MITOSIS
and
ASEXUAL
REPRODUCTION
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.
2.
3.
CHROMATIN: small twisted threads of
DNA in non-dividing cells
CHROMOSOMES: when chromatin
shortens and thickens in dividing cells
(humans have 46 chromosomes)
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 SIMILAR
EXCEPT:
 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 CELL
in 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
spindle microtubules
chromatids
PROPHASE
centromere
Doubled chromosomes become visible (chromatids)
Chromatids connected at a region called the centromere
Two pairs of centrioles move to opposite poles of the cell
Microtubules extend from centrioles forming asters and a
spindle
Some microtubules attach to centromeres of the
chromosomes
Doubled chromosomes move toward the equator of the cell
Nuclear membrane and nucleoli disappear
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
two new nuclei
 Chromosomes reach poles and spindles disappear
 Nuclear membrane forms and nucleoli reappear
 Two identical daughter cells are formed
MITOSIS in a ANIMAL CELL
in 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
Now let’s put it all together
http://www.cellsalive.com/mitosis.htm
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 pairs
2. nucleus
3. nucleolus
4. chromatin
5. asters
6. spindle microtubules
7. centromeres
8. chromatids
9. asters
10. spindle microtubules
11. equatorial plate
12. poles
13. sister chromatids
14. new forming nuclei
15. 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
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
1.
advantages to vegetative
reproduction:
 exact replica
 faster growth than from seed
 produces fruit faster
 gives high yields of fruit and nuts