biology

1. SEXUALAND ASEXUAL
REPRODUCTION
Evangeline D. Pascual
Institute of Biological Sciences, UPLB

2. Objectives
1. Differentiate sexual from asexual reproduction in terms
of
i. number of individuals involved
ii. similarities of offspring to parents
2. Describe the process of fertilization

3. Sexual Reproduction

4. Offspring inherits genetic material from
two parents (1/2 from each)

5. Three sexual life cycles
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Animal Plants & some algae Fungi & some protists

6. The Human
Life Cycle
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
fertilization restores
diploid condition
- combining two
haploid sets of
chromosomes

7. Reproductive System
• automatic classification
• which set of sex organs we have

8. Male Reproductive System

9. Female Reproductive System

10. Sex Determination

11. FERTILIZATION
- when egg and sperm meet
a. external
- female sheds eggs
-male fertilizes eggs in the environment
- moist habitats
-sea urchins, fish, amphibians

12. Fertilization
b. internal
- sperm deposited in/nearby
female reproductive tract
- thousands of sperms surround egg
but only one can enter

13. http://library.med.utah.edu

14. http://www.biocyclopedia.com

15.  10 hrs
 18 cm
 48 hours
 hundreds, only one
 (Picture: "From Conception to Birth"
by Alexander Tsiaras and Barry
Werth)
Sperm cells

16. • http://londonstimestshirts.files.wordpress.com/

17. http://www.cabrillo.edu

18. a. First trimester
- fertilization
- division of zygote
- blastocyst implantation
- placenta
- organogenesis
- heartbeat by four weeks!
Human Pregnancy

19. Fertilization and implantation

21. Pregnancy test

22. www.natlstar.com

23. Sexual Reproduction in Plants

24. Development of a male gametophyte
(in pollen grain)
(a)
Microsporangium
(pollen sac)
Microsporocyte
Microspores (4)
Each of 4
microspores
Generative cell
(will form 2 sperm)
(LM)
75 m
20 m
MEIOSIS
MITOSIS
Male
gametophyte
(in pollen grain)
Nucleus of tube cell
Ragweed pollen grain
(colorized SEM)
Key to labels
Haploid (n)
Diploid (2n)

25. (b) Development of a female gametophyte
(embryo sac)
100m
MEIOSIS
MITOSIS
Key to labels
Haploid (n)
Diploid (2n) (LM)
Embryo sac
Ovule
Megasporangium
Megasporocyte
Integuments
Micropyle
Surviving
megaspore
Antipodal cells (3)
Polar nuclei (2)
Egg (1)
Synergids (2)
Ovule
Integuments
Femalegametophyte
(embryosac)

26. http://mac122.icu.ac.jp/gen-ed/higher-plants-etc-gifs/10fl-plant-life-

27. b. Plant Reproduction
• http://www.fs.fed.us/wildflowers/pollinators/whatispollination.sht
ml

28. • http://www.washingtonch.k12.oh.us

29. • www.ag.auburn.edu

30. • http://www.esu.edu

31. botanistinthekitchen.wordpress.com

32. Asexual Reproduction
 like begets like
- offspring whose genes all come from one
parent
- without fusion of egg and sperm

33. Asexual Reproduction
- relies entirely on mitosis
single individual – sole parent
offspring
- genome = exact copy of parent's

34. http://search.dilbert.com/

35. Asexual Reproduction
 Invertebrates
1. Fission – parent divides
approximately in half
ex. sea anemone

36. Sea anemone
Longitudinal fission involves a complete
lengthwise split creating 2 individuals
http://creationwiki.org/Image:Anemone129181039_689f020
1bf.jpg

37. Asexual Reproduction
2. Budding – new individuals split off from
existing ones
ex. Hydra (relative of jellyfish)
- bud: localized mass of
mitotically dividing cells

39. Asexual Reproduction
3. Fragmentation and regeneration
– breaking of the body into
several pieces
- develop into adults
ex. sponges

40. Asexual Reproduction
 Advantages:
- animals that live in isolation produce
offspring without locating mates
- many offspring in a short amount of
time

41. Asexual Reproduction
Plants
1.Vegetative reproduction
- modified stems
- runner, rhizome, corm, tuber, bulb

43. Ginger rhizome
http://en.wikipedia.org/wiki/File:Gingembre.jpg
taro
Taro corms Colocasia esculenta
http://en.wikipedia.org/wiki/Colocasia_esculenta

44. • http://waynesword.palomar.edu/

45. Asexual Reproduction
 horizontal stem
- runner : aboveground
- rhizome : underground

46. Asexual Reproduction
- Tuber : enlarged tip of slender rhizome
 short underground stem
- Bulb : with overlapping fleshy scales
- Corm : with less or no scales

47. Tuber
Bulb
CormRhizome
Runner

48. gladiolus
• www.e-bloomin.com urbanext.illinois.edu

49. www.bryophyllum.com

50. Asexual Reproduction
2. Parthenogenesis
- embryo without nuclear/cellular
fusion or from tissue
surrounding embryo sac

51. Asexual Reproduction
3. Vegetative propagation
 cuttings
 grafts
 leaves
www.pinterest.com

52. Artificial Vegetative Propagation
• Cutting- use of plant to
reproduce (Ex. )
• Layering- stem is over and covered with
 will root and form plant (Ex. )
• Grafting- stem or bud of one plant is
to another plant
(Ex. )
part
Spider plant
bent soil
new raspberry
joined
Seedless fruit tree
permanently

53. Modes of Reproduction
4.Tissue culture
propagation
- new plant induced
to arise from
cell/tissue
- orchid, rice, corn,
wheat

55. Summary
Sexual Reproduction
• Two parents
• Offspring are a
combination of both
parents and are therefore
different from each parent
• Variation/diversity
Asexual Reproduction
• Single parent
• Offsprings are identical to
parents