DNMU bilology lecture 6

1. Theme:
REPRODUCTION

2. PLAN OF LECTURE
1. THE FORMS OF REPRODUCTION
2. ASEXUAL REPRODUCTION
3. SEXUAL REPRODUCTION
4. GAMETOGENESIS
5. FERTILISATION

3. STUDENTS' INDEPENDENT STUDY PROGRAM
1. Evolution of the forms of reproduction: asexual and sexual
reproduction.
2. Asexual reproduction in unicellular and multicellular
organisms.
3. Sexual reproduction in unicellular and multicellular
organisms.
4. Spermatogenesis and oogenesis.
5. Morphogenetical specialisation of sex cells: a sperm and
an ovum
6. Fertilisation: an egg's activation and syngamy.
8. Natural and artificial parthenogenesis.
9. Biological peculiarities of human reproduction.
Applicable literature materials:
Medical biology / K. L. Lasarev – Simferopol:
IAD CSMU, 2002. pp. 58 - 74.

4. Reproduction is the method by
which individuals give rise to
other individuals of same type.
Reproduction can be asexual
and sexual.
At an asexual reproduction the
genetic information does not
vary.
In a basis of an asexual
reproduction the mitosis lays.

5. SEXUAL REPRODUCTION
AT SEXUAL REPRODUCTION THE
GENETIC INFORMATION VARIES AS A
RESULT OF COMBINATION.
IN A BASIS OF SEXUAL
REPRODUCTION THE MEIOSIS LAYS
AS A SOURCE COMBINATION OF
VARIABILITY.

6. TYPES OF ASEXUAL REPRODUCTION IN
SINGLECELLULAR ORGANISMS
1.BINARY FISSION
2.BUDDING
3.ENDODIOGENY
4.SHIZOGONY (OR MULTIPLE FISSION)
5.SPOROGONY

7. 1.BINARY FISSION –
PARENT CELL SPLITS IN TWO CELLS.

8. ENDODIOGENY –
IN PARENT CELL FORMS ONLY TWO
DAUGHTER CELLS BY INTERNAL BUDDING.

9. BUDDING - AFTER KARYOKINESIS THE SPECIAL
REGION IN PARENT CELL RAPID GROWS AND
ORGANIZED INTO NEW ORGANISM.

10. Sporogony - is reproduction by the
spores, if its are the result of
mitosis.
• Shizogony (or multiple fission) -
in parent cell forms a great
amount of daughter cells.

13. THE TYPES OF ASEXUAL REPRODUCTION IN
MULTICELLULAR ORGANISMS
The types of asexual reproduction in
multicellular organisms are:
1) Vegetative (regeneration) - a group of cells
from the parent organism separates and
new organism forms from its.
2) Polyembrionya - the production of two or
more embrions from the one zygote.
3) Sporogony - is reproduction by the spores, if
its are the result of mitosis.
As result of asexual reproduction is that
offspring is genetically identical to its
parent.

14. VEGETATIVE (REGENERATION)

15. POLYEMBRIONYA

17. The Types of Sexual Reproduction in
Single-cellular Organisms
• The types of sexual reproduction in
singlecellular organisms are:
1)Conjugation - a cytoplasm bridge forms
between two organisms, the nuclei transfer
across this bridge and after exchange ones
forms a new gene combination but no new
offspring.
2)Copulation - two individuals acquire the
gametes properties, fuse and form a zygote
the life of a new individual begins.

19. Types of reproduction on the value of
gametes
• Isogamy - observes at the first stages of
sexual reproduction, in which the gametes
morphological differentiation doesn't
present.
• Anisogamy - is such period of gamete
differentiation in which they become some
different from each other by their sizes:
some of them are smaller and another are
the largest.
• Ovogamy - is the form of anisogamy in
which gametes are very different from
each other.

20. Isogamy -
Anisogamy -
Ovogamy -
Conjugation -

22. The Types of Sexual Reproduction in
Multicellular Organisms
• In multicellular organism sexual
reproduction may be two forms:
• 1) with fertilisation and
• 2) without fertilisation.
• Parthenogenesis is the types of
sexual reproduction when
development of new organism from
an egg without fertilisation.

23. PARTHENOGENESIS

25. GAMETOGENESIS (making gametes) –
the development of the male
and female sex cells, or gametes

26. REPRODUCTIVE CELLS OR GAMETES
GAMETES ARE FORMED AFTER
COMPLETION OF THE PROCESS OF
MEIOSIS, WHICH HALVES THE NUMBER
OF CHROMOSOMES. MALE GAMETES
ARE MOTILE, WHEREAS FEMALE
GAMETES ARE LARGER AND ARE
STATIONARY; THE FUNCTION OF THE
LATTER IS TO STORE SUPPLIES OF
FOOD FOR THE DEVELOPING EMBRYO.

27. Gametogenesis is divided into four periods:
1) reproduction (multiplication), 2) growing,
3) maturation and 4) formation.

28. TESTIS

29. SPERMATOGENESIS
SPERMATOZOON DEVELOPMENT BEGINS IN
SPERMATOGONIA.
A DIPLOID SPERMATOGONIUM DIVIDES MITOTICALLY
AND BECOMES A PRIMARY SPERMATOCYTE AS IT
MOVES TOWARD THE LUMEN OF THE TUBULE. IN
MEIOSIS-I, EACH SPERMATOGONIUM HALVES ITS
GENETICALLY MATERIAL TO FORM TWO SECONDARY
SPERMATOCYTES.

30. In meiosis II, each secondary
spermatocyte divides to yield
two equal - sized spermatids.
Therefore, each cell
undergoing meiosis in male can
potentially divide to yield a
maximum of four spermatids.

31. Spermatogenesis

33. SPERMATOZOON STRUCURE
THE HEAD HAS A HAPLOID NUCLEUS.
AN ACROSOME - A SMALL BUMP ON THE
FRONT END OF THE HEAD CONTAINS ENZYMES
THAT HELP THE CELL PENETRATE THE OVUM'S
OUTER MEMBRANE.
THE BODY OR MIDPIECE HAS MITOCHONDRIA
TO PROVIDE THE CELL ENERGY AND
CENTRIOLES.
A TAIL CONSISTS OF MICROTUBULES FOR
MOVING.

34. EACH
SPERMATOZOON
CONSISTS OF:
1)A HEAD
REGION;
2) A BODY OR
MIDPIECE;
3) A TAIL OR
FLAGELLUM.

36. OOGENESIS - (EGG-MAKING) BEGINS
IN A DIPLOID OOGONIUM.
AN OOGONIUM ACCUMULATES
CYTOPLASM AND REPLICATES ITS
CHROMOSOMES, BECOMING A PRIMARY
OOCYTE. IN MEIOSIS I, THE PRIMARY
OOCYTE DIVIDES TO FORM A SMALL POLAR
BODY AND A LARGE, HAPLOID SECONDARY
OOCYTE.

37. IN MEIOSIS II, THE SECONDARY OOCYTE
DIVIDES TO YIELD ANOTHER SMALL POLAR
BODY AND A MATURE OVUM.
THEREFORE, EACH CELL UNDERGOING
MEIOSIS IN FEMALE CAN POTENTIALLY
DIVIDE TO YIELD MAXIMUM OF FOUR
CELLS, ONLY ONE OF WHICH WILL BECOME
THE OVUM.

38. Ovary

39. OOGENESIS

40. AN OVUM (THE NAME FOR AN EGG CELL
AFTER IT LEAVES AN OVARY) IS ENORMOUS IN
SIZE.
CORONA RADIATA OUTSIDE THE CELL
CONSISTS OF THE GREAT AMOUNT OF
FOLLICULAR CELLS, WHICH PRODUCE
FOLLICULAR FLUID FOR ATTRACTING THE
SPERMS.

42. Corona radiata
Zona pellucida
Nucleus
Cytoplasm with
various inclusion
bodies, including
mitochondria
REPRESENTATION
OF HUMAN EGG

43. Ovulation - dischange (going out) of a
secondary oocyte from a follicule of the ovary.

44. FERTILISATION
The fusion of haploid
gametes to form a new diploid
cell is called fertilisation .
During fertilisation two
processes take place:
1. EGG'S ACTIVATION
2. SYNGAMY

45. EGG'S ACTIVATION

46. EGG'S ACTIVATION - A WAVE OF
CHEMICAL REACTIONS SWEEPS
ACROSS THE SURFACE OF THE NEWLY
AROUSED EGG, CAUSING THAT
SURFACE TO HARDEN AND PRESENT A
BARRIER TO THE ENTRY OF ANY
ADDITIONAL SPERM. THE EGG'S
OXYGEN CONSUMPTION SKYROCKETS,
AS DOES ITS RATE OF PROTEIN
SYNTHESIS.

47. EGG'S ACTIVATION

48. FERTILIZATION

49. SYNGAMY
- MALE AND FEMALE HAPLOID
NUCLEI CONVERGE AND FUSE
TO FORM THE ZYGOTE'S SINGLE
DIPLOID NUCLEUS.

50. S
Y
N
G
A
M
Y

51. SYNGAMY

52. As a result of
a fertilization
the zygote
will be
derivated,
the embryo
begins to
develop.

54. Toxic exposures such
as alcohol, cocaine
ets.,
may change the
process of normal
gametogenesis
resulting in genetic
material mutation in
sex cells.
The alteration of
these cells by toxic
substances provokes
birth defects.

55. Key words and phrases:
mitosis, asexual and sexual reproduction,
generation replacement, cloning, sex cells,
gametogenesis, meiosis, biological peculiarities of
human reproduction, endogony, shizogony,
budding, sporogony, polyembrionya, sexual
reproduction, conjugation, copulation,
parthenogenesis, oogenesis, polar body, primary
oocyte, secondary oocyte, spermatogenesis,
primary spermatocyte, secondary spermatocyte,
spermatid, ovum, spermatozoon, ovary, ovulation,
fertilisation, syngamy, zygote .

58. THE
END