Biochem Qs bank Flashcards
(138 cards)
1
Q
which amino acid is important in the buffering action of proteins at physiological pH values?
A
histidine
2
Q
Which of the following is a ketogenic amino acid?
A
lysine
3
Q
a protein domain is defined as:
A
an independent folded structure within a polypeptide with an independent function
4
Q
in competitive enzyme inhibition, Km:
A
always goes up
5
Q
a prosthetic group is defined as:
A
non-protein component bound to a protein for its activity
6
Q
sugar acids are monosaccharides that have:
A
a hydroxyl group oxidised to a carbonyl group
7
Q
which of these statements are false?
A
facilitated diffusion requires GTP
8
Q
pyruvate dehydrogenase is made up of which three enzymes?
A
pyruvate decarboxylase (PD), dihydrolipoyl dehydrogenase (DD), and lipoamide reductase transacetylase (LRT)
9
Q
if delta G for a reaction is positive, the reaction is said to be?
A
endothermic
10
Q
conversion of phosphoenol pyruvate into pyruvate is the last reaction of glycolysis. This reaction is catalysed by:
A
pyruvate kinase
11
Q
an example of peripheral membrane protein is:
A
spectrin
12
Q
specialised membrane transport proteins, termed channel proteins:
A
all of the above
13
Q
which is a ketogenic amino acid?
A
lysine
14
Q
what does the charge relay system consist of?
A
serine, histidine, and aspartate
15
Q
how do you work out pH/?
A
pH=-log10(H+)
16
Q
which of these enzymes are inhibited by NADH and ATP in the TCA cycle?
A
alpha ketoglutarate dehydrogenase and isocitrate dehydrogenase
17
Q
two sources of glucose in the body
A
diet and liver
18
Q
ribosomes are…
A
protein factories
19
Q
what is the major buffer in saliva?
A
carbonic acid
20
Q
which amino acid does not have an asymmetric carbon atom?
A
glycine
21
Q
which amino acid causes a bend in the peptide chain?
A
proline
22
Q
what is the optically inactive amino acid?
A
glycine
23
Q
what happens to enzymes after a reaction
A
unaltered
24
Q
the organelle in which complex carbohydrates such as GAGs are synthesised in?
A
golgi apparatus
25
what is a zymogen?
inactive enzyme
26
XXX reduces the enzyme effect but inhibition is 95% reversed when the substrate is increased by 1000 fold. What inhibition is this?
competitive inhibition
27
what does competitive inhibition do to the Km?
increases it
28
what is an example of oxidative deamination
glutamate to alpha ketoglutarate and ammonia
29
where is pyruvate converted to oxaloacetate?
mitochondria
30
which of the following about protein domains is true:
independent subunits with independent function
31
which of these amino acids do not have D dextrarotatory right-handed optical isomerism?
glycine
32
an enzyme with a high Km has a...
low affinity
33
PDC catalyses the conversion of pyruvate into?
acetyl CoA
34
what is the linkage for branching in glycogen?
alpha 2-->6
35
if delta G is close to 0 what affects the reaction?
concentration
36
which one is not one of the four biologically important organic molecules?
fats
37
which is a system involved in homeostasis?
endocrine system
38
porins can be found in:
gram negative cell wall
39
the carbonic acid concentration in the mouth is approximately
1.3mMol/L
40
what is an alpha carbon?
carbon to which the amino acid carboxylic groups are attached
41
the majority of amino acids in the body are
L
42
the pK value for carboxylic acid is
2.2
43
the pK value for amino group is
9.4
44
which is not an example of an aliphatic amino acid?
lysine
45
example of an aromatic amino acid includes
phenylalanine
46
which amino acid has a weakly acidic hydroxyl group?
tyrosine
47
example of an imino acid includes
proline
48
amino acids carry a
negative charge
49
which amino acid is not involved in the addition of sugars?
tyrosine
50
secondary structure of proteins involves
hydrogen bonds
51
tertiary structure of proteins involves
non-covalent interactions
52
disulphide bonds can be formed by
cysteine
53
protein domains are formed in
tertiary structure
54
keratin is a
fibrous protein
55
collagen is a
fibrous protein
56
high Km values show
weak bonds
57
reversible inhibition involves
non-covalent interactions
58
irreversible inhibition involves
covalent interactions
59
which is not a glucogenic amino acid?
leucine
60
insulin secretion is stimulatd by
parasympathetic
61
pyruvate dehydrogenase complex converts pyruvate to:
CO2, NADH, and acetyl CoA
62
in gluconeogenesis, pyruvate is converted to oxaloacetate in which cellular compartment?
mitochondria
63
how many ATP molecules are used in one turn of the urea cycle?
3
64
metaphase is when:
centrometres of chromatids line up at the midline of the cell
65
which of the following is a purine nucleoside?
guanosine
66
which of the following is true?
nucleolus is enclosed within a membrane structure inside the nucleus
67
oxidative deamination involves:
conversion of glutamate into alpha-ketoglutarate and ammonia
68
which of the following is false?
in a DNA double helix molecule, the sugar-phosphate backbones are responsible for holding the two strands together
69
which one of these is a purine?
adenine
70
which is not required in translation?
RNA primer
71
Regarding nucleotides, which of the following is true?
they contain a base sugar and phosphate
72
what happens in interphase?
prepare for mitosis
73
which of the following is false?
siRNA is single stranded
74
what occurs in anaphase?
identical chromosomes separate to poles
75
what is the tRNA nucleotide sequence that specifies the AA methionine that initiates the translation sequence?
UAC
76
in anaerobic conditions, what happens to pyruvate?
reduced to lactate
77
which enzyme converts PEP to pyruvate
pyruvate kinase
78
how many molecules of NADH are produced in glycolysis and the TCA cycle per glucose molecule?
glycolysis=2
TCA cycle=6
79
what amino acids are involved in the charge relay system in chymotrypsin?
Serine, Histidine, and Aspartate
80
How does lymph leave the lymph nodes?
Efferent lymph nodes
81
What does Km measure?
The strength of attraction between an enzyme and a substrate
82
What activates PFK-1?
Fructose-2 bisphosphate and AMP
83
What are the two sources of glucose for the body?
Diet and liver
84
What is the function of calcitonin?
Reduce blood serum levels of Ca2+ and phosphate by increasing excretion of the ions and preventing bone resorption
85
What are phase 2 reactions?
Conjugation
86
What happens in interphase?
Prepare for mitosis
87
What is metaphase
When the centromeres line up at the equator
88
Name a purine nucleoside
Guanosine
89
Which of these isn't a nucleoside in mRNA?
Thymidine
90
Which one is false?
Phosphate backbone holds DNA strands together
91
Chymotrypsinogen is made up of
245 Aas
92
The number of disulphide bonds in chymotrypsinogen is
5
93
glucokinase is found in
liver
94
which enzyme is involved in phosphorylation of glucose?
Hexokinase
95
Malonate is a competitive inhibitor that inhibits
Succinate dehydrogenase
96
Alanine is a non-competitive inhibitor of
Pyruvate kinase
97
N-acetyl sugars are made up of
8C
98
Anomers are
stereoisomers that have different orientation of hydroxyl at carbon 1
99
heparin is used as a
anti-coagulant
100
maltose is a
disaccharide
101
glycogen branches every
10 residues
102
starch branches every
24 residues
103
simplest GAG is
HA
104
which glycosaminoglycan is used for the treatment of osteoarthritis?
Chondroitin sulphate
105
Which glycosaminoglycan is used as an anti-coagulant?
Heparin
106
What is esterification?
Triacylglycerol synthesis
107
Fatty acids get converted into acetyl CoA by
Beta oxidation
108
what causes the release of lactate?
skeletal muscle
109
the cori cycle works between
liver and skeletal muscle
110
GLUT4 is present on
skeletal muscle and adipose tissue
111
coupled reactions usually involve
hydrolysis of ATP
112
GLUT3 is present on
plasma membrane
113
GLUT2 is present on
liver and pancreatic beta cells
114
where does glucokinase work?
liver
115
which is the rate limiting factor of glycolysis?
PFK
116
Rate limiting step for glycogen synthesis is
glycogen synthase
117
glucose 6-phosphatase is predominantly found in
liver
118
where is pyruvate carboxylase found?
mitochondria
119
where is glucose 6-phosphatase found?
Endoplasmic reticulum
120
pyruvate kinase can be split into
PEP carboxykinase and pyruvate carboxylase
121
The limiting factor for krebs cycle is
oxaloacetate
122
pyruvate is converted into lactate by
lactate dehydrogenase
123
pyruvate is converted into PEP by
PEPCK, PC, and MDH
124
which reaction is known as Claisen condensation?
Citrate synthase
125
which reaction involves the addition of water molecule to double bond?
fumarase
126
which is an enzyme for transamination reaction?
amino carboxylase
127
phenylalanine hydroxylase catalyses
phenylalanine to tyrosine
128
the role of helicase is to
separate the fragments
129
the role of DNA polymerase I and RNAse H is to
replace RNA primers with DNA
130
the role of RNA primase is to
synthesise small portions of RNA primer required for initiation
131
in which direction does DNA synthesis take place
5' to 3'
132
what is glycogenolysis
breakdown of glycogen in the liver
133
what is gluconeogenesis?
production of glucose from amino acids
134
which is a factor involved in gestational diabetes
lactogen placenta
135
secondary diabetes mellitus does not arise from
meningitis
136
which is the main function of calcium?
bone and tooth formation
137
which is the main protein that calcium is bound to?
albumin
138
what does parafollicular cells secrete?
calcitonin
