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biochem > proteins > Flashcards

proteins Flashcards

1
Q

What does the basic structure of amino acids consist of?

A

Basic structure consists of a central a-carbon atom surrounded by four groups: a hydrogen atom, carboxyl group, amino group, and an R-group specific to each amino acid

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2
Q

Amino acids are building blocks of polypeptides. And proteins consists of chains of polypeptides (amino acids).

True or false?

A

True

Amino acids are building blocks of polypeptides. And proteins consists of chains of polypeptides (amino acids).

Amino acids - polypeptides - proteins

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3
Q

In glycine, the R group is replaced by

an amino group

oxygen

hydrogen

nothing

A

hydrogen

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4
Q

An alpha-keto acid is similar to an amino acid, except that an alpha-keto acid has hydrogen rather than an amino group bound to its alpha- carbon.

When proteins are broken down and used for energy, most of this energy is derived from oxidation of alpha-keto acids. These substances enter the Krebs cycle.

true or false?

A

An alpha-keto acid is similar to an amino acid, except that an alpha-keto acid has oxygen rather than an amino group bound to its alpha- carbon.

When proteins are broken down and used for energy, most of this energy is derived from oxidation of alpha-keto acids. These substances enter the Krebs cycle. The amino acids are converted to alpha-keto acids.

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5
Q

Amino acids are covalently linked by peptide bonds at their amino (N terminus) and carboxyl (C-terminus) groups. These bonds are not stable. True or false?

A

False.

Amino acids are covalently linked by peptide bonds at their amino (N terminus) and carboxyl (C-terminus) groups. These bonds are stable.

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6
Q

tyrosine, Alanine, threonine, glycine, isoleucine, Serine, leucine, valine, proline

Classify as - Aliphatic or Hydroxylic

A

aliphatic- leucine, isoleucine, valine, Alanine, glycine, proline
Hydroxylic- Serine, tyrosine, threonine

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7
Q

Arginine, Asparagine, aspartate, glutamate, histidine, glutamine, lysine
Classify as acidic and basic

A

Acidic- Asparagine, aspartate, glutamate, glutamine
Basic- lysine, Arginine, histidine

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8
Q

Asparagine, Histidine, aspartate, tyrosine, glutamate, glutamine
phenylalanine, Arginine, lysine, tryptophan

Identify which are aromatic?

A

Aromatic- tryptophan, tyrosine, Histidine, phenylalanine

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9
Q

lysine, Cysteine, Arginine, histidine, methionine, Proline.

Which are sulfur amino acids (thiol)

A

Cysteine, methionine

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10
Q

aliphatic, acidic, basic, aromatic, sulfur-containing

classify as polar and non- polar and mention which is found in the interior of proteins and which on the exterior.

A

Non-polar - aliphatic, aromatic, sulfur-containing

polar - acidic, basic

the non-polar amino acids tend to be found in the interior and polar amino acids are found in the exterior.

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11
Q

tyrosine gives rise to ?

A

tyrosine =

thyroid hormones

Dopa (which gives rise to dopamine, nor-epi, epi, and melanin

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12
Q

methionine gives rise to ?

A

methionine =

cysteine

homocysteine

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13
Q

tryptophan gives rise to ?

A

tryptophan =

niacin

serotonin

melatonin

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14
Q

glutamate gives rise to ?

A

glutamate =

GABA

also arginine which gives rise to nitric oxide

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15
Q

glycine gives rise to ?

A

glycine =

porphyrin (heme)

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16
Q

arginine gives rise to ?

A

arginine =

nitric oxide

urea

creatine

it arises from glutamate

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17
Q

histidine gives rise to ?

A

histidine =

histamine

histidine is derived from ribose-5-P

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18
Q

phenylalanine gives rise to ?

A

phenylalanine =

tyrosine

tyrosine which will give rise to thyroid hormones and dopa

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19
Q

There are 13 essential and 7 non-essential amino acids.

essential amino acids must be obtained from dietary intake. Non-essential amino acids are synthesized in the body.

true or false?

A

False. There are 9 essential and 11 non-essential amino acids.

True. Essential amino acids must be obtained from dietary intake. Non-essential amino acids are synthesized in the body. All synthesized from glucose in TCA cycle (from α-ketoacids, α-amino acids, transaminases, vitamin B 6), except tyrosine, which is derived from phenylalanine

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20
Q

Phenylalanine

Lysine

Leucine

Glycine

Valine

Glutamate

Methionine

Threonine

Aspartate

Alanine

Tryptophan

Isoleucine

Serine

Histidine

Arginine

Asparagine

Cysteine

Glutamine

Proline

Tyrosine

A

Essential (PVT TIM HaLL)

Phenylalanine
Valine
Threonine
Tryptophan
Isoleucine
Methionine
Histidine
Lysine
Leucine
Nonessential (11) -

Arginine
Aspartate
Asparagine
Alanine
Cysteine
Glycine
Glutamate
Glutamine
Proline
Serine
Tyrosine

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21
Q

amino acids are used for-

as substrates for the generation of energy

as substrates for protein synthesis

as substrates for the synthesis of many products including heme, purines, pyrimidines, coenzymes, melanin and biogenic amines.

true or false

A

true

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22
Q

An amino acid can be ketogenic (used for ketogenesis) or glucogenic (used for glucogenesis)

Ketogenic yields pyruvate and glucogenic yields acetyl-CoA

True or false?

A

True. An amino acid can be ketogenic (used for ketogenesis) or glucogenic (used for glucogenesis)

False. Ketogenic yields acetyl-CoA and Glucogenic yields pyruvate

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23
Q

Classify amino acids as ketogenic, glucogenic or both.

A

Ketogenic- Leucine, lysine

Both- (PITTT)- Isoleucine, phenylalanine, tryptophan, tyrosine, threonine

Glucogenic Arginine, aspartate, asparagine, alanine, cysteine,

histidine, proline, serine, valine

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24
Q

nucleosomes = repeating subunits of ________ = DNA chain coiled around histone core (arginine and lysine, DNA associated proteins)

The histones are _______ charged.

Complete

A

True. nucleosomes = repeating subunits of chromatin = DNA chain coiled around histone core (arginine and lysine, DNA associated proteins)

The histones are positively charged. They help neutralize the negative charge of the DNA phosphate group and stabilize DNA in a compact form.

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25
Q

proteins consisting of one polypeptide can have a quaternary structure.

the formation of a disulfide bond in a protein requires that the two participating cysteine residues be adjacent to each other in the primary sequence of the protein.

the stability of quaternary structure in proteins is mainly due to covalent bonds among the subunits.

the information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain.

true or false?

A

False. quaternary structures only arise when a protein is made up of two or more polypeptide chains.

False. the two cysteine residues that react to form the disulfide bond may be a great distance apart in the primary structure but are bought into close proximity by 3-dimensional folding

False. the stability of quaternary structure in proteins is mainly due to non-covalent and sulfide bonds among the subunits.

true. the information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain.

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26
Q

Plasma protein are derived from the _______ and immunoglobulins are derived from the ______

liver

plasma cells

kidneys

t cells

A

Plasma protein are derived from the liver and immunoglobulins are derived from the plasma cells

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27
Q

which of the following plasma protein is not a glycoprotein-

lipoprotein

globulin

albumin

transferrin

prothrombin

A

albumin

it accounts for 60% of the total plasma protein and 80% of the colloid osmotic pressure of the plasma.

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28
Q

colloid osmotic pressure is necessary to prevent edema.

Edema can be caused by a decrease in capillary permeability, venous obstruction, impaired lymph flow and CHF with an increased venous pressure.

true or false?

A

true. colloid osmotic pressure is necessary to prevent edema.

False. Edema can be caused by an increase in capillary permeability, venous obstruction, impaired lymph flow and CHF with an increased venous pressure.

29
Q

Match with the correct description-

fibrinogen, prothrombin, globulins, transferrin, regulatory proteins, lipoproteins,

Used for transport of ions, hormones, and lipids. Also, assist in immune function.

responsible in the transport in the blood of triglycerides, phospholipids, cholesterol

essential for clotting of blood

transport of iron

a blood clotting protein

are proteins such a enzymes, proenzymes and hormones.

A

globulin- Used for transport of ions, hormones, and lipids. Also, assist in immune function.

fibrinogen - essential for clotting of blood

regulatory proteins- are proteins such a enzymes, proenzymes and hormones.

lipoproteins- responsible in the transport in the blood of triglycerides, phospholipids, cholesterol

transferrin- transport of iron

prothrombin- a blood clotting protein

30
Q

A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule

A sulfide bond is formed from the sulfhydryl group of each of two cysteine residues to produce a cysteine residue.

true or false

A

true

true

31
Q

hydroxyproline is a constituent of collage and widely found in other proteins

vitamin c is required from hydroxylation of proline

deficiency of vitamin C causes scurvy

Glycine is the only chiral amino acid

true or false?

A

false. hydroxyproline is a constituent of collage and rarely found in other proteins
true. vitamin c is required from hydroxylation of proline
true. deficiency of vitamin C causes scurvy
false. Glycine is the only non- chiral amino acid

32
Q

myoglobin consists of a single polypeptide with a non-covalently bond heme group

hemoglobin consists of a single polypeptide with four non-covalently bond heme group

true or false?

A

true

true

33
Q

match with correct description- adult hemoglobin, fetal hemoglobin

two alpha chains, two beta chains

two alpha chain, two gamma chains

A

adult hemoglobin- two alpha chains, two beta chains

fetal hemoglobin- two alpha chain, two gamma chains

34
Q

rank from highest to the lowest affinity for oxygen-

myoglobin, adult hemoglobin, fetal hemoglobin

A

myoglobin, fetal hemoglobin, adult hemoglobin

35
Q

myoglobin is found in muscle tissues

the heme in the hemoglobin and myoglobin are in the ferric state

true or false?

A

myoglobin is found in muscle tissues

the heme in the hemoglobin and myoglobin are in the ferrous state. oxidation to the ferric state produces useless methemoglobin.

36
Q

All amino acids in protein are of -

D- configuraion

L- configuration

F-configuration

C- cpnfiguration

A
37
Q

select all that apply

cytochromes are found-

the mitochondrial outer membranes and endoplasmic reticulum in eukaryotes

in viruses

in the chloroplast in plants

in photosynthetic micro-organism

in bacteria

in parasites

A

in the chloroplast in plants

in photosynthetic micro-organism

in bacteria

Also,

the mitochondrial inner membranes and endoplasmic reticulum in eukaryotes

38
Q

electron transport and ATP synthesis by oxidative phosphorylation process intermittently in all cells of the body that contain mitochondria.

true or false?

A

False.

electron transport and ATP synthesis by oxidative phosphorylation process continuously in all cells of the body that contain mitochondria.

39
Q

electron transport chain is the final common pathway by which electron derived from different fuels of the body flow to oxygen

coenzyme Q (ubiquinone) - cyc b - cyc c - cyt c1 - cyct a - atc a3

Cytochrome a and a3 are the terminal members of ETS and exist as a complex called Complex V or cytochrome oxidase complex.

True or false?

A

True. electron transport chain is the final common pathway by which electron derived from different fuels of the body flow to oxygen

False. coenzyme Q (ubiquinone) - cyc b - cyt c1 -cyc c - cyt a3 - cyt a

Cytochrome a and a3 are the terminal members of ETS and exist as a complex called Complex IV or cytochrome oxidase complex.

40
Q

complete the following -

alpha-ketoglutarate - _________ - _______________

A

alpha-ketoglutarate - glutamate - glutamine, proline, arginine

41
Q

3-phosphoglycerate - _________ - _______________

A

3-phosphoglycerate - serine - glycine, cysteine

42
Q

_____________ - glutamate - ____________

A

alpha-ketoglutarate - glutamate - glutamine, proline, arginine

43
Q

__________ - serine - ___________

A

3-phosphoglycerate - serine - glycine, cysteine

44
Q

oxaloacetate - ________ - ____________

A

oxaloacetate - aspartate - aspargine, methionine, threonine, lysine

45
Q

__________ - ________ - aspargine, __________

A

oxaloacetate - aspartate - aspargine, methionine, threonine, lysine

46
Q

threonine, _______ - isoleucine

A

threonine, pyruvate - isoleucine

47
Q

pyruvate - ____________

A

pyruvate - alanine, valine, leucine, isoleucine

48
Q

________ - alanine, _________

A

pyruvate - alanine, valine, leucine, isoleucine

49
Q

phosphoenolpyruvate + __________- shikimate - chorismate - _________________

A

phosphoenolpyruvate + erythrose-4-phosphate - shikimate - chorismate - tryptophan, tyrosine, phenylalanine

50
Q

_____________ + erythrose-4-phosphate - shikimate - ___________ - ______________

A

phosphoenolpyruvate + erythrose-4-phosphate - shikimate - chorismate - tryptophan, tyrosine, phenylalanine

51
Q

phosphoenolpyruvate + erythrose-4-phosphate - shikimate - chorismate - tryptophan, tyrosine, phenylalanine

This biosynthetic pathway occurs only in humans. true or false

A

False

This biosynthetic pathway occurs only plants and bacteria, not in humans

52
Q

phenylketonuria is the deficiency of phenylalanine

true or false?

A

False.

phenylketonuria is the deficiency of phenylalanine hydroxylase

tyrosine is synthesized from phenylalanine in humans. This reaction is catalyzed. by phenylalanine hydroxylase

53
Q

Ribose-5- phosphate — ________

A

Ribose-5- phosphate — histidine

54
Q

Lysyl oxidase is required for the synthesis of elastin and not collagen.

Desmosine is present in both collagen and elastin

true or false?

A

false

Like collagen, elastin contains covalent crosslink that is derived from allysine. Therefore, lysyl oxidase is required for the synthesis of both elastin and collagen.

The covalent cross-links of elastin are similar to those of collagen except for desmosine which is present in elastin but not collagen.

55
Q

collagen is produced by- fibroblast, epithelial cells, odontoblasts, osteoblasts, chondrocytes.

it is the organic matrix in the pulp.

it is made up of glycine, proline and lysine

true or false

A

true. collagen is produced by- fibroblast, epithelial cells, odontoblasts, osteoblasts, chondrocytes.
false. it is the organic matric in dentin and cementum.
false. it is made up of glycine, proline, and alanine

56
Q

Elastin is found in

skin

tendons

cartilage

ligaments

dentin

arterial walls

A

Found in skin, ligaments, arterial walls

the polypeptide subunit is tropoelastin

57
Q

Elastin does not contain hydroxyproline, which makes it much more elastic than collagen.

The polypeptide subunit for elastin is tropoelastin and for collagen is tropocollagen

A

False. Elastin does not contain hydroxylysine, which makes it much more elastic than collagen.

True. The polypeptide subunit for elastin is tropoelastin and for collagen is tropocollagen.

58
Q

fibrillin-5 is defective in Marfan syndrome.

A

False.

fibrillin-1 is defective in Marfan syndrome.

the amorphous elastin is surrounded by microfibrils. The most important microfibril, fibrillin-1 is defective in Marfan syndrome (characterised by heart and aortic complication, unusually tall, long limbs, long/thin fingers)

59
Q

Match description with primary, secondary, tertiary, quaternary structure

The overall three-dimensional conformation of a polypeptide.

The folding (spatial arrangement) of portions of a polypeptide chain.
The spatial arrangement of two or more polypeptide chains (subunit). Associated via noncovalent interactions

The specific sequence of amino acids linked by a covalent peptide bond.

A

Primary structure: The specific sequence of amino acids linked by covalent peptide bond.

Secondary structure: The folding (spatial arrangement) of portions of a polypeptide chain.

  • a-Helix: Coiled configuration.
  • b-Pleated sheet: Zigzag or pleated configuration.
  • b-Turn: Reverse turns that link two sides of a b-pleated sheet

Tertiary structure: The overall three-dimensional conformation of a polypeptide.
Quarternary structure: The spatial arrangement of two or more polypeptide chains (subunit). Associated via noncovalent interactions

60
Q

Intracellular events
rER: Synthesis of a-chains with glycine-x-y sequence.
rER: Hydroxylation of proline and lysine residues, forming hydroxyproline and hydroxylysine. Requires vitamin C.
Golgi: Glycosylation of α-chains, forming procollagen

Extracellular events
tropocollagen is formed from procollagen
Cross-linking of tropocollagen molecules, forming collagen fibrils.
Requires oxidation of lysine via lysine oxidase (contains copper)

A
61
Q

which of the following serves as a principal source of nonessential amino acids

fats

water

carbohydrates

urea

A

carbohydrates

ten of the nonessential amino acids can be derived from glucose. Tyrosine is synthesized by hydroxylation of the essential amino acid phenylalanine.

62
Q

Amino acids are degraded to

oxygen

carbon dioxide

ammonia

water

hydrogen

urea

A

Amino acids are degraded to

carbon dioxide

water

urea

amino acids are first transferred to alpha-ketoglutarate, which forms glutamate. The glutamate is then oxidatively deaminated to form ammonia by glutamate dehydrogenase. Because ammonia is toxic it is converted to urea in the urea cycle in the liver.

63
Q

a patient of yours suffers from phenylketonuria (PKU). you offer her a bottle of soda the patient

should not have it because it contains tyrosine, which she is unable to metabolize

should not have it because it contains phenylalanine, which she is unable to metabolize

What supplement should she be taking

tyrosine

phenylalanine

both

none

A

should not have it because it contains phenylalanine, which she is unable to metabolize

tyrosine

64
Q

Albinism is caused by the absence of ______

A

Albinism is caused by the absence of tyrosinase (an enzyme necessary for the synthesis of melanin from tyrosine).

65
Q

Epinephrine and norepinephrine are produced by the ____.

liver

adrenal medulla

pancreas

kidney

They cause potent _______

vasoconstriction and bronchodilation.

vasodilation and bronchoconstriction

vasoconstriction and bronchoconstriction

vasoconstriction and bronchoconstriction

A

Epinephrine and norepinephrine are produced by the adrenal medulla

They cause potent vasoconstriction and bronchodilation.

66
Q

Serotonin is released largely by ________ causing vasoconstriction.

stomach and platelets

liver and platelets

gastric mucosa and platelets

gallbladder and platelets

A

Serotonin is released largely by gastric mucosa and platelets, causing vasoconstriction. It is a potent neurotransmitter in the CNS.

67
Q

Histamine is released largely by basophils and mast cells,
causing vasodilation and bronchoconstriction.

A
68
Q

Match with the description - H1 receptors H2 receptors

mediate type I hypersensitivity.

mediate gastric acid and pepsin secretion.

A

H1 receptors mediate type I hypersensitivity.
H2 receptors mediate gastric acid and pepsin secretion.

69
Q
A

biochem (4 decks)

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