Molecular Genetics

Which of the following best describes the semiconservative nature of DNA replication?

The nucleotides from DNA are reused once the strand is damaged

A newly synthesized strand contains both old and new nucleotides

Two newly synthesized strands of DNA form the double helix

Each DNA strand comprises a newly synthesized segment and an original template piece

Only one strand of the parent strand is used as a template for replication

Each DNA strand comprises a newly synthesized segment and an original template piece

What type of bond forms the sugar-phosphate backbone in DNA?

Phosphodiester bonds

Which of the following is unique to the leading strand in DNA replication?

The new DNA strand is synthesized continuously

What type of bond forms between two nucleotides on opposite strands of DNA?

Disulfide bonds

Van der Waals forces

Hydrogen bonds

Peptide bonds

Phosphodiester bonds

Hydrogen bonds

Which of the following is true for both the leading and lagging strand during replication?

Both require a single DNA primer for initiation

Both require the activity of DNA ligase to join Okazaki fragments

Both are synthesized in the 5’ to 3’ direction

Both strands are synthesized via an RNA Polymerase

Both create Okazaki fragments

Both are synthesized in the 5’ to 3’ direction

Which of the following enzymes is essential for synthesizing the leading and lagging strands of DNA?

DNA Polymerase III

What is the function of DNA Polymerase I?

Initiate termination of DNA replication

Replace the RNA primer with DNA nucleotides

Joins segments of DNA together 

Break and rejoin the DNA double helix ahead of the replication fork

Synthesize RNA primers needed to initiate DNA replication

Replace the RNA primer with DNA nucleotides

Which enzyme functions to unzip the DNA, creating a replication fork?

Helicase

DNA Polymerase III

Topoisomerase 

DNA Polymerase I

Primase

Helicase

Which of the following functions to keep DNA uncoiled, preventing reattachment of the strands to each other?

Helicase

Single stranded binding proteins

Topoisomerase. 

DNA ligase

Primase

Single stranded binding proteins

Which of the following statements best explains why the lagging strand creates Okazaki fragments?

The lagging strand is synthesized in a continuous manner

The lagging strand is longer than the leading strand

To avoid supercoiling of the DNA

Primers are placed in a semiconservative matter on the lagging strand

The lagging strand synthesizes in the opposite direction of the replication fork unwinding

The lagging strand synthesizes in the opposite direction of the replication fork unwinding

Which of the following best represents the flow of genetic information as described by the central dogma of biology?

DNA → RNA → Protein

In eukaryotes, the production of RNA molecules occurs in the _______.

nucleus

Which of the following best describes the function of the promoter region in DNA?

Encodes the amino acid sequence of proteins

Initiates alternative splicing of mRNA

Signals the removal of introns during mRNA splicing

Creates transcription factors to recruit RNA Polymerase

Serves as a binding site for RNA Polymerase upstream of the transcription start site

Serves as a binding site for RNA Polymerase upstream of the transcription start site

Which of the following occurs during the initiation phase of eukaryotic transcription?

The transcription factors recruit the RNA Polymerase to bind to the promoter site 

RNA Polymerase reads the DNA and creates an RNA molecule

The polyadenylation signal stops transcription

The RNA gets translated into proteins 

The 5’ cap and poly-A-tail is added to the mRNA molecule

The transcription factors recruit the RNA Polymerase to bind to the promoter site 

What is the primary purpose of alternative splicing in mRNA processing?

To eliminate mutations in the mRNA

Enhance stability of the mRNA molecules

Increase diversity of proteins produced by a single gene

Prevent degradation of mRNA

Increase the number of genes in the genome

Increase diversity of proteins produced by a single gene

Which of the following is the most effective way to prevent gene expression?

A. 

Increase the number of ribosomes

B. 

Delete the promoter region

C. 

Decrease the number of repressor proteins

D. 

Increase the number of transcription factors

E. 

Splicing out introns from the pre-mRNA

Delete the promoter region

Which of the following best defines the reading frame in translation?

A. 

The sequence of amino acids that forms a protein

B. 

The order in which ribosomes attach to the DNA

C. 

Nucleotide triplet sequence that determines amino acid sequence

D. 

The combinations of exons from a mRNA strand

E. 

The three-dimensional structure of a protein

Nucleotide triplet sequence that determines amino acid sequence

How many codons code for an amino acid?

A. 

64

B. 

20

C. 

24

D. 

61

E. 

48

61

All of the following are binding sites located on ribosomes EXCEPT one. Which one is the EXCEPTION?

A. 

A site

B. 

E site

C. 

mRNA binding site

D. 

S site

E. 

P site

S site

What is the primary role of transfer RNA (tRNA) in the process of translation?

A. 

To splice introns from pre-mRNA

B. 

Synthesize mRNA from DNA

C. 

To carry amino acids to the ribosome

D. 

Serve as the template for amino acids

E. 

Signal termination of the polypeptide chain

To carry amino acids to the ribosome

In both prokaryotes and eukaryotes, translation takes place in the ________ of the cell.

A. 

Nucleus

B. 

Cytosol

C. 

Smooth ER

D. 

Nucleoid

E. 

Golgi apparatus

Cytosol

Which of the following best describes the process of tRNA charging?

A. 

The binding of the ribosomal subunits to the mRNA

B. 

The attachment of an amino acid to its corresponding tRNA molecule

C. 

Formation of a bond between two amino acids

D. 

The attachment of tRNA to the mRNA

E. 

The removal of the final polypeptide chain from the tRNA

The attachment of an amino acid to its corresponding tRNA molecule

In what order do tRNA molecules move through the ribosomal sites during translation?

A. 

A site → P site —> E site

B. 

E site → P site —> A site

C. 

A site → E site —> P site

D. 

P site → A site —> E site

E. 

P site → E site —> A site

A site → P site —> E site

Which ribosomal site holds the growing polypeptide chain during translation?

P site

In translation, what triggers the termination of the polypeptide chain?

A. 

The mRNA runs out

B. 

The tRNA reads the codon AUG

C. 

Transcription factors bind to the promoter region

D. 

The tRNA leaves at the E site

E. 

Release factors bind at the A site

Release factors bind at the A site

During translation, which of the following accurately describes the function of mRNA?

A. 

Carries amino acids to the A site of the ribosome

B. 

Serves as the template for protein synthesis

C. 

Joins amino acids together to form a polypeptide chain

D. 

Binds to the promoter region to initiate transcription

E. 

Removes introns from pre-mRNA

Serves as the template for protein synthesis

What is the initiator amino acid found at the start of every amino acid chain?

A. 

Adenine

B. 

Tyrosine

C. 

Glucose

D. 

Tryptophan

E. 

Methionine

Methionine - AUG

Which of the following statements is an exception to the central dogma of biology?

A. 

DNA makes copies of itself via replication

B. 

RNA can be reverse transcribed to DNA

C. 

Specific sequence of each monomer encodes information

D. 

Each polymer acts as a template to build the next polymer

E. 

RNA is translated into proteins

RNA can be reverse transcribed to DNA

Which statement best describes the role of proteins in the central dogma of biology?

A. 

Proteins are directly transcribed from DNA

B. 

Proteins regulate the splicing of introns from RNA

C. 

Proteins are the primary way genetic information is stored

D. 

Proteins serve as the functional product of gene expression

E. 

Proteins serve as the intermediate for the expression of gene

Proteins serve as the functional product of gene expression

Which of the following best explains why RNA likely did not remain the primary form of storing genetic material?

A. 

RNA is single-stranded

B. 

RNA contains uracil

C. 

DNA is double-stranded

D. 

RNA contains two hydroxyl groups

E. 

DNA contains thymine

RNA contains two hydroxyl groups - making it more reactive and less stable = RNA unfavorable for long-term genetic storage, DNA more stable

The RNA world hypothesis proposes which of the following statements?

A. 

Proteins were the first molecules to catalyze reactions in early life forms

B. 

RNA was the first form of genetic material to arise

C. 

DNA is self-replicating and is the precursor to RNA

D. 

RNA cannot catalyze chemical reactions like enzymes

E. 

RNA is more stable than DNA and evolved last

RNA was the first form of genetic material to arise

Which of the following statements best supports the RNA world hypothesis?

A. 

RNA can store genetic information and catalyze chemical reactions

B. 

RNA is single-stranded and is less complex than DNA

C. 

RNA is more prone to mutations

D. 

Proteins are the primary catalyst in modern biology

E. 

RNA is more stable than DNA

RNA can store genetic information and catalyze chemical reactions

Which of the following best describes telomeres?

A. 

The central region of a chromosome where sister chromatids attach

B. 

The repeat stretch of adenine nucleotides added to the end of the mRNA

C. 

Site on DNA where transcription stops

D. 

Region of DNA that RNA Polymerase binds to

E. 

Repeating nucleotide sequences at the end of chromosomes

Repeating nucleotide sequences at the end of chromosomes

What is the main function of telomeres?

A. 

Suppress gene expression

B. 

Mitigate chromosome shortening

C. 

Enhance the process of translation

D. 

To facilitate the transport of mRNA out of the nucleus

E. 

To serve as attachment points for spindle fibers

Mitigate chromosome shortening

Which of the following explains why chromosomes end up shorter after replication?

A. 

The ends of DNA cannot be filled in after primer removal

B. 

Shortening of spindle fibers shortens chromosomes

C. 

DNA Polymerase runs out of nucleotides

D. 

Primase runs out of primers

E. 

Prokaryotic circular DNA has no distinct end or starting point

The ends of DNA cannot be filled in after primer removal - When the primer is removed from the very ends, it cannot be filled in by DNA Polymerase because there are no nucleotides available for DNA Polymerase to latch on to and extend from.

What is the order in which telomerase extends telomeres? 

I. Telomerase makes the template strand longer
II. Telomerase binds to the 3' DNA overhang
III. Primer is added to the opposing strand
IV. DNA Polymerase elongates the opposing strand

A. 

I, II, III, IV

B. 

III, IV, II, I

C. 

II, I, III, IV

D. 

II, III, I, IV

E. 

I, III, IV, II

II, I, III, IV

What best describes the Hayflick limit?

A. 

The limit on cell replication based on the shortening of telomeres

B. 

The maximum length a telomere can extend

C. 

The ability of a cell to regenerate its telomeres without limit

D. 

When a cell divides uncontrollably after extreme shortening

E. 

The rate at which cells age due to external stress factors

The limit on cell replication based on the shortening of telomeres

Which type of mutation results in the same amino acid being encoded?

A. 

Nonsense mutation

B. 

Missense mutation

C. 

Silent mutation

D. 

Frameshift mutation

E. 

Splice site mutation

Silent mutation due to the degeneracy of the genetic code

Which type of mutation leads to the premature termination of protein translation?

Nonsense mutation

Which of the following best defines a frameshift mutation?

A. 

A substitution that results in a new amino acid

B. 

A mutation which terminates protein synthesis

C. 

A mutation that duplicates the genome

D. 

A point mutation which alters the mRNA reading frame

E. 

A substitution that results in a start codon

A point mutation which alters the mRNA reading frame

Which of the following mutations is most likely to cause a frameshift mutation?

A. 

Substitution of a single nucleotide

B. 

Deletion of three consecutive nucleotides

C. 

Insertion of a single nucleotide

D. 

Insertion of three consecutive nucleotides

E. 

Reversal of two adjacent nucleotides

Insertion of a single nucleotide - cause frameshift

Which type of mutation occurs when a nucleotide substitution results in a change in the amino acid originally coded for?

Missense mutation

If a mutant fly grows an extra pair of legs in place of its antennae, which of the following genes is most likely mutated?

Hox gene - controls embryonic anatomical development

Which of the following best describes why prokaryotes have a higher gene density than eukaryotes?

Prokaryotes contain more repetitive DNA sequences

B. 

Eukaryotes have a bigger genome than prokaryotes

C. 

Prokaryotes have circular DNA

D. 

Prokaryotes can replicate faster than eukaryotes

E. 

Eukaryotes have introns

Eukaryotes have introns

Which of the following is true regarding gene number?

A. 

The number of genes is proportional to the complexity of an organism

B. 

Larger genomes always have a higher gene number

C. 

Eukaryotes have more coding sequences than prokaryotes

D. 

Alternative splicing in prokaryotes produces more products to combat the lower gene number

E. 

Gene number is consistent across all individuals of a species

Eukaryotes have more coding sequences than prokaryotes

In prokaryotes, transcription occurs in the ______, and translation occurs in the ______.

A. 

Cytoplasm, nucleus

B. 

Nucleus, cytoplasm

C. 

Nucleus, nucleus

D. 

Cytoplasm, cytoplasm

Cytoplasm, cytoplasm

Eukaryotes have three RNA polymerases that each synthesize a different type of RNA. Which combination correctly lists the types of RNA that is produced?

A. 

tRNA, mRNA, and rRNA

B. 

DNA, mRNA, and tRNA

C. 

SNP, CNV, and rRNA

D. 

miRNA, siRNA, and tRNA

E. 

mRNA, proteins, and DNA

tRNA, mRNA, and rRNA

In prokaryotes, which of the following aids RNA polymerase in binding to the promoter region during the initiation of transcription?

A. 

Ribosomes

B. 

Histone proteins

C. 

Transcription factors

D. 

Transposon genes

E. 

Sigma factor

Sigma factor

Where does DNA replication start?

A. 

Operon

B. 

Promoter

C. 

Telomeres

D. 

TATA box

E. 

Origin of Replication

Origin of Replication

All of the following describe prokaryotic genetics EXCEPT one. Which one is the EXCEPTION?

A. 

Transcription occurs in the cytoplasm

B. 

No mRNA processing

C. 

Monocistronic

D. 

Translation occurs in the cytoplasm

E. 

One RNA polymerase synthesizes all RNA types

Monocistronic - Prokaryotes are polycistronic, meaning a single mRNA transcript codes for many different proteins. In contrast, eukaryotes are monocistronic, where a single mRNA only contains the information to code for a single protein.