Semester 2, Day 10

Agenda  Complete Homework  Review for Quiz  Turn in Homework  Take Quiz  Lecture on Genotype, Phenotype, and Natural Selection  Reading/Work Time

Complete Homework  30 minutes  Questions  13.1 #1-5  13.2 #1-5  13.3 #1-5  Chapter 13 Assessment #1-15, 17-21

Review for Quiz  Define:  Genetic Engineering  Transgenic Organism  Cloning  T-DNA  Know the steps of what Agrobacterium tumefaciens does in nature (transformation of plant cell)  Three examples of genetic engineering  Where should DNA be inserted in order to affect the ENTIRE organism?  Know the steps of cloning and why the lamb is a clone of the “heart” sheep.

Turn in Homework

Take Quiz  Silence during quiz  Eyes on your own paper  Put pencil down when finished.

Mendelian Genetics  Gregor Mendel: Austrian monk & plant breeder. Considered the father of genetics due to his findings in breeding pea plants in Image Source: commons.wikimedia.org

Mendelian Genetics  Inheritance / Heredity: Passing of traits to the next generation.  Genetics: Study of heredity. Image Source:

Mendelian Genetics  Mendel’s Work  Mendel determined there must be 2 forms of a trait in pea plants  alleles!  Same Trait: Color  Different Alleles: Yellow or Green  Also said the trait seen in F 1 = dominant, while masked (hidden) trait in F 1 = recessive.  Dominant Allele: Yellow  Recessive Allele: Green  Dominant allele is labeled with a capital letter and the recessive allele is labeled with the corresponding lower case letter.  Yellow (Dominant): Y  Green (Recessive): y Generation Parental (P) (Pure-Breeding) First Filial Generation (F 1 ) Second Filial Generation (F 2 ) x YellowGreen All Yellow 6022 Yellow: 2001 Green = 3:1

Mendelian Genetics  Genotype: the organism’s allele pair  Zygosity: the similarity of alleles for a trait  Phenotype: observable characteristic of allele pair  Homozygous Dominant Genotype  Phenotype  Heterozygous Genotype  Phenotype  Homozygous Recessive Genotype  Phenotype Example Y = yellow pea color y = green pea color GenotypeZygosityPhenotype Y Homozygous Dominant Yellow Y y Heterozygous Yellow yy Homozygous Recessive Green “Same”“Dominant Alleles” “Same”“Recessive Alleles” “Different Alleles” Y Y = “Dominant” “Dominant” = Yellow “Yellow” “Yellow” Y y = “Dominant” “Recessive” = Yellow “Yellow” “Green” (Dominant allele masks recessive allele) y y = “Recessive” “Recessive” = Green “Green” “Green” (No dominant allele to mask recessive)

Evolution  Change in a group of organisms over many generations  CANNOT OCCUR IN AN INDIVIDUAL!  5 Mechanisms of Evolution:  Natural Selection  Mutations  Gene Flow  Genetic Drift  Nonrandom Mating

Darwin  Father of Natural Selection  Sailed to the Galapagos Islands  Each island: unique finch species  Hypothesis: new species can appear gradually through small changes over time  Artificial Selection: pigeon breeders exaggerate traits over time.

Evolution  Organism: living individual  Need water, food, and a place to live  Fitness: ability to survive and reproduce (tall vs. short)

Natural Selection  Species: group of similar organisms capable of interbreeding (mules are not a species)  Individual: single organism in a species  Population: many of those individual in same place

Natural Selection  Some are better equipped for survival than others.  Those less equipped die and don’t reproduce.  Over time, “good” traits “build up” until we have a new species (can’t breed with previous generations)

Basic Principles of Natural Selection  1 – Variation  Individuals differ from one another  2 – Heritability  Variations passed down  3 – Overproduction  More offspring produced than can survive  4 – Reproductive Advantage  Some survive and reproduce more

Genotype vs. Phenotype  Genotype: The allele pair  Phenotype: What you see GenotypeZygosityPhenotype B Homozygous DominantBrown B bHeterozygousBrown b Homozygous RecessiveGreen

Types of Natural Selection  4 Types  Stabilizing Selection  Directional Selection  Disruptive Selection  Sexual Selection

Natural Selection  Stabilizing Selection Example: Human Birth Weight  Average is most “fit”, extremes are selected against

Natural Selection  Disruptive Selection Example: Bunnies  Both extremes are most “fit”, average is selected against

Natural Selection  Directional Selection Example: Giraffes  One extreme is most “fit”, other extreme is selected against

Natural Selection  Sexual Selection Example: Peacocks and Antelopes  Traits that give an organism a better chance at mating get passed on more to later generations  Peacocks: prettier feathers to attract females  Antelopes: fiercer fighting to obtain males

Reading/Work Time  Cornell Notes:  Pages  (stop BEFORE “Adaptations: Evidence for Evolution”)  Pages  (stop BEFORE “The Evolution of Species”)  Questions:  15.1 #1, 5  15.2 #1  Chapter 15 Assessment #2, 6, 9, 11, 16, 18-20