cell cycle

Question 1

What is meiosis

Answer 1

Process in which sex cells, gametes, are made in reproductive organs
Involves the reduction division of a diploid germline cell into 4 genetically distinct haploid nuclei

Question 2

Prophase 1

Answer 2

Chromosomes condense
Nuclear membrane dissolves
Homologous chromosomes form bivalents, sister chromatids
Crossing over occurs

Question 3

Metaphase 1

Answer 3

Spindle fibres from opposing centrosomes connect to bivalents at the centromeres and align them all along the middle of the cell
Independent assortment

Question 4

Anaphase 1

Answer 4

Spindle fibres contract
Homologous chromosomes move to opposite poles of the cell
Crossing over occurs creating genetic varitation

Question 5

Telophase 1

Answer 5

Chromosomes decondenses and assemble at each pole, nuclear membrane may reform, cell divides( via cytokinesis) to form 2 haploid daughter cells

Question 6

Prophase 2

Answer 6

Chromosomes remain in pair up and recondense
Nuclear envelope breaks down again
Spindle fibres reform
Centrioles move to opposite poles of the cell

Question 7

Metaphase 2

Answer 7

Sister chromatids are aligned on the equator of the cell by the spindle fibres

Question 8

Anaphase 2

Answer 8

Centromere divides
Sister chromatids are separated
Spindle fibres contract
Chromatids, now called chromosomes move to the poles of the cells

Question 9

Telophase 2

Answer 9

Chromosomes uncoil and de condense.
Spindle fibres break down
Nuclear envelopes reform
Cell undergoes cytokines

Question 10

Cytokines - meiosis

Answer 10

Cytoplasm and surface membrane divide

Creating 4 independent haploid daughter cells

Question 11

Importance of cell cycle

Answer 11

Growth of tissue
Replacement of damaged cells
Repair of body tissue
Asexual reproduction- fungi

Question 12

2 stages of cell cycle

Answer 12

Interphase: growth phase 1, synthesis , growth phases 2

M phase: mitosis, cytokines

Question 13

Growth phase 1

Answer 13

Synthesis of proteins
Organelles replicate
Cell increases in size

Question 14

Synthesis phase

Answer 14

Replication of each chromosomes in the nucleus

Question 15

Growth phases 2

Answer 15

Cell continues to grow in size
Duplicated DNA is checked for errors
Energy stores are increased

Question 16

Growth phase zero

Answer 16

Phase where the cell leaves the cell cycle ( resting)

If dna is damaged
Or is no longer able to divide

Question 17

Problems if DNA is not checked

Answer 17

Mutation in DNA sequence
Daughter cells will not receive identical genetic information
Proteins not made or do not function properly

Question 18

Prophase , mitosis

Answer 18

Chromosomes condense and thicken , becoming visible
Sister chromatids join at the centromere
2 centrioles migrate to opposite poles of the cell
Spindle fibres attach to specific areas on the centromeres and stat to move the sister chromatids to the equator of the cell
Nuclear envelope disappears

Question 19

Metaphase mitosis

Answer 19

Pairs of chromatids are moved by the spindle fibres to align at the metaphase plate

Question 20

Anaphase , mitosis

Answer 20

Centromeres holding the pairs of chromatids in each chromosome divide
Chromatids separate
Spindle contracts (fibres shorten)
Each chromatid is pulled by their centromere to opposite poles of the cell

Question 21

Telophase mitosis

Answer 21

Chromatids have reach opposite poles of the cell, they uncoil
Chromsomes assemble at each pole
Nuclear envelope reforms and encloses around the chromosomes at each pole

Question 22

Cytokines, mitosis

Answer 22

cleavage furrow ( animals ) , cell plate ( plants ) forms 
Results in 2 genetically identical daughter cells being formed

Question 23

G1 checkpoint

Answer 23

End of growth phase one, and before synthesis
Checks that chemicals needed for replication are present
Checks for damage to DNA before entering synthesis phase
Cell size
Nutrients
Growth factors

Question 24

G2 checkpoint

Answer 24

Cell size
DNA replication
DNA damage

Question 25

How do fungus cells divide

Answer 25

Budding

Question 26

Features found in mature plant cells that are not found in unspecialised cells

Answer 26

Nucleus cytoplasm cell wall

Question 27

What features of the DNA molecules is changed due to mutation

Answer 27

Sequence of bases

Question 28

Possible effects of mutation

Answer 28

shorter due to deflection/ stop codon | Longer due to duplication

Question 29

What is meant by a homologous pair of Chromosomes

Answer 29

``` 1 maternal one paternal Carry the same genes as their parents Carry different alleles Similar length Centromere in the same position Pair up in meiosis to form a bivalent ```

Question 30

Interphase

Answer 30

DNA is replicated and checked for errors Protien synthesis occurs Mitochondria grow and divide, increasing in number Chloroplast grow and divide in plant + algae Normal metabolic processes of cells occur

Question 31

Significance of meiosis

Answer 31

Formation of sex cells, gametes | Creates genetic variation

Question 32

How does meiosis create genetic variation

Answer 32

Independent assortment of homologous chromosomes - metaphase 1 Crossing over of sister chromatids - anaphase 1 Independent assortment- metphase 2

Question 33

Significance of meiosis

Answer 33

Formation of sex cells, gametes | Creates genetic variation

Question 34

How does meiosis create genetic variation

Answer 34

Crossing over- part of each homologous chromosome switches (at points called chiasmata) as the are moved through the liquid cytoplasm, they entangle. This also causes mutation Independent assortment- orientation and positions of homologous chromosomes is random along the metaphase plate

Question 35

How to measure rate of mitosis

Answer 35

Dissect samples from different parts of plant then stain and view under light microscope and record how many cells are undergoing mitosis. The parts with more mitosis have a faster rate of growth

Question 36

M checkpoint

Answer 36

Checks sister chromatids are attached to spindle fibres