Genetic Variation and Mutation Test Review SEX CHROMOSOMES XX---Female XY---Male

Multiple Alleles Traits that have more than 2 phenotypes Example Blood Type A, B, O

Sex-linked traits occur more often in males- --ex hemophilia and colorblindness How to find a genetic disorder? a. analysis of pedigree Genetic counseling Prenatal testing Pedigree Basics… Squares are males Circles are females….colored in shapes have trait….non---colored do not have trait

Crossing Over When chromosomes exchange genetic information that leads to more varations in the population

Gives most variation in a population… Crossing over Recombination of parents genes through--- Sexual reproduction (MEIOSIS) Mutations Organisms with different traits that cross produce more variations in their offspring

Populations with many different traits/variations have a better chance to survive---especial when the environment changes Mutations can lead to variations in a population because they change an organism’s PHENOTYPE

Mutations A mutation is ANY change in the DNA that causes a change in the phenotype or appearance They can be harmful, helpful or neutral

Nonsense Mutation When the nucleotide/base of DNA is changed and this causes the codon to be translated into a STOP codon instead of amino acid Creates a protein we cant use

Silent Mutation When a nucleotide/base is changed but is translated as the same amino acid….causeing no problems Missense Mutation When a nucleotide/base is changed…causing the codon to be translated into a DIFFERENT amino acid causing problems

Frame shift Mutations When you insert one or more nucleotides/bases into the DNA strand causing the codons and reading of those codons to shift Also can happen when one or more nucleotide/base is deleted….

Nondisjunction Failure of chromosomes to separate during Meiosis Causes Monosomy---one less chromosome in cell Causes Trisomy---one more chromosome in the cell Example Down Syndrome, Edward’s Syndrome and Klinefelter’s

Body cell mutations: Affect the person with it….such as mutated skin cells…when they divide they pass on the mutation to that new skin cell. Cant be passed on because they do not affect the egg and sperm…AKA Gametes Germ cell mutations or mutations of the gametes…results in the offspring’s phenotype being changed.

Chromosomal Mutations Inversion----piece of chromosome breaks off and reattaches to the SAME in the reverse order Deletion---piece of chromosome breaks off and is gone Translocation---piece of chromosome breaks off and reattaches to the DIFFERENT in the reverse order

OPEN ENDED QUESTIONS….Know them….

X-linked Cross Normal Female----carrier Normal Male XN Xn XN Y Results: XN XN 50% females normal noncarriers XN Xn 50% females normal carrier Xn Y 50% All males with disorder XN Y 50% All males normal

Sex-Linked Traits Found on SEX CHROMOSOMES…usually X Both sexes can have trait…males more likely Hemophilia and Colorblindness Sex Limited Traits Found on Autosomes Only 1 sex expresses the trait Beard growth or Milk Production Sex-Influenced Traits Found on Autosomes Both sexes…… Baldness THIS IS THE CHART

STUDY Nondisjunction Notes…. GET OUT YOUR NOTES AND LOOK AT THESE PICTURES KARYOTYPE Pictures for Monosomy, Trisomy and DIPLOID