Block 1 Biochem

Front 1

what is a protein?

Back 1

polymer of amino acids

Front 2

what is a carbohydrate?

Back 2

monomer, dimer, oligomer or polymer of sugars

Front 3

what is a fat?

Back 3

ester of carboxylic acids

Front 4

how many common amino acids are there?

Back 4

20

Front 5

what links amino acids to form peptides, polypeptides and proteins?

Back 5

peptide bonds

Front 6

Which enzyme is deficient in PKU?

Back 6

phenylalanine hydroxylase

Front 7

what does phsnylalanine hydroxylase do?

Back 7

converts phenylalanine to tyrosine

Front 8

what is starch composed of?

Back 8

amylose (25%) and amylopectin (75%)

Front 9

which disaccharide is composed of two glucose molecules?

Back 9

maltose

Front 10

where is glycogen stored?

Back 10

hepatocytes

Front 11

what are the two components of a triglyceride?

Back 11

glycerol molecule, fatty acids

Front 12

what is the primary site of nutrient digestion and absorption?

Back 12

small intestine

Front 13

What is ATP?

Back 13

adenosine 5-triphosphate... a mobile source of energy for cells

Front 14

what is the action of water on ATP?

Back 14

cleaves the terminal phosphate leaving ADP and phosphate (releases energy)

Front 15

what is the turnover rate of ATP?

Back 15

40 kg per day

Front 16

What is NAD+?

Back 16

nicotinamide adenine dinucleotide (oxidised), reduced form is NADH

Front 17

what is coenzyme A?

Back 17

a carrier for fatty acids

Front 18

What are the key outcomes of the citric acid cycle?

Back 18

nutrient substrates are fed into the cycle as 2C units (Acetyl CoA), electrons are stripped from nutrient substrates and are transferred to NAD+ and FAD to generate NADH and FADH2 and CO2 is generated

Front 19

what is the major pathway for extraction of energy from carbohydrates?

Back 19

glycolysis (conversion of glucose to pyruvate or lactate)

Front 20

true or false... glycolysis can handle glucose and galactose but not fructose

Back 20

false, it can handle all three

Front 21

how many molecules of ATP are generated in the glycolytic pathway?

Back 21

2 per glucose molecule

Front 22

where does glycolysis occur?

Back 22

in the cytoplasm

Front 23

What are the requirements for the conversion of pyruvate to acetyl CoA (and entry to the Citric Acid Cycle)?

Back 23

source of NAD+, source of CoA (CO2 generated), entry from cytoplasm into mitochondrial matrix

Front 24

which enzyme converts pyruvate to acetyl CoA?

Back 24

pyruvate dehydrogenase

Front 25

what are the conditions for the mitochondrial metabolism of pyruvate?

Back 25

adequate levels of oxygen, adequate levels of NAD+ and adequate levels of thiamine

Front 26

Without adequate levels of oxygen, NAD+ and thiamine, what will pyruvate be converted to?

Back 26

lactate

Front 27

List some causes of lactic acidosis

Back 27

hypoxaemia, thiamine deficiency, pyruvate dehydrogenase deficiency, drugs (biguanides, alcohol)

Front 28

t/f... in lactic acidosis, ATP synthesis exceeds ATP breakdown

Back 28

false, the opposite is true

Front 29

t/f... protons are released as a result of net ATP breakdown

Back 29

true

Front 30

what are the clinical features of lactic acidosis?

Back 30

low pH, high serum lactate levels, elevated resp rate, muscle achea

Front 31

What is the pathway for the conversion of fatty acids to Acetyl CoA?

Back 31

fatty acid oxidation

Front 32

t/f... the reactions involved in fatty acid oxidation occur at the alpha carbon?

Back 32

false, they occur at the beta carbon

Front 33

how does alcohol dependence lead to thiamine deficiency?

Back 33

alcohol displaces other nutrients, interferes with thiamine absorption, may accelerate thiamine turnover

Front 34

what is another name for ubiquinone?

Back 34

coenzyme Q

Front 35

where is coenzyme Q synthesised?

Back 35

mitochondrial matrix

Front 36

what tethers ubiquinone to the inner mitochondrial membrane?

Back 36

the hydrophobic isoprenoid side chain

Front 37

what is the fully reduced form of ubiquinone?

Back 37

ubiquinol (QH2)

Front 38

how many amino acids does cytochrome C have?

Back 38

120

Front 39

what lies at the centre of a heme molecule?

Back 39

an iron binding nucleus

Front 40

which protein complex accepts the electrons from NADH?

Back 40

Complex I

Front 41

What is another name for Complex III?

Back 41

cytochrome C reductase

Front 42

what is another name for complex IV?

Back 42

cytochrome oxidase

Front 43

what is the function of Complex I?

Back 43

it uses NADH to reduce Q (QH2 forms)

Front 44

Which complex uses QH2 to reduce Cytochrome C?

Back 44

Complex III (cytochrome C reductase)

Front 45

At what stage in the electron transport chain is water generated?

Back 45

Complex IV (uses reduced cytochrome C to reduce O2 to H2O)

Front 46

Which complex uses FADH2 to reduce Q?

Back 46

Complex II

Front 47

t/f... complexes I, III and IV (but not II) are electron-driven proton pumps

Back 47

true

Front 48

What is another name for Complex V?

Back 48

ATP synthase

Front 49

what is oxidative phosphorylation?

Back 49

extraction of electrons from nutrients to drive ATP synthesis

Front 50

what happens if oxidative phosphorylation is uncoupled?

Back 50

ATP synthesis fails and heat is generated

Front 51

what are the similarities between DNA and RNA?

Back 51

sugar-phosphate backbone, presence of purine and pyrimidine bases

Front 52

what are the differences between DNA and RNA?

Back 52

double stranded v single stranded, sugar: 2'-deoxyribose v ribose, bases: AGCT v AGCU

Front 53

Name the pyrimidines of RNA.

Back 53

cytosine and uracil

Front 54

name the pyrimidines of DNA

Back 54

cytosine and thymine

Front 55

name the purines of DNA/RNA

Back 55

adenine, guanine

Front 56

what is the function of transfer RNA?

Back 56

recruit amino acids for protein synthesis

Front 57

which type of RNA is derived from a template strand of genomic DNA?

Back 57

messenger RNA

Front 58

what modifications are made during processing of mRNA?

Back 58

capping (at 5' end), cleavage at 3' end, polyadenylation, splicing, editing

Front 59

t/f... RNA does not form double helices but it can base pair

Back 59

true

Front 60

where does translation occur?

Back 60

on ribosomes

Front 61

where are ribosomes located?

Back 61

cytoplasm, mitochondrial matrix

Front 62

where does ribosome assembly occur?

Back 62

nucleolus

Front 63

What is meant by positive sense RNA?

Back 63

single stranded DNA which is recognised as mRNA and immediately translated

Front 64

which of these RNA viruses are negative sense? Hep C, retroviruses, SARS,influenza, measles, rabies, rotavirus, mumps

Back 64

influenza, measles, mumps, rabies.
(positive sense: SARS, Hep C, retroviruses;
double stranded: rotavirus)

Front 65

what is the additional capability of retroviruses?

Back 65

ability to synthesise DNA (reverse transcriptase)

Front 66

what is the name of the plane in which the 6 atoms of a peptide bond group are located?

Back 66

amide plane

Front 67

what maintains the position of atoms in the amide plane?

Back 67

the peptide bond has a partial double bond character which limits the mobility of surrounding atoms

Front 68

where are the two degrees of freedom for each amino acid?

Back 68

angle about C(alpha)-N bond (phi) and the angle about C(alpha)-C bond (psi)

Front 69

which secondary protein structure is sheet like?

Back 69

beta

Front 70

what is the alpha secondary structure?

Back 70

helix

Front 71

in the alpha-helix, how many amino acids complete one turn?

Back 71

4

Front 72

where are H-bonds located in the alpha helix?

Back 72

between the backbone C=O and HN residues along peptide chain

Front 73

t/f... the side chains point towards the centre of the alpha helix?

Back 73

false, they point outwards from the centre

Front 74

where do the side chains point in a beta sheet?

Back 74

alternately down and up

Front 75

how are sheets and helices joined?

Back 75

by loops (antiparallel and parallel structures)

Front 76

what is an enzyme?

Back 76

biological catalyst that markedly enhances the rate of a chemical reaction

Front 77

how does activation energy relate to the speed of a reaction?

Back 77

the higher the activation energy, the slower the reaction

Front 78

why do catalysed reactions run faster?

Back 78

activation energy is lower

Front 79

what are the three types of inhibition?

Back 79

competitive - inhibitor and substrate compete for enzyme's active site
non-ompetitive - inhibitor binding site and substrate-binding site are distinct
un-competitive - inhibitor binding site and substrate-binding site are distinct/inhibitor binds preferentially to the EX complex

Front 80

what is the major configuration in nature of fatty acids?

Back 80

cis

Front 81

how is carbohydrate stored?

Back 81

as glycogen in the liver (and muscle)

Front 82

where is protein stored?

Back 82

skeletal muscle, liver

Front 83

where is fat stored?

Back 83

truglycerides in adipose tissue, liver

Front 84

what stimulates glycogen synthase activity?

Back 84

insulin

Front 85

what stimulates glycogen phosphorylase activity?

Back 85

glucagon

Front 86

where does gluconeogenesis occur?

Back 86

liver and kidney

Front 87

what are some acute triggers for insulin release?

Back 87

elevated plasma glucose level, elevated plasma amino acids, elevated free fatty acid levels, release of gut peptides

Front 88

what is the acute trigger for glucagon release?

Back 88

low plasma glucose

Front 89

what is the site of insulin and glucagon production?

Back 89

pancreatic islets