Module 2 - cell division

Question 1

what is the G1 phase ?

Answer 1

proteins required for organelles are synthesised

Question 2

what is the s phase?

Answer 2

Dna replication takes place, resulting in the double mass of DNA in the cell

Question 3

what is the G2 phase?

Answer 3

organelles grow and divide, energy reserves and increases

Question 4

what three steps is the interphase composed of?

Answer 4

• G1 phase
• S phase
  G2 phase

Question 5

what is mitosis ?

Answer 5

when the nucleus divides into two

Question 6

what is cytokinesis?

Answer 6

• the cytoplasm divides to form two genetically identical daughter cells

Question 7

where do the checkpoints occur?

Answer 7

• the end of G1 - before DNA replication occurs
• end of the G2 stage before mitosis begins
• spindle assembly to esnure chromosomes are aligned on the spindle

Question 8

what happens in prophase ?

Answer 8

• chromsomes comprimise of two genetically identical threads called sister chromatids joined by a centromere
• nuclear envelope disappears
• the centrioles move to the poles of the cells, producing a network of spindle fibres between them

Question 9

what happens in metaphase ?

Answer 9

• the chromosomes move to the equator of the cell
• each one becomes attached to a spindle fibre by its centromere

Question 10

what happens in anaphase ?

Answer 10

• the spindle fibres contract, which separates the sister chromatids
• spindle fibres pull the chromatids towards opposite poles of the cell centromere

Question 11

what is telophase ?

Answer 11

• nuclear envelope forms around each pole to form two new nuclei
• chromosomes start to uncoil
• spindle fibres breakdown
• two new daughter cells are formed

Question 12

what is the significant of mitosis?

Answer 12

• asexual reproduction
• growth
• tissue repair

Question 13

what is prophase 1 in meiosis?

Answer 13

chromatids condense, homologous chromosomes form bivalents,crossing over occurs

Question 14

what is metaphase 1 in meiosis?

Answer 14

bivalents line up at the equator, independent assortment occurs

Question 15

what is anaphase 1 in meiosis?

Answer 15

• spindle fibres pull homologous chromosomes opposite poles of the cell

Question 16

what is telophase 1 in meiosis?

Answer 16

• followed by cytokinesis
• nuclear envelope forms around nuclei

Question 17

what is prophase 2 in meiosis?

Answer 17

chromosomes condense, spindle fibres re-form nuclear envelope breaks down again

Question 18

what is metaphase 2 in meiosis?

Answer 18

• chromosomes randomly arrange themselves on spindle fibres at equator by centromeres, so independent assortment occurs

Question 19

what is anaphase 2 in meiosis?

Answer 19

chromatids are pulled by apart by contracting spindle fibres to poles of the cell

Question 20

what is telophase 2 in meiosis?

Answer 20

followed by cytokinesis
nuclear envelope forms around new haploid nuclei

Question 21

what is hapolid cell?

Answer 21

it has half the chromosomes of the dipolid parent cells

Question 22

what are homologous chromosomes?

Answer 22

• pair of chromosomes that have the same genes at the same nuceli

Question 23

what is crossing over?

Answer 23

homologous pairs form bivalents so that the non-sister chromatids can cross over at locations called chiasmata and exchange sections of chromosomes

Question 24

what is independent assortment?

Answer 24

caused by the random distribution and separation of homologous chromosome during metaphase 1 and the random distribution and segregation of sister chromatids and metaphase 2.

Question 25

what is a cell?

Answer 25

the fundamental unit of life

Question 26

what is a tissue ?

Answer 26

a collection of similar cells working together with a common function

Question 27

what is an organ?

Answer 27

a collection of tissues working together to perform a particular function

Question 28

what is an organ system?

Answer 28

- a collection of organs working together in a specific role

Question 29

what are eryhrocytes?

Answer 29

red blood cells that contain haemoglobin to transport oxygen from lungs to body tissues

Question 30

what is a cilitated epithelial cell?

Answer 30

has tiny extensions called cilia to move mucus along the mucous membrane or ova long the fallopian tubes

Question 31

what is a neutrophill?

Answer 31

a type of white blood cell involved in phagocytosis with a cytoplasm filled with lysosomes to break down phagocytosed material

Question 32

what is a squamous epithelial cell?

Answer 32

found in the lining of surfaces such as lungs and blood vessels. Has a flat, thin shape to facilitate diffusion of materials across it.

Question 33

what is a sperm cell?

Answer 33

flasgellum used to swim to ovum using energy released by the hydrolysis of ATP in the mitochdria in middle section

Question 34

what is a palisade cell?

Answer 34

long and thin so that many chloroplasts can absorb maximum sunlight

Question 35

what is a guard cell?

Answer 35

- arranged in pairs around the stoamata to control water vapour loss from plants. - they have a thickened cell wall surrounding the pore which causes the bending of the cell when its turgid

Question 36

what is the root hair cell?

Answer 36

long hair maximises surface area in contact with soil for uptake of water and mineral ions

Question 37

what are totipotent cells?

Answer 37

- occurs only for a limited amount of time in early mammalian embryos - can differentiate to produce any type of body cell, including plancental cells

Question 38

what are pluripotent cells?

Answer 38

- found in embryos - can differentiate into all tissue types except placental cells

Question 39

what are multipotent cells?

Answer 39

- found in many tissues any post embryonic life stage - can differentiate to form a limited number of different cell types