Useful Genetics Professor Rosie Redfield The University of British Columbia This video is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported license.
Lecture 1F • Life cycles and ploidy ?? Outline: The cell cycle Typical plant/animal life cycles Ploidy: haploid gametes shuffle DNA versions into diploid organisms Learning objectives: • Follow changes in DNA through the life cycle and through generations • Explain the difference between asexual and sexual generations
Cell growth and reproduction are often represented as a cycle: ‘S-phase’ (DNA replication) Mitosis (cell division)
Typical generations of asexual organisms*: Unicellular: Multicellular: Stolon (runner) Asexual seed * Human reproduction is obligately sexual, so if we don’t have sex we don’t have any generations at all.
Typical generations of sexual organisms: pollen egg seed sperm + egg egg sperm (These are open-source bunnies.)
Essential terms: Haploid Diploid N Not usually used to distinguish the amounts of DNA before and after DNA replication – ploidy doesn’t change in the cell cycle.
Genetic consequences of sexual reproduction Each generation gets new genetic combinations from the previous generation. New combinations of chromosome versions (always in full sets) New combinations within each chromosome Module 6:How breaking and joining of single bonds in DNA determines which of your grandparents’ alleles you inherit.
Question: How many different versions of chromosome 11 are in a class of 200 students? 200 400 Just under 1000 About 1.3x105 About 1x106 This chromosome is about 130 Mb long (1.3 x 108bp). (Ignore new mutations.)
Your Mom's Your Dad's from his Mom from her Dad from his Dad meiosis Consider inheritance of a particular chromosome (e.g.human chrom. 8) from her Mom meiosis meiosis Yours from your Mom from your Dad Your kids'
Your Mom's Your Dad's from his Mom from her Dad from his Dad from your Mom from your Dad meiosis Consider inheritance of a particular chromosome (e.g.human chrom. 8) from her Mom meiosis meiosis Yours Your kids'
What we’ve done The cell ‘cycle’ Asexual reproduction Sexual life cycles Ploidy Sexual reproduction shuffles combinations of alleles
Coming up.... ? Lecture 1G • Homology and variation