chromosome structure and cell division processes

Question 1

chromosome structure

Answer 1

• dna in chromosomes is tightly coiled and packaged with proteins, allowing it to fit inside the cell nucleus
• histone proteins play a role in coiling and structuring dna into a compact form, forming nucleosomes
• each chromosome has a centromere, which is the region where two sister chromatids are connected if duplicated

Question 2

chromosome function

Answer 2

• ensure accurate genetic information transfer during cell division, crucial for growth and repiar
• they are essential in both mitosis (for somatic cell division) and meiosis (for gamete formation)
• chromosomes determine organism traits through genes that regulate metabolism, development, and reproduction

Question 3

chromatin structure

Answer 3

• consists of dna wrapped around histones, forming nucleosomes that resemble beads on a string
• nucleosomes further coil and fold into compact structures, allowing DNA to fit within the nucleus
• the structure of chromatin can be categorized into euchromatin (loosely packed, active) and heterochromatin (tightly packed, inactive)

Question 3

chromatin function

Answer 3

-gene regulation is influenced by chromatin structure, determining gene accessibility for transcription
- chromatin allows efficient DNA packaging into the nucleus, protecting it from damage.
- the dynamic nature of chromatin plays a role in DNA repair and gene expression regulation

Question 4

phases of the cell cycle

Answer 4

G1 - the cell grows, synthesizes enzymes for DNA replication, and prepared for the S phase
S - dna replication occurs, resulting in two sister chromatids for each chromosome
G2 - the cell continues to grow, checks for dna damage and prepares for mitosis

Question 5

stages of mitosis

Answer 5

prophase - chromatin condenses into distinct chromosomes, and the mitotic spindle begins to form
metaphase - chromosomes align at the metaphase plate, and the spindle checkpoint ensures proper attachment
anaphase - sister chromatids are pulled apar and move toward opposite poles of the cell
telophase - two nucelues start to form
cytokinesis - two daughter cells by dividing the cytoplasm

Question 6

cytokinesis in animal cells

Answer 6

a contractile ring forms

Question 7

cytokinesis in plant cells

Answer 7

a cell plate develops

Question 8

centrosome structure

Answer 8

consists of two centrioles surrounded by pericentriolar material, organizing microtubules

Question 9

centrosome function

Answer 9

plays a critical role in microtubule organization, cell division, and maintain genomic stability

Question 10

kinetochore structure

Answer 10

is a multi-layers complex on the centromere, which microtubules attach during cell division

Question 11

kinetochore function

Answer 11

ensures proper chromosome attachment, alignment, and segregation, activating the spindle assembly checkpoint

Question 12

G1 checkpoint

Answer 12

assesses cell readiness for DNA replication, checking for DNA damage and nutrient availability

Question 13

G2 checkpoint

Answer 13

ensures all DNA is replicated correctly and checks for damage before mitosis

Question 14

M checkpoint

Answer 14

confirms proper attachment of chromosomes to the spindle apparatus before anaphase