Lecture 1/29/25

Question 1

Diagram the cell cycle and describe what happens in each phase?

Answer 1

G0: Resting phase, no division. G1: Cell grows, prepares for DNA replication. S: DNA replication. G2: Cell prepares for mitosis. M: Mitosis occurs.

Question 2

What are homologous chromosomes?

Answer 2

Chromosome pairs, one from each parent, that contain the same genes but may have different alleles.

Question 3

Explain the progressive levels of DNA/chromosome condensation?

Answer 3

DNA wraps around histones forming nucleosomes, condenses into chromatin fibers, loops into scaffolds, and further compacts into chromosomes.

Question 4

What is the difference between homologous chromosomes and sister chromatids?

Answer 4

Homologous chromosomes are similar but from different parents; sister chromatids are identical copies of a chromosome.

Question 5

Diagram the stages of mitosis and explain briefly what is happening in each step?

Answer 5

Prophase: Chromosomes condense, spindle forms. Metaphase: Chromosomes align at the equator. Anaphase: Sister chromatids separate. Telophase: Nuclear membranes reform.

Question 6

What is a centromere?

Answer 6

The region where sister chromatids are joined, essential for chromosome movement.

Question 7

What is a telomere?

Answer 7

A protective cap at chromosome ends that prevents degradation.

Question 8

What is telomerase, and how is it different from a polymerase?

Answer 8

Telomerase extends telomeres, maintaining chromosome length; polymerases replicate DNA but do not extend telomeres.

Question 9

How do bacteria package their genomes?

Answer 9

Bacteria use supercoiling and nucleoid-associated proteins to compact their circular DNA.