1. Chromosomes & Genes
Packet #32
Chapter #13
Thursday, November 15, 2018

2. Types of Reproduction
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3. Types of Reproduction Reproduction occurs at two levels
Organism Reproduction
Sexual Reproduction
Humans
Asexual
Bacteria
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4. Types of Reproduction II
Cellular Reproduction
Sexual Reproduction
Meiosis
Involves the combining of genes from two different individuals into new arrangements
Genes are arranged (sorted) into new arrangements.
Asexual Reproduction
Mitosis (Cell Cycle)
Involves the production of a new organism of species from a cell or cells of a single parent.
Reproduction without the sorting of genes.
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5. The Cell Theory—Revisited
Scheleiden and Schwann stated that cells are the fundamental unit of life.
Virchow stated that cells arise from preexisting cells.
Weismann described that cells have a “common ancestor.”
What is the relationship between the cell theory and cellular reproduction?
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6. Chromosomes & Genes
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7. Chromosomes Chromosome Genes Chromosome set
A linear end to end arrangement of genes, other DNA and associated proteins.
Genes
Segments of DNA, that code for an observable or biochemical characteristic (phenotype).
Chromosome set
Represented by the letter n, contains a specified number of chromosomes.
2n represents two chromosome sets.
Focus will be on eukaryotic cells.
Thursday, November 15, 2018

8. Ploidy
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9. Haploid vs. Diploid Cells
Ploidy
Number of sets of chromosomes in the nucleus of a cell.
Haploid
A cell having one chromosome set
Human Sperm 1 set of 23 chromosomes
Female Egg 1 set of 23 chromosomes
In human sex cells n, we represent the chromosome set by n
Diploid
A cell having 2 chromosome sets
As an individual, human somatic cells contain 46 chromosomes ( )
In human somatic cells, we represent the sets by 2n (2 * 23 chromosomes)
Sex cells still have 1 set of 23 chromosomes
More on ploidy to come later
Aneuploidy
Euploidy
Thursday, November 15, 2018

10. Other Important Information
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11. Chromatids Chromatid Crossing over
One of the two side-by-side replicas produced by chromosome division
Centromere
Place where chromatids are held together
Crossing over
Genetic material can be exchanged during mitosis (rarely) and meiosis during crossing over.
Occurs at a location called the chiasma/chiasmata.
More to come on the vocabulary found on this slide later…
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12. Meiosis & Mitosis Connection
What is the relationship between meiosis and mitosis (cell cycle)?
Thursday, November 15, 2018