1. Reproduction
Humans and Plants

2. Reproduction Individual organisms do not live forever.
Therefore the continuity of a species relies on
individuals reproducing.
There are two types of reproduction: asexual reproduction and sexual reproduction.

3. Two Types of Reproduction
Asexual
Offspring are produced by a single parent
Found in stable environments to which they are very well suited
No sperm and egg
Sexual
Involves the fusion of two gametes (sex cells), one from a male and the other from a female
Diversity allows adaptation to changing environment
Egg and Sperm

4. Asexual Reproduction Methods
There are several ways an organism may reproduce asexually:
Fission and Budding
Fragmentation
Spore Formation
Vegetative Reproduction
Parthenogenesis

5. Fission and Budding
Fission is common among unicellular organisms such as bacteria
occurs when a parent cell splits into two daughter cells forming a new organism
Budding can be seen in unicellular organisms and small multicellular animals
similar to fission except that the division of the cytoplasm is unequal and the new individual arises from an outgrowth, or bud, from the parent

6. Fission and Budding

7. Fragmentation
Fragmentation occurs in multicellular organisms when the body of the organism breaks into two or more parts each of which will form a new organism
common in flatworms, marine worms, and echinoderms (starfish)
With worms and new individual may form when the worm gets so long that it simply falls apart forming new organisms.

8. Spore Formation
Spores are formed by fungi and are often contained within a structure known as a sporangium which will disintegrate releasing the spores into the environment
When a spore lands in a suitable environment it will germinate forming a new fungus.
Spores are formed by budding.

9. Vegetative Reproduction
Many plants are capable of vegetative reproduction which is the separation of one plant to form a new, independent plant
Vegetative reproduction may arise from many parts of a plant including the leaves and underground stems

10. Parthenogenesis
Parthenogenesis is the development of an unfertilized egg into a new individual that is a clone of the parent
In order to obtain the needed diploid set of chromosomes the egg will often duplicate by mitosis and then fuse to give the egg two sets of chromosomes.
Animals that are parthenogenic include bees, wasps, ants, and some species of birds and lizards.

11. Parthenogenesis
The fertilized eggs of bees, wasps and ants will develop into females
A population of these organisms in some regions may be composed entirely of female organisms
An unfertilized egg however will duplicate by mitosis, fuse to form a diploid cell, then further divide and form into males

12. Hermaphrodite
Both male and female sex organs

13. Sexual Reproduction Sexual reproduction involves:
Gamete production by a type of cell division called meiosis
Normal body cells have a diploid number of 46 chromosomes
Gametes have the haploid number of 23 chromosomes
When the gametes fuse, they form a zygote with the diploid number of 46 chromosomes
Further mitotic divisions allow the zygote to grow and produce a large number of cells that differentiate to form the various different types of tissues that make up the new individual

15. Reproductive Systems
Reproductive systems are composed of primary and secondary sex organs
In animals the primary sex organs which produce the gametes are the ovaries in females and the testes in males
Secondary sex organs include:
various glands that produce nutrition and lubrication for gametes
ducts and chambers that provide areas for storage and development of the gametes
organs for mating and protection of the developing embryo

16. Fertilization Fertilization can be:
Internal: reptiles, birds and mammals
External: most fish and amphibians

17. Process of Fertilization in Animals
Upon meeting the ovum, sperm start to break down the jelly coated membrane
Only one sperm head containing the nucleus will enter the egg
Once the sperm has entered the egg, the membrane changes so that no other sperm can enter
is the fusion of gametes to produce a new organism.

18. Human Reproduction

19. Development of Gametes

20. Male Gametes
Male gametes are called sperm and are produced in the testes
acrosome – releases enzymes to penetrate egg
nucleus – contains DNA
mitochondria – energy to swim
tail – to swim
- delivers sperm
- stores sperm
- produces sperm and testosterone
- keeps sperm 1–2 ° lower than body temperature

21. fluids for transport and nutrition of sperm
Structure of Male Reproductive System
kidney
urinary bladder
ureter
urethra
seminal vesicle
prostate gland
vas deferens
penis
scrotum
epididymis
testis (testes)
fluids for transport and nutrition of sperm

22. Female Gametes
Female gametes are called ova (eggs) and are produced in the ovaries
Cytoplasm – storage of food for ovum
Nucleus – contains DNA
Membrane – hardens after one
sperm enters to keep others out
- where baby develops
- muscle that opens for baby to be born
- receives sperm
produces eggs -
and hormones
egg fertilization and
travel -
- where embryo implants

23. Structure of Female Reproductive System
kidney
ureter
fallopian tube
ovary
urinary bladder
uterus
urethra
cervix
vagina

24. Egg Development in Ovary
Females are born with all the egg cells they will ever have, but they are not completely developed
By puberty, a female’s ovaries contain about 400,000 follicles, each containing a primary oocyte (egg cell)
Every 28 days or so hormones cause one follicle and egg to mature, break open and the oocyte is released

25. Human Egg Fertilization

26. Male Gamete Female Gamete
Male Gamete
Female Gamete
Size
Relatively smaller
Relatively larger
Key
Structures
Head (nucleus and acrosome)
Middle piece (mitochondria)
Tail (flagellum)
Nucleus
Outer membrane (jelly coat)
Large amount of cytoplasm
Relative Numbers
50 million million sperms released during ejaculation
1 ovum matured and released each month
Motility
Motile (able to move by propelling its tail)
Mobile (Passive movement due to action of cilia and peristalsis of oviduct wall)
X or Y Chromosomes
Each sperm contains either an X or a Y chromosome
All ova contain only the X chromosome

28. Plant Reproduction

29. Alternation of Generations
All land plants undergo alternation of generations.
In this process, individuals have a multicellular haploid phase called the gametophyte and a multicellular diploid phase known as the sporophyte.
The two phases of the life cycle are connected by distinct types of reproductive cells—gametes and spores.

30. All Land Plants Undergo Alternation of Generations2.
FERTILIZATION
Gametophyte (n; multicellular, haploid)
MITOSIS
MEIOSIS
Sporophyte (2n; multicellular, diploid)
Spores (n)
Haploid (n)
Diploid (2n)
Gametes (n)
Zygote (2n) 1. 3. 5. 4.
Alternation of generations always involves the same five key events:
(1) Haploid gametophytes produce haploid gametes by mitosis.
(2) Two gametes unite during fertilization to form a diploid zygote.
(3) The zygote divides by mitosis, developing into a multicellular, diploid sporophyte.
(4) The sporophyte produces haploid spores by meiosis.
(5) Spores divide by mitosis and develop into a haploid gametophyte.

31. Gametophyte-Dominated Life Cycles Evolved Early
Haploid (n)
Diploid (2n)
Eggs form in archegonia
Sperm form in antheridia
Sperm swim to egg
Spores (n) are produced in sporangia by meiosis, dispersed by wind
Mature sporophyte     (2n)
Egg (n)
Zygote (2n)
Developing sporophyte (2n)
Archegonium
Mature gametophyte (n)
Developing gametophyte
Spore (n)
FERTILIZATION
MITOSIS
MEIOSIS
Mosses: Gametophyte is large and long lived; sporophyte depends on gametophyte for nutrition.

32. Sporophyte-Dominated Life Cycles Evolved Later
Ferns: Sporophyte is large and long lived but, when young, depends on gametophyte for nutrition.
Spore (n, dispersed by wind)
Mature gametophyte (n, underside)
Sperm develop in antheridia
1 mm
Eggs develop in archegonia
Sperm swim to egg
Zygote (2n)
Sporophyte (2n; develops on gametophyte)
Developing gametophyte (n)
Spores are produced in sporangia
Gametophyte (n; side view)
Mature sporophyte (2n)
FERTILIZATION
MITOSIS
MEIOSIS
Archegonium

33. Heterospory
Another important innovation found in seed plants is heterospory, the production of two distinct types of spores, male and female.
The two types of spore-producing structures in heterosporous species are microsporangia and macrosporangia.
Microsporangia produce microspores that develop into male gametophytes that produce sperm.
Macrosporangia produce megaspores that develop into female gametophytes that produce eggs.
Thus, the gametophytes of seed plants are either male or female, but never both.

34. Pollen
When pollen evolved, heterosporous plants lost their dependence on water for fertilization.
Seeds
Seeds allow embryos to be dispersed to a new habitat, away from the parent plant.
Seeds are often dispersed by wind, water, or animals.
The evolution of heterospory, pollen, and seeds triggered a dramatic increase of seed plants starting about 290 million years ago.

35. Heterospory (micro- and megaspores) in Gymnosperms
Mature sporophyte (2n)
Developing sporophyte
Seed (disperses via wind or animals)
Embryo (2n)
Ovules (contain megasporangia)
Ovulate cone
Female gametophyte (n)
Archegonia
Eggs (n)
Mother cell (2n)
Pollen produces sperm
Cones with microsporangia
Microspore (n) forms pollen grain
Pollen grain (male gametophyte
Megasporangium
Pollen grain
Megaspore divides to form female gametophyte (n), which produces archegonia and eggs by mitosis. (Only one egg is fertilized and develops.) Note that the red dots here and elsewhere represent nuclei
Pollen grains disperse via wind
Four meiotic products; one is large and forms the megaspore (n)
Three meiotic products die
MEIOSIS
MITOSIS
POLLINATION
FERTILIZATION
MITOSIS

36. Flowers
Flowering plants, or angiosperms, are the most diverse land plants living today. About 250,000 species have been described, and more are discovered each year.
The success of angiosperms in terms of geographical distribution, number of individuals, and number of species revolves around a reproductive organ: the flower.
Flowers contain two key reproductive structures: stamen and pistils (carpels).
The stamen contains the anther, where microsporangia develop.
The pistil (carpel) contains the ovary in which the ovules are found. Ovules contain the megasporangia.

37. Heterospory in Angiosperms
Megasporangium
Sperm travel down growing pollen tube to reach egg
Pollen lands near female gametophyte; produces pollen tube and sperm
Pollen grains disperse via wind or animals (the red dots here and elsewhere are nuclei)
Nutritive tissue
Embryo (2n)
Developing sporophyte
Seed (disperses via wind or animals)
Zygote (2n)
Endosperm (3n) forms nutritive tissue in seed
Mature sporophyte flower (2n)
Flower
Ovule
Ovary
Carpel
Stamen
Anther
Microspore (n) forms pollen grain
Pollen grain (male gametophyte)
Egg
Megaspore (n: retained in ovary)
Female gametophyte (n: retained in ovary)
MEIOSIS
MITOSIS
POLLINATION
FERTILIZATION

38. Flowers
Flowers vary in size, structure, scent, and color in order to attract different pollinators.
The evolution of the flower made efficient pollination possible.
Fruits
For the Discovery Channel Video Plant Pollination, go to Animation and Video Files
A fruit is a structure that is derived from the ovary and encloses one or more seeds.
The evolution of fruit made efficient seed dispersal possible.

39. Flower Parts

40. Pistil and Stamen STAMEN consists of:
Filament: positions the anther to release pollen
Anther: makes pollen (male gametes)
Ovary: contains ovules which contain the egg cell (female gamete)
Style: positions the stigma to receive pollen
Stigma: receives pollen
PISTIL (carpel) consists of:

41. Pollination
Pollination is the transfer of pollen from the anther to the stigma
Cross-pollination occurs when the pollen from one flower lands on the stigma of a different flower
This is ideal and creates variation in genetics
Self-pollination occurs when the pollen of one flower lands on the stigma of the same flower
Not as desirable since it reduces variation
Flowers will prevent self-pollination by having the stigma higher than the stamen or by having the stamen and stigma mature at different times

42. Life Cycle of an Angiosperm