FINGER MITOSIS/MEIOSIS. Video link

Transcription

1 FINGER MITOSIS/MEIOSIS Video link 1

2 CHAPTER 8: REPRODUCTION TODAY: MOSTLY FOCUSING ON ANIMAL REPRODUCTION 2

3 LEARNING OBJECTIVES You should be able to: Define, compare and contrast sexual and asexual reproduction Describe and identify binary fission, fragmentation, budding, conjugation, internal/external fertilization Assess the merits of internal and external fertilization 3

4 REPRODUCTION Makes new members of species Many species able to reproduce in more than one way 4

5 ASEXUAL VS SEXUAL REPRODUCTION Asexual Reproduction One parent Offspring genetically identical to parent All prokaryotes, some eukaryotes 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 5

6 BINARY FISSION Used by single-celled organisms (including all prokaryotes) Mitosis (basically) 5

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8 FRAGMENTATION Parent splits: new organisms grow from different fragments E.g. segmented worms, echinoderms (sea stars, sea urchins) 8

9 FRAGMENTATION But just because we can, doesn t mean we should Parent splits: new organisms grow from different fragments E.g. segmented worms, echinoderms (sea stars, sea urchins) 9

10 BUDDING Make small, genetically identical polyps that bud off from parent Mature polyps then break off, form new organisms E.g. hydra, yeast 10

11 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 11

12 PRACTICE: WHAT TYPE OF REPRODUCTION? 1) Poros 12

13 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. 13

14 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. 14

15 PRACTICE: WHAT TYPE OF REPRODUCTION? 4) 15

16 PRACTICE: WHAT TYPE OF REPRODUCTION? Challenge) 16

17 ASEXUAL VS SEXUAL REPRODUCTION Asexual Reproduction One parent Offspring genetically identical to parent All prokaryotes, some eukaryotes 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 17

18 CONJUGATION Genetic transfer between bacteria Requires cell-to-cell contact (image details not testable) 18

19 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) 19

20 EXTERNAL FERTILIZATION Sperm and egg join outside of body Spawning: releasing eggs and sperm into water E.g. marine animals (amphibians, fish, invertebrates) 20

21 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 between parents (good for sessile* or slow-moving species) * sessile: unable to move from one spot (e.g. plants, anemones) 21

22 DISCUSSION How does bacterial conjugation differ from other forms of reproduction? - Does not produce new offspring 22

23 REPRODUCING IN MORE THAN ONE WAY (Following examples for illustrative purposes only: NOT testable) 23

24 SEA STARS Asexual: fragmentation Sexual: external fertilization (video) 24

25 E. COLI Asexual: binary fission Sexual: conjugation 25

26 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