NOTE: This presentation was not made for public use. Please do not use this presentation without my permission and the permission of each of the authors of the photographs, quotes, and other materials that they contain. Thank you, Vicki Hughes

Alleles = different forms of a gene Chromosome Gene Allele Genes come in “versions” Alleles = different forms of a gene Ex. brown vs. blue eye color (let’s pretend there are only two possible eye colors) Alleles are inherited separately = each parent gives one allele (either a brown or a blue) Some alleles mask others brown eye color masks blue

True-breeding = self-pollinate to produce identical offspring. self-pollination

OK, who took all the yellows? true-breeding green Parent true-breeding yellow Parent All green F1! F1= First Generation OK, who took all the yellows?

Bb bb Dominant alleles mask recessive alleles. The capital letters represent the dominant trait… And the lowercase letters represent the recessive trait. Phenotype = traits you see Genotype = actual genes Bb bb Dominant alleles mask recessive alleles. Why does the blue man have all brown eyes?

aa Bb rr Ss Ww Tt Aa Yy BB RR bb Ee Homo = same Hetero = different Homozygous dominant = Homozygous recessive = Heterozygous = AA Homo = same Hetero = different aa Aa aa Bb rr Ss Ww Tt Aa Yy BB RR bb Ee

Bb x Bb Punnett Squares = used to predict genetic outcomes. X Probability = mathematical chance some event will occur. What is the probability that this couple will have a blue-eyed baby? X male female _______ _______ _________% _______ _______ What would be the F1 generation?

There is always a 50% chance for either gender! XY XX Males have XY alleles. The Y makes it a boy! Females have XX alleles. What is the chance that this couple will have a baby BOY? X male _______ _______ female _________% There is always a 50% chance for either gender! _______ _______

Let’s put it all together. Bb Bb Let’s put it all together. What is the chance that this couple will have a baby BOY with BLUE eyes? Do we need to put the X’s and Y’s? NO Why not? Because there is always a 50% chance of either gender. X male female _______ _______ _________% _______ _______ Human Genetic Traits 2:02 http://www.youtube.com/watch?v=9SdCoNpDzqw

How do we predict two traits at one time? We use a Dihybrid Cross (mating of two individuals involving two traits). Both Bob and Sue are heterozygous for both height and eye color. Height: Tall = T; short = t Eye color: Brown = B; blue = b ________ ________ X How many different gametes could be produced?

TtBb Done for you…Figuring out gamete pairs. Dihybrid Cross (mating of two individuals involving two traits). Both Bob and Sue are heterozygous for both height and eye color. Height: Tall = T; short = t Eye color: Brown = B; blue = b TtBb TtBb ________ ________ X How many different gametes could be produced? TB Tb tB tb TB Tb tB tb TtBb

Law of Independent Assortment Alleles will sort out independently when gametes are formed. How many different gametes can we make? TtBb TtBb ________ ________ X TB Tb tB tb TB Tb tB tb

Heterozygous Dihybrid Cross T = tall t = short B = brown hair b = blonde hair Parents: TtBb x TtBb Heterozygous Dihybrid Cross 9:3:3:1 Tall/Brown Tall/blonde Short/Brown Short/blonde

Meiosis and Genetic Variation Meiosis = process of making gametes Gametes = sex cells (egg & sperm or pollen & ovule) Variation = all the different possible individuals

46 23 23 MEIOSIS MEIOSIS Not Good! 46 + 46 = 92! “Sweet Mama” “Big Daddy” Everyone knows it takes two to make babies. That’s how we get variation! BUT HOW? 46 + 46 = 92! Not Good! How can we get the right number of chromosomes in the babies? 46 chromosomes 46 chromosomes 3.bp.blogspot.com 1.bp.blogspot.com MEIOSIS MEIOSIS spanishdict.com www.greatwhatsit.com hihi11.seesaa.net meandvinnie.blogspot.com babyinsane.com durtbagz.wordpress.com Mutant Baby! 46 www.babble.com metropolitician.blogs.com 23 23 OK, you can only work with what you’ve got.

Somatic Cell = has 2 copies of each chromosomes (2n) Diploid = 2n (has two copies of each chromosome) Haploid = 1n (has only one copies of each chromosome) Homologous Chromosomes = matching chromosomes “Sweet Mama” 46 chromosomes 2n 2n 3.bp.blogspot.com 1n 1n MEIOSIS metropolitician.blogs.com 23

Genetic Recombination = mixing up chromosomes during meiosis MEIOSIS (meiosis divides twice!) Done for you: Cytokinesis! Parent 2n Telophase I Prophase I Metaphase I Anaphase I Cytokinesis! 1n Telophase II Anaphase II Metaphase II End with four haploid gametes Genetic Recombination = mixing up chromosomes during meiosis

Variation = differences in genetic makeup Crossing-Over = chromosomes literally cross ends and swap genes. Genetic Recombination = mixing up chromosomes with Meiosis

Variation = differences in genetic makeup Mutations = change in DNA Can you spot the mutation in the DNA below? Hint 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 7 8 9 10 11 12 13 14 15 16

Patterns of Inheritance Incomplete dominance = dominant gene does not completely mask recessive gene Hybrid = mix of two true-breeding individuals Hybrids have “in-between” appearance RR = red flowers rr = white flowers Rr = pink flowers

Codominance x = Equal dominance Chickens Codominance = dominant and recessive genes are expressed. (expressed = are visible as a trait) Codominance Equal dominance Chickens A black-feathered chicken is crossed with a white-feathered chicken. All of the babies are white with black speckling. Both white and black show up equally. x =

Multiple Alleles = more than one allele available PHENOTYPES for Blood are A, B, AB, or O. Alleles to make these types include IA, IB and i. IA and IB are codominant. i is recessive So… Type A = IA IA or IA i Type B = IB IB or IB i Type AB = IA IB Type O = ii

XHY HH XHXh Hh x XH Y XHXH XHXH XHY XHY XH Xh XHXh XHXh XhY XhY Sex-linked = trait is carried on X chromosome. XHY HH XHXh Hh 2 normal parents, but mother is carrier x XH Y XHXH XHXH XHY XHY XH Xh XHXh XHXh XhY XhY

Human skin color Polygenic = “many genes” AaBbCc x AaBbCc range of shades most children = intermediate skin color some can be very light & very dark

Linked Genes = genes found on the same chromosome

Phenotype is a result of both genetics and environment. www.safeandsoundlostandfound.org Cold Environment Siamese cats that grow up in a cold environment are darker… www.cats-central.com …than those that grow up in a warmer environment. Warm Environment

You got questions? ASK THE TEACHER! ACT L34