DNA Structure Quiz

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Questions and Answers

During which phase of mitosis do chromosomes get pulled apart and move to opposite poles of the cell?

Metaphase

Anaphase (correct)

Prophase

Telophase

What is the primary role of the enzyme RNA polymerase in transcription?

To synthesize proteins from amino acids

To copy a segment of DNA into RNA (correct)

To replicate DNA

To degrade RNA molecules

What occurs during telophase of mitosis?

Nuclear membranes form around two sets of chromosomes (correct)

Chromosomes condense and the nuclear envelope breaks down

Chromosomes align in the center of the cell

Chromosomes are split and pulled apart

How do oncogenes contribute to cancer development?

By causing cells to grow and divide uncontrollably Signup and view all the answers

What is the function of cyclins in the cell cycle?

To activate CDK enzymes for cell cycle progression Signup and view all the answers

Which stage of the cell cycle does DNA replication primarily occur?

S phase Signup and view all the answers

What occurs during the elongation step of transcription?

RNA polymerase synthesizes the RNA strand Signup and view all the answers

What characterizes the prometaphase stage of mitosis?

Kinetochores form and chromosomes attach to the mitotic spindle Signup and view all the answers

What distinguishes a nucleotide from a nucleoside?

A nucleotide has one or more phosphate groups attached. Signup and view all the answers

Which nitrogenous bases are classified as purines?

Adenine and Guanine Signup and view all the answers

In which stage of the cell cycle does DNA replication occur?

Interphase Signup and view all the answers

What is the characteristic of heterochromatin compared to euchromatin?

Heterochromatin is tightly packed. Signup and view all the answers

What reflects the semi-conservative nature of DNA replication?

Each new double helix contains one original and one new strand. Signup and view all the answers

Which carbon of the sugar molecule does the nitrogenous base attach to?

1’ carbon Signup and view all the answers

How many hydrogen bonds are formed between adenine and thymine?

2 hydrogen bonds Signup and view all the answers

What allows the phosphate group of a nucleotide to interact with histone proteins?

The negative charge of the phosphate group Signup and view all the answers

What is the primary role of single strand binding protein during DNA replication?

To keep DNA strands separate Signup and view all the answers

Which enzyme is responsible for creating the RNA primers needed for DNA synthesis?

Primase Signup and view all the answers

What distinguishes the leading strand from the lagging strand during DNA replication?

Leading strand is synthesized continuously, whereas lagging is in fragments Signup and view all the answers

What are Okazaki fragments and why do they occur?

They are produced due to the directionality of DNA synthesis. Signup and view all the answers

What is the role of topoisomerase in DNA replication?

To cut and pass one DNA strand through another Signup and view all the answers

During DNA replication, which function does DNA Polymerase 1 serve?

To join Okazaki fragments Signup and view all the answers

What happens to DNA strands when helicase functions during replication?

They are unwound and separated. Signup and view all the answers

How does etoposide function as an anti-cancer drug in relation to topoisomerase?

It binds to topoisomerase, trapping it on broken DNA. Signup and view all the answers

Study Notes

DNA Structure

Nucleotides are the building blocks of DNA and RNA. They consist of a nitrogenous base, a sugar molecule, and a phosphate group.
Nucleosides consist of a nitrogenous base and a five-carbon sugar.
Nucleotides have one or more phosphate groups attached to a nucleoside.
The negative charge of phosphate groups makes nucleotides hydrophilic and able to interact with water.
The nitrogenous bases are adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U).
Purines are adenine and guanine; pyrimidines are cytosine, thymine, and uracil.
Deoxyribose sugar has one less oxygen atom than ribose.
The nitrogenous base attaches to the 1' carbon of the sugar molecule.
The phosphate group attaches to the 5' carbon of the sugar molecule.
A hydroxyl group (OH) is present on the 3' carbon of the sugar molecule.
A and T are connected by 2 hydrogen bonds, while C and G are connected by 3 hydrogen bonds.
Phosphate groups are negatively charged, allowing them to interact with histone proteins.
Chromatin exists in two forms: euchromatin (loosely packed) and heterochromatin (tightly packed).

DNA Replication

DNA replication occurs during interphase.
The origin of replication is a region of DNA rich in A-T nucleotides. Multiple origins may be present.
The pre-replication protein complex recruits additional enzymes and proteins to the origin of replication.
Single-strand binding proteins keep the DNA strands separated.
Nucleases break down nucleotides.
Helicase splits the DNA.
Topoisomerase relieves the DNA from winding tension during replication.
Topoisomerase can be a target for cancer drugs.
DNA polymerase 3 synthesizes new DNA strands.
Primase synthesizes short RNA segments called primers to provide a starting point for DNA polymerase.
Okazaki fragments are short DNA fragments formed on the lagging strand during replication.
DNA polymerase 1 removes RNA primers and fills in the gaps with DNA nucleotides.
DNA ligase joins Okazaki fragments together to create a continuous DNA strand.

Cell Cycle

Interphase is the longest phase of the cell cycle where DNA replication occurs.
Mitosis has four stages: prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis.
During prophase, chromosomes condense, nuclear envelope breaks down, and centrioles move to opposite poles.
During metaphase, chromosomes align at the center of the cell.
During anaphase, sister chromatids separate and move to opposite poles.
During telophase, chromosomes decondense, and new nuclear envelopes form.
Cytokinesis divides the cytoplasm, forming two daughter cells.

Transcription

Transcription is the process where a segment of DNA is copied into RNA.
RNA polymerase is the enzyme responsible for transcription.
The process includes initiation, elongation, and termination steps.

Translation

Translation is the process where mRNA is decoded to synthesize a specific protein.
Ribosomes are the site of translation.

Mutations and Cancer

Oncogenes are mutated genes that cause uncontrollable cell growth and division.
Tumor suppressor genes regulate cell growth and division.
p53 is a tumor suppressor gene that regulates cell division and DNA repair.
Cyclins and CDKs regulate the cell cycle by phosphorylating proteins.

Meiosis

Meiosis is a type of cell division that reduces the chromosome number by half.
Meiosis has two rounds of division: meiosis I and meiosis II.
Meiosis I separates homologous chromosomes.
Meiosis II separates sister chromatids.

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Description

Test your understanding of the fundamental components of DNA in this quiz. Explore the roles of nucleotides, nitrogenous bases, and the structural differences between RNA and DNA. This quiz will help reinforce your knowledge of the molecular biology of DNA.