Transcript Reproduction Chapter 6 x - SandyBiology1-2

Reproduction
Ways of reproducing
Chapter 6- Unit 1 Biology
Producing the next generation
Asexual reproduction involves the formation of individuals whose
genes all come from one parent.
There is no fusion of sperm and egg.
Sexual reproduction is the formation of offspring by the fusion
of haploid gametes (sex cells).
Ovum: female gamete - usually large and nonmotile.
Spermatozooan: male gamete - usually small and motile.
Asexual reproduction results in little variation among offspring.
Sexual reproduction increases genetic variation among offspring.
Asexual Reproduction- Cloning!
•Offspring are genetically identical to their parent.
•An organism basically makes an exact copy of itself.
Fission:
(similar to mitosis) in which a parent cell splits to form 2 identical
daughter cells.
Binary Fission of a Man
Bacterial Fission
Asexual Reproduction
2N
2N
2N
Asexual Reproduction in Protozoans
Binary fission begins with mitosis.
Cytoplasmic division (cytokinesis) results
in two identical cells.
Binary fission is:
(a) longitudinal in some protozoans and
(b) transverse in others.
2N
2N
Sexual Reproduction
Diploid
female sex
organ cells
2N
Haploid female
sex cells-gametes
N
Diploid zygote 2N
Fertilization
MEIOSIS
MITOSIS
Diploid embryo 2N
Diploid
male sex
organ cells
2N
Haploid male sex
cells-gametes N
Mitosis v Meiosis
Asexual Reproductions involves Mitosis
Sexual Reproduction involves Meiosis then Mitosis
MITOSIS
MEIOSIS
Other Types of Asexual Reproduction
Budding
 Fragmentation
 Vegetative Reproduction
 Parthenogenesis
 Spore formation

Budding:
Development of a new organism from an outgrowth of the parent organism
Fragmentation:
Individual cells or groups of cells from the parent organism can develop into a
complete new organism eg sponges , flatworms
Parthenogensis:

Egg development without fertilization is
possible in:
◦ Many plants
◦ Aphid
◦ Daphnia
◦ Honeybee
◦ Whiptail lizard
◦ Komodo Dragon
◦ Hammerhead Shark
Spores:
A reproductive cell that can grow into a new individual by mitosis
N
Mitosis
N
Meiosis
2N
2N
2N
Fertilization
Forms of
Vegetative
Propagation:
Stems: Runners are stems that
grow horizontally above the
ground.
They have nodes where buds are
formed.
These buds grow into a new
plant.
Forms of Vegetative Propagation:
A Corm is a short, vertical, swollen
underground plant stem that
serves as a storage organ used by
some plants to survive winter or other
adverse conditions such as summer
drought and heat .
Forms of Vegetative Propagation:
Rhizomes are a stem that is usually
found underground, often sending
out roots and shoots from its nodes.
Tubers: Roots
Tubers Roots: New plants will grow out of swollen, modified roots called
tubers. Buds develop at the base of the stem and then grow into new plants.
Bulbs:
Bulbs are an underground stem.
Leaves are attached to the stem. These leaves contain much stored food. At
the centre of the bulb is an apical bud. Also attached are lateral buds.
The apical bud will produce leaves and a flower while the lateral buds will
produce new shoots.
As the plant grows and develops it will form a new bulb underground.
Leaves & Plantlets:
Leaves: Leaves of some plants will
grow into a new plant if they become
detached from the parent plant.
Other plants grow small plants called
plantlets on the edge of their leaves.
Plant Cuttings:
Small pieces of plant leaf or stem can strike roots
and grow into a new plant.
Flowering Plant Sexual Reproduction
Flowers are the sexual organs of Angiosperms
Plant Reproduction : Fertilization
Can be either:
SELF-POLLINATION – if the
pollen attaches to the stigma of the
same flower.
CROSS-POLLINATION – if the
pollen attaches to the stigma of a
different flower.
Non Flowering Plant Reproduction
Non Flowering Plant Reproduction
Sexuality:
Hermaphroditism versus Gonochorism
Hermaphroditism: both sexes in the same individuals
Gonochorism: sexes are separate
Acropora sp., a
hermaphoditic coral
Fungia scutaria, a
gonochoric coral
eggs
sperm packet
egg cloud
Internal and external fertilization both depend on
mechanisms ensuring that mature sperm
encounter fertile eggs of the same species
External Fertilization: requires a moist habitat
that will protect a developing egg from desiccation and
heat stress.
Specific mating behaviors assure that sperm and egg will
be in the same place at the same time.
Brooding vs Broadcast Spawning
Brooding: eggs develop to planula stage in gastrovascular cavity of parent polyp
Broadcast Spawning: eggs and sperm are shed into the water column where
fertilization and development occurs
released gametes
planula in polyp
Pocillopora damicornis, a brooder
broadcast spawner
Internal Fertilization:
Internal fertilization requires cooperative behavior that leads to
copulation.
Pheromones:
chemical signals released by one organism that influence the behavior
of other individuals of the same species.
Many act as male attractants.
male
Species with internal fertilization usually produce
fewer zygotes but provide more parental
protection than species with external fertilization
Internal fertilization usually results in the production of fewer zygotes than
does external fertilization however, the survival rate is lower for external
fertilization than it is for internal fertilization.
 The externally fertilized eggs of fishes and amphibians
are surrounded by a gelatinous coat.
 The internally fertilized amniote eggs of birds,
reptiles and monotremes are protected by calcium and
protein shells.
 In most mammals the embryo is retained within the
females reproductive tract.
Complex reproductive systems have
evolved in many animal phyla

The least complex
reproductive systems lack
gonads.
 Polychaete worms lack gonads.
 Eggs and sperm develop from
undifferentiated cells lining the
coelom.

Some reproductive systems,
such as that seen in parasitic
flatworms, can be very
complex.
Most insects have separate sexes with
complex reproductive systems.
In many species the female reproductive system includes a spermatheca, a
sac in which sperm may be stored for a year or more.
The basic plan of all
vertebrate
reproductive systems
are very similar.
However, there are variations.
In many non-mammalian
vertebrates the digestive, excretory,
and reproductive systems share a
common opening to the outside, the
cloaca.
Mammals have separate opening
for the digestive and reproductive
systems.
Female mammals also have separate
openings for the excretory and
reproductive systems.
Human reproduction involves intricate
anatomy and complex behavior
Male Reproductive System
The scrotum and the penis are the external components of the reproductive
system.
The internal reproductive organs consist of gonads, accessory sex glands, and
ducts.
Testes are the male gonads.
Testes are located in the scrotum, outside
the body cavity.

Keeps testicular temperature cooler than the
body cavity.
Consists of many highly coiled
seminiferous tubules.

Sperm form in seminiferous tubules.
Leydig cells scattered between
seminiferous tubules produce androgens
(eg. testosterone).
Sperm pass from the seminiferous tubules
to the coiled tubules of the epididymis.
 It takes about 20 days for sperm to pass
through the tubules of the epididymis.
 In the epididymis sperm become motile
and gain the ability to fertilize.
Testes:
Seminiferous Tubules
Spermatogenesis
Mature Spermatozoa
Prostate
gland:
Location- surrounds and opens
into the urethra where it leaves
the bladder.
Secretion- slightly alkaline fluid
that activates the sperm and
prevents them from sticking
together
External structure of the penis:
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The shaft of the penis is covered by relatively thick skin.
The sensitive glans penis is covered by thinner skin.
The penis is composed of three layers of spongy erectile tissue.
During sexual arousal the erectile tissue fills with blood from arteries.
The resultant increased pressure seals off the veins that drain the penis.
The engorgement of the penis with blood causes an erection.
An erection is essential to the insertion of the penis into the vagina.
 Ejaculation propels sperm from the epididymis to the vas deferens.
 The vas deferens run from the scrotum and behind the urinary bladder.
 Here each vas deferens joins with a duct from the seminal vesicle to form
an ejaculatory duct.
 The ejaculatory ducts open into the urethra.
 The urethra drains both the excretory and reproductive systems.
◦ A male usually ejaculates about 2 – 5 mL of semen; each milliliter
containing about 50 –130 million sperm.
Female Reproductive Tract
External reproductive structures:
• labia
• clitoris
• vaginal opening
Internal reproductive structures:
• ovaries
• fallopian tube (uterine tube)
• cervix
• uterus
• vagina
• fimbrae
Female Reproductive Tract
Ovulation:
OVULATION
Oogenesis in the Ovary
•Ovary- contains 400,000 oocytes; release about 500 in a lifetime
•Ovary- under influence of FSH. The follicles mature every 28 days
•Primary follicle produces estrogens
•And primary oocyte completes its 1st division produces 2ndary oocyte and
polar body
•Approx 1/2 way through the 28 day cycle the follicle reaches the mature
Vesticular or Graffian follicle stage.
•Estrogen levels rise and release LH and FSH and triggers ovulation.
•The 2ndary oocyte travels down the uterine tube to the uterus.
•If fertilized by sperm, it will produce a zygote
Hormone , Follicle & Endometrial
Development :
Oogenesis
Ovarian Cycle
Ovulation, fertilization & implantation
Fertilisation
Fertilization &
Embryonic
Development
Fertilization & Embryonic Development
Gestation Period
After fertilisation the zygote is implanted onto the
endometrium, this marks the beginning of pregnancy.
The zygote is supplied with blood via the umbilical
cord and the embryo develops. The umbilical cord
connects to the placenta with is supplied with blood
from the mother’s circulatory system. At 8 weeks the
embryo is now a foetus. It will continue to grow for
another 32-33 weeks.
Meiosis Video
http://www.youtube.com/watch?v=kVMb4Js99tA

Meiosis Square Dance