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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