Integrated Science Quiz - Rozas

The central dogma of molecular biology describes the flow of genetic information as:

A) RNA → DNA → Protein

B) DNA → RNA → Protein

C) Protein → DNA → RNA

D) RNA → Protein → DNA

B) DNA → RNA → Protein

During the cell cycle, DNA content doubles during which phase?

A) G1

B) S

C) G2

D) M

B) S

How many chromosomes are present in a human karyotype?

A) 23

B) 46

C) 24

D) 48

B) 46

In DNA sequences, the 5' to 3' direction refers to:

A) The orientation of the nitrogenous bases

B) The directionality of the DNA backbone

C) The length of the DNA molecule

D) The number of nucleotide pairs

B) The directionality of the DNA backbone

Which of the following is NOT a component of nucleic acids?

A) Nitrogenous base

B) 5-carbon sugar

C) Amino acid

D) Phosphate group

C) Amino acid

Which of these bases is unique to RNA?

A) Adenine

B) Guanine

C) Thymine

D) Uracil

D) Uracil

The carbon atoms in nucleic acid sugars are numbered from 1' to 5'. Which carbon attaches to the nitrogenous base?

A) 1'

B) 2'

C) 3'

D) 5'

A) 1'

The two strands of DNA in a double helix are:

A) Identical and parallel

B) Complementary and parallel

C) Complementary and antiparallel

D) Identical and antiparallel

C) Complementary and antiparallel

In DNA, adenine pairs with ___ and guanine pairs with ___.

A) Thymine; Cytosine

B) Cytosine; Thymine

C) Uracil; Cytosine

D) Thymine; Uracil

A) Thymine; Cytosine

When treated with alkali, RNA molecules:

A) Become double-stranded

B) Form stronger bonds

C) Degrade into nucleotides

D) Convert to DNA

C) Degrade into nucleotides

Nucleosomes are composed of DNA and which type of proteins?

A) Enzymes

B) Histones

C) Ribosomes

D) Polymerases

B) Histones

Which feature of chromosomes helps prevent DNA loss during replication?

A) Centromeres

B) Origins of replication

C) Telomeres

D) Genes

C) Telomeres

Alleles are:

A) Genes that have identical sequences

B) Alternative versions of a gene

C) Sequences that form RNA

D) The same as chromosomes

B) Alternative versions of a gene

Bacterial chromosomes are replicated from:

A) Multiple origins

B) A single origin

C) Two origins

D) No defined origin

B) A single origin

What relieves the supercoiling of DNA during replication?

A) Helicase

B) Ligase

C) Topoisomerase

D) Polymerase

C) Topoisomerase

Topoisomerase I functions by:

A) Joining DNA fragments

B) Unwinding DNA strands

C) Cleaving one DNA strand to allow rotation

D) Sealing DNA ends

C) Cleaving one DNA strand to allow rotation

DNA polymerase adds nucleotides to which end of a growing DNA strand?

A) 5'-end

B) 3'-end

C) Both 3' and 5'-ends

D) Either end

B) 3'-end

DNA polymerase proofreading activity involves:

A) Adding nucleotides randomly

B) Removing incorrectly paired bases

C) Extending the DNA strand

D) Adding primers

B) Removing incorrectly paired bases

Okazaki fragments are formed on the:

A) Leading strand

B) Lagging strand

C) Both strands

D) Template strand

B) Lagging strand

Which enzyme joins Okazaki fragments on the lagging strand?

A) Primase

B) DNA polymerase

C) DNA ligase

D) Helicase

C) DNA ligase

The end-replication problem is due to:

A) DNA polymerase inefficiency

B) Lagging strand synthesis at chromosome ends

C) Limited dNTP supply

D) Supercoiling

B) Lagging strand synthesis at chromosome ends

Telomerase solves the end-replication problem by:

A) Removing primers

B) Extending telomeres with repeated sequences

C) Joining DNA fragments

D) Unwinding DNA strands

B) Extending telomeres with repeated sequences

In gene transcription, upstream refers to the direction:

A) Toward the 3' end

B) Toward the 5' end

C) Perpendicular to the DNA strand

D) In the opposite direction of transcription

B) Toward the 5' end

RNA polymerase synthesizes RNA in the ___ direction.

A) 5' to 3'

B) 3' to 5'

C) 5' to 5'

D) Random

A) 5' to 3'

In eukaryotes, RNA Polymerase II transcribes:

A) rRNA

B) mRNA

C) tRNA

D) All RNA types

B) mRNA

The DNA strand that is used as a template during transcription is called the:

A) Coding strand

B) Template strand

C) Sense strand

D) Guide strand

B) Template strand

Which feature of the eukaryotic promoter indicates the transcription start site?

A) TATA box

B) Poly(A) site

C) +1 position

D) Termination site

C) +1 position

Ribosomes are composed of:

A) RNA only

B) Proteins only

C) RNA and proteins

D) DNA and proteins

C) RNA and proteins

What binds to a codon on mRNA during translation?

A) rRNA

B) tRNA

C) mRNA

D) DNA

B) tRNA

The start codon in mRNA is:

A) UAA

B) AUG

C) UGA

D) GUA

B) AUG

Which hypothesis explains why there are fewer tRNAs than codons?

A) Codon hypothesis

B) Genetic code hypothesis

C) Wobble hypothesis

D) Redundancy hypothesis

C) Wobble hypothesis

The effect of alkali treatment on DNA is:

A) Complete degradation

B) Separation of strands

C) Formation of double-stranded RNA

D) Increased covalent bonding

B) Separation of strands

Nucleosomes consist of DNA wrapped around:

A) Ribosomes

B) Histones

C) Polymerases

D) Nucleotides

B) Histones

Which chromosomal structure serves to protect DNA ends during replication?

A) Centromeres

B) Telomeres

C) Promoters

D) Genes

B) Telomeres

Alleles refer to:

A) Identical copies of genes

B) Different versions of the same gene

C) Repetitive DNA sequences

D) All genes in a genome

B) Different versions of the same gene

DNA topoisomerase helps relieve:

A) Template mismatches

B) Primer synthesis

C) Supercoiling

D) DNA degradation

C) Supercoiling

Which enzyme is responsible for initiating Okazaki fragment synthesis on the lagging strand?

A) Helicase

B) DNA ligase

C) Primase

D) Topoisomerase

C) Primase

The replication fork contains which component that separates DNA strands?

A) Helicase

B) DNA polymerase

C) Ligase

D) Topoisomerase

A) Helicase

Which enzyme fills in gaps left by removed RNA primers on the lagging strand?

A) DNA ligase

B) RNA polymerase

C) DNA polymerase

D) Helicase

C) DNA polymerase

What is PCNA’s role in DNA replication?

A) Primer removal

B) Processivity of DNA polymerase

C) Ligating DNA fragments

D) Synthesizing Okazaki fragments

B) Processivity of DNA polymerase

The enzyme that helps prevent chromosome shortening by adding telomere repeats is:

A) DNA ligase

B) Primase

C) Telomerase

D) Topoisomerase

C) Telomerase

In prokaryotic transcription, a single promoter can control multiple genes. This structure is called a(n):

A) Exon

B) Operon

C) Intron

D) Polysome

B) Operon

Which transcription factor binds to the TATA box to initiate transcription?

A) TFIIA

B) TFIID

C) TFIIF

D) TFIIH

B) TFIID

What structure is added to the 5’ end of mRNA during processing?

A) Poly(A) tail

B) Intron

C) 5’-CAP

D) Promoter

C) 5'-CAP

Introns are removed from the primary transcript through:

A) Capping

B) Splicing

C) Polyadenylation

D) Transcription

B) Splicing

What is the name of the loop formed by introns during splicing?

A) Exon loop

B) RNA duplex

C) Lariat

D) Hairpin

C) Lariat

The enzyme reverse transcriptase in HIV functions to:

A) Transcribe viral DNA into RNA

B) Integrate viral DNA into the host genome

C) Convert viral RNA into DNA

D) Process viral proteins

C) Convert viral RNA into DNA

The enzyme that links an amino acid to its corresponding tRNA is:

A) Peptidyl transferase

B) Aminoacyl-tRNA synthetase

C) RNA polymerase

D) Ribosome

B) Aminoacyl-tRNA synthetase

The site on the ribosome where the growing polypeptide chain is held is called the:

A) A site

B) P site

C) E site

D) D site

B) P site

Which codon signals the beginning of translation?

A) UGA

B) UAA

C) AUG

D) UAG

C) AUG

The Wobble Hypothesis explains:

A) Why there are multiple stop codons

B) The flexibility in the third base pairing of tRNA anticodons

C) The need for tRNA modifications

D) Ribosomal movement during translation

B) The flexibility in the third base pairing of tRNA anticodons

A single mRNA molecule translated by multiple ribosomes is known as a:

A) Polypeptide

B) Polysome

C) Spliceosome

D) Ribosome complex

B) Polysome

The function of chaperones in protein synthesis is to:

A) Aid in translation initiation

B) Assist in proper protein folding

C) Attach amino acids to tRNAs

D) Add glycosylation to proteins

B) Assist in proper protein folding

What directs proteins to the rough endoplasmic reticulum (RER) for synthesis?

A) Signal peptide

B) tRNA

C) Ribosomal RNA

D) Promoter

A) Signal peptide

Which antibiotic targets bacterial protein synthesis by binding to ribosomes?

A) Penicillin

B) Tetracycline

C) Aspirin

D) Ibuprofen

B) Tetracycline

Which of the following is NOT a type of posttranslational modification?

A) Folding

B) Splicing

C) Cleavage

D) Glycosylation

B) Splicing