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Peer teaching > IMMS > Flashcards

IMMS Flashcards

1
Q

<p>cell membrane structure and contents</p>

A

<p>phospholipid bilayer

cholesterol - supports fluidity
proteins - act as transporters
glycolipids and glycoproteins - involved in cell signalling</p>

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2
Q

<p>cell membrane functions</p>

A

<p>semi-permeable membrane

cell membrane receptors

regulates what goes in and out of cell

separates intracellular cell contents from extracellular</p>

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3
Q

<p>tight junction function</p>

A

<p>seals neighbouring cells together in epithelial sheet to prevent leakage of molecules between them</p>

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4
Q

<p>adherent junction function</p>

A

<p>joins an actin bundle in one cell to a similar bundle in a neighbouring cell</p>

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5
Q

<p>desmosome function</p>

A

<p>joins intermediate filaments in one cell to those in a neighbour</p>

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6
Q

<p>gap junction function</p>

A

<p>allows passage of small water-soluble ions and molecules</p>

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7
Q

<p>hemidesmosome function</p>

A

<p>anchors intermediate filaments in a cell to the basal lamina</p>

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8
Q

<p>hormones - peptide vs steroid</p>

A

<p>steroid - slow response (sex hormones)

peptide - fast response (insulin, TSH)</p>

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9
Q

<p>homeostasis definition</p>

A

<p>the maintenance of a constant internal environment</p>

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10
Q

<p>types of cell signalling</p>

A

<p>autocrine
paracrine
endocrine
exocrine</p>

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11
Q

<p>water distribution in the body</p>

A

<p>2/3 intracellular - 28L

| 1/3 extracellular -14L</p>

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12
Q

<p>components of extracellular fluid</p>

A

<p>plasma - 3L
transcellular - 1L
interstitial - 10L</p>

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13
Q

<p>contents of ECF </p>

A

<p>glucose, urea, Cl-, HCO3-

main cation in Na+</p>

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14
Q

<p>contents of ICF</p>

A

<p>main cation is K+</p>

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15
Q

<p>osmolality definition</p>

A

<p>concentration of solutes in plasma per kilogram of solvent</p>

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16
Q

<p>osmolarity definition</p>

A

<p>concentration of solutes in plasma per litre of solution</p>

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17
Q

<p>osmotic pressure definition</p>

A

<p>the pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis

measure of how easily a solution can take in water
</p>

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18
Q

<p>oncotic pressure</p>

A

<p>form of osmotic pressure induced by proteins, notably albumin, in a blood vessel's plasma that displaces water molecules, thus creating a relative water molecule deficit with water molecules moving back into the circulatory system within the lower pressure venous end of capillaries

</p>

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19
Q

<p>oedema definition</p>

A

<p>increased movement of fluid from plasma into interstitial space</p>

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20
Q

<p>monosaccharide definition</p>

A

<p>any sugar that can't be hydrolysed</p>

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21
Q

<p>types of monosaccharides</p>

A

<p>glucose, fructose, galactose</p>

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22
Q

<p>oligosaccharide definition</p>

A

<p>substance made of 3-10 monosaccharides</p>

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23
Q

<p>polysaccharide definition</p>

A

<p>complex carbohydrate composed of more than 10 monosaccharides joined by glycosidic bonds</p>

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24
Q

<p>formation of glycosidic bonds</p>

A

<p>condensation reaction of 2 monosaccharides water is by-product</p>

<p><br></br>
</p>

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25
Q

lipid structure

A

3 fatty acids bound to one glycerol

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26
Q

amino acid structure

A

amino group (NH2) and carboxyl group (COOH) bound to carbon with H and side chain

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27
Q

structures of proteins

A

primary, secondary, tertiary, quaternary

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28
Q

primary protein structure

A

sequence of a chain of amino acids

held together by peptide bonds (CONH)

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29
Q

secondary protein structure

A

local folding of polypeptide chain into alpha helices or beta pleated sheet

alpha helix - hydrogen bond from NH to CO 3-4 residues earlier

beta strands connected laterally by 3-4 backbone hydrogen bonds

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30
Q

tertiary protein structure

A

3D folding pattern of a protein due to side chain interactions

disulfide bonds, hydrogen bonds, salt bridges, non-polar hydrophobic interactions

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31
Q

quaternary protein structure

A

more than one aa chain

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32
Q

ATP-ADP cycle

A

ATP + water -> ADP + Pi + energy for cells

ADP + Pi + energy from food -> ATP

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33
Q

metabolism definition

A

chemical reactions that occur in a living organism

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34
Q

BMR definition

A

Basal Metabolic Rate

measure of energy required to maintain non-exercise bodily functions

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35
Q

example of BMR

A

respiration/biosynthesis - only measured if not eaten in past 12 hours, controlled temperature

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36
Q

what is oxidative phosphorylation?

A

electron transport chain

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37
Q

where does oxidative phosphorylation occur?

A

inner mitochondrial membrane

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38
Q

what happens in oxidative phosphorylation?

A

H+ pumped into intermembrane space via proton pumps to form electrochemical gradient

electrons transferred to 02 to split to form water

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39
Q

where do electrons come from in oxidative phosphorylation?

A

NADH -> NAD+ + e-

FADH2 -> FAD + e-

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40
Q

how many ATPs produced per NADH/FADH?

A

3 and 2, respectively

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41
Q

how much ATP is produced per molecule of glucose?

A

34

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42
Q

how is ATP formed in oxidative phosphorylation?

A

H+ ions flow down electrochemical gradient through ATP synthase to form ATP

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43
Q

fatty acid oxidation definition

A

production of ATP from fat consumption (diet) and fat storage using beta oxidation

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44
Q

examples of fatty acids

A

linoleic acid, oleic acid, palmitic acid, arachidonic acid

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45
Q

where can acetyl-CoA be derived from?

A

beta oxidation of fatty acids

fatty acid has to be activated first to form acyl-CoA

acyl-CoA enters carnitine shuttle to enter mitochondria for beta oxidation

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46
Q

pathology of fatty acid oxidation

A

diabetic ketoacidosis

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47
Q

multifactorial disease

A

spina bifida
diabetes
schizophrenia

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48
Q

environmental diseases

A

poor diet

infection

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49
Q

categories of diseases

A

genetic, multifactorial, environmental

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50
Q

what is gametogenesis?

A

first stage is the proliferation of primordial germ cells by mitosis

timing of mitosis differs in males and females

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51
Q

primary spermatocytes

A

some mitosis occurs in embryonic stages to produce primary spermatocytes at birth

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52
Q

gametogenesis in males

A

mitosis begins in puberty, throughout life

cytoplasm divides evenly

four equal size gametes

millions of mature sperm continually produced

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53
Q

how long does male gametogenesis take?

A

60-65 days

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54
Q

when does meiosis occur in oogonia?

A

prophase 1 by 8th month of intrauterine life

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55
Q

when do cells enter ovulation?

A

10-50 years later

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56
Q

how does the cytoplasm in female gametogenesis divide?

A

unequally - 1 egg and 3 polar bodies (apoptose - go on to die)

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57
Q

when does meiosis 1 occur?

A

completed at ovulation. one big cell and one small, diploid DNA

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58
Q

when is meiosis 2 completed?

A

if fertilisation occurs

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59
Q

what is non-disjunction? what can it lead to?

A

failure of chromosome pairs to separate in meiosis 1 or sister chromatids to separate properly in meiosis 2

downs syndrome/monosomy (Turners syndrome)

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60
Q

what is monosomy?

A

loss of a chromosome

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61
Q

what is Turners syndrome?

A

only 1 X chromosome

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62
Q

what is the karyotype?

A

number and appearance of chromosomes in a cell

spreads arranged in size order, biggest is pair 1 and smallest is pair 22

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63
Q

hwo many bp are in a chromosome?

A

10^7

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64
Q

how many genes do we have?

A

30000

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65
Q

structure of chromosome

A

long arm (q) and short arm (p - petit)

separated by centromere

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66
Q

what is monosomy?

A

loss of chromosome

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67
Q

what is Turner’s syndrome?

A

only 1 X chromosome

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68
Q

what can problems with meiosis lead to?

A

non disjunction

downs, monosomy

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69
Q

what is non-disjunction?

A

failure of chromosome pairs to separate in meiosis 1 or sister chromatids to separate in meiosis 2

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70
Q

what is downs syndrome?

A

trisomy 21

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71
Q

what is gonadal mosaicism?

A

precursor germline cells to ova or spermatozoa are a mixture of 2+ genetically different cell lines (error in mitosis)

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72
Q

who does gonadal mosaicism affect?

A

advancing paternal age

parent healthy, fetus maybe affected

more common in males

any inheritance pattern, more common in autosomal dominant and X-linked

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73
Q

why does lyonisation occur?

A

to prevent female cells from having twice as many gene products from the x chromosome as males

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74
Q

what is the barrbody?

A

inactive X chromosome since packaged in heterochromatin

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75
Q

what is imprinting?

A

non-mendelian

for some genes only 1/2 alleles is active, the other is inactive for some it’s always maternal/paternal allele

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76
Q

what is Knudson’s 2-HIT hypothesis?

A

gene mutations may be inherited or acquired during a person’s life

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77
Q

what are sporadic cancers?

A

2 acquired mutations

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78
Q

what are hereditary cancers?

A

1 inherited mutation and 1 acquired mutation

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79
Q

what is an ideogram?

A

diagrammatic form of chromosome bands - bands are numbered according to distance to centromere

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80
Q

classification of genetic disease

A

chromosomal, mendelian (autosomal dominant/recessive or X-linked), non-traditional (mitochondrial)

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81
Q

where is mitochondria inherited from?

A

mother

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82
Q

what is the general formula of carbohydrates?

A

Cn(H2O)n

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83
Q

what is lactose made of?

A

glucose + galactose

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84
Q

what is sucrose made of?

A

glucose + fructose

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85
Q

what is maltose made of?

A

glucose + glucose

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86
Q

what is a monosaccharide?

A

chain of carbons, hydroxyl group, one carbonyl group

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87
Q

D + L monosaccharides

A

same chemical properties but different biological ones

optically active and different forms

most are D in living organisms

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88
Q

what are ring structures?

A

cyclised

reaction of aldehyde/ketone group with hydroxyl group of same molecule

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89
Q

what is a glycosidic bond?

A

hydroxyl group of a monosaccharide reacts with an OH or NH group

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90
Q

what do O-glycosidic bonds form?

A

disaccharides, oligosaccharides, polysaccharides

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91
Q

what do N-glycosidic bonds form?

A

nucleotides and DNA

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92
Q

what are disaccharides?

A

2 monosaccharides joined by an O-glyosidic bond

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93
Q

what is starch?

A

storage in plants

made of amylose (glucose alpha 1,4) and amylopectin (glucose alpha 1,4 and alpha 1,6 bonds)

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94
Q

what are proteoglycans?

A

long, unbranched polysaccharides radiating from a core protein

found in animals

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95
Q

what is glycogen?

A

storage in animals

branched polysaccharide formed of glucose residues

alpha 1,4 (between carbons and alpha 1,6 (side chain and main chain)

branching at regular intervals

core protein is glycogenic

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96
Q

what are properties of peptide bonds?

A

very stable

cleaved by proteolytic enzymes - proteases or peptidases

partial double bonds

flexibility around C atoms not involved in bond

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97
Q

regulation of enzymes

A

altering conc. of substrates, products, inhibitors or activators, or modifying enzyme by phosphorylation

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98
Q

what is an isoenzyme?

A

enzymes w/ different structure and sequence, catalyse same reaction

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99
Q

what are coenzymes?

A

cannot catalyse a reaction themselves, but help enzymes do so.

bind w/ enzyme protein molecule to form active enzyme

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100
Q

what is the process of DNA transcription?

A

transcription complex forms around TATA box on 5’ of 1st exon

topoisomerase unwinds double helix by relieving supercoils

DNA helicase separates DNA, exposing nucleotides

SSBs coat strands to prevent reannealing

free mRNA nucleotides line up their complementary bases on template/antisense strand

RNA polymerase 2 joins mRNA nucleotides to form antiparallel mRNA strand starting at promoter

mRNA leaves nucleus and attaches to 8Os ribosome

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101
Q

oxidation-reduction coenzymes

A

involved in reactions where electrons are transferred from one compound to the other

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102
Q

what is myoglobin?

A

porphyrin ring - iron atom

muscle, reserve supply of oxygen, facilitates movement of O2 in muscles

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103
Q

specificity of antibody-antigen binding

A

one antibody matches only one antigen

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104
Q

what are antigens bound by?

A

portion of antibody called variable domain

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105
Q

what is the primer?

A

short strand of DNA that’s the start point for DNA synthesis as DNA polymerases can only add nucleotides onto an existing strand of DNA

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106
Q

what is the SSB?

A

single strand binding protein

keeps 2 strands of DNA apart while synthesis of new DNA occurs

prevents annealing to form double stranded DNA

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107
Q

what is the primase enzyme?

A

RNA polymerase that synthesises the short RNA primers needed to start strand replication process

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108
Q

what is RNAse H?

A

removes RNA primers that previously began DNA strand synthesis

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109
Q

what are transcription factors?

A

proteins which bind to promotor regions

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110
Q

what is the promoter?

A

5’ of 1st exon

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111
Q

what is the TATA box?

A

reads thymine, adenine, etx

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112
Q

what is the structure of the antiparallel mRNA strand?

A

5’ CAP head and 3’ Poly A tail

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113
Q

what does mRNA attach to after leaving the nucleus?

A

80s ribosome

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114
Q

what does the mRNA do at the ribosome?

A

mRNA sequence used as template to bind to complementary tRNA molecules at anticodon (3 bases complementary to codon on mRNA)

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115
Q

what codes for a particular amino acid?

A

one codon

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116
Q

where is the amino acid carried by the tRNA?

A

on its 3’ end

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117
Q

how are bases read?

A

5’ to 3’

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118
Q

how are proteins created?

A

enzymes remove amino acid from tRNA and amino acids linked together by a peptide bond (condensation) - creating polypeptide chain

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119
Q

what is the start codon?

A

AUG

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120
Q

what are the stop codons?

A

UGA, UAG, UAA

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121
Q

how does a ribosome recognise mRNA?

A

from its CAP on the 5’ end

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122
Q

what are the exons?

A

contain the coding sequence

123
Q

what is the promoter region?

A

what RNA polymerase recognises and where it starts

124
Q

primary -> mature

A

non-coding introns are removed and exonic regions are joined

125
Q

what is exon shuffling?

A

exons not in same order

allows new proteins to be made

huge variants of antibodies to produce

126
Q

gene for producing immunoglobulins in macrophage vs B cell

A

macrophage (not produced) - in heterochromatin form

B cell (produced) - euchromatin form

127
Q

out of frame deletion

A

clearly disrupts protein - shifts, meaning the reading frame of the gene is changed

catastrophic effects, early mortality

128
Q

in frame deletion

A

complete codon is removed - only one amino acid is lost

less catastrophic

reading frame is not altered

milder disease, later onset death

129
Q

mutations of regulatory sequence

A

coding sequence still intact but gene itself is switched on or off

130
Q

DNA damage/repair issues

A

chemicals, UV, radiation

base/nucleotide excision, mismatch repair, transcription-coupled repair

131
Q

mis sense mutation

A

A point mutation in which a single nucleotide change results in a codon that codes for a different amino acid (substitution). This can have a varied affect and can result in a silent mutation and a non functional protein

132
Q

missense mutation in sickle cell disease

A

CAG replaced with CTG

133
Q

nonsense mutation

A

Point mutation that produces a stop codon - results in an incomplete, usually non-functional protein. E.g. Duchenne’s muscular dystrophy

134
Q

splice-site mutation

A

affects accurate removal of an intron

excision doesn’t occur as enzyme doesn’t recognise cutting site, sequence of intron is translated

135
Q

expansion of a tri-nucleotide repeat (e.g. Huntingtons)

A

triple repeat repeated several times in first part of coding sequence

normal range is 15-20

repeats 36+ Huntingtons, earlier onset
<36 -> no disease

Huntingtons: CAG

136
Q

anticipation

A

repeats get bigger when transmitted to next generation -> earlier symptoms of greater severity

137
Q

types of communication

A

autocrine, paracrine, endocrine, exocrine

138
Q

autocrine

A

chemical released from cell into ECF, acts upon cell that secreted it

139
Q

paracrine

A

messengers involved in communication between cells, released into ECF - short distances, local communication

140
Q

differences between endocrine and paracrine

A

hormone travel in blood in endocrine, in paracrine only in ECF
endocrine affects more things and travels further

141
Q

primary hypothyroidism

A

thyroid producing too little thyroxine to induce negative feedback - TSH levels in blood keep increasing as pituitary doesn’t think theres enough

142
Q

primary hyperthyroidism

A

thyroid produces too much thyroxine and keeps producing regardless of TSH produced by pituitary, TSH falls, thyroxine rises

143
Q

types of hormones

A

peptide, steroid and amino-acid derivative

144
Q

what are peptide hormones made of?

A

short chain amino acids - vary in size

carbohydrate side chains (glycoproteins)

they are large hydrophilic charged molecules that can’t diffuse across a membrane

145
Q

what are the properties of peptide hormones? how do they get across membranes?

A

large, hydrophilic charged molecules

cannot diffused across membrane - bind to receptors on it

146
Q

how are peptide hormones made/released?

A

premade and stored in cell, then released and dissolved into blood when needed

147
Q

how quickly do peptide hormones react? what is their response?

A

chemical reaction produces quick response from the cell

2nd messenger released - very fast (signal transduction cascade)

148
Q

examples of peptide hormones

A

insulin, growth hormone, thyroid stimulating hormone, ADH/vasopressin

149
Q

what is steroid hormone synthesised from?

A

synthesised from cholesterol, water, insoluble and soluble lipid

150
Q

how do steroid hormones cross membranes?

A

can cross

transport proteins in blood

targets intracellular receptor

151
Q

how is steroid hormone made/released?

A

made by cell

diffuses out once made (not stored)

152
Q

how is steroid hormone transported in the blood?

A

bound to transport proteins cannot dissolve in water

153
Q

what receptor does steroid hormone bind to?

A

receptor inside cell

154
Q

how quick is the steroid hormone response? what is its effect?

A

slow (hours/days) - directly affects DNA

155
Q

examples of steroid hormones

A

testosterone, oestrogen, cortisol

156
Q

what are the effects of angiotensin II and aldosterone?

A

increase Na+ reabsorption in kidneys in exchange for potassium or hydrogen excretion

stimulate ADH release

157
Q

what are examples of amino acid hormones?

A

adrenaline, thyroid hormones (thyroxine (T4) and triiodothyronine (T3))

158
Q

interstitial fluid

A

surrounds the cells, doesn’t circulate

159
Q

transcellular fluid

A

makes up CSF, digestive juices, mucus

160
Q

plasma

A

circulates as the extracellular component of blood

161
Q

where is water taken in/lost from?

A

diet, drink, IV fluid

kidneys, insensible losses (sweat, breath, vomiting, faeces)

162
Q

what is osmosis?

A

net movement of solvent molecules through a semipermeable membrane to a higher solute concentration (lower water conc.)

163
Q

what is hydrostatic pressure?

A

pressure difference between capillary blood (plasma) and interstitial fluid - water and solutes move from plasma into interstitial fluid

164
Q

what happens when water is lost from ECF?

A

increase in solutes/decrease in water = increase in osmolality in ECF

osmoreceptors in hypothalamus detect this

-> ADH/vasopressin release from posterior pituitary

ADH increases water reabsorption

165
Q

what happens when there is decreased renal blood flow?

A

decrease in water in ECF = decrease in effective circulating volume

release of renin from juxtaglomerular cells in kidneys

renin converts angiotensinogen to angiotensin I, ACE converts it to angiotensin II, triggering release of aldosterone from adrenal cortex

166
Q

what releases aldosterone? what is it triggered by?

A

adrenal glands (cortex)

angiotensin II

167
Q

what are the effects of angiotensin II and aldosterone?

A

increase Na+ reabsorption in kidneys in exchange for potassium or hydrogen excretion

168
Q

how does sodium resorption affect water?

A

brings water with it

169
Q

causes of dehydration

A

water deprivation, vomiting, burns, heavy sweating, diabetes insipidus, diabetes mellitus, drugs

170
Q

consequences of dehydration

A

thirst, dry mouth, inelastic skin, sunken eyes, raised hematocrit, weight loss, confusion, hypertension

171
Q

causes of water excess

A

high intake, decreased loss of water, excess ADH

172
Q

consequences of water excess

A

hyponatraemia, cerebral overperfusion, headaches, confusion, convulsions

173
Q

what is serous effusion?

A

excess water in a body cavity

174
Q

what is hypernatraemia? what are its causes and consequences?

A

high sodium

renal failure, mineralocorticoid excess, osmotic diuresis (increased urine rate due to high water amount), diabetes insipidus

cerebral intracellular dehydration, lower water conc,

175
Q

what is hyponatraemia? what are its causes and consequences?

A

low sodium

diuresis (increased urine rate), Addison’s disease, excess IV fluids and oedema

intracellular over hydration - hypotension

176
Q

what is potassium excretion from the kidney controlled by?

A

aldosterone - controls Na/K pump

177
Q

what is hyperkalaemia? what are its causes and consequences?

A

high potassium

renal failure, diuretics/ACE inhibitors, Addison’s, acidosis

risk of myocardial infarction - mess w/ resting potential in heart

178
Q

what is hypokalaemia? what are its causes and consequences?

A

low potassium

diarrhoea, vomiting, alkalosis, hypomagnesaemia

weakness and cardiac dysrhythmia

179
Q

what is hypercalcaemia? what are its causes and consequences?

A

high calcium

primary hyperparathyroidism (too much parathyroid hormone, calcium leached from bone to increase blood levels), skeletal metastases, vit D toxicity, TB

metastatic calcification, kidney stones (renal calculi)

180
Q

what is metastatic calcification?

A

deposition of calcium salts in otherwise normal tissues

stones

181
Q

what is hypocalcaemia? what are its causes and consequences?

A

low calcium

vit D deficiency, magnesium deficiency, renal disease, parathyroidectomy, intestinal malabsorption

consequences: tetany

182
Q

what is tetany?

A

spasms of the hands, feet and voice box

183
Q

what is facilitated diffusion?

A

movement of solutes from a region of high conc to low conc through protein channels (w/out carrier proteins)
continues until dynamic equilibrium is reached

184
Q

what is active transport? what does it require?

A

movement of solutes from a region of low conc. to high conc. against the conc. gradient

transmembrane carrier protein and ATP required

185
Q

what is a receptor?

A

a specific protein in either the plasma membrane or the interior of a target cell that a chemical messenger binds with - invokes a biologically relevant response

186
Q

what is specificity?

A

ability of a receptor to bind only one type/limited number of structurally related types of chemical messengers

187
Q

what is saturation?

A

the degree to which receptors are occupied by messengers

188
Q

what is affinity?

A

the strength with which a chemical messenger binds to its receptor

189
Q

what is competition?

A

the ability of different molecules to compete with a ligand for binding to its receptor. competitors usually similar in structure

190
Q

what is an antagonist?

A

a molecule that competes with a ligand for binding to its receptor but doesn’t activate signalling normally associated with it

prevents actions of the natural ligand

191
Q

what is an example of an antagonist?

A

antihistamines

192
Q

what is an agonist?

A

a chemical messenger that binds to a receptor and triggers the cell’s response

drug that mimics a normal messenger’s action

193
Q

what is an example of an agonist?

A

decongestants

194
Q

what is down-regulation?

A

a decrease in total number of target-cell receptors for a given messenger - may occur due to chronic high extracellular conc. of messenger

195
Q

what is up-regulation?

A

an increase in the total number of target-cell receptors for a given messenger - may occur due to chronic low extracellular conc.

196
Q

what is increased sensitivity?

A

increased responsiveness of a target cell to a given messenger - may result from upregulation

197
Q

what is the main cause of down-regulation?

A

internalisation - taken into cell by receptor mediated endocytosis

increases rate of receptor degradation

198
Q

what is receptor activation?

A

combination of messenger with receptor causing change in conformation of the receptor

199
Q

what are potential cell reactions to the messenger?

A

changes in the permeability, transport properties or electrical state of the plasma membrane

changes in metabolism, secretory activity, rate of proliferation/differentiation, contractile activity

200
Q

what are signal transduction pathways?

A

diverse sequences of events linking receptor activation to cellular responses

201
Q

what do the lipid-soluble messengers do in the nucleus?

A

acts as a transcription factor

binds to DNA at a regulatory region of a gene - increases rate of transcription

202
Q

effects of cortisol

A

inhibits transcription of genes whose protein products mediate inflammatory responses following injury/infection

lipid-soluble

203
Q

what are first messengers?

A

extracellular chemical messengers that reach the cell and bind to specific plasma membrane receptors

204
Q

what are second messengers?

A

substances that enter/generated in cytoplasm due to receptor activation by 1st messenger

205
Q

what is a protein kinase?

A

enzyme that phosphorylates other proteins by transferring a phosphate group to them from ATP

206
Q

what underlies the cell’s biochemical response to the first messenger?

A

ultimate phosphorylation of key proteins, e.g. transporters, metabolic enzymes, ion channels, contractile proteins

207
Q

what are protein phosphatases?

A

dephosphorylate proteins

208
Q

ligand-gated ion channels

A

activation of receptor by first messenger (ligand) -> conformational change of the receptor -> forming an open channel through plasma membrane

209
Q

where are ligand-gated ion channels prominent?

A

plasma membranes of neurons

210
Q

what does opening of the ligand-gated ion channels lead to?

A

increase in net diffusion of ions across membrane - changes membrane potential

211
Q

types of plasma membrane receptors

A

ligand gated ion channels

receptors that function as enzymes

receptors that are bound to and activate cytoplasmic janus kinases

G-protein-coupled receptors

212
Q

what are receptor tyrosine kinases?

A

many receptors with intrinsic enzyme activity are protein kinases, majority specifically phosphorylate tyrosine residues

213
Q

what is the sequence of events for receptors w/ intrinsic tyrosine kinase activity?

A

binding changes receptor so its enzymatic portion, on cytoplasmic side, is activated

leads to autophosphorylation of the receptor

phosphotyrosines on cytoplasmic portion of the receptor serve as docking sites for cytoplasmic proteins

bound docking proteins bind and activate proteins, which activate signalling pathways

214
Q

what is autophosphorylation?

A

receptor tyrosine kinases phosphorylates some of its own tyrosine residues - creates phosphotyrosines on cytoplasmic side

215
Q

what do phosphotyrosines do?

A

(on cytoplasmic side) docking sites for cytoplasmic proteins which activate signalling pathways

216
Q

what catalyses the formation of cGMP

A

a receptor acting as a receptor and as a guanylyl cyclase catalyses the formation in cytoplasm

217
Q

what does cGMP do?

A

acts as a 2nd messenger to activate a protein kinase called cGMP-dependent protein kinase

218
Q

what does cGMP-dependent protein kinase do?

A

phosphorylates specific proteins that mediate the cell’s response to the original messenger

219
Q

where are receptors that function as ligand-binding molecules and guanylyl cyclases predominant?

A

retina of eye - processing visual inputs

220
Q

what happens when guanylyl cyclase enzymes are in the cytoplasm?

A

first messenger, NO, diffuses into cytosol of the cell to trigger the formation of cGMP

221
Q

what is NO? what is it produced by?

A

lipid-soluble gas

amino acid gas arginine by enzyme nitric acid synthase (present in cell types)

222
Q

in what way does NO act?

A

paracrine

223
Q

what are JAKs?

A

janus kinases - family of separate cytoplasmic kinases associated with the receptor

224
Q

process in JAKs

A

acts as a functional unit with receptor

binding of first messenger -> conformational change -> activation of janus kinase

225
Q

what do different JAKs do?

A

phosphorylate different target proteins, many acting as transcription factors

synthesise new proteins

226
Q

what are cytokines?

A

proteins that are secreted by cells of the immune system that play a critical role in immune defences

227
Q

what are G proteins?

A

family of proteins bound to inactive receptor on cytosolic surface of plasma membrane

3 subunits

228
Q

what are the subunits of G proteins? what do they do?

A

alpha, beta and gamma subunits

alpha subunit can bind GDP and GTP

beta and gamma subunits help anchor alpha subunit in the membrane

229
Q

what does the activated receptor associated with G proteins do?

A

increases the affinity of alpha subunit of G protein for GTP

when bound to GTP, the alpha subunit dissociates from the beta and gamma subunits of the trimeric G protein

allows it to link up with another plasma membrane protein - ion channel or enzyme

230
Q

what effects can the G protein have?

A

may cause ion channel to open -> change in electrical signals

activate/inhibit membrane enzymes - may generate second messengers

231
Q

what happens once the alpha subunit of the G protein activates its effector protein?

A

GTPase activity inherent in alpha subunit cleaves the GTP to GDP and Pi

makes alpha subunit inactive, recombines with beta and gamma subunits

232
Q

what inactivates alpha subunits? what does this lead to?

A

GTPase activity inherent in alpha subunit cleaves GTP to GDP and Pi

recombine with beta and gamma subunits

233
Q

what are the most common effector protein enzymes regulated by G proteins?

A

adenylyl cyclase and cyclic AMP

234
Q

what is the G protein in the adenylyl cyclase/cAMP pathway?

A

Gs (stimulatory)

235
Q

what is the effector protein of Gs?

A

adenylyl cyclase (membrane enzyme)

236
Q

what does adenylyl cyclase do?

A

activated by binding of the first messenger to receptor, leading to activation of G protein

catalytic site located on cytosolic surface of plasma membrane

catalyses conversion of cytosolic ATP to cyclic 3’,5’-adenosine monophosphate

237
Q

what is cAMP? what is it formed by?

A

cyclic 3’,5’- adenosine monophosphate

adenylyl cyclase catalyses conversion of cytosolic ATP to cAMP

238
Q

what does cAMP do?

A

acts as second messenger

239
Q

how does ATP provide energy?

A

energy released when phosphate bonds are broken

input of energy needed to break bonds

as bonds reform in hydrolysis of ATP energy is released

energy released is greater than energy required to break bonds (weak)

240
Q

what are the methods for generating ATP?

A

glycolysis, Kreb’s cycle, oxidative phosphorylation, substrate level phosphorylation, ETC, beta oxidation

241
Q

where does glycolysis take place?

A

cytosol

242
Q

what is the overall reaction of glycolysis?

A

glucose + 2ADP +2NAD+ -> 2pyruvate + 4ATP + 2NADH + 2H+ + 2H2O

243
Q

what is the simplified glycolysis equation?

A

glucose + 2ADP + 2Pi + 2NAD+ -> 2pyruvate + 2ATP + 2NADH + 2H+ + 2H2O

244
Q

what is a kinase?

A

enzyme that adds/removes phosphate group to things from an ATP

245
Q

what is an isomerase?

A

enzyme that rearranges structure of substrate without changing the molecular formula (similar to mutase)

246
Q

what is an aldolase?

A

enzyme that creates or breaks carbon-carbon bonds

247
Q

what is a dehydrogenase?

A

enzyme that moves hydride ion (H-) to an electron acceptor e.g. NAD+ or FAD+

248
Q

what is an enolase?

A

enzyme that produces a carbon=carbon double bond by removing a hydroxyl group (OH)

249
Q

NAD+/H+ in glycolysis

A

the NAD+ and H+ released in step 6 of glycolysis is used in the conversion of pyruvate to lactate which releases NAD+ that can be reused in step 6

250
Q

when is pyruvate converted to lactate?

A

anaerobic conditions - cannot enter the Kreb’s cycle or undergo oxidative phosphorylation (require oxygen

251
Q

what is the reaction for pyruvate -> lactate

A

glucose + 2ADP + 2Pi -> 2lactate + 2ATP + 2H2O

252
Q

what is the fate of lactate?

A

some of the lactate is released into the blood and taken up by heart and brain, then converted back to pyruvate and used for energy

taken up by liver as a precursor for formation of glucose, then released into blood

253
Q

glycolysis in erythrocytes

A

contain all enzymes required but no mitochondria

anaerobic glycolysis

254
Q

glycolysis in skeletal muscles

A

considerable amounts of glycolytic enzymes

few mitochondria

255
Q

glycolysis in most cells

A

most don’t have enough enzymes/glucose to rely on glycolysis alone

256
Q

why is glycolysis inhibited in acidosis?

A

PFK-1 is pH dependent and inhibited by acidic conditions

257
Q

what is PFK-1 inhibited by?

A

acidic conditions

258
Q

what are regulators of glycolysis?

A

AMP, ATP

259
Q

what effect does AMP have on glycolysis?

A

allosteric activator of PFK-1

binds to PFK-1 leading to conformational change - increasing affinity of PFK-1 for fructose-6-phosphate

260
Q

what is an allosteric activator?

A

modifies the active site of the enzyme so the affinity for the substrate increases

261
Q

what effect does ATP have on glycolysis?

A

allosteric inhibitor of PFK-1

low ATP levels = fast reaction speed of PFK-1 -> fructose-1,6-bisphosphate

high ATP levels = slow reaction speed of PFK-1 -> fructose-1,6-bisphosphate

262
Q

AMP-ATP interaction

A

AMP opposes the allosteric inhibition by ATP

263
Q

where does the Kreb’s cycle take place?

A

mitochondrial matrix

264
Q

what is the overall reaction in the Kreb’s cycle?

A

acetyl CoA + 3NAD+ + FAD + GDP + ADP + Pi + 2H2O -> 2CO2 + CoA + 3NADH + 3H+ + FADH2 + GTP + ATP

265
Q

what is the primary molecule entering the Kreb’s cycle? where is it derived from? what is its function?

A

acetyl coenzyme A

B vitamin pantothenic acid

transfer acetyl groups (2 carbons) from one molecule to another

266
Q

what can acetyl CoA be made from?

A

pyruvate, beta-oxidation of fatty acids or amino acid breakdown

267
Q

requirements of Kreb’s cycle

A

aerobic conditions - oxidative phosphorylation needed to convert NADH and FADH2 back to NAD+ and FAD

268
Q

what are NAD+ and FAD used for?

A

conversion of isocitrate to a-Ketoglutarate and a-Ketoglutaate to succinyl CoA and succinate to fumarate and malate to oxaloacetate

269
Q

mnemonic for Kreb’s steps

A

can I keep selling socks for money officer?

Citrate 
Isocitrate 
a-Ketoglutarate 
Succinyl CoA 
Succinate 
Fumarate 
Malate 
Oxaloacetate
270
Q

mnemonic for Kreb’s enzymes

A

so at another dance devon sipped down five drinks

citrate Synthetase
Aconitase
Aconitase
isocitrate Dehydrogenase
alpha-ketoglutarate Dehydrogenase
succinyl-CoA Synthetase
succinate Dehydrogenase
Fumarase
malate Dehydrogenase
271
Q

glycolysis steps mnemonic

A

Girls Get Free Food
Guys Dine with Good Girls
Boys Pretend to Pay for the Pricy People

Glucose
Glucose 6 phosphate
Fructose 6 phosphate
Fructose 1,6 bisphosphate
Glyceraldehyde 4 phosphate and Dihydroxyacetone phosphate
G3P and G3P
1,3 Bisphosphoglycerate
3 Phosphoglycerate
2 Phosphoglycerate
Phosphoenolpyruvate
Pyruvic acid
272
Q

glycolysis enzymes mnemonic

A

Hungry Peter Pan And The Growling Pink Panther Eat Pies

Hexokinase
Glucose-6-phosphate isomerase
Phosphofructokinase-1
Aldolase
Glyceraldehyde-3-phosphate dehydrogenase
Triosephosphate isomerase
Phosphoglycerate kinase
Phosphoglycerate mutase
Enolase
Pyruvate kinase
273
Q

what are the conditions of beta oxidation?

A

strictly aerobic

dependent on oxygen, good blood supply and adequate numbers of mitochondria

274
Q

what can acetyl CoA be derived from?

A

oxidation of fatty acids

must be activated in cytoplasm before being oxidised in the mitochondria

275
Q

what is a fatty acid?

A

carboxylic acid group with many carbons attached

276
Q

how are fatty acids activated?

A

in cytoplasm

fatty acid + ATP + CoA -> acyl CoA + PPi + AMP

adenosine taken away from ATP and used to make acyl-CoA

277
Q

what is PPi?

A

pyrophosphate

278
Q

where oxidation of fatty acids occur?

A

in mitochondria

most fatty acids that are over 12 carbons long, can’t get through the outer-mitochondrial membrane on their own

279
Q

what converts the acyl CoA? what does this now allow?

A

carnitine acyltransferase

acyl CoA -> acyl carnitine

acyl carnitine can now be transported into the mitochondria through outer membrane

280
Q

where is carnitine acyltransferase 1 located?

A

outer mitochondrial membrane

281
Q

what is the process of acyl CoA conversion?

A

Coenzyme A is removed from acyl CoA and is recycled

carnitine is added

282
Q

what happens to the acyl carnitine once inside the mitochondria?

A

carnitine acyltransferase 2 converts acyl carnitine back to acyl CoA

Coenzyme A is readded and carnitine ripped off

283
Q

what is the carnitine shuttle?

A

carnitine can diffuse through outer mitochondrial membrane to be used again to convert acyl CoA to acyl carnitine

284
Q

what is beta oxidation?

A

sequential removal of 2 carbon units by oxidation at the beta-carbon position of the fatty acyl-CoA

oxidation to carbonyl group

fatty acids are broken down to produce acetyl-CoA (krebs) and NADH and FADH2 (ETC)

285
Q

what are the products of beta oxidation used for?

A

acetyl-CoA used in Krebs

NADH and FADH2 produced from beta oxidation and Krebs are used in oxidative phosphorylation

286
Q

energy yielded from oxidation of fatty acids vs carbohydrates

A

significantly more energy per carbon

287
Q

what is the net result of the oxidation of 1 mole of oleic acid vs 1 mole of glucose?

A

oleic acid is an 18-carbon fatty acid

145 moles of ATP vs 38

288
Q

fatty acids as a fuel source in the nervous system

A

don’t act as a fuel source as they can’t get through the BBB

289
Q

when are fatty acids used as fuel?

A

when hormones signal fasting or increased demand

290
Q

examples of fatty acids

A 
linoleic acid (18 carbons)
oleic acid (18 carbons)
palmitic acid (16 carbons 
arachidonic acid (20 carbons)
291
Q

where does oxidative phosphorylation occur?

A

inner mitochondrial membrane

292
Q

what are the components of the ETC?

A

cytochromes (contain iron and copper cofactors, structure resembles iron haemoglobin) and associated proteins in inner mitochondrial membrane

293
Q

what happens in the ETC?

A

2 electrons from hydrogen atoms are transferred from NADH, H+ or FADH2 to one of the proteins (oxidised)

electrons successively transferred to other compounds in redox reactions

electrons finally transferred to molecular oxygen, which combines with hydrogen ions to form water

294
Q

where do hydrogen ions in the ETC come from?

A

free hydrogen ions and hydrogen bearing coenzymes (NADH and FADH2) that had been released earlier in ETC when electrons from hydrogen atoms were transferred to the cytochromes

295
Q

as well as transferring the coenzyme hydrogens to water, what else does this process do?

A

regenerates hydrogen-free forms of coenzymes which can become available to accept 2 hydrogens from intermediates in krebs, glycolysis or beta oxidation

296
Q

what does ETC provide?

A

aerobic mechanism for regenerating the hydrogen-free form of the coenzymes

297
Q

energy released in the ETC. what is it used for? what does this create?

A

small amounts are released

as electrons are transferred, some is used by cytochromes to pump hydrogen ions from the matrix into the intermembranal space

source of potential energy - hydrogen-ion concentration gradient across membrane

298
Q

what is embedded in the inner mitochondrial membrane?

A

enzymes - ATP synthase

299
Q

where is ATP synthase found?

A

embedded in the inner mitochondrial membrane

300
Q

what does ATP synthase do?

A

forms a channel in the membrane, allowing hydrogen ions to flow back into matrix via chemiosmosis

energy of the conc. gradient is converted into chemical bond energy by ATP synthase, which catalyses the formation of ATP from ADP and Pi

301
Q

by what mechanism do the hydrogen ions move back into the matrix? what is this?

A

chemiosmosis - moving from an area of high conc of hydrogen ions to low conc

302
Q

what does the transfer of electrons to oxygen produce?

A

2.5 and 1.5 molecules of ATP for each molecule of NADH and H+ and FADH2 respectively

303
Q

what is the overall reaction for respiration?

A

C6H12O6 + 6O2 + 38ADP + 38 Pi -> 6CO2 + 6H2O + 34-38 ATP

304
Q

how much ATP is produced from glycolysis?

A

34-38

38 is theoretical and assumes all of the NADH produced in glycolysis and krebs cycle enters into oxidative phosphorylation and all the free hydrogen ions are used in chemiosmosis for ATP

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