1. 8-1 Cell Reproduction

2. Objectives Describe the structure of a chromosome.
Compare prokaryotic chromosomes with eukaryotic chromosomes
Explain the differences between sex chromosomes and autosomes.
Give examples of diploid and haploid cells.

3. The Nucleic Acids history
Discovery of DNA
named by biochemist Johann Friedrich Miescher ( ) and his student
isolated an acidic substance rich in phosphorus from salmon sperm
believed it was heriditary matter of cell, but no real evidence
Discovery of the double helix
by 1900:components of DNA were known
by 1953: xray diffraction determined geometry of DNA molecule
Nobel Prize awarded in 1962 to 3 men: Watson, Crick and Wilkins but not to Rosalind Franklin who died of cancer at 37 from the xray data that provided the answers.
BRYSON
Difficulty of Xray dif. Is that it requires a single crystal to be grown, so you have to isolate a single molecule. Its useless for multistep processes.
Franklin often gets little recognition, it was her pictures that led to Watson and Cricks discovery, and she didn’t even know they were using her work.

4. What’s DNA?
Long thin molecule to store information on how to make proteins.
If your cell was a basketball you’d have 40 miles of DNA crammed in there.

5. Nucleotide Structure
Nucleic acids like DNA are polymers of nucleotides
Nucleotides consist of
sugar
RNA - ribose
DNA - deoxyribose
phosphate group
nitrogenous base
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The sugars and phosphates for the vertical part of the ladder, and hydrogen boding between the bases cause

6. Your cells grow and split
You pack all that DNA in by coiling it up into chromosomes.
DNA & proteins that wrap up DNA (histones)
We can stain and see chromosomes.

7. Chromosome

8. Each half of the chromosome is identical
Chromatid: ½ of the chromosome
Cells need these copies when they split in two.
Centromere: Place in the middle where chromatids are joined
Like an anchor

9. Eukaryotes vs. Prokaryotes
Prokaryotes don’t have as much DNA so they might only have 1 chromosome.
Eukaryotes usually have more
up to more than 100.

10. Sex chromosomes and autosomes
Animals have different kinds of chromosomes
Sex chromosomes determine if you’re a boy or a girl
Everything else is an Autosome

11. Every cell in you has two copies of every autosome
Two copies of chromosomes with the same size, shape, and genes are: Homologous chromosomes
Homo = the same

12. Chromosome Numbers in Different Species
Buffalo 60
Cat 38
Cattle 60
Dog 78
Donkey 62
Goat 60
Horse 64
Human 46
Pig 38
Sheep 54
If two species can interbreed what does that say about their chromosome ? It must be similar for example the horse & Donkey. How many chromosomes do you predict a mule would have? 63 since mules have an odd number of chromosomes they don’t match up; mating can’t happen no viable offspring

13. If two species can interbreed what does that say about their chromosome ? It must be similar for example the horse & Donkey. How many chromosomes do you predict a mule would have? 63 since mules have an odd number of chromosomes they don’t match up; mating can’t happen no viable offspring
Both lions and tigers have 38

14. Liger
Both lions and tigers have 38

15. Karyotypes
Stained chromosomes lined up by size and a picture is taken

16. Extremes in Chromosome #
The record for minimum number of chromosomes belongs to a subspecies of the ant Myrmecia pilosula, in which females have a single pair of chromosomes. This species reproduces by a process called haplodiploidy, in which fertilized eggs (diploid) become females, while unfertilized eggs (haploid) develop into males. Hence, the males of this group of ants have, in each of their cells, a single chromosome.
The record for maximum number of chromosomes is found in found in the fern family. Polyploidy is a common conduction in plants, but seemingly taken to its limits in the Ophioglossum reticulatum. This fern has roughly 630 pairs of chromosomes or 1260 chromosomes per cell. The fact that these cells can accurately segregate these enormous numbers of chromosomes during mitosis is truly remarkable.

17. Myrmecia pilosula & Ophioglossum

18. Spectral Karyotype
Fluorescent dyes are hybridized to the chromosomes

19. Diploid vs. Haploid Cells
Cells with two sets of chromosomes; Diploid cells
Have two copies of each autosome and sex chromosome
All of our cells except sperm and eggs are diploid
Abbreviated 2n
Haploid: only one set of chromosomes
Abbreviated 1n