lectures 6&7 btech quiz

What is the common structural feature shared by all alpha amino acids?

a) Amino group (-NH2) and hydroxyl group (-OH) on alpha carbon

b) Amino group (-NH2) and carboxyl group (-COOH) on alpha carbon

c) Carbonyl group (C=O) and hydroxyl group (-OH) on alpha carbon

d) Carboxyl group (-COOH) and hydroxyl group (-OH) on alpha carbon

b) Amino group (-NH2) and carboxyl group (-COOH) on alpha carbon

Which functional group imparts unique properties to each alpha amino acid?

a) Amino group

b) Carboxyl group

c) Hydroxyl group

d) Side chain (R group)

d) Side chain (R group)

What is the primary property associated with hydrocarbon molecules in side chains?

a) Polar and hydrophilic

b) Nonpolar and hydrophobic

c) Charged and reactive

d) Amphipathic and neutral

b) Nonpolar and hydrophobic

How do nonpolar amino acids behave in protein structure?

a) Form hydrogen bonds with water

b) Interact with water on surface

c) Cluster in interior

d) Repel other amino acids

c) Cluster in interior

What is the reason for hydrophobic side chains being in protein core?

a) Promote interactions

b) Increase flexibility

c) Minimize contact with polar solvents

d) Interact with water

c) Minimize contact with polar solvents

How does hydrophobicity change with larger hydrocarbon groups?

a) Decreases

b) Stays same

c) Increases

d) Becomes polar

c) Increases

What do benzene rings contribute to amino acids?

a) Hydrophilicity

b) Hydrophobicity and non-reactivity

c) Polarity

d) Flexibility

b) Hydrophobicity and non-reactivity

What characterizes uncharged polar side chains?

a) Dipole + hydrogen bonding

b) Hydrophobic

c) Positive charge

d) Inside protein core

a) Dipole + hydrogen bonding

Charge of uncharged polar side chains at physiological pH?

a) Negative

b) Positive

c) Neutral

d) Variable

c) Neutral

Where are uncharged polar side chains located?

a) Core

b) With nonpolar groups

c) Outside interacting with water

d) Lipid bilayer

c) Outside interacting with water

Key feature of cysteine for disulfide bonds?

a) Amino group

b) Carboxyl group

c) Thiol group

d) Hydroxyl group

c) Thiol group

Bond formed when cysteine oxidizes?

a) Hydrogen

b) Peptide

c) Ionic

d) Disulfide

d) Disulfide

What is unique about glycine's side chain?

a) Carboxyl

b) Amino

c) Single hydrogen

d) Hydroxyl

c) Single hydrogen

Role of glycine in proteins?

a) Hydrogen bonding

b) Rigidity

c) Flexible hinge

d) Stabilization

c) Flexible hinge

Advantage of glycine flexibility?

a) Tight packing

b) Disulfide formation

c) Hydrophobic solubility

d) Functional adaptability

d) Functional adaptability

What distinguishes proline?

a) Hydrophilic group

b) Ring with alpha carbon + nitrogen

c) Charged side chain

d) Sulfur

b) Ring with alpha carbon + nitrogen

Where is proline commonly found?

a) Beta sheets

b) Alpha helices

c) Turns/loops

d) Core

c) Turns/loops

Role of proline?

a) Increases flexibility

b) Restricts flexibility

c) Stabilizes via H-bonds

d) Promotes assembly

b) Restricts flexibility

How do charged polar amino acids interact?

a) Covalent bonds

b) Conformational change

c) Ionic interactions

d) Hydrophobic interactions

c) Ionic interactions

pKa of arginine guanidino group?

a) 5

b) 7

c) 10.5

d) 12.5

d) 12.5

Why is arginine positively charged?

a) Protonation

b) Deprotonation

c) Carboxyl group

d) Hydrogen bonds

a) Protonation

How does arginine bind nucleic acids?

a) Disrupt H-bonds

b) Covalent bonds

c) Hydrogen bonds

d) Electrostatic interaction

d) Electrostatic interaction

Function of lysine positive charge?

a) DNA interaction

b) Disulfide bonds

c) Inhibits histones

d) Nonpolar solubility

a) DNA interaction

Charge of lysine below pH 10.5?

a) Negative

b) Positive

c) Neutral

d) Hydrophobic

b) Positive

Aspartic acid deprotonated at?

a) Below 3.9

b) 3.9

c) Above 3.9

c) Above 3.9

Role of aspartic acid?

a) Energy storage

b) Lipid synthesis

c) Protein interactions

d) DNA replication

c) Protein interactions

Glutamic acid deprotonated at?

a) 4

b) Below 4

c) Above 4

c) Above 4

Significance of histidine imidazole?

a) Solubility

b) Metal binding

c) pH switch

d) H-bond regulation

c) pH switch

Histidine buffering role?

a) Covalent bonds

b) Accept/donate H+

b) Accept/donate H+

Histidine in enzymes?

a) Stabilizer

b) Cofactor

c) Acid/base

d) Substrate

c) Acid/base

Where does pre-mRNA processing occur?

A) Ribosomes

B) Golgi apparatus

C) Nucleus

D) Mitochondria

C) Nucleus

Function of post-transcriptional modification?

A) Promote degradation

B) DNA replication

C) Export mRNA

D) Inhibit protein synthesis

C) Export mRNA

Processes in mRNA modification?

A) 5' cap

B) Poly-A tail

C) Splicing

D) All of the above

D) All of the above

Function of 5' cap?

A) Degrade mRNA

B) Splicing

C) Protect + initiate translation

D) Regulate transcription

C) Protect + initiate translation

Polyadenylation function?

A) Poly-U tail

B) Cytoplasm

C) Stability in nucleus

D) Degradation

C) Stability in nucleus

What is removed in splicing?

A) Exons

B) Introns

C) Both

D) Poly-A tail

B) Introns

Where do ribosomal subunits assemble?

a) Cytoplasm

b) ER

c) Nucleus

d) rRNA sites

a) Cytoplasm

Role of small subunit?

a) Peptide bonds

b) DNA replication

c) Bind mRNA

d) Export

c) Bind mRNA

Role of large subunit?

a) mRNA maturation

b) Peptide bonds

c) Start codon

d) Decoding

b) Peptide bonds

Prokaryotic ribosome size?

a) 80S

b) 70S

c) 50S

d) 30S

b) 70S

Eukaryotic ribosome size?

a) 70S

b) 80S

c) 50S

d) 60S

b) 80S

Svedberg unit measures?

a) Mass

b) Volume

c) Sedimentation rate

d) Speed

c) Sedimentation rate

Small subunit scans for?

a) Peptide bonds

b) Transcription

c) Start codon

d) Stabilization

c) Start codon

Start codon?

a) UAA

b) AUG

c) GUA

d) CAG

b) AUG

Amino acid for AUG?

a) Glycine

b) Methionine

c) Lysine

d) Proline

b) Methionine

Function of A site?

a) Hold chain

b) Bind aminoacyl-tRNA

c) Exit tRNA

d) Catalyze bonds

b) Bind aminoacyl-tRNA

Where is polypeptide held?

a) A site

b) P site

c) E site

d) mRNA site

b) P site

Role of E site?

a) Bind tRNA

b) Hold chain

c) Exit tRNA

d) Catalyze bonds

c) Exit tRNA

Ribosome movement direction?

a) 3'→5'

b) 5'→3'

c) Both

d) None

b) 5'→3'

Termination signal?

a) Large subunit binding

b) Start codon

c) Stop codon

d) Initiation factors

c) Stop codon

Codon length?

a) 1

b) 2

c) 3

d) 4

c) 3

Total codons?

a) 20

b) 64

c) 40

d) 32

b) 64

Number of amino acids?

a) 64

b) 20

c) 40

d) 32

b) 20

Degeneracy meaning?

a) One codon per amino acid

b) Multiple codons per amino acid

c) Inefficient code

d) No variation

b) Multiple codons per amino acid

Redundancy benefit?

a) More errors

b) More mutations

c) Same amino acid despite mutation

d) Fewer amino acids

c) Same amino acid despite mutation