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Asexual Reproduction. Genes all come from one parent Common to many invertebrates Advantages Enables animals to live in isolation – no need to locate mates Organism can create numerous offspring in a short amount of time – rapidly colonize habitat

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asexual reproduction
Asexual Reproduction
  • Genes all come from one parent
  • Common to many invertebrates
  • Advantages
    • Enables animals to live in isolation – no need to locate mates
    • Organism can create numerous offspring in a short amount of time – rapidly colonize habitat
    • Advantageous in __________, favorable environments
      • Perpetuates successful genotypes precisely
forms of asexual reproduction
Forms of Asexual Reproduction
  • _____________
    • separation of parent into two or more individuals of approximately equal size.
  • _____________
    • new individuals split off from existing ones
  • __________________
    • Broken off body part grows into new individual
    • Regeneration of body parts
  • _________________
    • Eggs develop without being fertilized

Queen Worker Drone

forms of asexual reproduction3
Forms of Asexual Reproduction
  • Parthenogenosis
    • Egg develops ___________ being fertilized
    • Adults produced by parthenogenesis are _____________
      • Example: drone (male) bees form from single unfertilized egg and do not need to undergo meiosis to make their own new reproductive cells
    • SOMETIMES, in certain species, whether parthenogenesis occurs may be determined by season/conditions
      • Favorable conditions leads to asexual repro.
        • Everythings going well, why change?
      • Environmental stress leads to sexual repro
        • If conditions are bad, better hope some variety will come up with a solution!
sexual reproduction
Sexual Reproduction
  • Creation of offspring by fusion of haploid gametes to form a zygote
  • Increases genetic variation
  • Probably enhances reproductive success when pathogens or other environmental factors ________ rapidly
    • If there’s variety, chances are better than someone will have a genetic solution to an environmental problem
hermaphrodites
Hermaphrodites
  • Each individual has both male and female reproductive systems
    • NOT ASEXUAL
    • Helps when finding a mate is not easy
      • Every individual encountered is a potential ___________ (as opposed to just ½ the individuals encountered)
    • Each partner donates sperm to female repro organs of the other.
two types of fertilization
TWO Types of Fertilization
  • ____________ fertilization

Requires environment where egg/zygote can develop without drying out.

    • The eggs are unprotected and vulnerable to water loss, etc.
    • Thus, almost always occurs in ____________ areas
external fertilization
External Fertilization
  • Parents may not even make physical contact
    • Eggs/sperm released into water
    • Timing is still important
    • Some do use specific mates and mating behaviors
    • __________________ are used to draw animals together
external fertilization8
External Fertilization
  • GENERAL rule
    • _______ of zygotes produced
    • _________ parental care
    • Have lots of babies and hope at least a few of them survive
    • Very small proportion of zygotes survive to full development
internal fertilization
Internal Fertilization
  • Protects _________________
    • Neither sperm nor egg is ever exposed to environment
    • Sperm placed directly inside the female
  • Protects _______________
    • Embryos develop either:
      • Inside shelled eggs
      • Inside the female
    • Don’t come out until they can survive dry environment
internal fertilization10
Internal Fertilization
  • ALL internal fertilization requires
    • Sophisticated reproductive systems including organs that
      • deliver sperm
      • receptacles that receive, store and transport sperm to ripe eggs.
    • Cooperativebehaviors leading to copulation
      • Uncharacteristic sexual behaviors are eliminated by ____________________________
      • Example – female spiders eat males if they don’t use the proper reproductive signals
internal fertilization11
Internal Fertilization
  • Generally produces _______________ zygotes than external
  • But proportion of zygotes that develop and survive is ____________. This is because of:
    • greater protection of eggs/zygotes/embryos
      • Within a shell OR
      • Within the female
    • Due to better parental care of eggs and offspring
      • Don’t abandon young
internal fertilization12
Internal Fertilization
  • Two possible outcomes:
    • _______________ to be laid on land
      • Reptiles, Birds
      • And 1 very small mammal group – montremes (platypus and spiny echidna)
    • Embryos develop _______________________
      • Mammals (placental and marsupial)
  • Both animal types are called ______________ due to the embryonic structures they share in common
amniotes
AMNIOTES
  • Amniotic eggs
    • Shell is NOT the only part that protects
    • EXTRAEMBRYONIC MEMBRANES make the anmiontic egg successful
      • AMNION
        • surrounds baby with water
        • “little ocean”
      • Yolk Sac
        • Stored Food
      • Allantois
        • Waste sac
      • Chorion
        • Functions with allantois in GAS EXCHANGE
amniotes14
AMNIOTES

Amnion

  • Internal Development
  • Mammals –
    • both placental and marsupial
    • NOT monotremes (EGG LAYERS!)
  • Shelled egg not used, but
    • amnion present and
    • ________ extraembryonic membranes give rise to ____________, etc.
male reproductive organs
Male Reproductive Organs
  • Testes
    • Seminiferous Tubules
      • Sperm production
  • Epididymis
    • Sperm maturation
  • Vas Deferens
    • Carry sperm to urethra
  • Urethra
    • exit body
seminiferous tubules
Seminiferous Tubules
  • Highly coiled tubes
    • Sperm are formed HERE
    • ____________ HAPPENS HERE!!
    • Also contain cells (Leydig cells) which make male hormones
      • Testosterone and other androgens

Cross section through Sem. Tubule

slide17
___________________________
  • General term for creation of gametes
    • SEX CELLS
    • ___________________
    • TWO TERMS
      • Spermatogenesis
        • Gametogenesis (meiosis) in males
      • Oogenesis
        • Gametogenesis (meiosis) in females
spermatogenesis meiosis to create sperm
Spermatogenesis – MEIOSIS to create sperm

Least Mature

Also called

spermatogonium

Testis

Epididymis

Germ cell

(diploid)

Coiled

seminiferous

tubules

spermatocyte

(diploid)

MEIOSIS I

spermatocytes

(haploid)

MEIOSIS II

Vas deferens

Spermatids

(haploid)

Meiosis happens

Inside

Seminiferous

tubules

Most Mature

Spermatozoa

Cross-section of

seminiferous tubule

spermatogenesis
Spermatogenesis
  • __________________________
    • Products of meiosis
    • ____ created from each primary spermatocyte
    • ____________________
    • Immature sperm
      • Tailess
    • Sertoli cells
      • Provide nourishment to spermatids as they further develop into sperm at center of seminiferous tubule
mature sperm
Mature Sperm
  • Sperm structure
    • Head
      • ___________________
        • Contains enzymes to penetrate egg
      • Nucleus
        • Males genetic contribution
    • Mid-piece
      • Mitochondria
        • For energy - swimming
    • Tail
      • Microtubules
        • ____________
fertilization
Fertilization
  • Joining of sperm & egg
    • sperm head (nucleus) enters egg
female reproductive system
Female reproductive system
  • Ovaries
    • produces eggs & hormones
  • Uterus
    • nurtures fetus; lining builds up each month
  • Fallopian tubes
    • tubes for eggs to travel from ovaries to uterus
    • Called OVIDUCTS in every other animal
  • Cervix
    • opening to uterus, dilates 10cm (4 inches) for birthing baby
  • Vagina
    • birth canal
female reproductive organs
Female Reproductive Organs
  • Ovaries
    • Each ovary contains many follicles
    • ___________________
      • One egg cell surrounded by folliclecells
      • Follicle cells nourish and protect developing egg
      • Follicle cells also produce primary female sex hormones
        • estrogens
oogenesis
Oogenesis
  • Oogonia
    • Cells that create cells that undergo ________
    • ________________
    • Repeatedly divide to create _______ oogonia
      • ______________
  • Primary oocyte
    • Cell that has entered into _____________
  • Secondary oocyte
    • Cell that has entered into _____________
  • ____________
oogenesis26
Oogenesis
  • ________ divisions
    • Make one really good egg and ___ polar bodies

Meiosis 1 completed

during egg maturation

ovulation

Meiosis 2 completed

triggered by fertilization

reproductive hormones
Reproductive hormones

LH &FSH

  • ______________
    • from testes
    • functions
      • sperm production
      • 2° sexual characteristics
  • _____________
    • from ___________
    • functions
      • egg production
      • prepare uterus for fertilized egg
      • 2° sexual characteristics

testesorovaries

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