The Hierarchical Organization of Life

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?

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?

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

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

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

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

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

Genomes Genome = all the genetic material contained in an organism, including its chromosomes, genes and DNA The human genome consists of about 30 000 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

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 19 099 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!

Helpful websites Nature.ca: http://nature.ca/genome/03/a/03a_e.cfm Video: Evolution of the Human Genome http://www.youtube.com/watch?v=gngsL9 FRpqc&feature=related