Central Dogma of Molecular Biology – Exam Reviewer

Question-and-answer flashcards summarizing key points on DNA replication, transcription, mRNA processing, translation, and mutation types to aid exam preparation.

What does the central dogma of molecular biology describe?

The flow of genetic information from DNA to RNA to Protein.

Which molecule stores hereditary information in cells?

DNA (Deoxyribonucleic Acid).

What are the complementary base pairs in DNA?

Adenine–Thymine and Guanine–Cytosine.

Which DNA strand is used as the template during transcription?

The antisense (template) strand.

Which nucleotide replaces thymine in RNA?

Uracil (U).

Name the three major types of RNA.

mRNA, tRNA, and rRNA.

How many nucleotides constitute a codon, and what does a codon specify?

Three nucleotides; each codon specifies one amino acid.

What replication model best describes DNA duplication?

Semi-conservative replication.

Which enzyme unwinds the DNA double helix at the replication fork?

Helicase.

What is the function of primase during DNA replication?

It synthesizes short RNA primers to initiate DNA synthesis.

Which enzyme elongates the new DNA strand by adding nucleotides?

DNA Polymerase III.

What are Okazaki fragments?

Short DNA fragments synthesized on the lagging strand.

Which enzyme replaces RNA primers with DNA during replication termination?

DNA Polymerase I.

Which enzyme seals the nicks between Okazaki fragments?

DNA Ligase.

Define a point mutation.

A change in a single nucleotide of the DNA sequence.

Differentiate between transition and transversion mutations.

Transition: purine↔purine or pyrimidine↔pyrimidine change; Transversion: purine↔pyrimidine change.

What is the first step of transcription?

Initiation, where RNA polymerase binds to the promoter.

In which direction is RNA synthesized during transcription?

5′ to 3′ direction.

What polyadenylation signal sequence helps terminate transcription in eukaryotes?

AAUAAA.

List the three primary mRNA processing events in eukaryotes.

5′ capping, poly-A tail addition, and splicing of introns.

Which codon typically serves as the start codon for translation?

AUG.

During translation, which molecule delivers specific amino acids to the ribosome?

tRNA.

What triggers termination of translation?

A stop codon reaching the ribosome, prompting release of the polypeptide.