2014

CELL DIVISION - MEIOSIS

Výukový materiál MB 04 - 96Tvůrce: Mgr. Šárka Vopěnková

Tvůrce anglické verze: ThMgr. Ing. Jiří FollerProjekt: S anglickým jazykem do dalších předmětů

Registrační číslo: CZ.1.07/1.1.36/03.0005Tento projekt je spolufinancován ESF a SR ČR

sexual reproduction sexual cells = gametes gamete + gamete = zygote zygote > germ > adult individual gametes have got the half number of chromosomes 46 chromosomes > 2 sets each of 23 chromosome 2 sets of chromosomes = diploid cells one set of chromosomes = haploid cells

MEIOSIS

meiosis completes a special type of cell cycle, by which gametes develop

meiosis = gametogenesis interphase ( G1 , S phase a G2 phase) > meiosis: only one replication of DNA in S phase and two cell divisions followed quickly after each

other therefore - > originated cells are haploid meiosis = reducing division

MEIOSIS

a) first meiotic division = heterotypical reducing:

different from mitosis from 1 diploid cell develop 2 haploid cells b) second meiotic division = homeotypical: Identical with mitosis from 2 haploid cells develop 4 haploid cells

MEIOSIS

a) first meiotic division = heterotypical reducing: prophase: conserved nucleolus and nuclear membrane 2 sets of homological chromosomes pair homological chromosomes attach to each

other = synapsis ( „zip fastening“) pairs of connected homological chromosomes are

called bivalents

MEIOSIS

bivalents are four-thread formations= tetrads recombination process – crossing – over: reciprocal exchange of parts non-sister

chromatids, which are not genetically identical new combinations of gather and mother genes

develop synapsis ends by the isolation of homological

chromosomes

MEIOSIS

metaphase: equatorial plane ! division of centromeres does not happen > neither

chromosomes anaphase: reduction of the chromosome number > to the poles

travel whole, not divided two-chromatid chromosomes

random segregation of father and mother chromosomes > various combinations in gametes

MEIOSIS

telophase ……… b) second meiotic division= homeotypical: normal mitosis 2 haploid cells prophase, metaphase, anaphase, telophase 4 haploid cells originate

MEIOSIS

1) reduction of chromosome number 2) recombination of father and mother genes

by the process crossing – over 3) random meiotic segregation great genetic importance

MEIOSIS - SIMMARY

male (haploid) + female gamete (haploid) = diploid zygote by multiple division of the zygote ( = more

mitosis) the whole organism develops the most cells are diploid (multicellular

organisms) lower plants (non-vascular) + bacteria are

haploid

MEIOSIS

diversification of cells into different types all cells have the same, complete genetic

base they use only a part of the genetic

information by their specialisation

DIFFERENCIATION OF CELLS

PROCESS OF MEIOSIS – A SCHEMA

Genetic schema of miotic division of cell nucleus: a – e heterotypical prophase – a) laptotene b) zygotene c) pachytene d) diplotene e) diakinesis f) heterotypical metaphase (bivalents attached to the threads of division spindle)g) heterotypical anaphase (bichromatide chromosomes from bivalents separate from each

other h) homeotypical prophase i) Homeotypical metaphase j) homeotypical anaphase j) (monochromatide daughter chromosomes go to the poles of the division spindle)

DESCRIBE THE PICTURE

COMPARISON OF MITOSIS AND MEIOSIS

Meioza

I

Meio II.

COMPLETE INTO THE PICTURE

MEIOSIS MITOSIS

SOURCESSOURCES

CHALUPOVÁ-KARLOVSKÁ, Vlastimila. Obecná biologie: středoškolská učebnice : evoluce, biologie buňky, genetika : s 558 řešenými testovými otázkami. 2., opr. vyd. Olomouc: Nakladatelství Olomouc, 2010, 206 s. ISBN 978-807-1822-820

KUBIŠTA, Václav. Obecná biologie: úvodní učební text biologie pro 1. ročník gymnázií. 3. upr. vyd. Praha: Fortuna, c2000, 103 s. ISBN 80-716-8714-6.

ZÁVODSKÁ, Radka. Biologie buněk: základy cytologie, bakteriologie, virologie. 1. vyd. Praha: Scientia, 2006, 160 s. ISBN 80-869-6015-3