5.1-5.3 Mitosis, Meiosis

CHAPTER 5: CELL DIVISION

•

•

Cells: •

Wear out after some time

•

Get damaged

•

Grow old naturally and die

Therefore organisms need to produce new cells to : •

•

replace those cells that are worn out, damaged or dead Perpetuate their own species either by asexual or sexual reproduction

Why produce new cells

•

Two types of cell division: a) itosis  b) eiosis

Types o! cells d"#"s"on

easons

Cell division

Cells wear out Cells get damaged Cells grow old and die

•

•

•

(rganisms grow  *eed more cells for reproduction

$"%os"s

Cell divide !by mitosis) to supply new daughter cells that are identical to parents cells

$ignificance Repair of tissues: "dentical new cells to replace worn out or damaged cells# $%in cells and cells lining gut constantly die and are replaced

Growth : ore cells for growth Asexual reprodu reproduction ction: &inary fission &udding 'egetative reproduction

•

itosis produced new cells that genetically identical to their parents to: +#

Continue with the specific cell functions of their parent cells within a particular tissue

#

-vo void id disrupting the stable internal environment of life l ife or its processes

.#

Produce offspring that have complete functions of an adult organism to ensure the survival of that species

$"%os"s

CELL DIVISION : $ITOSIS

Or&'n"('%"on o! ph'ses 'nd su)ph'ses "n ' cell cycle G+

"nterphase

Prophase

$ G

etaphase

Cell cycle

itosis

-naphase

 Phase Cyto%inesis

Telophase

E**ECTS O* +NCONTROLLED $ITOSIS IN LIVIN, THIN,

•

utation : the change in the /*- structure of the cell

•

0ead to uncontrolled mitosis 1 tumors

•

Tumors : •

2ave no function

•

"nterfere with the normal activity of surrounding cells

•

Two Tw o types ty pes : •

&enign tumors

•

alignant tumors

$u%'%"on

•

•

•

•

"nactive, relatively harmless emain at its original site 3 do not spread to other parts of the body $ome may progress to become cancerous tumors if left untreated 4sually treated by surgery, radiation, chemotherapy

-en"&n %u.ors

-en"&n Tu.ors

$'l"&n'n% %u.ors

 APPLICATION O* /NOWLED,E  APPLICAT ON $ITOSIS IN CLONIN,

-pplication of %nowledge on mitosis in cloning

Cloning of microbes

Cell culture 5ermenters

Cloning of  plants

Tissue Tis sue culture cultur e

Cloning of animals

Therapeutic cloning

$omatic cell cloning

eproductive cloning 6mbryo cloning

T"ssue Cul%ure

C'llus

E.)ryo clon" clon"n& n&

So.'%"c Cell Clon"n&

Dolly

$EIOSIS

Species

Diploid chromosomal number of somatic cells (2n)

Haploid chromosomal number (n)

5ruit fly (Drosophila melanogaster)

7

8

2ouse fly (Musca domestica)

+

9

Corn (Zea mays)



+

(nion (Allium sp.)

.

+9

2uman (Homo sapiens)

89

.

Chic%en (Gallus domesticus)

;7

.<

House mouse (Mus muscullus)

8

20

/iploid !n=9) ale parent

/iploid !n=9) offspring 2aploid !n = .) sperm /iploid >ygote !n = 9)

/iploid !n=9) 5emale parent

2aploid !n = .)  egg

6mbryo !n)

 Au%oso.es 0 Se1 Chro.oso.es

•

Two Tw o types of chromosomes: •

-utosomes

•

$ex chromosomes

Chro.oso.es

S!

A"#$S$%S

S! &HR$%$S$% S

S$%A#'& S$%A# '& & & 

ale

88 ?  pairs

@A

88 B @A

emale

88 ?  pairs

@@

** + !!

•

Caused by: •

•

"mproper separation of the chromosomes  *ondisDunction

Down2s Syndro.e

Down2s Syndro.e

$ITOSIS VS $EIOSIS

REVISION

%eiosis

,- : #he crossin. o/er process occur durin. prophase ,2 : #he tetrad (sister chromatids) chromatids) are formed

,rophase Anaphase -

&rossin. o/er

,- : (the crossin. o/er results) in exchan.e of .enetic .e netic material between non sister chromatids

,2 : (which results in) the formation of new combinations of alleles on a chromosome  causes /ariation

Down1s Sndrome