Notes 1 2nd Semester Genetics

11-1 The Work of Gregor Mendel Bellwork: Mon. Jan. 4, 2016 Do you think that all zebra have the same stripe patterns? What might affect the stripe pattern? photo credit: W. Perry Conway/CORBIS Heredity and genes!!!! Today we know this “STUFF” as DNA

Genetics Notes: Mendelian Genetics Heredity: passing on of characteristics from one generation to the next Genetics: the scientific study of heredity. Gregor Mendel: Austrian monk who studied garden peas to help him explain heredity.

Mendel knew that the male part of each flower produces pollen, (containing sperm). the female part of the flower produces egg cells. To cross-pollinate pea plants, Mendel cut off the male parts of one flower and then dusted it with pollen from another flower.

Two types of reproduction: sexual and asexual Gametes are involved in sexual reproduction Gametes: sex cells During sexual reproduction, sperm and egg cells join in a process called fertilization. Fertilization: sexual reproduction resulting in a new cell.

Pea flowers are self-pollinating Sperm cells in pollen fertilize egg cells in same flower. Seeds produced by self-pollination inherit all their characteristics from the single plant that made them. What type of reproduction is this? Do you think most plants reproduce this way? What are the advantages/disadvantages of this reproduction method?

Mendel had: true-breeding pea plants that, produce offspring identical to themselves. Mendel wanted to produce seeds by joining male and female reproductive cells from two different plants. He cut away the pollen-bearing male parts of the plant and dusted the plant’s flower with pollen from another plant.

This process is called cross- pollination. Mendel was able to produce seeds that had two different parents. To cross-pollinate pea plants, Mendel cut off the male parts of one flower and then dusted it with pollen from another flower.

Mendel’s 1st Conclusion An individual’s characteristics are determined by factors passed from one generation to the next. And these factors are called traits!

trait: specific characteristic that varies from one individual to another. What are some examples of traits in humans? Think about the lab we did before break.

Genes and Dominance Mendel studied 7 pea plant traits, with 2 contrasting characteristics. Such as: Plant size (tall or dwarf) Pod shape (wrinkled or smooth) Seed color (green or yellow) Flower position (axial or terminal)….. He crossed plants with the 7 contrasting characters and studied their offspring.

Luckily the traits Mendel studied were each controlled by one gene with 2 contrasting forms  producing different characters for that trait.

Luckily the traits Mendel studied were each controlled by one gene with 2 contrasting forms  producing different characters for that trait.

in the first generation of offspring the dominant trait showed up when he crossed plants with opposing traits

Mendel called the F1, or “first filial,” Offspring of parental plants P (parental) generation = Original pair of plants F1, or “first filial,” Offspring of parental plants F2, or “second filial,” Offspring of F1 generation Hybrids: offspring of crosses between parents with different traits. He found the F1 hybrid plants all had the character of only one of the parents.

Genes and Dominance Genes: factors that determine traits. Mendel's 1st conclusion: biological inheritance is determined by factors passed from one generation to the next. Genes: factors that determine traits. Alleles: different forms of a gene

Organisms with dominant alleles for a trait will always exhibit (show) that form of the trait. Organisms with recessive alleles for a trait will exhibit that form only when the dominant allele for that trait is not present… in pea plants  Green Pod Color is Dominant over yellow pod color In humans….if you have red hair, that means you lack a dominant trait for hair color 

Mendel’s 2nd Conclusion Principle of Dominance: some alleles are dominant and others are recessive. What dominant alleles does this little girl have? What recessive?

C T C S G A R Y s g c r y a t Rr Yy Cc Ss Gg Aa Tt

Looking at tall which is dominant to short… t = short

Phenotype: physical appearance (tall, short) Think “ph” for physical make-up The phenotype of these plants are: __________________ &________________ Genotype: genetic makeup ( TT, Tt, tt) Think “gene” for gene make-up The genotypes of these plants are: for the tall plant it could be _________ OR_________ Short Plant: it has to be___________________

Homozygous both alleles same (TT or tt) TT = homozygous dominant tt = homozygous recessive Heterozygous two alleles different (Tt)

Punnett squares Bellwork: Tues. Jan 6. 2016 Show the cross for 2 guinea pigs heterozygous for short hair (S) which is dominant over long hair (s) Write the cross: __ __ x __ __ phenotypic ratio: genotypic ratio: What percentage of the offspring will have short hair? _____%_ What percentage of the offspring will have long hair?  _____%_

http://www.youtube.com/watch?v=6OPJnO9W_rQ

Bellwork: Tues. Jan. 15, 2013 In seals, the gene for the length of the whiskers is controlled by a single gene. The dominant allele (W) codes long whiskers & the recessive allele (w) codes for short whiskers. If a homozygous dominate male seal and homozygous recessive female seal mate, what is the probability that their pups will have long whiskers? Draw a Punnett Square indicate the cross: ______ X ______ and show the: genotypic ratio:______:______ phenotypic ratio:_____:______ 28

Mendel's First Law law of segregation: when gametes are made, each member of the allele pair separates from the other member to form the genetic make-up of the gamete

Segregation Mendel crossed the F1 generation with itself to produce the F2 (second filial) generation. The traits controlled by recessive alleles reappeared in one fourth of the F2 plants.

Segregation Mendel's F2 Generation F1 Generation F2 Generation P Generation When Mendel allowed the F1 plants to reproduce by self-pollination, the traits controlled by recessive alleles reappeared in about one fourth of the F2 plants in each cross. Tall Short Tall Tall Tall Tall Tall Short

Now, let’s look at something a bit more interesting First write these two statements in your notes: The AICAR Drug is ___________________ and makes cells_________________________________________________ Epigenetics means_______________________________ ________________________________________________________ http://www.pbs.org/wgbh/nova/body/marathon- mouse.html epigenetics

Mouse Workout http://www.youtube.com/watch?v=2F2SLLu3kq0

Mega Brain Mouse

Now, let’s look at something a bit more interesting First write these two statements in your notes: The AICAR Drug is an endurance drug and makes cells make more mitochondria cells – as if they were exercising. Epigenetics means: “above the genome” – our genome is like a computer’s hard drive, and the “epigenome” is the software that tells the computer what to do… what happens if something changes the software – like a computer virus? epigenetic changes: tiny chemical tags that accumulate over time and can turn genes on or off. Unlike genetic damage, epigenetic changes can sometimes be reversed

Gametes are also known as genes. sex cells. alleles. hybrids.

The offspring of crosses between parents with different traits are called alleles. hybrids. gametes. dominant. Copyright Pearson Prentice Hall

In Mendel’s pea experiments, the male gametes are the eggs. seeds. pollen. sperm.

In a cross of a true-breeding tall pea plant with a true-breeding short pea plant, the F1 generation consists of all short plants. all tall plants. half tall plants and half short plants. all plants of intermediate height.

If a particular form of a trait is always present when the allele controlling it is present, then the allele must be mixed. recessive. hybrid. dominant.

Mendel's Second Law - the law of independent assortment; during gamete formation the segregation of the alleles of one allelic pair is independent of the segregation of the alleles of another allelic pair (To this point we have followed the expression of only one gene. Mendel also performed crosses in which he followed the segregation of two genes. These experiments formed the basis of his discovery of his second law, the law of independent assortment. )