Meiosis

Question 1

Meiosis

Answer 1

a process of cell division that halves the number of chromsomes going into the gametes so that the diploud number is retained in a zygote

Question 2

interphase

Answer 2

chromosomes are replicated

Question 3

meiosis I - prophase I

Answer 3

one chromosome made up of sister chromatids line up in its homologous pairs and form tetrads. homologous chromosomes pair and exchange segments these are called chiasmata, they break and rejoin so parts of the dna are swapped. the pairs need to be swapped as we want the same parts of the same chromosome swapped

Question 4

Metaphase I

Answer 4

tetrad line up down the cell equator. the chiasmata line up along the equator/ metaphase plate with the chromosome facing each pole. both chromatids are of homologous pair and are attached to kinetochore mircotubules from one pole and from the other pole on the other side

Question 5

Anaphase I

Answer 5

the pairs are broken apart. the proteins that are responsible for the cohesion of the sister chromatids at the arms is broken down and the pairs move to opposite poles guided by the shortening microtubules. the sister chromatid cohesion consists at the centromere holding them together

Question 6

telophase 1 and cytokinesis

Answer 6

when this begins each cell has a complete haploid set of duplicated chromosomes each made of 2 sister chromatids with swapped regions.
cytokinesis - division of the cytoplasm
cleave furrows form, no chromosomes duplicate after this.

Question 7

Meiosis II - Prophase II

Answer 7

spindle apparatus forms, chromosomes composed of 2 sister chromatids move towards the metaphase plate

Question 8

Metaphase II

Answer 8

the chromosomes are positioned in the metaphase plate like in mitosis.
because of crossing over the 2 sister chromatids of each chromosome are not genetically identical
kinetochore attached to the mirocubules extending from the poles

Question 9

Anaphase II

Answer 9

break down of the proteins holding the sister chromatids together at the centromere allowing them to seperate.
chromatids move to opposite poles as individual chromosomes

Question 10

telophase II and cytokinesis

Answer 10

nucleus forms and the chromosomes begin condensing and cytokinesis occurs.
4 daughter cells are produces with a haploid set of un-replicated chromosomes, they are genetically distinct from one another.