Cells-Cellular division

Question 1

What is a Chromosome?

Answer 1

DNA in coiled form
 formed during interphase of cell division (mitosis/meiosis) in Animals/Plants
 made of 2 identical/sister chromatids joined by a centromere
 carries 2 copies of the same DNA molecule

Question 2

What is a homologous pair of chromosomes?

Answer 2

a pair of chromosomes: 1 maternal (from mother)/1 paternal (from father)
carries same genes but different alleles – there are 23 pairs in humans

Question 3

What is Cell Division?

Answer 3

 formation of new cells in multicellular organisms (animals & plants)
 2 methods = mitosis & meiosis
 mitosis = produces genetically identical cells for growth & repair of tissues
 meiosis = produces genetically different haploid cells as gametes for sexual reproduction

Question 4

What does Mitosis (cell cycle) produce?

Answer 4

2 genetically identical cells, diploid (have full set of chromosomes/DNA)

Question 5

Benefit of Mitosis?

Answer 5

growth and repair of tissues

Question 6

Stages of Mitosis?

Answer 6

Interphase/Mitosis/Cytokinesis

Question 7

Interphase?

Answer 7

G1: protein synthesis
S: DNA replication (doubles set of DNA)
G2: organelle synthesis

Question 8

Mitosis?

Answer 8

Prophase: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form
Metaphase: chromosomes line up in middle of cell and attach to spindle fibre via centromere
Anaphase: spindle fibres pull, centromere splits, sister chromatids move to opposite sides
Telophase: chromatids uncoil, nucleus reforms (left with 2 genetically identical nuclei)

Question 9

Cytokinesis?

Answer 9

separating cell into 2 (each receives a nucleus and organelles/cytoplasm)

Question 10

What is Cancer?

Answer 10

formation of a tumour due to uncontrolled cell division (uncontrolled mitosis)

Question 11

How does uncontrolled cell division occur?

Answer 11

 due to mutation of DNA/cells forming cancer cells

 mutation can occur randomly or due to mutagens

Question 12

Treatment for Cancer?

Answer 12

 Target the cell cycle.
 G1:prevents synthesis of enzymes needed for DNA replication. The cell is unable to enter S Phase and will kill itself
 S-phase: Radiation damages DNA. The cell will kill itself.

Question 13

How do Bacteria do Cell Division?

Answer 13

 Binary Fission
 Copy their DNA (Single Loop and Plasmids) and then separate into 2 new genetically identical bacteria
[Asexual Reproduction]