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