Asexual Reproduction

and Mitosis

SB2 e: Compare the advantages of sexual reproduction and asexual

reproduction in different situations

Occurs only through the process of mitosis

Each offspring has the same genetic information

Where can asexual reproduction be found?

BACTERIA YEAST PLANTS

There are 5 different types of asexual reproduction.

1. Budding

Parent divides unequally; new individuals develop from budsex – yeast & hydra

2. Binary Fission

Most simple form of asexual reproduction; Parent divides equally and results in two separate individualsEx.-paramecium, bacteria

3. Spore Formation

Single specialized cells that germinate when released from parent. Usually covered by a protective coating for preservation.

4. Regeneration/fragmentation

Ability to regrow new body parts/ability to grow new Organism from parts.ex – hyrda, planaria, starfish, the bad guy from Terminator 2

5. Vegetative Reproduction/Propagation

Refers to roots, stems, and leaves. Cells divide then differentiateto produce the same organismEx.- strawberry plant, pick-a-back plant

Period of time from one division to the next

Unicellular division results in formation of new individuals of the species

Multicellular division results in replacement of old or damaged cells

Process by which the nucleus divides while maintaining number of chromosomes

Division of the cytoplasm

Asexual Reproduction

Reproduction that only involves one parentso therefore no special reproductive organsare needed

Cell Cycle

Mitosis

Cytokinesis

Nuclear DNA wound around proteins knownas histones

Condensed rolls of chromatin that are able to be seen during mitosis (rod-like structures)

There are 5 phases in MITOSIS

Interphase

MetaphaseProphase

AnaphaseTelophase

Chromatin

Chromosomes

Cytokinesis

Interphase Known as “resting phase”

•Cells grow in size by producing more nucleic acids, proteins,and cellular organelles

•Chromosomes make copies of themselves, but they can’t be •seen

•Nucleus of the cell is contained within the nuclear envelope

•Centrioles are present and duplicate themselves

Mitosis Begins

• Mitosis is the division of the nuclei• Happens in somatic/ body cells

Prophase

•Double chromosomes become visible - Chromatid

•Chromosomes are 2 sister chromatids connected by a centromere

Centromere

Sister Chromatids

•At the beginning, centrioles move to opposite poles

•Spindle fibers attach

•By the end, the nuclear envelope and nucleus have disappeared

EARLY LATE

DON’T DRAW

Metaphase= “Middle”

•Centromeres line up on the middle

Anaphase= “Away”•Daughter chromosomes move to opposite sides of cell (poles)

Telophase=“The End”

•Chromosomes uncoil and return to previous shape (threadlike)

•Nuclear membrane and nuclei reform

NOTE: Cytokinesis begins during late anaphase and finishes during telophase

• Two identical daughter cells are formed.• Each cell has the diploid (2n) number of chromosomes.• In humans this is 46 chromosomes.

Cytokinesis

Same as mitosis in animals except:

• Plants have no centrioles – spindle fibers take their place

• Asters do not form

• Cell wall does not pinch because it is too rigid

• Cell plate divides the cell into two