stroke volume

A

volume of blood pumped by the ventricles in each heart beat

cardiac output / heart rate

137
Q

heart rate

A

number of beats per minute

cardiac output / stroke volume

138
Q

haemoglobin

A

group of chemically similar molecules found in many different organisms
-chemical structure may differ between organisms e.g. sequence of amino acids
found in rbc
-no nucleus
-biconcave shape; increases SA for rapid diffusion/absorption of oxygen

139
Q

structure of haemoglobin

A

quaternary structured protein- made of 4 polypeptide chains;
each polypeptide contains a haem group containing an iron (II) ion which combines with oxygen

140
Q

transport of oxygen using haemoglobin

A

haemoglobin in rbc carries oxygen (oxyhaemglobin);
haemoglobin can carry 4 oxygen molecules-one at haem group

141
Q

transport of oxygen at high pO2

A

haemoglobin has a high affinity for oxygen;
oxygen readily loads/associates with haemoglobin

142
Q

transport of oxygen at low pO2

A

oxygen readily unloads/dissociates from haemoglobin;
concentration of CO2 is high so rate of unloading is high

143
Q

simple diffusion

A

net movement of small, non polar molecules across a partially permeable membrane down its concentration gradient

-passive

144
Q

factors affecting rate of simple diffusion

A

surface area;
concentration gradient;
diffusion pathway

145
Q

facilitated diffusion

A

net movement of larger/polar molecules across a partially permeable membrane down its concentration gradient through a transport protein

-passive

146
Q

factors affecting the rate of facilitated diffusion

A

surface area;
concentration gradient;
number of channel/carrier proteins

147
Q

role of transport proteins

A

carrier proteins transport large molecules; changes shape when molecule attaches
channel proteins transport charged/polar molecules through its pore
different carrier and channel proteins facilitate the diffusion of different specific molecules

148
Q

active transport

A

net movement of molecules/ions against a concentration gradient using carrier proteins using energy from ATP

149
Q

factors affecting the rate of active transport

A

pH/temperature;
speed of carrier protein;
number of carriers proteins;
rate of respiration (ATP production)

150
Q

osmosis

A

net movement of water molecules across a selectively permeable membrane down a water potential gradient

-passive

151
Q

water potential

A

the likelihood of water molecules to diffuse out of or into a solution;
pure water has the highest water potential

152
Q

factors affecting the rate of osmosis

A

surface area;
water potential gradient;
thickness of exchange surface

153
Q

antigen

A

proteins which can stimulate an immune response

154
Q

antigen allow the immune system to identify..

A

pathogens;
cells from other organisms of the same species (organs, blood);
abnormal cells (tumours);
toxins released from bacteria

155
Q

phagocytosis

A

phagocyte recognises foreign antigens on the pathogen and binds to the antigen;
phagocyte engulfs pathogen by surrounding it;
pathogen contained in phagosome and fused with lysosome to release lysozymes;
hydrolyse/digest the pathogen;
antigens presented on cell surface membrane

156
Q

rs between SA:V

A

rate of heat loss increases as SA:V increases
-more heat lost in smaller organisms
-so they need a higher metabolic rate to generate enough heat to maintain a constant body temperature

157
Q

why do larger organisms need a specialised surface

A

they have a smaller SA:V and a long diffusion pathway;
and a high demand for oxygen and to remove carbon dioxide

158
Q

adaptions for gas exchange in a single celled organism

A

-thin, flat shape
-large SA:V
-short diffusion pathway

for rapid diffusion

159
Q

adaptions for gas exchange in the tracheal system

A
  1. air moves through spiracles on the surface
  2. air moves through tracheae
  3. gas exchange at tracheoles directly to/from cells
    -oxygen diffuses to respiring cell
    -carbon dioxide diffuses out of respiring cells
160
Q

more adaptions of tracheal system

A

lots of thin, branching tracheoles;
short diffusion pathway and SA:V;
for rapid diffusion

thick waxy cuticle;
increases diffusion distance;
less evaporation

spiracles can open and close;
open to allow oxygen in, close when water loss too much

rhythmic abdominal movements increases the efficiency of gas exchange by increasing the amount of air/oxygen entering;
maintains greater concentration gradient for diffusion

161
Q

adaptions for gas exchange across the gills of fish

A

counter current flow
-blood flows through lamellae and water flows over lamellae in opposite directions
-always a higher conc of oxygen in water than the blood it’s near
-hence a conc gradient of oxygen between water and blood maintained along the whole length of lamellae
-equilibrium is never met
-maximises diffusion of oxygen

162
Q

physical adaptions of fish gills

A

each gill is made of lots of gill filaments which are covered in many lamellae;
gill filaments and lamellae provide a larger surface area;
vast network of capillaries on lamellae; remove oxygen to maintain a concentration gradient;
thin/flattened epithelium; short dp

163
Q

adaptions of gas exchange in leaves

A

lots of stomata that are close together;
-large SA for gas exchange;
interconnecting air space in mesophyll layer;
-gases come into contact with mesophyll cells;
mesophyll cells have a large SA;
-rapid diffusion;
thin;
-short dp

164
Q

adaptions for gas exchange in xerophytic plants

A

thick waxy cuticle
-increase diffusion distance; less evaporation
stomata and rolled leaves and hairs
-traps water vapour; water potential gradient decreased; less evaporation
spindles/meedles
-reduces SA:V

165
Q

co-transport (Na+ and glucose)

A
  1. sodium ions actively transported out of epithelial cells lining the ileum into the blood by the sodium-potassium pump; creates a sodium concentration gradient
  2. sodium ions and glucose move by facilitated diffusion into the epithelial cell from the lumen via a co transporter protein
  3. creates a glucose concentration gradient
  4. glucose moves out of cell into blood by facilitated diffusion through a protein channel
166
Q

cohesion-tension theory

A

water evaporates from the leaves via the stomata due to transpiration;
water potential is reduced and increases water potential gradient;
water drawn out of xylem creating tension;
cohesive forces between water molecules pull water up as a column;
water lost enters the roots via osmosis;
water is moving up against gravity and sticks to the edges of the column

167
Q

isomers

A

same molecular formula but different structure (alpha-glucose and beta-glucose)

168
Q

RNA function

A

transfer the genetic code from the DNA in the nucleus to the ribosomes

169
Q

DNA function

A

used to store your genetic info

170
Q

properties of ATP

A
  1. released in small, manageable amounts so energy is wasted
  2. small and soluble and can easily be transported around the cell
  3. only one bond needs to be broken to release energy
  4. can transfer energy to another molecule by transferring one of its phosphate groups
  5. cannot leave the cell, always in immediate supply
171
Q

how does the structure of ATP make it a good source of immediate energy?

A

the bonds between the phosphate groups have a low activation energy;
this means they can be easily broken;
breaking the bonds releases energy

172
Q

function of ATP

A

an immediate source of energy for biochemical processes and synthesis of biological molecules

173
Q

antigens

A

foreign proteins present on the cell-surface membrane that stimulates an immune response;
can mutate to change their tertiary structure so they’re not complementary (antigen variation)

174
Q

antigens are specific to allow the immune system to identify…

A
  • pathogens (disease causing organisms) e.g. viruses, fungi, bacteria
  • cells from other organisms of the same species e.g. organ transplant, blood transfusion
  • abnormal body cells e.g. cancerous cells / tumours
  • toxins released from bacteria
175
Q

phagocytosis

A
  1. phagocyte e.g. macrophage recognises foreign antigens on the pathogen and binds to the antigen
  2. phagocyte engulfs pathogen by surrounding it with its cell surface membrane / cytoplasm
  3. pathogen contained in vacuole/vesicle/phagosome in cytoplasm of phagocyte
  4. lysosome fuses with phagosome and releases lysozymes (hydrolytic enzymes) into the phagosome
  5. these hydrolyse / digest the pathogen
  6. phagocyte becomes antigen presenting and stimulates specific immune response
176
Q

cellular response (T-cell response)

A
  1. T-lymphocytes recognises APCs after phagocytosis (foreign antigen)
  2. specific Th cell with receptor complementary to specific antigen binds to it, becoming activated and dividing rapidly by mitosis to form clones which:

a) stimulate B cells for the humoral response
b) stimulate cytotoxic T cells to kill infected cells by producing perforin
c) stimulate phagocytes to engulf pathogens by phagocytosis

177
Q

humoral response (B-cell response)

A
  1. clonal selection:
    a) specific B cell binds to antigen presenting cell and is stimulated by helper T cells which releases cytokines
    b) divides rapidly by mitosis to form clones (clonal expansion)
  2. some become B plasma cells for the primary immune response – secrete large amounts of monoclonal antibody into blood
  3. some become B memory cells for the secondary immune response
178
Q

primary response

A

primary response – antigen enters body for the first time (role of plasma cells)
- produces antibodies slower and at a lower concentration because
- not many B cells available that can make the required antibody
- Th cells need to activate B plasma cells to make the antibodies (takes time)
- so infected individual will express symptoms

179
Q

pathogen

A

microorganism that causes diseases

179
Q

secondary response

A

at the second exposure, the immune system produces a quicker, stronger immune response
- clonal selection happens faster
- memory B-cells are activated and divide into plasma cells that produce the right antibody to the antigen
-memory T-cells are activated and divide into the correct type of T-cells to kill the cell carrying the antigen

this response often gets rid of the pathogen before you begin to show symptoms

180
Q

2 types of wbc

A

lymphocyte and phagocyte

181
Q

why must wbcs be able to differentiate between self and foreign cells?

A

allows the white blood cells to know what is part of your body, and what is not;
so that the body’s own tissues aren’t destroyed

182
Q

what is used to identify cells as self or non-self?

A

proteins on the cell surface membrane

183
Q

what is the immune system able to identify?

A
  1. pathogens (e.g. HIV)
  2. non-self material (e.g. cells from another organism);
  3. toxins;
  4. abnormal body cells (e.g. cancer)
184
Q

what issue may arise with the immune system, due to transplants?

A

the immune system may recognise the tissues as non-self, and therefore attack transplanted organs/tissues.

185
Q

plasma cells

A

identical to B-cells (clones);
they secrete loads of antibodies specific to the antigen – monoclonal antibodies – which bind to the antigens on the surface of the pathogen to form antigen-antibody complexes

186
Q

neutrophils

A

engulf and digest pathogens (and dead human cells/debris)

187
Q

macrophages

A

can punch holes in the bacteria or stick proteins to the outside of the bacteria to make them more appealing for the neutrophils to destroy

188
Q

role of phagocyte

A

ingest and destroy pathogens

189
Q

what attracts phagocytes?

A

chemical products of pathogens, or dead, damaged or abnormal cells

190
Q

what allows phagocytes to recognise and attach to chemicals on the surface of the pathogen?

A

receptors on the cell-surface membrane

191
Q

T-cell response to being infected by a pathogen

A
  1. phagocyte ingests pathogen
  2. pathogen’s antigens are placed onto the phagocyte’s surface membrane (It becomes an APC)
  3. the receptors of a specific Th cell bind perfectly to the antigen being presented
  4. this binding activates the Th cell to divide and produce many clones (clonal expansion)
  5. these cloned cells specialise
192
Q

in what way might cloned Th cells differentiate?

A
  1. develop into memory cells
  2. stimulate phagocytes
  3. stimulate B-cells to divide and secrete antibodies
  4. activate Tc cells (cytotoxic cells)
193
Q

cell-mediated response

A

-once a pathogen has been destroyed by a phagocyte, the antigens are positioned on its cell surface and its referred to as an antigen-presenting cell
- helper T-cells have receptors on its surface that attach to the antigens on the APC
- once attached, the T-cells divide by mitosis to replicate and make large numbers of clones
- cloned helper T-cells differentiate into different cells
- some remain as helper T-cells and activate B-lymphocytes
- some stimulate macrophages to perform more phagocytosis
- some become memory cells for that shaped antigen
- some become cytotoxic T-cells (killer T-cells)

194
Q

cytotoxic T-cells

A
  • destroy abnormal or infected cells
  • they release a protein (perforin) which embeds in the cell surface membrane and makes a pore so substances can enter and leave a cell, causing the cell death
  • most common in viral infections as they affect body cells
195
Q

why are there millions of types of B-cells?

A

each one creates an antibody to respond to a specific antigen;
the variations in antigens require a large number of different antibodies

196
Q

how is a B-cell stimulated to divide by mitosis?

A

an activated Th cell binds to the processed antigens on the B cell to stimulate it to divide by mitosis, creating clones;
this is clonal selection

197
Q

what are the antibodies created from cloned B-cells called?

A

monoclonal antibodies

198
Q

what do memory cells do?

A

involved in secondary immune response

they last a long time in the body, when they encounter the complimentary antigen to their antibody, they are stimulated to divide rapidly;
this creates lots of memory and plasma cells quickly, and therefore lots of antibodies are created quickly

199
Q

what does an antibody do?

A

it binds to a specific antigen, which is complimentary to its specific binding site

200
Q

what are antibodies made of?

A

they are made of 4 polypeptide chains;
2 long (heavy chains), 2 short (light chains)

201
Q

what is the name given to the binding site of an antibody?

A

the variable region; has a specific tertiary structure

202
Q

what do antibodies do to pathogens?

A
  1. cause agglutination through binding to two pathogens at once; clumps together many pathogens
  2. they act as markers to stimulate phagocytosis
203
Q

vesicle

A

fluid filled sac, transports substances around the cell

204
Q

spiracles

A

tiny pores along the length of the abdomen;
opened and closed by valves, they usually stay closed to prevent water loss

205
Q

trachea

A

network of internal tubes; have rings to strangthen them and keep them open

206
Q
A
207
Q

smaller organisms have…

A

a higher SA:V so they lose heat more quickly

208
Q

adaptions for larger organisms (gas exchange)

A

need a specialised surface/organ;
they have a smaller SA:V and long diffusion pathway;
high demand for oxygen and removal CO2

209
Q

process of gas exchange in leaves

A

CO2/O2 diffuse through the stomata;
stomata opened by guard cells;
CO2/O2 diffuse into mesophyll layer into air spaces;
CO2/O2 diffuse down concentration

210
Q

process of gas exchange in leaves

A

CO2/O2 diffuse through the stomata;
stomata opened by guard cells;
CO2/O2 diffuse into mesophyll layer into air spaces;
CO2/O2 diffuse down concentration

211
Q

structure of human gas exchange system

A

trachea
splits into 2 bronchi;
splits into bronchioles;
ends in alveoli;
diaphragm underneath

212
Q

how does gas exchange happen in the alveoli? (O2)

A

oxygen diffuses from alveoli;
down conc gradient;
across alveolar epithelium;
across capillary endothelium;
into the blood (haemoglobin)

213
Q

how does gas exchange happen in the alveoli? (CO2)

A

carbon dioxide diffuses from capillary;
down conc gradient;
across alveolar epithelium;
across capillary endothelium;
into alveoli

214
Q

why is ventilation needed?

A

maintains an oxygen concentration gradient;
brings in air with high O2 conc and removes air with low O2 conc

215
Q

calculating heart rate from cardiac cycle data

A

one beat=one cardiac cycle;
find the length of one cardiac cycle (human average=0.83 seconds)
heart rate in beats=60 seconds/length of one cardiac cycle

216
Q

how to interpret if semi lunar valves are closed

A

when pressure in aorta/pulmonary artery is higher than ventricle;
prevents back flow of blood from artery to ventricles

217
Q

how to interpret if semi lunar valves are open

A

when pressure in ventricle is higher than aorta/pulmonary artery;
blood is flowing from ventricle to aorta

218
Q

how to interpret if atrioventricular valves are closed

A

when pressure in atrium is higher than in ventricle;
prevents backflow of blood from ventricle to atrium

219
Q

how to interpret if the atrioventricular valves are open

A

when pressure is higher in ventricle than atrium;
blood flows from ventricle to atrium

220
Q

how to interpret if the atrioventricular valves are open

A

when pressure is higher in ventricle than atrium;
blood flows from ventricle to atrium

221
Q

cardiovascular diseases

A

conditions affecting structures or functions of the heart e.g. chd

222
Q

how an atheroma can result in a heart attack

A

atheroma causes narrowing of coronary arteries;
restricts blood flow to heart muscle supplying glucose, oxygen etc.
heart respires anaerobically, less ATP produced, not enough energy for heart to contract, lactate produced, damages heart tissue/muscle

223
Q

risk factors of cardiovascular diseases

A

age, diet high in salt or saturated fat, high consumption of alcohol, stressful lifestyle, smoking cigarettes, genetics;
also high blood pressure increases damage to the artery endothelium which increases risk of atheroma which can cause blood clots

224
Q

adaptions of the xylem

A

elongated cells arranged end to end to form a continuous column;
few organelles so no disruption to water flow;
end walls break down for flow;
thick cell walls with lignin-rigid so less likely to collapse under low pressure;
water proof to prevent water loss;
pits allow lateral water movements;
narrow lumen increases height water can rise due to cohesion-tension/capillary action

225
Q

translocation

A

movement of solutes from source to sink
e.g. sugars made from photosynthesis in the leaves are transported to the site of respiration

226
Q

movement of substances at the source

A

high conc of solute;
active transport loads solute from companion cells to sieve tubes of the phloem;
lowering the water potential inside the sieve tubes;
water enters sieve tubes by osmosis from xylem and companion cells;
increasing pressure inside sieve tubes at the source end

227
Q

movement of substances at the sink

A

low conc of solute;
solutes removed to be used up;
increasing water potential inside the sieve tubes;
water leaves tubes via osmosis;
lowering pressure inside sieve tubes

228
Q

mass flow hypothesis process

A
  1. active transport moves sucrose from a companion cell into the sieve tube elements, reducing the water potential inside
  2. osmosis moves water into the phloem, which increases the hydrostatic pressure (pressure higher near the source cell and lower near the sink)
  3. solutes move down the pressure gradient, moving into the sink cells where they are converted into the molecules
  4. as the solutes are removed, the water potential near the sink end increases, causing osmosis to move water out of the phloem in order to maintain hydrostatic pressure gradient between the source and the sink
229
Q

source cells

A

cells that produce sugars and pump them into the phloem

230
Q

sink cells

A

areas which needs the substances from the source e.g. leaves

231
Q

what happens when sucrose reaches the sink

A

it is converted into starch for carbohydrate storage, which maintains the concentration gradient between the source and the sink to increase movement of sucrose into the source

232
Q

mass flow hypothesis def

A

theory which states that mass flow of solutes takes place in the phloem

233
Q

adaptions of the phloem

A

sieve tube elements have no nucleus and few organelles;
companion cell for each sieve tube element to carry out the living functions for the sieve cells
e.g. lots of mitochondria for ATP needed for active transport

234
Q

how DNA is stored in eukaryotes

A

long, linear, associated with proteins called histones, tightly coiled into chromosomes

235
Q

how DNA is stored in prokaryotes

A

short, circular, not associated with histones

236
Q

DNA in mitochondria and chloroplasts

A

short, circular, not associated with histones

237
Q

genes

A

sequence of DNA bases that codes for:
-amino acid sequence of a polypeptide
-a functional RNA
a gene occupies a locus (fixed position) on particular DNA molecules

238
Q

nature of genetic code

A

sequence of DNA triplets (or codons) codes for a sequence of amino acids
universal: same specific DNA base triplets code for the same amino acids in all living organisms
non overlapping: discrete, each base can only be used once and in only one triplet
degenerate: the same AA can be coded for by more than one base triplet

239
Q

genome

A

the complete set of genes in a cell, including those in mitochondria and/or chloroplasts

240
Q

proteome

A

the full range of proteins that a cell/genome is able to produce

241
Q

alleles

A

different version of the same gene
diff triplets

242
Q

homologous pair of chromosomes

A

same size chromosomes with the same genes but different alleles

243
Q

transcription

A

production of mRNA from DNA
occurs in the nucleus

244
Q

translation

A

production of polypeptides from the sequence of codons carried by mRNA
occurs in the cytoplasm on ribosomes

245
Q

mRNA

A

made by transcription;
acts as a template for translation in the cytoplasm;
sequence of bases on RNA determines sequence of AA;
straight chain molecule;
sequence of bases on RNA determined by sequence of bases on DNA;
chemically unstable so breaks down after a few days

246
Q

tRNA

A

carries an amino acid (binding site);
anticodon=3 bases
anticodon bases complementary to mRNA codon;
each tRNA specific to one amino acid, in relation to its anticodon
single polynucleotide strand (3 leafed clover shape-held together by H bonds)

247
Q

similarities between mRNA and tRNA

A

both single polynucleotide strand

248
Q

differences between mRNA and tRNA

A

mRNA single helix/straight chained; tRNA folded into clover shape
mRNA is longer; tRNA is shorter
mRNA contains no paired bases or H bonds; tRNA has some paired bases and H bonds

249
Q

transcription process

A

1.DNA double helix unwound by DNA helicase; H bonds broken
2. RNA nucleotides align next to their complementary bases on their template strand; forms temp H bonds and U replaces T
3. RNA polymerase joins adjacent nucleotides; condensation reaction; forming phosphodiester bonds
4. when RNA polymerase reaches stop codon, mRNa (prokaryotes) or pre-mRNA (eukaryotes) detaches from DNA
5. mRNA leaves nucleus via nuclear pore

250
Q

post transcriptional modification

A

eukaryotic genes contain:
exons-coding
introns-non coding

pre-mRNA contains introns and exons

splicing
introns removed and exons spliced together;
spliced together in different combos for different proteins

prokaryotic DNA doesn’t contain introns;
no splicing; mRNA produced directly from DNA

251
Q

translation

A

sequence of mRNA codons determines sequence of amino acids;
tRNAs carry specific amino acids, in relation to their anticodon;
at the ribosome, tRNA codon binds to mRNA codon
-tRNA anticodon complementary to mRNA codon
-H bonds formed
two AA joined by condensation, forming a peptide bond using energy from ATP;
tRNA detaches without AA and ribosome moves along mRNA to next codon
continues until stop codon where polypeptide is released

252
Q

role of ATP in translation

A

hydrolysis of ATP releases energy;
for the bond between the AA and it’s corresponding tRNA molecule—AA attaches at binding site;
for peptide bond formation between amino acids

253
Q

role of tRNA in translation

A

tRNA attaches to and transports a specific AA;
tRNA anticodon complementary base pairs to mRNA codon, forming H bonds;
2 tRNAs being AA tg for the formation of peptide bonds;
around 60 types of tRNA to carry 20 diff AA—genetic code is degenerate

254
Q

role of ribosomes in translation

A

attaches to mRNA and houses tRNA, allowing codon-anticodon complementary base pairing;
allows peptide bonds to form between amino acids

255
Q

gene mutation

A

a change in the base sequence of DNA on chromosomes;
can arise spontaneously during DNA replication (interphase);
involves base deletion/substitution

256
Q

how can a mutation lead to the production of a non-functional protein

A

change in base/triplet sequence of DNA/gene;
changes sequence of codons on mRNA;
changes sequence of AA in the primary structure of the polypeptide;
changes position of H/ionic/disulphide bonds in tertiary structure of protein

257
Q

how can a mutation lead to the production of a non-functional enzyme

A

change in base/triplet sequence of DNA/gene;
changes sequence of codons on mRNA;
changes sequence of AA in the primary structure of the polypeptide;
changes position of H/ionic/disulphide bonds in tertiary structure of active site;
substrate can’t bind to active site and form an ES complex

258
Q

base deletion

A

one nucleotide/base removed from DNA sequence;
changes triplet/codon sequence from the point of mutation;
changes sequence of codons on mRNA after point of mutation;
changes sequence of amino acids in primary structure of polypeptide;
change position of hydrogen/ionic/disulphidr bonds in tertiary structure of protein;
change tertiary structure/shape of protein

259
Q

base substitution

A

nucleotide/base in DNA replaced with another nucleotide/base; change in one base=changes one triplet;

changes one mRNA codon and one amino acid-> sequence of amino acids in primary structure of polypeptide changes

ORR

due to the genetic nature of the genetic code, the new triplet may still code for the same AA so the sequence of amino acids in the primary structure of the polypeptide remains unchanged

260
Q

mutagenic agents

A

increase the rate of gene mutation
e.g. UV light or alpha particles

261
Q

skipped meiosis

A
262
Q

genetic diversity

A

number of different alleles of a gene in a population

263
Q

population

A

group of interbreeding individuals of the same species

264
Q

principles of natural selection

A
  1. variation of alleles exist in population due to random DNA mutations—e.g. some bacteria contain genes for antibiotic resistance due to a mutation
  2. selection pressure/change in environment—e.g. antibiotic introduced
  3. those with advantageous alleles have increased chance of survival and reproduction—e.g. bacteria w gene for resistance survive and reproduce while those without it die
  4. those surviving/reproducing pass on advantageous allele to offspring
  5. frequency of advantageous allele increases in the population
  6. happens over many generations
265
Q

directional selection

A

change to environment;
selection pressure moves to one extreme or the other;
one extreme phenotype is more likely to survive and reproduce;
mean phenotype changes

266
Q

stabilising selection

A

stable environment;
selection pressure acts either side of the mean;
both extremes of phenotype less likely to survive and reproduce (very small or very large babies);
mean phenotype stays the same

267
Q

how/why does natural selection result in better adapted species

A

these adaptions all increase an organisms chance of survival
ANATOMICAL: structural features of an organisms body e.g. polar bears fur or whales thick layer of blubber keeps them warm
PHYSIOLOGICAL: processes inside the body e.g. brown bears hibernate in winter, lower metabolism to conserve energy so they don’t need to look for food when it’s scarce
BEHAVIOURAL: ways an organisms acts e.g. possum plays dead if they’re being threatened by a predator to escape attack

268
Q

species

A

when two organisms are able to produce fertile offspring

269
Q

courtship behaviour

A

allows recognition of members of the same species because courtship behaviour is species specific;
indication of sexual maturity;
stimulate release of gametes

270
Q

phylogenetic classification system

A

arranges species into groups based on their evolutionary origins and relationships
hierarchical: no overlap between groups

271
Q

genome sequencing

A

compare the order of base sequence of whole genome of different species
high%=more closely related

272
Q

immunology

A

DNA-> mRNA -> sequence of amino acids in polypeptide;
so tertiary structure of protein tells us about sequence of DNA;
if same antibody binds to a specific antigen then it’s closely related to

273
Q

biodiversity

A

the variety of living organisms in an area

274
Q

3 types of biodiversity

A

species diversity
genetic diversity
ecosystem diversity

275
Q

species diversity

A

the number of different species and the number of individuals of each species within a community

276
Q

community

A

all of the different species in a habitat

277
Q

local biodiversity

A

the variety of species living in a small habitat e.g. pond/meadow

278
Q

global biodiversity

A

the variety of species living on earth

279
Q

species richness

A

the number of different species in a community

280
Q

index of diversity

A

describes the relationship between the number of species in a community and the number of individuals in each species
N=total number of organisms of ALL species
n=total number of organisms of each individual species
lowest possible number=1

281
Q

why is index of diversity more useful than species richness

A

it measures both the number of species and the number of individuals in each species;
takes into account that some species may be present in low/high numbers

282
Q

farming techniques that reduce biodiversity

A

removal of woodlands and hedgerows;
monoculture e.g. replace natural meadows with one cereal crop;
use of pesticides, herbicides and organic fertilisers;
crops better competitors for resources

283
Q

variation

A

differences in characteristics between individuals within a species or between different species;
could be the result of
-genetic factors
-environmental factors
-or both

284
Q

continuous variation

A

-no distinct categories;
-data tends to be quantitative;
-controlled by many genes
-strongly influenced by the environment

285
Q

discontinuous variation

A

-distinct categories;
-data tends to be qualitative;
-controlled by a single/few genes;
Yeah yeah-unaffected/not strong,y influenced by the environment

286
Q

HIV core

A

genetic material (RNA) and reverse transcriptase (enzyme);
needed for viral replication

287
Q

capsid

A

outer protein coat

288
Q

HIV envelope

A

extra outer layer, made out of the host cell’s membeane

289
Q

protein attachments

A

on the exterior of the envelope to enable the virus to attach to the host’s Th cell

290
Q

HIV replication

A
  1. attachment proteins attach to receptors on Th cell
  2. nucleic acid/ RNA enters the cell
  3. reverse transcriptase converts DNA to RNA
  4. viral proteins produced
  5. virus particles assembled and released from cell
291
Q

antibiotic resistance in bacteria

A
  1. random mutations creates a resistance allele in the bacteria population
  2. when exposed to the antibiotic, only those with the resistance allele will survive and reproduce
  3. resistance allele frequency increases over generations
292
Q

describe the role of antibodies in producing a positive result in an ELISA test

A
  1. first antibody binds to antigen
  2. second antibody with enzyme attached is added
  3. second antibody attaches to antigen
  4. substrate added and colour changes
293
Q

describe the principles and limitations of using a TEM to investigate cell structure

A

PRINCIPLES:
1. electrons pass through thin specimen
2. denser parts absorb more electrons so appear darker
3. electrons have shorter wavelengths so gives higher resolution

LIMTATIONS:
1. cannot view living cells
2. complex + long preparation
3. specimen must be very thin

294
Q

describe and explain how cell fractionation can be used to isolate mitochondria from a suspension of animal cells

A
  1. homogenise in a blender to break down cells
  2. place in an ice cold, isotonic and buffered solution
  3. centrifuge at low speed to separate nuclei
  4. response supernatant at higher speed to separate mitochondria in the pellet
295
Q

name two ways in which meiosis produces genetic variation

A
  1. crossing over
  2. independent segregation
296
Q

a mutations can lead to the production of a non-functional enzyme. explain how.

A
  1. change in base/nucleotide sequence of DNA
  2. change in amino acid sequence/primary structure
  3. change in H/ionic/ disulfide bonds
  4. change in tertiary structure
  5. change in active site
  6. substrate no longer complementary / no ES complexes formed

biology (4 decks)

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