the cell cycle

Question 1

What are the key chemical components of DNA?

Answer 1

Pentose sugar, phosphate group, and nitrogenous base.

Question 2

What bonds hold DNA molecules together?

Answer 2

Hydrogen bonds between base pairs and phosphodiester bonds in the sugar-phosphate backbone.

Question 3

What is the geometry of the DNA molecule?

Answer 3

Double helix with major and minor grooves, 2 nm in diameter, 3.4 nm per helical turn.

Question 4

What base pairs form in DNA, and how do they bind?

Answer 4

Adenine pairs with Thymine (A-T) and Guanine pairs with Cytosine (G-C) through hydrogen bonds.

Question 5

What are the key enzymes involved in DNA replication?

Answer 5

h, primase, DNA polymerase, single-stranded binding proteins (SSB), topoisomerase, and ligase.

Question 6

What are Okazaki fragments?

Answer 6

Short DNA segments synthesized on the lagging strand during replication.

Question 7

How does eukaryotic DNA replication differ from prokaryotic?

Answer 7

Eukaryotic replication has multiple origins, occurs in the nucleus, involves distinct S phases, and has slower replication with telomere replication.

Question 8

What is the role of DNA polymerase?

Answer 8

Adds nucleotides to the RNA primer, catalyzes phosphodiester bonds, and proofreads for errors.

Question 9

What are the main phases of the cell cycle?

Answer 9

G1 (growth and preparation), S (DNA synthesis), G2 (preparation for mitosis), M (mitosis and cytokinesis).

Question 10

What are cell cycle checkpoints?

Answer 10

Control points where the cell assesses conditions (e.g., DNA damage) before progressing to the next phase.

Question 11

Why is the G1 phase critical?

Answer 11

It prepares cells for replication and is the phase where cells can exit the cycle into a resting state.

Question 12

What is the restriction point in the cell cycle?

Answer 12

A checkpoint in G1 where the cell commits to division.

Question 13

What is the main difference between mitosis and meiosis?

Answer 13

Mitosis produces two genetically identical diploid cells, while meiosis produces four genetically distinct haploid cells.

Question 14

What events in meiosis create genetic diversity?

Answer 14

Crossing over during Prophase I and independent assortment during Metaphase I.

Question 15

How does cytokinesis differ in mitosis and meiosis?

Answer 15

Mitosis results in two cells, while meiosis involves two rounds, ultimately producing four cells.

Question 16

How does the prokaryotic cell cycle differ from the eukaryotic?

Answer 16

Prokaryotes have continuous DNA replication with a single origin, while eukaryotes have defined phases and multiple origins.

Question 17

What is the significance of the C period in E. coli?

Answer 17

It corresponds to DNA replication and is nearly constant, taking about 40 minutes.

Question 18

How can E. coli divide with partially replicated genomes?

Answer 18

New replication cycles start before the previous division is complete.

Question 19

What proteins regulate the cell cycle?

Answer 19

Cyclins and cyclin-dependent kinases (Cdks).

Question 20

How does the cell respond to DNA damage?

Answer 20

Checkpoints arrest the cycle to allow repair or trigger apoptosis.

Question 21

What factors determine the timing of cell cycle stages?

Answer 21

Accumulation of regulatory proteins and feedback mechanisms about cellular conditions.

Question 22

What is flow cytometry used for?

Answer 22

Analyzing cell cycle progression by measuring DNA content and cell size.

Question 23

What is the significance of the S phase in cell cycle studies?

Answer 23

It represents DNA synthesis, a crucial marker for cell proliferation.

Question 24

What happens during metaphase?

Answer 24

Chromosomes align at the metaphase plate, and spindle fibers attach to centromeres.

Question 25

What marks the transition from metaphase to anaphase?

Answer 25

Separation of sister chromatids moving to opposite poles.

Question 26

What are the key events in telophase?

Answer 26

Chromosomes decondense, and the nuclear envelope re-forms.

Question 27

What occurs during Prophase I of meiosis?

Answer 27

Homologous chromosomes pair and exchange genetic material (crossing over).

Question 28

How does Meiosis II differ from Meiosis I?

Answer 28

Meiosis II separates sister chromatids without further DNA replication, producing four haploid cells.

Question 29

Why is meiosis important?

Answer 29

It ensures genetic variation and produces gametes for sexual reproduction.