DNA Replication and Gene Expression Quiz

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Questions and Answers

What is the primary function of telomerase in eukaryotic cells?

To lengthen telomeres and prevent chromosome shortening (correct)

To synthesize mRNA from DNA

To initiate DNA replication

To promote the degradation of chromosomes

Which statement accurately describes telomeres?

They are the ends of linear chromosomes, protecting genetic data. (correct)

They are involved in initiating DNA replication.

They are the mechanisms that hold sister chromatids together.

They function as the sites for protein synthesis.

During transcription, what is synthesized?

RNA (correct)

Amino acids

DNA

Proteins

In eukaryotes, where does transcription occur, and what follows this process?

Nucleus; translation in the cytoplasm Signup and view all the answers

Which of the following processes is directly involved in protein synthesis?

Translation Signup and view all the answers

Which statement about the central dogma is true?

It establishes a one-way flow from DNA to RNA to protein. Signup and view all the answers

Telomerase activity is essential for which of the following reasons?

It prevents potential losses of genetic information during replication. Signup and view all the answers

Which of the following is NOT a function of DNA ligase?

Transcribing DNA to RNA Signup and view all the answers

During the transcription process in eukaryotes, which of the following occurs?

Introns are removed from the mRNA. Signup and view all the answers

Which statement correctly differentiates between the leading and lagging strands during DNA replication?

The leading strand is synthesized continuously towards the replication fork, while the lagging strand is made in short segments away from the fork. Signup and view all the answers

Which of the following characteristics is NOT typical of prokaryotic DNA replication?

Involvement of multiple types of RNA polymerases. Signup and view all the answers

What is the role of DNA ligase during DNA replication?

It joins Okazaki fragments on the lagging strand. Signup and view all the answers

The unwinding of DNA during replication is primarily facilitated by which enzyme?

Helicase Signup and view all the answers

Which of the following correctly describes the 5’ and 3’ ends of DNA?

3’ end has a free OH group, while the 5’ end has a phosphate group. Signup and view all the answers

In DNA structure, which base pairs with adenine?

Thymine Signup and view all the answers

What is the primary function of telomerase in linear chromosomes?

It synthesizes telomeres to prevent chromosomal shortening. Signup and view all the answers

Which of the following best describes the synthesis of the leading and lagging strands during DNA replication?

The leading strand is synthesized continuously, while the lagging strand is made in small fragments. Signup and view all the answers

What distinguishes prokaryotic DNA replication from eukaryotic DNA replication?

Prokaryotic chromosomes have a single origin of replication. Signup and view all the answers

Which of the following proteins keeps the DNA strands apart during replication?

Single-strand DNA binding proteins Signup and view all the answers

What occurs at the replication fork during DNA replication?

The leading strand is made continuously while the lagging strand is made in segments. Signup and view all the answers

Which statement about prokaryotic DNA polymerases is correct?

They function exclusively in the 5’ to 3’ direction. Signup and view all the answers

Which of the following is FALSE regarding the DNA polymerase enzyme?

It synthesizes DNA from the 3’ to 5’ direction. Signup and view all the answers

Study Notes

DNA Replication and Gene Expression

DNA Replication: A process where DNA is copied, crucial for cell division and maintaining genetic information.
Eukaryotic Replication: Eukaryotes have multiple origins of replication on their chromosomes, in contrast to prokaryotes.
Prokaryotic Replication: Uses one origin of replication.
Leading Strand: Produced continuously in the 5' to 3' direction, following the replication fork.
Lagging Strand: Synthesized discontinuously in short fragments (Okazaki fragments) moving away from the replication fork, and are joined by DNA ligase.
DNA Polymerase: Enzyme that adds nucleotides during replication. It cannot start DNA synthesis independently and requires a primer.
Telomerase: Enzyme that adds telomeric repeats to the ends of linear chromosomes, preventing loss of genetic material during replication.
DNA Ligase: Enzyme that joins Okazaki fragments on the lagging strand.
Single-stranded Binding Proteins: Maintain separate DNA strands for replication.
Primase: Synthesizes RNA primers needed by DNA Polymerase for initiation.
Helicase: Unwinds DNA double helix.
Topoisomerases: Relieve the strain caused by unwinding of the double helix.

Gene Expression - Transcription and Translation

Transcription: The process of using a DNA template to synthesize an RNA molecule, specifically mRNA.
Initiation (Transcription): RNA polymerase binds to a promoter region on the DNA to begin transcription.
Elongation (Transcription): RNA polymerase moves along the DNA template, synthesizing mRNA in the 5' to 3' direction.
Termination (Transcription): RNA polymerase reaches a termination sequence, causing the release of the mRNA transcript.
mRNA Processing (Eukaryotes only): Pre-mRNA undergoes processing with addition of a 5' cap and a poly-A tail, and splicing of introns to generate mature mRNA.
Translation: The process of using mRNA to synthesize a polypeptide chain (protein).
Ribosomes: Cellular structures where translation occurs.
tRNA: Transfer RNA molecules that bring amino acids to the ribosome, matches to codons on the mRNA.
Genetic Code: A set of rules that dictates which codons correspond to which amino acids.
Codons (mRNA): Three-base sequences on mRNA that specify amino acids.
Anticodons (tRNA): Three-base sequences on tRNA that are complementary to codons.
Ribosomal Subunits: Two parts of Ribosomes (small and large) forming the complete ribosome.
Initiation (Translation): The start codon on the mRNA binds to a ribosome
Elongation (Translation): tRNA brings amino acids to the ribosome, and the ribosome forms peptide bonds.
Termination (Translation): The stop codon on the mRNA signals the end of a polypeptide chain formation.

Genetic Mutations

Point Mutation: A single base change.
Missense Mutation: Changes a codon, resulting in a different amino acid.
Nonsense Mutation: Changes a codon to a stop codon, leading to premature termination of translation.
Silent Mutation: A codon change that does not affect the amino acid.
Frameshift Mutation: Addition or deletion of a nucleotide, thereby shifting the reading frame of mRNA and producing an entirely different amino acid sequence that follows the alteration.
Chromosomal Mutations: Major structural alterations in chromosomes, such as duplications, deletions, inversions, and translocations.

Other Key Terms

Template Strand: The DNA strand used as a template for mRNA synthesis.
Coding Strand: The DNA strand complementary to the template strand, same sequence as the RNA transcript, but contains uracil instead of thymine.

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Description

Test your understanding of DNA replication and gene expression processes. This quiz covers concepts such as leading and lagging strands, DNA polymerase, and the role of telomerase in eukaryotic cells. Dive into the intricacies of how genetic information is copied and maintained.