DNA and RNA Structure and Function

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Questions and Answers

What process is responsible for producing RNA from a DNA template?

Transcription (correct)

Transformation

Replication

Translation

Which type of RNA has a base sequence that determines the order of amino acids in a protein?

tRNA

mRNA (correct)

rRNA

snRNA

What modification occurs to eukaryotic mRNA before translation?

Polymerization of amino acids

Removal of exons and addition of a 3' cap

Addition of a ribosomal binding site

Splicing to remove introns and adding a poly-A tail (correct)

Why is a mutation in DNA considered more harmful than a transcription mistake?

It propagates with every cell division Signup and view all the answers

What is the significance of the 50S and 30S ribosomal subunits combining to form a 70S subunit?

Sedimentation rates provide insight into how they function in translation. Signup and view all the answers

What happens to DNA when DNA gyrase cuts one part of a loop?

It passes the ends across another loop and reseals. Signup and view all the answers

Why are adenine-guanine base pairs normally not found in DNA?

They occupy more space than allowed in the DNA double helix. Signup and view all the answers

What is the reason for rejecting the proposal that phosphate groups could be at the center of a long DNA fiber?

Their negative charge leads to electrostatic repulsion. Signup and view all the answers

Why is it essential to specify that DNA is double-stranded when discussing base pairing?

The pairing rules of G=C and A=T do not apply otherwise. Signup and view all the answers

What is required for PCR to effectively replicate DNA?

Information about the DNA sequence to create primers. Signup and view all the answers

Why does DNA with a high A–T content have a lower transition temperature than DNA with a high G–C content?

G–C pairs provide more stability due to additional hydrogen bonds. Signup and view all the answers

Which of the following are the primary types of RNA?

mRNA, rRNA, and tRNA. Signup and view all the answers

What determines the base sequence of all types of RNA?

The template DNA strand from which the RNA is transcribed. Signup and view all the answers

What is the complementary DNA sequence for the strand ACGTAT?

TGCATA Signup and view all the answers

Which of the following is NOT a base found in RNA?

Thymine Signup and view all the answers

Which of the following statements about prokaryotic DNA is true?

It normally forms a closed circle. Signup and view all the answers

What characterizes B-DNA compared to Z-DNA?

B-DNA has significant differences between major and minor grooves. Signup and view all the answers

Which enzyme is responsible for relaxing supercoiled DNA?

Topoisomerase Signup and view all the answers

What describes the action of positive supercoiling in DNA?

It introduces twists not present in the double helix. Signup and view all the answers

What does a propeller twist refer to in DNA structure?

Movement of bases away from their aligned position. Signup and view all the answers

What is the main difference between the adenine-thymine and guanine-cytosine base pairs?

G-C pairs form three hydrogen bonds, while A-T pairs form two. Signup and view all the answers

Study Notes

DNA and RNA Structure and Function

DNA sequences are read 5' to 3'
DNA bases: Adenine (A), Cytosine (C), Guanine (G), Thymine (T)
RNA bases: Adenine (A), Cytosine (C), Guanine (G), Uracil (U)
DNA determines RNA sequence
DNA sequences can be used to determine if it is DNA or RNA, based on the presence of thymine or uracil.
RNA is usually involved in protein synthesis
DNA and RNA have different base pair composition resulting in slightly different structures, and different functions in the body.
DNA has a double helix structure, while RNA has a single strand
A-T base pairs have two hydrogen bonds; G-C base pairs have three hydrogen bonds.
Base pairs determine the shape and size of the DNA molecule (B-DNA, Z-DNA)
DNA can exist in different conformations (e.g., B-DNA, Z-DNA) with differing spatial characteristics
DNA can wrap around proteins forming chromatin
Supercoiling occurs with both positive and negative twists

DNA Replication

PCR (polymerase chain reaction) replicates DNA in forensic science.
DNA replication requires a primer (DNA or RNA)
Enzymes like DNA polymerase are needed for DNA replication.

DNA and RNA Differences

DNA is double stranded and RNA is single-stranded.
DNA uses thymine (T); RNA uses uracil (U).
DNA stores genetic info; RNA primarily translates genetic info into protein
DNA is usually found in the nucleus; RNA is found in the nucleus and cytoplasm of the cell.

Transcription and Translation

Transcription converts DNA to mRNA.
mRNA is translated to form amino acids which make up a protein.
DNA errors during replication lead to incorrect DNA.
Transcription errors lead to incorrect mRNA, which can impact protein formation.
mRNA undergoes modifications, such as splicing, addition of a poly-A tail, and a 5' cap before translation.
Incorrect mRNA may result from mistakes in transcription.

Ribosomes

Ribosomes are formed by ribosomal subunits (50S and 30S).
50S and 30S subunits combine to form a 70S ribosome.
Molecular weight, shape, and density of these components impact sedimentation.

Eukaryotic mRNA

Eukaryotic mRNA undergoes modifications (splicing, poly-A tail, 5' cap) before translation, enhancing stability and proper translation.
Eukaryotic mRNA modifications occur in the nucleus, and are then exported to the cytoplasm before translation.

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Description

Explore the fundamental concepts of DNA and RNA structure and function. This quiz covers key aspects such as base pair composition, structural differences, and the role of these nucleic acids in protein synthesis and replication. Test your knowledge on essential topics like base pairs, hydrogen bonds, and conformations.