1. The Hierarchical Organization of Life

2. Questions we will answer today:
Q – What is the difference between a cell in a tissue and a sex cell?
Q2 – How are boy and girl chromosomes different?
Q3 – Where are all our genes?
Q4 – How similar are we to other animals? To plants?

3. Chromosome review What do you remember about chromosomes?
What are they made of?
Where are they found?
What is a gene?
Where are genes found?

4. Chromosomes
Each human has 23 pairs of chromosomes in each nucleus of each somatic cell
Somatic cell: non reproductive cells. Tissue cells.
Ex: cells in you stomach
Each pair of chromosomes: one comes from mom, one comes from dad

5. Chromosomes cont’ 22 of the 23 pairs are homologous
Homologous chromosomes = chromosome pairs that look the same
The 23rd pair tell you if you are a boy or a girl
Girl = XX
Boy = XY
These chromosomes are called sex chromosomes

6. Chromosomes cont’
Karyotype = a picture of a person’s chromosomes arranged from #1 to #23

7. Chromosomes cont’ Chromosomes are represented by the letter “n”
Sex cells = n chromosomes
Called haploid
Somatic cells = 2n chromosomes
Call diploid

8. Chromosomes cont’
Different species have different number of chromosomes
See table 1 p. 53 in Synergy
Test your knowledge!
Complete the questions on p. 53 for homework

9. Genomes
Genome = all the genetic material contained in an organism, including its chromosomes, genes and DNA
The human genome consists of about genes
The Human Genome Project is a multinational effort to map the location of all the genes in the human body
It was completed in 2003
Finding out where genes are located within the 46 chromosomes allows doctors to figure out what their function is
Story time

10. Genomes cont’ FUN FACTS:
Other species have had their genomes mapped too:
The mapping of the worm’s genome was completed in 1998
They have genes, 40% of which are the same as ours!
We have 50% of the same genes as a fly!
We have 98% of the same genes as a chimpanzee!

11. Helpful websites Nature.ca: http://nature.ca/genome/03/a/03a_e.cfm
Video: Evolution of the Human Genome FRpqc&feature=related