1. Premedical- Biology
Meiosis 1

2. Reproduction The ability to produce new individual organisms,
either asexually from a single parent organism,
or sexually from two parent organisms.
Asexual reproduction
is not limited to single-celled organisms - most plants
- binary fission- Bacteria
- budding - yeasts and Hydras
- conjugation - bacteria may exchange genetic information
parthogenesis, fragmentation and spore formation 2

3. Parthenogenesis lower plants (where it is called apomixis)
Aphis
Aphid
Green-fly
Wingless female giving birth
baby hammerhead
Parthenogenesis
lower plants (where it is called apomixis)
invertebrates - water fleas, aphids, some bees and parasitic wasps
vertebrates - some reptiles, fish, and very rarely birds and sharks
Water flea = dafhnia Perloočky, Cladocera Cladocerans, water fleas Zástupci korýšů Crustacea podtřídy Phyllopoda řádu Cladocera.
and development of embryo or seed without fertilization by a male 3

4. male produce sperm or microspore in anisogamous species
Sexual reproduction
by combination of genetic material
contributed from two different members
of the species
Each contributes half of the offspring's genetic material
male produce sperm or microspore in anisogamous species
and female produce ovum or megaspore
Most organisms form two different types of gametes.
For example, in the green alga, Chlamydomonas reinhardtii, there are so-called "plus" and "minus" gametes.
Most animals (including humans) and plants reproduce sexually. 4

5. called alleles, offspring inherit one allele from each parent
Sexually reproducing organisms
have two sets of genes for every trait
called alleles, offspring inherit one allele from each parent
offspring is combination of parental genes
diploid and haploid phases alternation in cell lines
inbreeding = reproduction from mating of two genetically related parents
inbred line – genesis of homozygote offsprings by sexual reproduction 5

6. Human
reproduction
cycle
Lenght, duration

7. Meiosis
= division of germ cells - reduction of diploid chromosomal number to haploid
- formation of haploid gametes
To manage the most number of various alleles of genes.

8. First meiotic division
M I = reduction 2n = heterotypic
Prophase I:
leptotene – spiralisation of chromosomes
zygotene – pairing of homologous chromosomes –
synapsis - bivalents
synaptonemal complex 8

9. = three levels of protein structure
Synaptonemal komplex
= three levels of protein structure

10. 3. pachytene – each chromosome has two chromatids – tetrades
crossing-over = reciprocal exchange of homologous parts of non-sister chromatids
= recombination of maternal and paternal genetic material
Recombination possibilities between non-sister chromatids
and result products- two chiasmata on one bivalent
a - recombination only between 2 chromatids;
b - 4 chromatids in recombination;
c - 3 chromatids in recombination. 10

11. prerequisite of crossing-over = chiasma formation
4. diplotene – separation of homologs, connected only in sites of chiasmata.
prerequisite of crossing-over = chiasma formation
5. diakinesis – terminalisation of chiasmata and
maximal contraction of chromosomes
Metaphase I – lining of bivalents in equatorial plane of the cell. Chromosomes from the pairs split. 11

12. spermiogenesis, unequal in oogenesis
Anaphase I – migration of homologous chromosomes to the opposite poles - random according to their parental origin
Telophase I - chromosomes in opposite poles
Cytokinesis – division of cytoplasm - equal in
spermiogenesis, unequal in oogenesis
Interkinesis – a phase without replication

13. Second meiotic division
M II – homeotypic n
in Prophase II division and separation of centriols – spindle of microtubules
in Metaphase II centromers of chromosomes split
in Anaphase II separation of chromatids 13

16. Gametogenesis migration of primordial germ cells to the gonads
– formation of gametes
migration of primordial germ cells to the gonads
during early fetal development number of mitotic division

17. Spermatogenesis
is continuous process, which starts in the time of sexual maturity (top off testosteron threshold)
growth MI
mitotic division - spermatogonia primary spermatocyte (dipl)
M II
2 secondary spermatocytes (hapl) spermatids
diferentiation-spermiogenesis
4 sperm
1 cycle = about 10 weeks 17

19. 3 month of fetal life diplotene=dictyotene growth at the time of birth
Oogenesis
M I to the end of prophase
3 month of fetal life diplotene=dictyotene
growth at the time of birth
Oogonia primary oocyte (dipl)
mitotic division
in the time of sexual maturity M II
M I continues secondary oocyte ovulation in metaphase II st polar body
anaphase II + telophase II only after fertilization
oocyte
+ 2nd polar body 19

21. Oogenesis prenatal oogonia Mitotic division growth M I meiosis M II
primary oocyte
secondary oocyte
growth
M I
M II
meiosis
1st polar body
2nd polar body
3rd month of fetal life - Dictyotene MI division stops
at time of birth
Sexual maturity- Metaphase MII - ovulation
Fertilization – pronucleus
Ovum after MII pronucleus
Anaphase II, Telophase II only after fertilization
prenatal
zygote
egg cell
Sexual maturity
Oogenesis 21

22. Oogenesis a fertilization
I. meiotic division
polar body
oogonia
primary secondary
oocyte n 2n
fertilization a II. Meiotic division

23. 23

24. Differences in gametogenesis Male Female
Initiation Puberty Early embryonic life
Duration cca 72 days years
Numbers of mitoses
in gamete formation
Gamete production spermatids ovum+3 polar bodies
Gamete production million ovum per menstrual
per ejaculate cycle 24

25. Degeneration of germ cells in ovary
5th month of fetal life x of cells
time of birth x of cells
puberty of cells
ovulated of cells
Long period between M I and ovulation = factor of high probability of nondisjunction 25

26. Consequences of meiosis
reduction of diploid chromosomal number to haploid
segregation of alleles in M I, M II (2st Mendel´s law)
3. random assortment of homologues – random combination maternal and paternal chromosomes in gametes (3nd Mendel´s law)
4. increase of genetic variability by crossing-over (chromatids with segments of maternal and paternal origin) 26

27. Genetic determination of sex
23,Y 27

28. If you feel small, low-spirited and useless, remember:
Thanks to the perfect
Ovum and the fastest Sperm
and their genetic information, YOU ARE ABSOLUTELY UNIQUE
and NOT REPEATABLE ELEMENT
IN THE WHOLE UNIVERSE

29. Thank you for your attention
Campbell, Neil A., Reece, Jane B., Cain Michael L., Jackson, Robert B., Minorsky, Peter V., Biology, Benjamin-Cummings Publishing Company, 1996 –2010.

30. Repetition 7. Regulation of gene expression
1. What is the difference between prokaryotic and eukaryotic regulation of gene expression?
2. What is operon and how does it work? Example?
3. Which steps on the path between eukaryotic gene and protein can be regulated?
4. What does it mean „imprinting“?
5. What is the purpose if acetylation and deacetylation of histones?
6. What is the function of transcription factors?
7. What is alternative splicing?
8. Do you know any post-translational modifications?
9. How are proteins degradated?
10. What is the „central dogma“ of biology? (path of genetic information)