Two Types of Reproduction

Asexual Reproduction

•used by some plant and invertebrate species

•requires 1 parent•offspring are genetically identical to the parent

•uses body cells

Body Cells• called somatic cells (somato-

means “body”)• body cells are diploid =

contain 2 sets (pairs) of chromosomes (diplo- means “double”)

• made by the process of mitosis throughout the entire body

Steps of Asexual Reproduction

1.Body cells are made by mitosis

Steps of Asexual Reproduction

2. The organism undergoes binary fission, budding or regeneration to create an offspring

Sexual Reproduction• used by most species• requires male and female• offspring are genetically different

from the parents

Gametes Cells

• Gametes cells are haploid = contain 1 set (single) of chromosomes (haplo- means “single”)

• made by the process of meiosis inside reproductive organs

Steps of Sexual Reproduction

1. Gametes cells are made by meiosis (like “double mitosis”)

Cells divide twice

Steps of Sexual Reproduction

2. Male and female gamete cells come together to form one body cell (called a zygote)

Cell frommale

parent

Cell from female parent

zygote

Steps of Sexual Reproduction

3. The zygote undergoes mitosis repeatedly until it develops into a complete organism

Etc…

Memory Phrase

Meosis made ME-osis

Mitosis made my-TOES-es

Mitosis

mitosis• mitosis is the division of

the cell nucleus in which the chromosomes in the parent cell divide into two identical sets

• mitosis occurs in somatic cell = body cells

• The function of mitosis is to divide the nucleus so that new cells can receive the same chromosomes

• Cell division occurs in a series of stages, or phases

Interphase (Intro)• 'living' phase of the cell, in

which the cell obtains nutrients, grows, copies its DNA, and conducts other "normal" cell functions

• Chromosomes are copied (# doubles): This gives a total of 2 x 46 chromosomes (92)

• Prepares for cell division

• The chromosomes are not visible and the DNA appears as uncoiled chromatin.

Prophase (Prepare)

• Mitosis begins (cell begins to divide)

• chromatin coils and forms chromosomes

• Each chromatid pair (or pairs of chromosomes) is joined together, forming an 'x-shaped'

• The nuclear membrane, nuculeolus, endoplasmic reticulum and Golgi complex break up

• Centrioles (or poles) appear and begin to move to opposite ends of cell

• Spindle fibers form between the poles

Sister chromatids

Centromere

Metaphase (Middle)

• The chromosomes meet in the middle of the cell

• Chromatids (or pairs of chromosomes) attach to the spindle fibers

Sister chromatid

s

Anaphase (Away)• Chromatids (or pairs

of chromosomes) separate

• Chromatids move to opposite ends of the cell towards the poles

• Chromatids end up at opposite poles

Sister Chromatid

s split

Telophase (The end)• Identical set of chromatids at

opposite poles

• Centrioles and spindle fibers disappear

• Chromosomes appear as chromatin (threads rather than rods)

• Nuclear membrane and nucleolus reform

• Cell membrane moves inward to create two daughter cells - each with its own nucleus with identical chromosomes

• Cytoplasm pinches inward

Cytokinesis• cytokinesis is the

division of the cell = 2 daughter cells

• animal cells– cell pinches inward

to form two daughter cells

• plant cells– cell forms a cell

plate which develops into a cells wall separating two daughter cells

Onion Root Tip

http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/01.html