Cell Division (Complete)

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Cell division flash cards

Cell division 2

Cell division 1

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Meiosis info

What are germ line cells (Germinal epithelium) and what do they produce?

Germ line cells are the cells which undergo meiosis, during meiosis they produce haploid gametes which only have 1 copy of each chromosome

What happens to the haploid cells made in meiosis?

They fuse with opposite gametes I.E Sperm and eggs to form a diploid zygote which eventually becomes and embryo.

What happens during interphase?

The DNA is replicated during the s phase forming Sister chromatids which remain sister chromatids till Meiosis II

Protein synthesis

ATP synthesis

Organelle synthesis

How many cell division are there during Meiosis?

2

What happens in Meiosis I?

Two unique daughter cells are formed containing half the amount of DNA as the parent cells

What happens in Meiosis II?

Four unique haploid cells which only have 1 copy of each chromosome

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Meiosis Process

What is the begining of meiosis I and what happens in this stage?

-Prophase I:

In this stage the Chromatin (DNA) condense to form chromosomes

The duplicated chromatids from interphase are join together by a centromere

The nuclear membrane starts to break down, and the nucleolus disappears allowing the centrioles to move to the poles of the cell forming spindle

What are Chiasmata? And are what stage of meiosis does this happen?

Chiasmata are the regions of the chromosome which cross over to exchange DNA. This is known as crossing. This happens in Prophase I, and it is when the sister chromatids in a bivalent chromosome exchange their chromosomal material, changing the variation of the chromatids.

What happens to the sister chromosomes as a result of crossing over?

The chromosomes are no longer identical and are now genetically unique.

What happens in metaphase I?

The chromosomes are assorted randomly at the equator of the cell, the random assortment means they will always been in different combinations every time meiosis occurs.

What happens in anaphase I?

During this phase the homologous chromosomes from the bivalent are pulled to opposite ends of the cells by the contracting spindle fibres, (the sister chromatids/homologous chromosomes remain attached by the centromere).

What happens in telephase I?

The nuclear envelope and nuclelous reappear, and reform around the homologous chromosomes.

What happens in cytokensis?

The cytoplasm divides into 2 equal portions of forming 2 haploid cells.

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Meiosis II (Meiosis II happens on 2 haploid cells)

What is the difference between prophase I and II?

The only difference is that there is no crossing over.

What happens in prophase II?

The centrioles seperate and organise new spindle at right angles to the old spindle.

What is the difference between metaphase I and II?

They are the same, however because there is more random allignment this further increases the variation

What is the difference between anaphase I and II?

No sister chromatids

The chromatids from the sister chromatids are now pulled to opposite ends of the cell by the centromere. This is caused by the contraction of the spindle fibres.

What is the difference between telephase I and II?

The spindles disintergrate, and the nuclear membrane reforms and the membranes are on the opposite ends of the cell.

What happens in cytokensis of meiosis II?

The cytoplasm then divides into two haploid cells.

At the end of meiosis we get 4 haploid cells because we started with 2 cells from meiosis I

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Meiosis vs Mitosis (The differences)