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Biochemistry > Chapter 4 Proteins And Amino Acids > Flashcards

Chapter 4 Proteins And Amino Acids Flashcards

1
Q

Most of the aminoacids are?

A

Alpha- amino acids

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2
Q

Most abundant organic molecules of living system?

A

Proteins

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3
Q

Proteins constitute about ________% of dry weight of a cell?

A

50

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4
Q

Proteios means?

A

Holding the first place

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5
Q

Entire study of galaxy of proteins is given the term?

A

Proteiomics

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6
Q

Function of proteins may be grouped as?

A

1.Static (structural)
2.Dynamic

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7
Q

What are the structural proteins?

A

That perform brick and mortar functions.
Structure and strength

E.g:
Collagen
Elastin
- both in bone matrix and vascular tissues
a-keratin - in epidermal tissues

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8
Q

What are dynamic proteins?

A

Act as enzymes, harmones, immunoglobins, storage proteins etc

  • regarded as working horses of cell
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9
Q

Content of nitrogen in protein?

A

16%

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10
Q

Estimation of nitrogen in laboratory is mostly done by?

A

Kjeldahl’s Method

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11
Q

Proteins are polymers of?

A

L-a-aminoacids

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12
Q

Proteins are hydrolysed by?

A

Concentrated HCl

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13
Q

How many amino acids occur in nature?

A

300

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14
Q

How many amino acids are known as standard amino acids?

A

20

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15
Q

1.Trick to remember aliphatic amino acids?

  1. Trick to remember aromatic aminoacids?
A

Aliphatic amino acids;
(Glaciers in Alaska Valiantly Locate Isolated Prowlers)

Glycine (only one containing non-chiral carbon)
Alanaine
Valine
Leusine
Isoleusine
Proline (only one containing ring but not aromatic)

  1. (The Aroma of Fine pine & Yellow Timber are Worth the Tryp)
    Aroma—aromatic:

•Phenylalanine (F)
•Tyrosine (Y) (also contains OH group)
•Tryptophan (W)
(2 aromatic rings, 1st—5 membered, 2nd—6 membered)

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16
Q
  1. Trick to remember amino acids containing hydroxyl group?
  2. Trick for basic amino acids?
A
  1. (Alcohol is a Serious Threat)
    Alcohol—alcoholic group (-OH)

•Serine
•Threonine

  1. (Basically,
    His
    Lost Kid
    Always Returned)
    Basically—-basic amino acids

•Histidine (H)
•Lysine (K)
•Arginine (R)

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17
Q

Trick for acidic amino acids & their amide?.

What are the sulfur containing amino acids?

A

(As he Digested the Glue his stomach became acidic)

Aspartic acid (D)
(Amide—-Asparagine (N))
Glutamic acid (E)
(Amide—-Glutamine (Q))

  1. Methionine
    Cysteine
    Cystine
18
Q

Importance of amino acids regarding charges & polar/non-polar nature?

A
  1. charged
    Acid & basic amino acids
  2. Non-polar
    •All aliphatic
    •2 aromatic
    (phenylalanin & tryptophan)
    • methionine
  3. Polar
    •All alcohols & amide
    •Aromatic —-Tyrosine (bcz has OH group)
    •Cysteine
19
Q

1.All amino acids show optical isomers except?

  1. What type of amino acids are proteins composed of?
  2. Name the branched chain amino acids?
  3. Cystine is formed by?
  4. What are the 2 amino acids incorporated during protein synthesis? With special groups??
A

1.Glycine (no chiral/asymmetrical carbon)

  1. L-a-aminoacids
  2. There are 3 aliphatic amino acids with branched chains:
    Valine
    Leucine
    Isoleucine
  3. Condensation of 2 molecules of cysteine
  4. 2 sulfur containing;
    Methionine (thioether group)
    Cysteine (sulfhydryl group)
20
Q
  1. What are the dicarboxylic monoamino acids?
  2. Groups in arginine & histidine? What kind of aminoacids are these?
  3. What is an imino acid? Name it?
  4. Name heterocyclic amino acids?
A
  1. Aspartic acid & glutamic acid
  2. Arginine—-guanido
    Histidine—-imidazole
    —dibasic monocarboxylic aminoacids
  3. Containing imino group (=NH) instead of amino (-NH2)
    Proline (pyrridole ring)—is an a-imino acid
  4. Histidine
    Tryptophan
    Proline
21
Q
  1. What are the polar amino acids with positive R group?
  2. What are the polar amino acids with negative R group?
  3. Polar amino acid but with no charge?
A
  1. Basic amino acids:
    Histidine
    Lysine
    Arginine
  2. Acidic amino acids:(dicarboxylic):
    Aspartic acid
    Glutamic acid
  3. •Glycine
    Alcoholic
    •Serine
    •Threonine
    Sulfur containing
    •Cysteine
    Amide
    •Glutamine
    •Asparagine
    Aromatic
    •Tyrosine (-OH group)
22
Q
  1. What are essential amino acids? Which of these are semi essential?
A

Which can’t be synthesized in the body
(Argentina.Valley. HILL M.P Threat.Tryp)
Arginine
Valine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylanaline
Threonine
Tryptophan

Semi essential
Can be synthesized by adults but not by growing children;
(Ah)
Arginine
Histidine

23
Q
  1. What is the fate if amino acids?
A
  1. Either as precursor of
    •Glucose—-(glycogenic aminoacids)
    (AA)
    Alanine
    Aspartate
    Glycine
    Methionine.

•Fat—-(ketogenic aminoacids)
(LL)
Leucine
Lysine

•Glycogenic & ketogenic aminoacids
4 amino acids:
(3 aromatic and 1 aliphatic)
Tryptophan
Tyrosine
Phenylalanine
Isoleucine

24
Q
  1. What is the 21st amino acid? It is translated by which stop codon?
    Incorporated directly on protein by?
    It is found in?
    What is the difference in its structure compared to cysteine?
  2. What is the 22nd amino acid? It is translated by which stop codon?
A
  1. Selenocysteine
    –By UGA
    –By serine on tRNA
    – at the active sites of enzymes (selenoproteins) e.g
    Glutathione peroxidase
    5’-diodinase
    —-selenium in place of Sulfur atom of cysteine
  2. Pyrrolysine
    By UAG
25
Q

1.What is chinese restaurant synrome?

  1. Name amino acids that are
    Sweet
    Tasteless
    Bitter
A

Chinese restaurant syndrome is a term used to describe a collection of symptoms, such as headaches, flushing, and sweating, that some people may experience after consuming foods containing monosodium glutamate (MSG). (Ajinomoto(brand name) –flavour enchancer)
It was initially associated with Chinese cuisine, hence the name, but it can occur after consuming foods from various cuisines that contain MSG.

2.
Sweet— Glycine, Alanine, Valine
Tasteless—leucine
Bitter—Arginine, Isoleucine

26
Q
  1. What are ampholytes?
  2. Nature of amino acids in different pH?
  3. What is isoelectric pH?
A

1.Ampholytes are substances that can act as both acids and bases.
E.g aminoacids
They have the ability to donate (-COOH) (acidic) or
accept protons (-NH2) (basic) depending on the pH of the environment.
It’s like they can play both roles, kind of like being versatile!

  1. acidic pH(low pH)
    Amino acid—-+vely charged cation
    alkaline pH(high pH)
    Amino acid—- -vely charged anion
    Neutral PH
    As zwitter ion
    E.g leucine (pH=6.0)
  2. The isoelectric pH, also known as the pI (isoelectric point), is the pH at which a molecule or substance has no net electrical charge.
    It exists as zwitter ion or dipolar ion
    It’s like finding the perfect balance point where the molecule is neither positive nor negative.
27
Q
  1. What happens on decarboxylation of amino acids?
  2. Name biologically imp amines from corresponding amino acids?
  3. Amides are formed by reactions of?
  4. Which test is used for detection of amino acids & proteins?
A
  1. Amines are formed

2.
Histidine—-histamine
Tyrosine—-tyramine
Glutamate—-y-Amino Butyric Acid (GABA)

  1. Carboxyl group of dicarboxylic Aminoacids + NH3
  2. Ninhydrin test
    Amino acids + Ninhydrin—–purple/blue/pink complex
    But
    Proline & hydroxyproline—-yellow colour
28
Q
  1. Collagen contains amino acid derivatives?
  2. Which amino acid derivative is involved in blood clotting?
  3. Amino acid derivatives found in histones?
A

1.
4-Hydroxyproline
5-Hydroxylysine

  1. Y-Carboxyglutamic acid found in plasma proteins
  2. Methylated
    Phosphorylated
    Acetylated amino acids
29
Q
  1. D-amino acids are found in antibiotics?
  2. D-amino acids are found in brain tissue?

3.D-amino acids are found in bacterial cell wall?

A
  1. •Actinomycin - D
    •Valinomycin - D
    •Gramicidin - S
  2. •D- Serine
    •D- Aspartate
  3. •D-Glutamic Acid
    •D-Alanine
30
Q

1.Name 3 amino acids used as drugs?

  1. Which amino acid drug is used for treatment of cystic fibrosis?
  2. Which drug is used for the treatment of wilson’s disease?
  3. Which amino acid drug is used as an anticonvulsant?
A
  1. •D-pencillamine
    •N-Acetylcysteine
    •Gabapentin
  2. N-Acetylcysteine
    As it acts as antioxidant
    ( by thinning the mucus in the airways, making it easier to cough up.)
  3. D-penicillamine (D-dimethylglycine)
    Chelation of copper
    D-penicillamine treats Wilson disease by binding to copper and forming a complex that can be excreted in urine. This helps reduce copper levels in the body.
  4. Gabapentin (y-aminobutyrate)
    Linked to cyclohexane
    (by binding to certain receptors in the brain that help reduce abnormal electrical activity and prevent seizures.)
31
Q
  1. What is lathyrism?
  2. What amino acids are responsible for it?
  3. Which amino acids in it cause ammonia toxicity?
  4. Which amino acids is responsible for parkinson’s dimentia?
A

1.Lathyrism is a condition caused by the consumption of a legume called Lathyrus sativus (kesari dal), which contains a neurotoxin. It can lead to paralysis of the lower limbs.

  1. L-Homoarginine &
    B-N- OxalylDiAminoPropionic acid (ODAP) of lathyrus
  2. a,y-diaminobutyric acid
    (Analogue of ornithine)
    —-bcz it disrupts urea cycle
  3. L-B-Methylaminoalanine
    Of Cycad seeds
32
Q
  1. Peptide bonds is charged or uncharged? Peptides may be also regarded as?
  2. In polypeptide chains 2 adjacent a-carbons are placed?
  3. Which structure of protein is primarily responsible for its function?
  4. Which enzyme causes complete hydrolysis of proteins?
A
  1. Peptide bond—- uncharged
    But peptides —- charged (due to terminal carboxyl & amino group)
    Thus peptides—–polyelectrolytes
  2. 0.36nm apart
  3. Primary structure
  4. Prolase (a mixture of non-specific proteolytic enzyme)
33
Q
  1. How amino acids can be separated after protein hydrolysis?
A
  1. By chromatography
    (Amino acids can be separated by chromatography based on their different properties, such as size, charge, and affinity for the stationary phase. It’s like giving each amino acid its own unique pathway to travel, allowing them to be separated and identified. )
34
Q
  1. The non-covalent bonds between proteins are broken by?
  2. Disulfide linkages are cleaved by?
  3. Number of polypeptide chains can be identified by treatment of protein with?
  4. Enzymatic cleavage is done by?
  5. Chemical cleavage by?
A
  1. Urea or guanidine hydrochloride
    (Converts proteins —- polypeptides)
  2. Performic acid
  3. Dansyl chloride
  4. Trypsin
    (Carbonyl side of peptide linkage containing lysine & arginine)
  5. Cyanogen bromide (CNBr)
    (Carbonyl side of peptide linkage containing methionine)
35
Q
  1. Determination of amino acids by?
  2. Sequenator uses which principle?
A
  1. Sangers reagent
    (1-fluoro 2,4-dinitrobenzene)
    Edman’s reagent
    (Phenyl isothyiocyanate)

Then amino acid by chromatography

  1. An automated machine for amino acid sequence
    —Edman’s principle
    (PTH amino acid is liberated)
36
Q
  1. The a-helix is stabilized by?
  2. Each turn of a-helix has how many:
    Amino acids?
    Travels of distance of?
    Spacing of each amino acid?
  3. Which a-helix is more stable?
A
  1. Extensive Hydrogen bonding between H-atom of peptide N & O-atom of peptide C

2.
Amino acids—–3.6
Travels of distance of—0.54nm
Spacing of each amino acid—0.15nm

  1. Right handed a-helix is more stable than left
37
Q
  1. In globular proteins, the core structure is formed by?
  2. What are supersecondary structure of proteins?
    Stabilized by?
    Also called?
A
  1. B-sheets
  2. Intermediates between secondary & tertiary structures
    -combination of a-helices & B-structures
    —stabilized by;
    •H-bonding
    •Salt bridges
    •Hydrophobic interactions
    —also called — mortif
38
Q
  1. Bonds in tertiary structures of proteins?
  2. What is domain?
  3. A polypeptide with 200 amino acid contains how many domains?
  4. What are oligomeric proteins?
    Examples?
  5. Bonds in quaternary structure?
A
  1. •Hydrogen bonds
    •Disulfide bonds
    •Ionic interactions
    •Hydrophobic interactions
    •Van der waals forces
  2. Term used to represent the basic unit of tertiary protein structure
  3. 2 or more domains
  4. Having quaternary structure (2 or more polypeptides)
    E.g
    Hemoglobin
    Aspartate transcarbamoylase
    Lactate dehydrogenase
  5. •Hydrogen bond
    •Hydrophobic interaction
    •Ionic interaction
39
Q
  1. Chemically glutathione is?
  2. How is it essential for protein function?
  3. What is it’s significance in eryhthrocyte?
  4. Involved in amino acids transports in the intestine & kidney tubules by?
  5. Peroxidases & free radicals are scavenged by?
A
  1. y-glutamyl-cysteinyl-glycine
    Is a tripeptide composed of 3 amino acids
  2. Prevents oxidation of sulfhydryl groups of proteins to disulfide groups
    — also with glutathione reductase— formation of correct disulfide bonds
  3. Gutathione (reduced):
    •Maintains RBC membrane structure
    •Protects Hb from oxidation by H2O2
  4. y-glutamyl cycle/Meister cycle
  5. Glutathione peroxidase
    (A selenium containing enzyme)
40
Q
  1. Name different peptides with different numbers of aminoacids (peptides)
A

Dipeptide (2 amino acids)
•Aspartame
Tripeptides (3 amino acids)
•Thyrotrophin releasing hormone
•Glutathione
Pentapeptide
•Methionine enkephalin
Octapeptide
•Angiotensin II
Nonapeptides
•Oxytocin
•Vasopressin (ADH)
•Bradykinin
Decapeptides
•Angiotensin I
•Kallidin

41
Q
  1. What are pseudopeptides?
  2. Which peptide is found in brain? Its function?
  3. What is the function of bradykinin and kallidin?
  4. Aspartame is _____ times sweeter than?
    Used as?
    Produced by combination of?
A
  1. Duplicate peptides produced by pharmaceutical industries to the efficiency of drugs
    E.g
    B-peptides
    Y-peptides
    Oligoglycines
    Peptide nucleic acid (PNA)
    DNA cleaving pseudopeptides
  2. Methionine enkephalin (pentapeptide)
    —opiate like function
    —inhibits sense of pain
  3. Vasodilators
    - produced from plasma proteins by snake venom enzymes
  4. 200 times than sucrose
    —artificial sweetener
    —aspartic acid & phenylalanine
42
Q

What are covalent & non covalent bonds in protein structures?

A
  1. 2 covalent
    Peptide
    Disulfide
    4 non covalent
    Hydrogen bonds
    Hydrophobic bonds
    Electrostatic bonds
    Van der waals forces

Biochemistry (10 decks)

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