Genetic information/cell cycle.

Question 1

Reasons for cell division.

Answer 1

-Repairing/replacing tissues
-Organism growth
-Asexual reproduction
-Development of and embryo from a zygote.

Question 2

The cell cycle.

Answer 2

One cell dividing to become 2 identical daughter cells
IPMAT(C)
Mostly interphase.

Question 3

Processes in interphase.

Answer 3

Growth phase
Synthesis phase:
-DNA replication
-Organelle replication.
Growth phase(2)
-Cell growth(1 as well)

Transcription
Translation
Obtains nutrients
Respiration-ATP production.

Question 4

Cancer formation.

Answer 4

Uncontrolled/unrestricted cell division:
-Damage to genes that regulate the cell cycle
-leads to rapid replication
-Tumours
-Oncogenes(error at chekpoints).

Question 5

Cytokinesis.

Answer 5

Cytoplasm and cell contents divide to form 2 daughter cells.

Question 6

Chromatin.

Answer 6

DNA wrapped around histone proteins.

Question 7

Centrioles.

Answer 7

Produce spindle fibres for cell division
Near the nucleus.

Question 8

Chromosomes.

Answer 8

1 continuous strand of chromatin
Centromere in the middle
After S phase, 2 sister chromatids are formed
After mitosis, 1 chromasome in each nuclear envelope.

Question 9

Chromatid.

Answer 9

Genetically identical copies of a chromosome attached to one centromere.

Question 10

Mitosis stages.

Answer 10

Prophase:
-Chromosomes condense
-Centrioles move to opposite sides
-Spindle fibres form microtubules
-Nuclear envelope disintegrates.
Metaphase:
-Centromeres attach to spindle fibres
-Line up on the equator.
Anaphase:
-Fibres shorten
-Centromere separates
-Individual chromatids pulled to the poles.
Telophase:
-Spindle fibres break down
-Chromosomes uncoil
-Nuclear envelope reforms.

Question 11

Products of mitosis.

Answer 11

2 genetically identical daughter cells
Growth and repair of damaged cells
Asexual reproduction
Diploid daughter cells
Diploid parent cells.

Question 12

Homologous chromosomes.

Answer 12

Identical in shape and size
Carry same gene at loci(where gene is on chromosome)
One chromosome from each parent.
Arranged next to each other=bivalent.

Question 13

Meiosis products/key points.

Answer 13

Diploid parent cells
Produces 4 haploid unique gametes(sex cells)
2 divisions in process.

Question 14

Meiosis I stages.

Answer 14

Interphase(DOCTOR)
Prophase I:
-centrioles move to poles
-chromosomes condense
-nuclear membrane disappears
-crossing over occurs.
Metaphase I:
-Homologous chromosomes align on equator
-Each centromere attach to spindle fibres, each attached to a centriole
-Random assortment.
Anaphase I:
-Spindle contract, each chromosome pulled to different centriole(centromere first)
-Each chromosome is unique.
Telophase I:
-chromosomes reach poles
-nuclear membranes reform
-Each nucleus is haploid
Cytokinesis:
-2 unique haploid daughter cells form.

Question 15

Meiosis II stages.

Answer 15

No interphase.
Prophase II:
-centrioles go to poles
-chromosomes condense
-nuclear membrane disappears
Metaphase II:
-chromosomes align on equator
-each chromatid attached to spindle fibre, each fibre attached to centriole
-independent assortment.
Anaphase II:
-Spindles contract and each chromosome pulled to diff centriole
-Each chromosome unique.
Telophase II:
-Chromosomes reach poles
-nuclear membrane reforms
-Each nucleus is haploid.
Cytokinesis:
-4 haploid cells form=unique.

Question 16

Factors that make unique daughter cells in meiosis.

Answer 16

crossing over
Independent assortment.

Question 17

Crossing over process.

Answer 17

Bivalent chromosomes join at chiasma and bits of each chromosome go to different ones
Recombinant chromatids
4 unique
Prophase I.

Question 18

Random/independent assortment process.

Answer 18

Metaphase I and II.
When chromosomes line up in the centre of the cell, they are randomly assigned to either side of the equator=variation.