BIOL140 Lecture Notes - Lecture 6: Inta, Cytokinesis, Dna Replication

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21 Jun 2016
Department
Course
Professor
BIO Lecture #6
September 29th, 2015
Cells in human body have 46 Chromosomes
Diploid- 2n
Body Cells
Gametes have 23 chromosomes
Reproductive Cells
Increases the chance of survival in a changing environment
Increases Genetic Diversity
Meiosis is the only kind of cell division that produces gametes
Why did Miosis evolve when sexual reproduction evolved?
Chromosome Number and Cell Division
Egg + Sperm Zygote
Without reduction--- 46 + 46 92
With Reduction--- 23 + 23 46
2nn
Reduces Chromosome number
Reduction Division
Separates Chromosome pairs
1st Division
Chromosomes are copied before Meiosis
Separates chromatids
2nd Division
Involves two Divisions
Copy chromosomes increase # of gametesIncrease chance of successful reproduction
DNA Replication occurs prior to Meiosis
Meiosis
Cell gets ready for division
Synapsis-Homologous Chromosomes pair up
i.
Unique combinations of chromosomes in each gamete
>
Produces new combination of genes
Crossing Over- non- sister chromatids exchange pieces of DNA
ii.
Prophase 1
1.
Homologous Chromosomes line up along Metaphase plate
Metaphase I
2.
Diploid Haploid
Separation of Homologous chromosomes
Anaphase I
3.
Nuclear Membrane is rebuilt
Telophase I
4.
Meiosis I
A)
Parent cell divides into two daughter cells
Cytokinesis I (Interkinesis)
B)
Similar to Mitosis
Seperation of chromatids
Meiosis II
C)
Won't work because it results in too many
Chromosome = Different species
Situation #1
(No Copying)
Crossing Over
Metaphase I
Male Gametes
Creation of Sperm
Spermatogenesis
a)
Gamete Production
Meiosis I
Meiosis II
Maturing
Streamlining
Develop Motor & Tail
Lose Organelles
Sperm
Oogenesis
b)
Situation #2
(copying)
Homologous Pair
Meiosis
Lecture Six and Seven
October 4, 2015
5:28 AM
BIO 140 Page 1
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