Week 5

Question 1

Cell division - importance

Answer 1

in growth and repair of multicellular organisms

Question 2

Asexual reproduction

Answer 2

offsprings are clones
genetically identical to parents
any genetic variation is due to mutations

Question 3

single celled prokaryotes - reproduction

Answer 3

binary fission

Question 4

Single celled eukaryotes - reproduction

Answer 4

mitosis and cytokinesis

Question 5

mulitcellular eukaryotes - reproduction

Answer 5

reproduce by asexual

Question 6

Sexual reproduction

Answer 6

involves fusion of gametes
results in genetic variation
gametes formed by meiosis

Question 7

somatic cells

Answer 7

body cells

contains 2 sets of chromosomes that occur in homologous pairs

Question 8

Gametes

Answer 8

sex cells

one pair of chromosomes

Question 9

fertilisation

Answer 9

2 haploid cells form a zygote

Question 10

Sexual reproduction - essence

Answer 10

random selection

fusion of haploid gametes to make dipliod cell

Question 11

Four events of cell division

Answer 11

reproductive signals
DNA replication
DNA segregation
Cytokinesis

Question 12

Replication

Answer 12

ocurs as the DNA is threaded through a replication complex of proteins at center of the cell

Question 13

Segregation

Answer 13

as replication proceeds, the ori complexes move to opposite ends of the cell
DNA spequences adjacent to ori region bind to proteins for segregation using ATP
Actin protien provide filaments along which ori and other proteins move

Question 14

ori

Answer 14

where replication starts

Question 15

ter

Answer 15

where replication ends

Question 16

important regions of circular chromosome

Answer 16

ter

ori

Question 17

cytokinesis

Answer 17

after chromosome segregation, cell membrane pinches in and new cell walll is made

Question 18

Mitosis

Answer 18

one nucleus produces 2 daugther nuclei containing same number of chromosomes
continuous

Question 19

M phase: mitosis

Answer 19

segragation of chromosomes into 2 nuclei, followed by cytokinesis

Question 20

Interphase: Mitosis

Answer 20

cell nucleus is visible and cell functions occur, including DNA replication

Question 21

Interphase mitosis subphases

Answer 21

G1 - variable
S pahse - DNA is replicated
G2- cell prepares for mitosis , synthesises microtubules for segregating chromosomes

Question 22

Prophase

Answer 22

3 structures appear
condensed chromosomes
reoriented chromosomes
spindle

Question 23

Karotype

Answer 23

the condensed chromosomes distinguished by their sizes and centromere positions

Question 24

centrosome

Answer 24

determines orientation of spindle
consists of 2 centrioles
poles at which the chromosomes move twards

Question 25

centrioles

Answer 25

hollow tubes formed by microtubules

Question 26

spindle

Answer 26

made up of polar microtubules astral microtubules Kinetochore microtubules

Question 27

polar microtubules

Answer 27

overlap in middle region of cell and keep poles apart

Question 28

Astral microtubules

Answer 28

interact with proteins attached to cell membrane, keeps poles apart

Question 29

Kinetochore microtubules

Answer 29

attach to kinetochores on chromatid centromeres

Question 30

Prometaphase: mitosis

Answer 30

nuclear envelope breaks down and chromatids attach to kinetochore microtubules

Question 31

Metaphase: mitosis

Answer 31

the chromosomes line up at midline of cell

Question 32

Anaphase: mitosis

Answer 32

chromatids separate and daughter chromosomes move towards poles

Question 33

Telophase: mitosis

Answer 33

nuclear envelopes form around each set of chromosomes and nucleoli appear, and spindle breaks down and chromosomes become less compact

Question 34

Cytokinesis: mitosis

Answer 34

in animal cells, cell membrane pinches in between nuclei | in plant cells, vesicles appear along plane of cell division and fuse to form new cell membrane

Question 35

Cyclin dependent kinases

Answer 35

trigger substances catalyse phosphorylation of proteins that regulate cell cylce and are activated by binding to cyclin, which exposes the active site

Question 36

Meiosis

Answer 36

two nuclear division reduces chromosome number to haploi generates diversity

Question 37

Meiosis 1

Answer 37

chromosomes come together and line up along lengths | pairs seperate but individual chromosomes made up of 2 chromatids remain together

Question 38

Meiosis 2

Answer 38

not preceded by DNA replication sister chromatids seperate 4 haploid cells are produced

Question 39

crossing over

Answer 39

prophase 1 - chromosomes repel each other but remain attached at chiasmata genetic material is exchanged between non sister chromosomes increases genetic variation

Question 40

Independent assortment

Answer 40

at anaphase 1, matter of chance which member of homologous pair goes to which daughter cell

Question 41

Nondisjunction

Answer 41

homologous pairs fail to separate at anaphase 1 | sister chromatids fail to separate at anaphase 2

Question 42

aneuploidy

Answer 42

abnormal numbers of chromosomes

Question 43

polyploidy

Answer 43

organisms with triploid, tetraploid or higher can form | can occur through extra round of DNA replication or lack of spindle formation

Question 44

Translocation

Answer 44

crossing over between non homologous chromosomes

Question 45

necrosis

Answer 45

cell is damaged or starved for oxygen or nutrients | cells swell and burst

Question 46

Apoptosis

Answer 46

genetically programmed cell death