Presentation on theme: "Allele Genotype vs. Phenotype Flashcard Warm-up"— Presentation transcript:
1 Allele Genotype vs. Phenotype Flashcard Warm-up For any trait, such as hair color, there are different forms of the protein that create the different hair colors. Each different form is called an allele. We use capital letters to represent dominant alleles and lower case letters to represent the recessive alleles.Genotype vs. PhenotypeGenotype is the genetic makeup (AA, Aa, or aa)Phenotype is the physical trait, a result of the genotype
2 Where did my traits come from?? Unit 10- GeneticsWhere did my traits come from??
4 Traits: physical or physiological characteristics; like eye color, or blood type Phenotype: individual’s observable trait; brown hair
5 Genes: Portion of DNA that make proteins that control our traits and are found on chromosomes. Chromosomes exist in pairs, one from sperm one from egg.Alleles: different versions of genes; blue eye gene, brown eye gene; we use letters to represent allelesAlleles are inherited separately from each parent.
6 How does this work? Paired chromosomes have same kind of genes but may be different alleleseye color(blue?)eye color(brown?)hair color
7 Genes affect what you look like XbbBBBbBbBbBbWhere did the blue eyes go??
8 Genes affect what you look like… XbbBbBbBbbbbbWhy did the blue eyes stay??
9 What is a genotype and how do we write it? Genotype: the genetic makeup(the alleles you received from mom and dad)Examples of genotypes:Homozygous: Identical copies;AA – homozygous dominantaa - homozygous recessiveDominant genes mask or hide recessiveHeterozygous: one dominant and one recessive; Aa2 people can have the same appearance but have different genetics: BB vs Bb
10 Mendelian Genetics: Gregor Mendel : Father of Genetics Studied pea plantsWhy pea plants?
11 Mendel’s Principles Three Principles: 1. Principle of Dominance: dominant alleles can mask/ hide recessive allelesHomozygous dominant: AA; Dominant trait is expressedHeterozygous: Aa; dominant masks/hides recessive and is expressedHomozygous recessive: aa; recessive trait is expressed2. Principle of Segregation: to separate, each parent can only pass on one allele per trait3. Principle of Independent Assortment: genes on separate chromosomes are passed on independently from one another.
14 Punnett squares B b BB Bb B b Bb bb Bb x Bb male / sperm female / eggs
15 Flashcard Warm-up Mendel’s Principles of Inheritance: Use your notes from yesterday to write down and briefly EXPLAIN the three principles
16 Punnett SquaresMonohybrid cross: a Punnett square involving only one trait; 4 boxesDihybrid cross: a punnett square involving two traits; 16 boxes
17 Flashcard Warm-Up Trait: Free earlobes- dominant = F Attached earlobes- recessive = fA woman has free earlobes, what are two possible genotypes she might have?The genotype for a man is Ff, what is his phenotype?What is a gene?
18 Incompletely Dominant Flashcard Warm-upCodominantIf two alleles are codominant, they are equally strong. Both alleles would be seen in the phenotype. An example is crossing a black chicken with a white chicken and the offspring having both black and white feathers.Incompletely DominantNeither allele is dominant, so when both alleles are present they mix or blend. These alleles are written with ONE letter that has a prime ‘
19 Non Mendelian Genetics: Codominance: Both alleles are equally dominant and will be expressedPhenotype:3 possibilitiesGenotype:2 Capital letters; BB, WW, or BWRed hair is dominantRRRoan is a mixture of red and white hair-RWWhite hair is dominantWW
20 Codominant Example:Cross a black cow with a white cow. Both hair colors are dominant.
21 Incomplete DominancePhenotype: neither allele is completely dominant to mask the otherGenotype: heterozygous RR’ results in a blended phenotype , capital letters for both traits and use a prime ‘ symbol for oneRR RR’ R’R’
22 Incomplete Dominance Example Cross a white flowered plant with a pink flower. Both white and red are incompletely dominant.
23 Ticket Out the DoorA) If feather color in a species of birds in codominant, cross a white bird with a black and white spotted bird. List all possible phenotypes.B) If fur color is incompletely dominant, cross a gray fur dog with a black dog. List all possible phenotypes.
24 Polygenic trait Flashcard Warm-up Sex chromosomes trait determined by many genes, results in a wide range of phenotypesExamples include height, skin color, hair colorSex chromosomesFor humans, the last set of chromosomes are the sex chromosomes that determine the gender. Females have two X chromosomes and males have one X and one Y. Examples of sex-linked traits are colorblindness and hemophilia, these traits are carried on the X chromosome.
25 Multiple Alleles: more than two alleles exist for a trait Blood Type:Phenotype: Type A, AB, B, OGenotype: IAIA or IAi IAIB IBIB or IBi ii
27 Blood Type ExampleCross a heterozygous type A mom with a Type O dad. What is the chance they have a child with Type O blood?
28 Sex Linked: trait found on the X sex chromosome Phenotype: Female – less likely but can show a sex-linked traitGenotype: XA XA, XA Xa , XaXaPhenotype: Male – sex-linked traits show up more because they have XY sex chromosomes,Genotype: XA Y, XaYNo male carriers for a sex-linked trait
29 Sex-linked ExampleCross a colorblind dad with a mom who is a carrier. What is the chance of this couple having a son who is not colorblind?
30 PolygeneticTraits that depend on many genes and create a range of phenotypes. Ex. Height, skin color NO PUNNETT SQUARE!
31 Human skin color AaBbCc x AaBbCc can produce a wide range of shades most children = intermediate skin colorsome can be very light & very dark
32 Nature vs. Nurture: Nature is heredity – your DNA Nurture is your environmentThe debate: Which has a greater influence?Example: We use identical twins to study the effects of the environment on genes.
33 Ticket Out the Door1. A sex-linked trait is found on the __ chromosome.2. Cross a mom with type AB blood with a dad who is type O. List all possible phenotypes.