1. 8.1:Chromosomes Chromosome Numbers Do Now:
1. If human cells contain 46 chromosomes, how many chromatids does each cell contain?
2. Complete your vocabulary chart for the terms CHROMOSOME, HISTONE, CHROMATID, and CENTROMERE, using the definitions given at the bottom of the page.
Chromosome Numbers

2. Quick review
DNA is organized into highly coiled structures called chromosomes.
Each chromosome contains thousands of individual genes.

3. Video… genetics 101

4. Dogs Have 78 Chromosomes!
Every species of organisms has a characteristic number of chromosomes. 78
Dog
Adder’s Tounge
Fern
1,262
Humans chimps

5. Autosomes and Sex Chromosomes
Human and animal chromosomes are categorized as autosomes or sex chromosomes.
Sex Chromosomes determine an organisim’s sex.
All of the others are called autosomes
Typical human male
44 autosomes,
1 X sex chromosome
1 Y sex chromosome
Typical human female
44 autosomes,
2 X sex chromosomes

6. Homologous Chromosomes
Every cell contains two copies of each autosome.
To put it another way, autosomes come in pairs. These two chromosomes are called
HOMOLOGUS CHROMOSOMES.
Genes for eye color are found at
The same location on both
Chromosomes. The gene for brown
Eyes I got from my dad is in exactly
The same location on one chromosome
As the gene for blue eyes I got from my
Mom on the other homologous
Chromosome.
Specific genes are found in the
Same location on each homolugous
Chromosome.
Consider me for example…

7. Diploid and Haploid Cells
Cells are considered diploid when they have 2 copies of each chromosome. Most of your body’s cells are diploid.
Cells are haploid if they have only one copy of each chromosome pair. This is the case for gametes, like sperm and egg cells, used for reproduction.

8. Diploid vs. Haploid

9. Karyotypes
A karyotype is a picture of all the chromosomes in a dividing cell.
A karyotype of one of your cells might look something like this:

10. Get familiar with that vocabulary!
1. Complete the worksheet you picked up today
2. Homework: Read pp “chromosome numbers” ANSWER SR #1, 4 on p. 147.