MITOSIS and ASEXUAL REPRODUCTION. Vocabulary 1. MITOSIS: when the nucleus divides to form two nuclei...

MITOSISandASEXUALREPRODUCTION

Vocabulary

1. MITOSIS: when the nucleus divides to form two nuclei and the hereditary material duplicates and divides into two identical sets

2. CYTOKINESIS: when the cytoplasm divides into two parts

Forms of DNA

1. CHROMATIN: small twisted threads of DNA in non-dividing cells

2. CHROMOSOMES: when chromatin shortens and thickens in dividing cells (humans have 46 chromosomes)

3. CHROMATIDS: Sister chromatids are when a chromosome replicates and then the two join together to make sister chromatids. A chromatid is just one of them. They are just one chromosome.

ASEXUAL REPRODUCTION only one parent no special reproductive cells involves mitosis and cytokinesis each offspring has identical hereditary

information little variation in the species usually rapid and produces large

numbers of offspring

SEXUAL REPRODUCTION

involves special reproductive cells usually two separate parents (or two

sexually different parts from one organism)

produces offspring genetically different from the parents

show combinations of characteristics ensures survival of the species by

making the population more varied

ASEXUAL REPRODUCTION IN PLANTS AND ANIMALS ARE SIMILAREXCEPT:

Animals have centrioles Plants - do not have centrioles

(spindles still form in plants) Animals – cell membrane

pinches in Plants – cell plate forms across

the middle of the cell and joins with the cell wall to divide the cell

MITOSIS in a ANIMAL CELLin the nucleus

INTERPHASE(end of interphase – just before cell division begins)

The cell’s resting state between mitotic cycles

The cell grows

Each chromosome duplicates (becomes a double chromosome)

Centrioles duplicate

PROPHASE

Doubled chromosomes become visible (chromatids)Chromatids connected at a region called the centromere Two pairs of centrioles move to opposite poles of the cellMicrotubules extend from centrioles forming asters and a spindleSome microtubules attach to centromeres of the chromosomesDoubled chromosomes move toward the equator of the cellNuclear membrane and nucleoli disappear

chromatids

spindle microtubules

centromere

METAPHASE

Doubled chromosomes line up at the equator

Centromeres divide and doubled chromosomes become separate chromosomes

ANAPHASE

Duplicate chromosomes move to opposite poles Microtubules of the spindle help this movement One complete set of chromosomes are at each pole

TELOPHASE

Chromosomes reach poles and spindles disappear

Nuclear membrane forms and nucleoli reappear

Two identical daughter cells are formed

two new nuclei

MITOSIS in a ANIMAL CELLin the cytoplasm

CYTOKINESIS

In late anaphase and telophase

Pinching in of the cell membrane

Daughter cells receive• half of the cytoplasm• one of the nuclei• half of the cell organelles

http://www.cellsalive.com/mitosis.htm

Now let’s put it all together

http://www.johnkyrk.com/mitosis.html

http://www.loci.wisc.edu/outreach/bioclips/CDBio.html

MITOSIS in a PLANT CELL

Similar process in plant and animal cells except

no centrioles in the plant – but spindles do form

cell membrane does not pinch in due to the rigid cell wall

a cell plate forms across the middle of the cell that divides the cell into two

MITOSIS in a PLANT CELL

Interphase and Mitotic Cell Division in Animal Cells

Fill in numbers 1 – 15 on the diagrams

1. centriole pairs2. nucleus3. nucleolus4. chromatin5. asters6. spindle microtubules7. centromeres8. chromatids9. asters10.spindle microtubules11.equatorial plate12.poles13.sister chromatids14.new forming nuclei15.pinching in of the nuclear membrane

Complete the worksheet on page 7 in your packet

BIANARY FISSION(IN AN AMEOBA)

one cell divides into two daughters (no parent left)

one celled organisms (bacteria, protozoa, algae)

BUDDING(IN YEAST)

parent divides into two unequal cells

new individual buds out of outer surface of parent

may break off or remain on to form a colony

yeast, hydra, sponges, and some worms

SPORE FORMATION

specialized cells released from parent (large numbers) has all parts of the cell and grows into new individual covered by hard outer wall fungi, algae, protozoa

REGENERATION

the ability of an organism to regrow lost parts

regeneration power decreased as organism becomes more complex

usually not used for reproduction purposes

hydra, planaria, starfish, earthworm

VEGATATIVE REPRODUCTION when roots, stems, or leaves give rise to a

new plant two kinds

1. Natural bulbs (tulips, onions) corms (gladioli, crocuses) tubers – large underground

stems (potatoes) runners (stolons) – sideways

surface growing stem (strawberries)

rhizomes – sideways underground growing stem (ferns, irises)

2. Artificial cutting – any part of a plant that

is used to produce a new individual

advantages to vegetative reproduction:

exact replica faster growth than from seed produces fruit faster gives high yields of fruit and nuts