FINGER MITOSIS/MEIOSIS

• Video link

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CHAPTER 8:

REPRODUCTION

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TODAY: MOSTLY FOCUSING ON ANIMAL REPRODUCTION

LEARNING OBJECTIVES

You should be able to:

• Define, compare and contrast sexual and asexualreproduction

• Describe and identify binary fission, fragmentation, budding, conjugation, internal/external fertilization

• Assess the merits of internal and external fertilization

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REPRODUCTION

• Makes new members of species

• Many species able to reproduce in more than one way

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ASEXUAL VS SEXUAL REPRODUCTION

Asexual Reproduction

• One parent

• Offspring geneticallyidentical to parent

• All prokaryotes, someeukaryotes

• Binary fission,fragmentation, budding,(parthenogenesis)

Sexual Reproduction

• Two parents

• Offspring a combination of parental genes

• Conjugation in prokaryotes

• In eukaryotes, involves meiosis (gametes) and fertilization

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BINARY FISSION

• Used by single-celled organisms (including all prokaryotes)

• Mitosis (basically)

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FRAGMENTATION

• Parent splits: new organisms grow from different fragments

• E.g. segmented worms, echinoderms (sea stars, sea urchins)

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FRAGMENTATION

• Parent splits: new organisms grow from different fragments

• E.g. segmented worms, echinoderms (sea stars, sea urchins)

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But just because we can, doesn’t mean we should…

BUDDING

• Make small, genetically identical polyps that ‘bud off’ from parent

• Mature polyps thenbreak off, form new organisms

• E.g. hydra, yeast

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PARTHENOGENESIS (NOT TESTABLE)

• Unfertilized egg develops into clone

• In one type of parthenogenesis, egg fuses with polar body diploid

• E.g. insects (bees, stickbugs), some snakes

PRACTICE: WHAT TYPE OF REPRODUCTION?

1) Poros

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PRACTICE: WHAT TYPE OF REPRODUCTION?

2) Female New Zealand mud snails are able to produce viable offspring that develop into mature adults from unfertilized eggs.

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PRACTICE: WHAT TYPE OF REPRODUCTION?

3) In a species of yeast, a new individual develops as an outgrowth on a parent, which then separates from the parent once it has matured.

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PRACTICE: WHAT TYPE OF REPRODUCTION?

4)

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PRACTICE: WHAT TYPE OF REPRODUCTION?

Challenge)

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ASEXUAL VS SEXUAL REPRODUCTION

Asexual Reproduction

• One parent

• Offspring geneticallyidentical to parent

• All prokaryotes, someeukaryotes

• Binary fission,fragmentation, budding,(parthenogenesis)

Sexual Reproduction

• Two parents

• Offspring a combination of parental genes

• Conjugation in prokaryotes

• In eukaryotes, involves meiosis (gametes) and fertilization

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CONJUGATION

• Genetic transfer between bacteria

• Requires cell-to-cell contact

• (image details nottestable)

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INTERNAL FERTILIZATION

• Fertilization inside one parent’s body (usually via sexual intercourse)

• Different kinds of embryo development:

• Inside mother (gestation, like in humans)

• Outside mother (egg, fed by yolk)

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EXTERNAL FERTILIZATION

• Sperm and egg join outside of body

• Spawning: releasing eggs and sperm into water

• E.g. marine animals(amphibians, fish,invertebrates)

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PROS AND CONS

Internal Fertilization

• High cost per offspring (yolk, parenting)

• Few offspring produced

• High survival rate

• Requires physical contact between parents

External Fertilization

• Low cost per offspring

• Many offspring produced

• Low survival rate

• No physical contact betweenparents (good for sessile* or slow-moving species)

* sessile: unable to move from one spot (e.g. plants, anemones) 21

DISCUSSION

How does bacterial conjugation differ from other forms of reproduction?

- Does not produce new offspring

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REPRODUCING IN MORE THAN ONE WAY

(Following examples for illustrative purposes only: NOT testable)

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SEA STARS

• Asexual: fragmentation

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• Sexual: external fertilization (video)

E. COLI

• Asexual: binary fission

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• Sexual: conjugation

HOMEWORK

• Study for Quiz Nov. 21/22

• Mitosis, meiosis, asexual/sexual reproduction

• No MC; some drawings (bring coloured pencils/pens)

• Cheatsheet: one-sided index card permitted

• Nov. 21/22 marks cutoff

• Finish mitosis/meiosis activity

• Not handing in, but good practice

• Answer key on website 26