1. Structure and Function
Chromosomes
Structure
and
Function
Title
Pic of chromosome structure

2. Chromosomes & DNA
DNA is a long, thin molecule that stores genetic Information and is located in the nucleus of eukaryotic cells.
During cell division, this DNA is coiled around proteins into very compact structures called chromosomes
DNA wraps around proteins called histones that keep the shape of chromosomes and help to pack DNA tightly

3. From DNA  Chromosome

4. Chromosome Structure
consists of identical halves (sister chromatids) which form after DNA replication
centromere holds the two chromatids together until they split during cell division (mitosis/meiosis)
centromeres aid in chromosome movement during cell division

5. Chromatin vs. Chromosomes
When cells are not dividing, DNA is not coiled up tightly into chromosomes. Why?
Uncoiled DNA can be easily read so the information can give your cells directions on how to carry out activities.
Only during cell reproduction is DNA in chromosome form.
The rest of the time DNA is called chromatin (uncoiled DNA).

6. Chromosome Numbers of Different Organisms
Each species has a specific number of chromosomes in each of their cells, which is NOT based on complexity.
Organism #of Chromosomes
Camel 70
Bat 44
Chicken 78
Apple 34
Fruit Fly 8
Pea 14
Dove 16
Fox 34
Earthworm 36
Cat 38

7. Chromosome Numbers in Organisms
Animals (including humans) have two categories of chromosomes:
1. sex chromosomes (determine gender)
XX - female, XY - male
2. autosomes (all other chromosomes, determine the rest of your
traits)
IMPORTANT POINT:
Cells have a copy of each autosome (one from each parent) called homologous chromosomes (pairs/diploid). Homologues are the same size, shape and carry genes for the same trait.
THEREFORE…
Humans have 46 chromosomes (2 sex chromosomes, 44 autosomal) in autosomal (body) cells and 23 in germ (sex) cells.
Complexity
Sex chrom
Autosomes
Homologous
Karyotype

8. Haploid versus Diploid
Cells with pairs of homologous chromosomes entact/together are diploid (2n), they have both parents’ sets of chromosomes.
Germ (sex) cells are haploid (1n), having one chromosome of each homologous pair and one sex chromosome.
For example:
human somatic (body) cells - 46
human germ (sex) cells - 23
Why must egg and sperm cells be haploid?

9. Using this karyotype, what is the sex of this person?
What is a Karyotype?
a picture of an organism’s chromosomes
it can tell help answer questions such as:
-What is the gender of the child?
-Will an unborn baby have a genetic disorder?
-What kind of genetic disorder?
-Which chromosome(s) is effected?
Using this karyotype, what is the sex of this person?