Chapter 13 Genes and Chromosomes

Could you be like Mike? Genetics vs. Environmental factors Genetics Environment

Everyone is a product genes and environment –Ex. Height –Siamese Cat fur Hot areas: white Cold areas: black

Identical versus Fraternal Twins Genetically identical – –Same fertilized egg splits into two Different environment – –Different food, sleep, experiences, emotions, sunlight differing traits=stronger environmental influence

Old Belief: Blending theory Belief: fertilization mixed your parent’s genes You are average of both Once mixed, cannot be separated

Events Contradicting “blending theory You don’t always look like parents Healthy parents have sick children

Gregor Mendel A monk, gardener, and high school science teacher 1860’s, grew garden peas Studied 28,000 pea plants around 8 years

Pea Plants as Subjects Easy to grow Little maintenance Self-fertilizing –Can be artificially fertilized Can obtain true- breeding plants –If bred to itself, always produce offspring identical to

Mendel Studied 7 characteristics –Pod shape: inflated or constricted –Stem length: tall or short –Other 5 are to the right

Generations Parental Generation or Pgen: First filial generation or F1: Second filial generation or F2:

Green pods w/ Yellow pods F1 generation: children are all green F2 generation: ¼ is yellow, ¾ green Defies blending theory Mendel came up with the concept of a inherited unit(gene)

Gene Gene Segment of DNA that encodes a functional protein Gene: eye color makes pigment proteins –Alleles: different forms –Ex. Brown vs. blue eye color Most traits are multigenic and environmental Ex. Hair color 5`3` A Gene A

Genes vs. alleles Genes are responsible for making a protein Alleles are different versions of gene –Make the same protein –Slightly different forms Gene makes a protein that makes the peas a certain color –One allele makes a certain protein Gives a green color –Another allele makes another version protein Yellow color

Genes and Chromosomes Chromosome: long continuous strands of DNA –Diploid organisms have homologous chromosomes –Two very similar chromosomes, one from mom, one from dad Holds thousands of genes at certain points Easy to study when they’re condensed 5`3`

Karyotype 1 A picture of an organisms chromosomes Each human cell has all 23 pairs of chromosomes Can look at picture to detect abnormalities and determine gender –Amnio test on unborn babies

Karyotype 2 White blood cells used Add chemicals to stop it in metaphase Placed on slide and treated with water –Spread chromosomes out –Easier to study Add stain which creates unique bands Take a picture

Karyotype..continued Then you take picture and cut out chromosomes Pair them up based on 1. size 2. banding patterns 3. location of centromere

Lab: Karyotyping Activity In pairs, you will learn how chromosomes are actually organized into karyotypes A picture of a human patient’s chromosomes were taken Cut out and organize into a karyotype