CHROMOSOMES

What Are Chromosomes?

• Rod shaped structures made of DNA & Protein

• DNA – stores the genetic information that cells will use

• Proteins- sphere shaped structures that the DNA wraps around

Proteins

DNA

Chromosome Shape

Centromere

Chromatids

CENTROMERES/ CHROMATIDS

• Centromere- holds the chromatids together

• Chromatids- identical sides of the chromosomes– Contain same genetic information on both

sides

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

PROKARYOTIC VS EUKARYOTIC CHROMOSOMES

• Prokaryotic Chromosomes –circular, smaller, NOT in Nucleus

• Eukaryotic – Larger,

rod shaped, in Nucleus

Chromosome

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

Which is more complex in terms of functions &

intelligence?Adders Tongue Fern

OR

Human

…OK Bad Example

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

SEX Chromosomes

• XX =

• XY =

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

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

Diploid vs Haploid Cells

Diploid Haploid

Description Both sets of homologous

chromosomes present

Only one of each homologous chromosome

present

Type of Cell All cells but sex cells (egg or

sperm)

Only sex cells- Egg or Sperm

Abbreviation 2n 1n