Chromosomes are rod-shaped structures made of DNA and proteins that contain genetic information. DNA is wrapped around protein structures called histones. Chromosomes exist in pairs called homologous chromosomes that contain the same genetic information. Chromosomes are only visible during cell division and exist as chromatin between divisions. Prokaryotes have circular chromosomes without nuclei, while eukaryotes have linear chromosomes within the cell nucleus. A karyotype maps the chromosomes, and cells are either diploid with two sets of chromosomes or haploid with one set.

1. CHROMOSOMES

2. What Are Chromosomes?
• Rod shaped structures
made of DNA & Protein DNA
• DNA – stores the
genetic information that
cells will use
• Proteins- sphere shaped Proteins
structures that the DNA
wraps around

3. Chromosome Shape
Chromatids
Centromere

4. CENTROMERES/ CHROMATIDS
• Centromere- holds the chromatids
together
• Chromatids- identical sides of the
chromosomes
– Contain same genetic information on both
sides

5. Chromatin
• Chromososomes are only present
during cell division. In
between cell division
chromosomes are unraveled and
called Chromatim

6. PROKARYOTIC VS EUKARYOTIC
CHROMOSOMES
Chromosome
• Prokaryotic
Chromosomes –
circular, smaller, NOT
in Nucleus
• Eukaryotic – Larger,
rod shaped, in
Nucleus

7. Chromosome Numbers
Organism # of
chromosome
Fruit Fly 8
Carrot & Lettuce 18
Cat 32
Earthworm 36
Human 46
Gorilla 48
Sand Dollar 52
Adder’s Tongue Fern 1262

8. Which is more complex in
terms of functions &
intelligence?
Adders Tongue Fern Human
OR

9. …OK Bad Example

10. Two Types of
Chromosomes
• SEX…ok get your minds out of the gutter
– Determine the gender of the individual
– Carry few other traits
– 2 of the 46 chromosomes
• AUTOSOMES
– Carry most of the traits that we inherit
– 44 of the 46 chromosomes

11. SEX Chromosomes
• XX =
• XY =

12. HOMOLOGOUS
CHROMOSOMES
• A pair of autosomes that have the identical trait
for a certain characteristic (eye color).
• You receive one of the homologous pairs from
your father and one homologous pair from your
mother
• Humans have 44 autosomes (minus the 2 sex
chromosomes) so they have 22 pairs of
homologous autosomes
• Homologous chromosomes are the same size
and shape

13. KARYOTYPE
• A picture taken from a microscope of all the
chromosomes within a cell. The chromosomes
are then arranged in homologous pairs and
given a set of numbers

14. Diploid vs Haploid Cells
Diploid Haploid
Description Both sets of Only one of each
homologous homologous
chromosomes present chromosome
present
Type of Cell All cells but sex Only sex cells-
cells (egg or Egg or Sperm
sperm)
Abbreviation 2n 1n