Molecular Genetics: Structure, Function, and Evolution

Question 1

Which of the following is the complementary base pair to adenine in DNA?

Accepted Answer

Thymine

Answer

Guanine

Answer

Cytosine

Answer

Uracil

Question 2

Which of the following is NOT a valid codon in the genetic code?

Accepted Answer

ZZZ

Answer

AUG

Answer

UAA

Answer

GAA

Question 3

What is the name of the process by which genetic information encoded in DNA is copied into an RNA molecule?

Accepted Answer

Transcription

Answer

Replication

Answer

Translation

Answer

Mutation

Question 4

Which of the following types of mutations results in the substitution of one codon for another, potentially changing the amino acid sequence of a protein?

Accepted Answer

Missense mutation

Answer

Silent mutation

Answer

Nonsense mutation

Answer

Frameshift mutation

Question 5

What is the primary function of the ribosome during translation?

Accepted Answer

To assemble amino acids in the correct order to synthesize a protein

Answer

To synthesize tRNA molecules

Answer

To unwind the DNA double helix

Answer

To proofread the newly synthesized protein

Question 6

What is the difference between a promoter and a terminator in molecular genetics?

Accepted Answer

A promoter is a sequence that signals the beginning of a gene, while a terminator is a sequence that signals the end of a gene

Answer

A promoter is a sequence that binds to RNA polymerase, while a terminator is a sequence that binds to DNA polymerase

Answer

A promoter is a sequence that is transcribed, while a terminator is a sequence that is translated

Answer

There is no difference between a promoter and a terminator

Question 7

What is the correct order of the steps in DNA replication?

Accepted Answer

Unwinding, base pairing, ligation

Answer

Base pairing, unwinding, ligation

Answer

Ligation, unwinding, base pairing

Answer

Unwinding, ligation, base pairing

Question 8

What is the role of introns in eukaryotic genes?

Accepted Answer

Introns are non-coding regions that are removed during RNA splicing, potentially allowing for alternative splicing and protein isoforms

Answer

Introns are coding regions that are translated into protein

Answer

Introns are regulatory regions that control gene expression

Answer

Introns play no role in gene expression

Question 9

The correct sequence of nitrogenous bases in a DNA molecule, from 5' to 3', is:

Accepted Answer

Adenine, thymine, guanine, cytosine

Answer

Guanine, adenine, thymine, cytosine

Answer

Thymine, adenine, cytosine, guanine

Answer

Cytosine, thymine, guanine, adenine

Question 10

Which process involves synthesizing a new strand of DNA complementary to an existing strand?

Accepted Answer

Replication

Answer

Transcription

Answer

Translation

Answer

Mutation

Question 11

Helicase is an enzyme that functions during DNA replication by:

Accepted Answer

Unwinding the DNA double helix

Answer

Adding nucleotides to the growing DNA strand

Answer

Joining fragments of DNA together

Answer

Proofreading newly synthesized DNA strands

Question 12

In protein synthesis, RNA serves the primary role of:

Accepted Answer

Carrying genetic information from DNA to the ribosome

Answer

Catalyzing the formation of peptide bonds

Answer

Providing structural support for the ribosome

Answer

Transporting amino acids to the ribosome

Question 13

Which type of mutation results in a change in the reading frame of a gene?

Accepted Answer

Frameshift mutation

Answer

Point mutation

Answer

Silent mutation

Answer

Deletion mutation

Question 14

The primary source of genetic variation in a population is:

Accepted Answer

Mutations

Answer

Recombination

Answer

Natural selection

Answer

Genetic drift

Question 15

A mutagen is considered strong if it:

Accepted Answer

Can induce multiple mutations in a single cell

Answer

Exclusively causes mutations in somatic cells

Answer

Always results in harmful mutations

Answer

Cannot be triggered by environmental factors

Question 16

Non-coding regions of DNA within eukaryotic genes are referred to as:

Accepted Answer

Introns

Answer

Exons

Answer

Promoters

Answer

Terminators

Question 17

Which technique is commonly used to assess gene expression levels?

Accepted Answer

Microarray

Answer

PCR

Answer

DNA sequencing

Answer

Gel electrophoresis

Question 18

How do mutations contribute to genetic diversity within a population?

Accepted Answer

By introducing new genetic variations

Answer

By increasing the rate of genetic recombination

Answer

By reducing the fitness of organisms

Answer

By eliminating harmful alleles

Question 19

How does gene regulation contribute to the variation in physical characteristics (phenotypes) observed among different organisms?

Accepted Answer

Gene regulation indirectly influences phenotypic traits by selectively controlling protein production within cells.

Answer

Gene regulation alone determines an organism's phenotype, regardless of environmental factors.

Answer

Gene regulation involves modifying the DNA sequence, resulting in phenotypic variations.

Answer

Alternative mRNA splicing is the only mechanism of gene regulation in eukaryotes.

Question 20

Which nitrogenous base is **not** present in DNA?

Accepted Answer

Uracil

Answer

Adenine

Answer

Thymine

Answer

Cytosine

Question 21

What is the name of the process by which DNA makes an identical copy of itself?

Accepted Answer

Replication

Answer

Transcription

Answer

Translation

Answer

Mutation

Question 22

Which type of RNA molecule transports the genetic code from the nucleus to the ribosome?

Accepted Answer

mRNA

Answer

rRNA

Answer

tRNA

Answer

snRNA

Question 23

Which of the following is **not** a function of DNA polymerase?

Accepted Answer

Unwinding the DNA double helix

Answer

Adding nucleotides to the growing DNA strand

Answer

Proofreading the newly synthesized DNA strand

Answer

Joining Okazaki fragments

Question 24

What is the primary function of RNA polymerase in transcription?

Accepted Answer

To synthesize a complementary RNA strand using DNA as a template

Answer

To edit the newly synthesized RNA strand

Answer

To transport the RNA strand to the ribosome

Answer

To catalyze the formation of peptide bonds

Question 25

What is the name of the enzyme that catalyzes the formation of peptide bonds during translation?

Accepted Answer

Peptidyl transferase

Answer

DNA polymerase

Answer

RNA polymerase

Answer

Ribosome

Question 26

Which of the following is a characteristic of a **neutral** mutation?

Accepted Answer

It has no effect on the phenotype

Answer

It is always inherited

Answer

It is always harmful

Answer

It is always beneficial

Question 27

During transcription, what is the primary function of RNA polymerase?

Accepted Answer

Unraveling the DNA helix and synthesizing a complementary RNA strand

Answer

Unraveling the RNA helix and synthesizing a complementary DNA strand

Answer

Breaking the hydrogen bonds between DNA strands

Answer

Joining the nucleotides in the RNA strand

Question 28

Identify the option that is NOT a recognized type of mutation:

Accepted Answer

Gene duplication

Answer

Base substitution

Answer

Frameshift mutation

Answer

Silent mutation

Question 29

Which of the following accurately describes a characteristic of prokaryotic DNA?

Accepted Answer

Circular shape and no association with histones

Answer

Linear shape and association with histones

Answer

Linear shape and no association with histones

Answer

Circular shape and association with histones

Question 30

Which technique is commonly used to separate DNA fragments based on their size?

Accepted Answer

Gel electrophoresis

Answer

PCR

Answer

DNA sequencing

Answer

DNA fingerprinting

Question 31

What is the primary significance of the genetic code?

Accepted Answer

Determining the sequence of amino acids in proteins

Answer

Controlling the regulation of gene expression

Answer

Protecting DNA from mutations

Answer

Providing instructions for cell division

Question 32

Explain the key difference between a proto-oncogene and an oncogene.

Accepted Answer

Proto-oncogenes are normal genes that can become oncogenes through mutations, while oncogenes are always mutated genes that cause cancer.

Answer

Oncogenes are normal genes that can become proto-oncogenes through mutations, while proto-oncogenes are always mutated genes that cause cancer.

Answer

Proto-oncogenes and oncogenes are essentially the same.

Answer

Proto-oncogenes are found exclusively in prokaryotes, while oncogenes are found exclusively in eukaryotes.

Question 33

Describe the structural components and organization of DNA, explaining how these characteristics influence its genetic function.

Accepted Answer

Double helix containing deoxyribose and phosphate molecules, with complementary base pairing

Answer

Linear chain of nucleotides connected by hydrogen bonds

Answer

Triple helix with alternating sugar-phosphate backbones

Answer

Circular structure found only in eukaryotic cells

Question 34

What is the main purpose of DNA replication?

Accepted Answer

To pass on unchanged genetic information to new cells.

Answer

To happen only when cells are dividing.

Answer

To introduce new mutations into the genetic code.

Question 35

Which nitrogenous base is found in RNA but not in DNA?

Accepted Answer

Uracil

Answer

Adenine

Answer

Guanine

Question 36

Which of the following is **NOT** a nitrogenous base found in DNA?

Accepted Answer

Uracil

Answer

Cytosine

Answer

Guanine

Answer

Adenine

Question 37

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Answer

Polymerase

Answer

Ligase

Answer

Topoisomerase

Question 38

Describe the function of RNA polymerase in transcription?

Accepted Answer

It synthesizes RNA molecules using DNA as a template

Answer

Joins Okazaki fragments during DNA replication

Answer

Unwinds the DNA double helix

Answer

Proofreads and repairs newly synthesized DNA

Question 39

Which type of RNA carries the genetic code from DNA to the ribosome?

Accepted Answer

Messenger RNA (mRNA)

Answer

Small nuclear RNA (snRNA)

Answer

Transfer RNA (tRNA)

Answer

Ribosomal RNA (rRNA)

Question 40

Explain the role of mutations in evolution?

Accepted Answer

They provide genetic variation on which natural selection can act

Answer

They are always beneficial to an organism

Answer

They only occur during meiosis

Question 41

Which of the following is a type of point mutation?

Accepted Answer

Substitution

Answer

Inversion

Answer

Deletion

Question 42

Name the process by which DNA is copied into RNA?

Accepted Answer

Transcription

Answer

Replication

Answer

Translation

Answer

Recombination

Question 43

Define the genetic code?

Accepted Answer

A set of three-nucleotide sequences (codons) that specify the order of amino acids in proteins

Answer

The sequence of amino acids in a protein

Answer

The sequence of nucleotides in a DNA molecule

Question 44

What is the term for a mutation that results in a premature stop codon?

Accepted Answer

Nonsense mutation

Answer

Silent mutation

Answer

Frameshift mutation

Answer

Missense mutation

Question 45

In DNA, which base is complementary to adenine?

Accepted Answer

Thymine

Answer

Cytosine

Answer

Guanine

Answer

Uracil

Question 46

Which type of RNA carries the genetic information from the nucleus to the ribosome?

Accepted Answer

Messenger RNA (mRNA)

Answer

Ribosomal RNA (rRNA)

Answer

MicroRNA (miRNA)

Answer

Transfer RNA (tRNA)

Question 47

During DNA replication, which enzyme is responsible for synthesizing new DNA strands?

Accepted Answer

DNA polymerase

Answer

RNA polymerase

Answer

Helicase

Answer

Ligase

Question 48

What is the primary function of introns in eukaryotic genes?

Accepted Answer

They are removed during RNA splicing to form mature mRNA

Answer

They code for essential proteins

Answer

They protect the gene from damage

Answer

They regulate gene expression

Question 49

Which technique is commonly used to amplify DNA in the laboratory?

Accepted Answer

Polymerase chain reaction (PCR)

Answer

Gel electrophoresis

Answer

Southern blotting

Answer

DNA sequencing

Question 50

Define the genetic code.

Accepted Answer

A set of nucleotide triplets that correspond to specific amino acids or stop codons

Answer

A sequence of nucleotides that control gene expression

Answer

The order of genes on a chromosome

Question 51

How does a proto-oncogene differ from an oncogene?

Accepted Answer

A proto-oncogene has the potential to transform into an oncogene through mutations or other genetic changes

Answer

A proto-oncogene is always dominant, while an oncogene is always recessive

Answer

A proto-oncogene is only found in cancer cells, while an oncogene is found in all healthy cells