Meiosis

Question 1

What does meiosis produce ?

Answer 1

Four genetically different haploid gametes

Question 2

What does mitosis produce ?

Answer 2

Two genetically identical diploid cells

Question 3

What are the sub stages of prophase I ?

Answer 3

1. Leptotene
2. Zygotene
3. Pachytene
4. Diplotene
5. Diakinesis

Question 4

Describe leptotene

Answer 4

Chromosomes condense

Question 5

Describe zygotene

Answer 5

1. Chromosomes align with homologous pair
2. Synaotonemal complex begins to form, joining homologous chromosomes together along the length of the chromatids

Question 6

Describe pachytene

Answer 6

1. Synapsis complete- chromatids joined along lengths of
2. Cross over events occur

Question 7

Describe diplotene

Answer 7

1. Synaotonemal complex dissolves, leaving chromatids free
2. Homologous chromosomes still joined together, but only via crossover junctions
3. Chiasma visible

Question 8

Describe diakinesis

Answer 8

1. meiotic spindle forms
2. Orientate in homologous pairs at the equator of the cell

Question 9

Describe metaphase I

Answer 9

1. Homologous pairs line up at the equator
   One kinetichore per chromosome attatched to spindle

Question 10

Describe anaphase I

Answer 10

Replicated pairs of chromatids move towards the poles of the cell

Question 11

Describe telophase I

Answer 11

1. Nuclear membrane begins to reform
2. Chromosomes docondense

Question 12

Describe prophase II

Answer 12

Chromosomes condense and attach to spindle

Question 13

Describe metaphase II

Answer 13

1. Chromosomes line up at the equator of cell
2. Each chromatid is attached to the spindle

Question 14

Describe anaphase II

Answer 14

1. Chromosomes pulled apart
2. Chromatids separate and are pulled to opposite ends of the cell

Question 15

Describe telophase II

Answer 15

1. Chromosomes de-condense
2. Nuclear envelop reforms

Question 16

Describe the crossover process

Answer 16

Occurs during Pachytene
1. Homologous chromosomes pair up tightly side by side in a structure called a Synaotonemal complex.
2. Non-sister chromatids of homologous chromosomes break at the same location and exchange DNA segments. These crossover points are called chiasma.
This results in chromatids with a mix of maternal and paternal genes.

Question 17

Describe cytokinesis in plants

Answer 17

1. A structure called the phragmoplast forms which is made of microtubules
2. Vesicles from the Golgi move along the phragmoplast towards the centre of the cell, forming the cell plate
3. The cell plate expands and fuses with the parent cell membrane and cell wall, dividing the cytoplasm into two