Molecular Biology Quiz: DNA Replication

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Questions and Answers

What is the primary role of DNA polymerase during DNA replication?

To synthesize RNA from the DNA template

To add new complementary nucleotide bases to the DNA strand (correct)

To unwind the DNA double helix

To remove primer sequences from the DNA

How do Okazaki fragments form during DNA replication?

By the action of RNA polymerase

By the action of helicase on the DNA template

By short, newly synthesized stretches of DNA on the lagging strand (correct)

By continuous synthesis on the leading strand

What distinguishes transcription from DNA replication?

Transcription creates a permanent RNA strand

DNA replication involves multiple polymerases

RNA strands are not permanently bonded to their DNA template (correct)

Transcription involves helicase activity

What enzyme is responsible for catalyzing the removal of primer sequences during DNA replication?

Exonuclease Signup and view all the answers

What is the significance of the genetic code being described as degenerate?

More than one codon can code for the same amino acid Signup and view all the answers

Which molecular chaperone system is primarily involved in protein folding, refolding, and degradation?

HSP70 chaperone system Signup and view all the answers

What role do transcription factors play in gene expression?

They facilitate RNA polymerase binding to DNA Signup and view all the answers

How are BAG1 and BAG3 related to the function of HSP70?

They link HSP70 to specific cellular processes Signup and view all the answers

What is the primary role of the TATA box in transcription?

To assist in the initiation of transcription in eukaryotic genes Signup and view all the answers

Which enzyme is primarily responsible for catalyzing transcription?

RNA polymerase Signup and view all the answers

What is the significance of the promoter region in transcription?

It directs the RNA polymerase to the correct DNA strand and starting point Signup and view all the answers

During transcription elongation, in which direction are nucleotides incorporated into the growing RNA strand?

5' to 3' Signup and view all the answers

What is the role of introns in pre-mRNA?

They are non-coding sequences that are spliced out before translation Signup and view all the answers

What process involves the addition of a poly(A) tail to pre-mRNA?

Polyadenylation Signup and view all the answers

What molecules mediate the binding of RNA polymerase to DNA in eukaryotic transcription initiation?

Transcription factors Signup and view all the answers

Where does translation take place within a eukaryotic cell?

Cytoplasm on a ribosome Signup and view all the answers

Study Notes

Central Dogma of Molecular Biology

Flow of genetic information is from DNA to RNA to protein.
DNA replication produces exact copies of DNA.

DNA Replication

Helicase unzips the DNA double helix during replication.
DNA polymerase adds complementary nucleotide bases to form new DNA strands.
DNA strands orient in two directions: 3' to 5' (leading strand) and 5' to 3' (lagging strand).
Okazaki fragments are short DNA segments synthesized on the lagging strand.
Exonuclease removes primer sequences during replication.
Resulting in two DNA molecules, each containing one old and one new nucleotide chain.

Transcription

Involves copying DNA information into mRNA.
RNA polymerase is the enzyme responsible for transcription.
RNA strands are not permanently bonded to the DNA template.
Eukaryotes have three classes of polymerases: Pol I, Pol II, Pol III.
RNA is shorter than DNA since it is transcribed from limited regions.

Genetic Code

Degenerate or redundant nature allows one amino acid to be coded by multiple codons.
Cells read DNA code in triplets, groups of three bases.

Molecular Chaperones

Two types: HSP60 and HSP70, assist in polypeptide chain folding.
Chaperones prevent protein aggregation by recognizing exposed hydrophobic regions.
Misfolded proteins are tagged for degradation by ubiquitin ligase, leading to proteasomal degradation.
HSP70 chaperone system manages protein folding, refolding, and degradation through an ATP-consuming mechanism.
Co-chaperones (HSP40, HIP, CHIP) regulate HSP70 activity and facilitate processes.

Transcription Factors

Bind to enhancer and promoter sequences to recruit RNA polymerase.
Promoter regions signal the transcription starting point and direction.
Initiation bubble forms to allow RNA polymerase access to the DNA strand.
TATA box: a conserved sequence crucial for initiating transcription in eukaryotes.

mRNA Processing

mRNA undergoes several processing steps:
- Introns (non-coding sections) are spliced out during RNA splicing.
- A 5' cap is added to protect RNA and facilitate ribosome recognition.
- Polyadenylation adds a poly(A) tail to enhance RNA stability.

Translation

Involves converting mRNA into proteins.
Takes place in the cytoplasm on ribosomes.
tRNA molecules serve as adaptors, reading mRNA codons and attaching specific amino acids.
rRNA acts as the catalytic component of ribosomes.

Open Reading Frame (ORF)

Refers to the portion of mature mRNA that is translated into protein.

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Description

Test your understanding of DNA replication and the central dogma of molecular biology. This quiz covers key concepts such as the roles of various enzymes and the orientation of DNA strands during replication. Perfect for students of molecular biology looking to enhance their knowledge!