Mitosis & Meiosis

SC.912.L.16.17 Compare and contrast mitosis and meiosis

and relate to the processes of sexual and asexual

reproduction and their consequences for genetic variation.

1. Students will describe specific events

occurring in each stage of the cell cycle

and/or phases of mitosis, including cytokinesis.

Cell Division: the process of copying and dividing entire cells

The cell grows, prepares for division, and then divides to form new

daughter cells.

Unicellular organisms – allows duplicate using asexual reproduction

Multicellular organisms – allows to grow, develop from single cell to

multicellular, makes other cells to repair and replace worn out cells

Three types: binary fission (bacteria and fungi), mitosis, and meiosis

1. Students will describe specific events

occurring in each stage of the cell cycle

and/or phases of mitosis, including cytokinesis.

Cells divide

through a process

called the cell

cycle which

consists of

interphase, mitosis,

and cytokinesis.

Note: majority of

the cell cycle is

Interphase, while a

smaller portion is

mitosis/cytokinesis.

1. Students will describe specific events

occurring in each stage of the cell cycle

and/or phases of mitosis, including cytokinesis.

Interphase: longest part of the cell cycle; growth, metabolism, and

preparation for division occurs, duplicates chromosomes (DNA

Replication)

1. Students will describe specific events

occurring in each stage of the cell cycle

and/or phases of mitosis, including cytokinesis.

MITOSIS – division of nucleus of the cell

Prophase: duplicated chromosomes and spindle fibers

appear

Metaphase: duplicated chromosomes line up randomly in

center of cell between spindle fibers

Anaphase: duplicated chromosomes pulled to opposite

ends of cell

Telophase: nuclear membrane forms around

chromosomes at each end of the cell; spindle fibers

disappear; chromosomes disperse

1. Students will describe specific events

occurring in each stage of the cell cycle

and/or phases of mitosis, including cytokinesis.

Cytokinesis: division of plasma membrane; two daughter cells result

with exact genetic information

In plants, a cell plate forms along the center and cuts the cell in

half.

In animals, a cleavage furrow develops to cut the cell in half.

RESULTS OF MITOSIS:

Two identical daughter cells

Produces and occurs in somatic cells (body cells)

Diploid = same number of chromosomes as

original cell (humans = 46)

1. Students will describe specific events

occurring in each stage of the cell cycle

and/or phases of mitosis, including cytokinesis.

2. Students will explain how meiosis results in

the formation of haploid gametes or spores.

In meiosis, the cells will also start with interphase.

There are TWO cell divisions instead of one, but the cell only

does interphase ONCE prior to the first cell division.

Meiosis is a reduction division process (chromosome numbers

are divided in half)

Each cell division consists of prophase, metaphase, anaphase,

and telophase

Occurs only in sex cells (gametes) and produces only gametes

(egg and sperm)

First Division: Produces cells containing half # of double stranded

chromosomes

Prophase 1 –

crossing over

occurs

Metaphase 1 –

chromosomes line up in

homologous pairs,

independent assortment

occurs

Anaphase 1 –

chromosomes

move towards

each side

Telophase 1 – cells

contain HALF of #

of chromosomes

2. Students will explain how meiosis results

in the formation of haploid gametes or

spores.

2. Students will explain how meiosis results

in the formation of haploid gametes or

spores.

Crossing over: genes are essentially “switching” places

on chromosomes in prophase I

Independent assortment: the genes randomly move

towards ends of cell in metaphase I

THESE BOTH RESULT IN GENETIC VARIATION!

Second Division: Results in formation of four cells, each haploid

(half the number of original chromosomes) (humans = 23)

2. Students will explain how meiosis results in

the formation of haploid gametes or spores.

RESULTS OF MEIOSIS:

Four unique daughter cells

Unique due to genetic variation such as crossing over and independent assortment

Produces and occurs in gametes (sex cells)

Haploid = half number of chromosomes as original cell (humans = 23)

Sex cells combine during sexual reproduction to produce a diploid individual

2. Students will explain how meiosis results in

the formation of haploid gametes or spores.

3. Students will compare and contrast

sexual and asexual reproduction.

SEXUAL REPRODUCTION

Pattern of reproduction that involves the production

and fusion of haploid sex cells

Haploid sperm from father fertilizes haploid egg from

mother to make a diploid zygote

3. Students will compare and contrast

sexual and asexual reproduction.

ASEXUAL REPRODUCTION

A single parent produces one or more identical

offspring by dividing into two cells.

Diploid cells are clones of parent cell.