1. Cell Reproduction
Regular Biology
Waggy

2. Chapter Objectives 1. Describe the structure of a chromosome.
2. Explain the differences between sex chromosomes & autosomes.
3. Distinguish between diploid & haploid cells.
4. Summarize the events of mitosis

3. 5. Explain binary fission in prokaryotic cells
6. Discuss the pros and cons of Stem Cells.
7. Summarize the steps of meiosis
8. Compare the end products of mitosis to meiosis

4. Deoxyribonucleic Acid (DNA)
Long thin molecule that holds genetic information
If stretched out, one strand of DNA would measure 3 meters in length
DNA is made up of nucleotides
The human genome has approximately 3 billion nucleotides
So how does it fit into a single cell?

5. Supercoiling The DNA coils into a thick rope
The DNA continues to coil until completely coiled into small structure called a chromatid

6. The two identical chromatids find each other and form the final structure that DNA takes: the chromosome
The sister chromatids are connected at the centromere (sticky protein disk)

7. Types of chromosomes
Chromosomes are put into two different categories:
1. Sex chromosomes
Determine the sex of an organism
In humans: XX = female XY = male

8. 2. Autosomes
All other chromosomes
Most body cells contain two copies of each autosome

9. Diploid vs. Haploid
Diploid cells contain TWO copies of each chromosome
All body cells are diploid EXCEPT for the sex cells (sperm & egg)
Shorthand for diploid cells is written: 2n

10. Haploid cells contain ONLY ONE copy of each chromosome
Haploid cells are the sex cells
Shorthand for haploid cells is written: n

11. Karyotypes Used to examine a persons chromosomes
Can sometimes help identify some genetic disorders like monosomy (missing chromosome) or trisomy (extra chromosome)
Down’s Syndrome = Trisomy 21