cell cycle

duplication of genetic material

Mitosis:

duplication of organelles

‣ Cytokinesis:

reduction division only in gonads

‣ Meiosis:

‣ Time between divisions

• G1: primary growth phase

• S: DNA duplication

• G2: Centrioles complete duplication, mitochondria

Interphase

primary growth phase

• G1:

DNA duplication

• S:

Centrioles complete duplication, mitochondria replicate. chromosomes condense and coil

• G2:

• Chromosomes become visible as chromatids are joined

by centromere.

• Two kinetochores at the centromere

• Centrioles move to opposite poles

• Nuclear membrane breakdown

• Microtubules attach kinetochores to spindle

Prophase

• Chromatids align at equator of cell

• Centromere divides

‣ Metaphase

• Divided centromere pulls chromatids to opposite pole

• Cytokinesis begins

‣ Anaphase

‣

• Chromosomes uncoil and decondense

• Spindle apparatus breaks down

• New nuclear membrane forms

• Cytokinesis nearly complete

Telophase

‣ The division of the cell’s cytoplasm to produce two new cells.

‣ begins in anaphase and continues through

telophase.

➡ Cytokinesis

- Cleavage furrow forms

- Cell is pinched into daughter cells

Animal cells

- Cell plate forms at equator

- Cell plate becomes new cell wall

Plant cells

‣ Occurs only in gonads

‣ Reduces genetic material from diploid to haploid

‣ Two divisions resulting in four cells

➡ Meiosis

• Homologous chromosomes pair and cross over

Prophase I

• Chromosomes align along equator

‣ Metaphase I

• Centromeres pulled to poles. One member each pole

‣ Anaphase I

• One of each pair is at each pole

‣ Telophase I

• Spindle forms; centrioles move to poles

‣ Prophase II

• Chromosomes line up at the equator

‣ Metaphase II

• Centromeres divide

‣ Anaphase II

• Chromatids at each pole; new nuclear membrane forms

‣ Telophase II

In ____ we end up with four daughter cells (four 23

chromosomes), each containing only half the genetic material,

whereas in ____ we end up with two daughter cells (two 46

chromosomes), each containing the full complement of genetic

material.

meiosis; mitosis

comparison (mitosis and meiosis)

2 diploid cells

mitosis

comparison (mitosis and meiosis)

asexual

mitosis

comparison (mitosis and meiosis)

one division

mitosis

comparison (mitosis and meiosis)

no crossover

mitosis

comparison (mitosis and meiosis)

growth, maintenance, repair

mitosis

comparison (mitosis and meiosis)

most cells of our body

mitosis

comparison (mitosis and meiosis)

4 haploid cells

meiosis

comparison (mitosis and meiosis)

sexual

meiosis

comparison (mitosis and meiosis)

two divisions

meiosis

comparison (mitosis and meiosis)

there is crossover

meiosis

comparison (mitosis and meiosis)

reproduction

meiosis

comparison (mitosis and meiosis)

only in gonads

meiosis