Presentation on theme: "Words to know… Heredity - the passing of traits from parent to offspring. Genetics - the study of heredity. Trait- a specific characteristic Gene- chemical."— Presentation transcript:
1Words to know…Heredity - the passing of traits from parent to offspring.Genetics - the study of heredity.Trait- a specific characteristicGene- chemical factor that determines a traitAllele- A segment of a geneHybrid- the offspring crosses between parents with different traits
2Gregor Mendel Father of Genetics He lived in a monastery; He was a teacher and took care of the gardenMendel’s knowledge helped us understand heredity.He studied the pea plant most of all.
3Mendel's ProcessMendel took a true-breeding (or pure) plants that always produce offspring with the same trait when they self-pollinate and cross pollinated it with a true breeding plant with a different trait.The P generation is the true-breeding generation or the parent generation.
4PollinationSelf pollination occurs when pollen is transferred from the anthers (male) of one flower to the stigma (female) of the same flower.Cross-pollination occurs between two plants.
5The F1 generation is the offspring of the P generation. Mendel called the plants in the second generation the second F2
6Mendel established three principles (or Laws) from his research The Principle of Dominance and Recessiveness - one trait is masked or covered up by another traitPrinciple of Segregation - the two factors (alleles) for a trait separate during gamete formationPrinciple of Independent Assortment - factors of a trait separate independently of one another during gamete formation; another way to look at this is, whether a flower is purple has nothing to do with the length of the plants stems - each trait is independently inherited
8Results of Monohybrid Crosses Mendelian Genetics3/25/2017Results of Monohybrid CrossesInheritable factors or genes are responsible for all heritable characteristicsPhenotype is based on GenotypeEach trait is based on two genes, one from the mother and the other from the fatherTrue-breeding individuals are homozygous ( both alleles) are the samecopyright cmassengale
9copyright cmassengale Mendelian Genetics3/25/2017Law of DominanceIn a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation.All the offspring will be heterozygous and express only the dominant trait.RR x rr yields all Rr (round seeds)copyright cmassengale
10copyright cmassengale Mendelian Genetics3/25/2017Law of Dominancecopyright cmassengale
11copyright cmassengale Mendelian Genetics3/25/2017Law of SegregationDuring the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other.Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring.copyright cmassengale
12Applying the Law of Segregation Mendelian Genetics3/25/2017Applying the Law of Segregationcopyright cmassengale
13Law of Independent Assortment Mendelian Genetics3/25/2017Law of Independent AssortmentAlleles for different traits are distributed to sex cells (& offspring) independently of one another.This law can be illustrated using dihybrid crosses.copyright cmassengale
14Dominant- stronger & mask other genes; the trait that shows up more frequently represented by a capital letterRecessive- “weaker” the trait that shows up less frequentlyrepresented by a lower case letter
15A chromosome is made up of DNA A chromosome is made up of DNA. A gene is a segment of DNA on a chromosome that controls a particular hereditary trait.Each of two or more alternative forms of a gene is called an allele. Mendel’s factors are now called an allele.
16Particulate Inheritance Mendelian Genetics3/25/2017Particulate InheritanceMendel stated that physical traits are inherited as “particles”Mendel did not know that the “particles” were actually Chromosomes & DNAcopyright cmassengale
17Probability is the likelihood that a specific even will occur. It is the mathematical chance that something will occur.
18copyright cmassengale Mendelian Genetics3/25/2017Punnett SquareUsed to help solve genetics problemscopyright cmassengale
19Types of Genetic Crosses Mendelian Genetics3/25/2017Types of Genetic CrossesMonohybrid cross - cross involving a single trait e.g. flower colorDihybrid cross - cross involving two traits e.g. flower color & plant heightcopyright cmassengale
20copyright cmassengale Mendelian Genetics3/25/2017More TerminologyGenotype - gene combination for a trait (e.g. RR, Rr, rr)Phenotype - the physical feature resulting from a genotype (e.g. red, white)copyright cmassengale
21copyright cmassengale Mendelian Genetics3/25/2017GenotypesHomozygous genotype - gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr); also called pure Heterozygous genotype - gene combination of one dominant & one recessive allele (e.g. Rr); also called hybridcopyright cmassengale
22?????? What is the phenotype of a heterozygous flower? What is the genotype of a heterozygous flower?What is the genotype of a homozygous dominant?
25copyright cmassengale Mendelian Genetics3/25/2017Test CrossA mating between an individual of unknown genotype and a homozygous recessive individual.copyright cmassengale
26Its not all that easy!Multiple alleles- trait that is determined by more than two alleles (ex. Human blood types)Polygenic traits- trait influenced by several genes; genes may be on same chromosome or on different one (ex. Human eye color, weight, skin tone)
27Incomplete dominanceThe phenotype is in between that of the parents. It is like a mixture (pink flower)Example: Snap Dragon
28CodominanceBoth alleles are expressed. With Codominance you can see two dominant alleles.
29copyright cmassengale Mendelian Genetics3/25/2017CodominanceTwo alleles are expressed (multiple alleles) in heterozygous individuals.Example: blood type1. type A = IAIA or IAi2. type B = IBIB or IBi3. type AB = IAIB4. type O = iicopyright cmassengale
30copyright cmassengale Mendelian Genetics3/25/2017Codominance ProblemExample: homozygous male Type B (IBIB)x heterozygous female Type A (IAi)IBIAiIAIBIBi1/2 = IAIB1/2 = IBicopyright cmassengale
31Another Codominance Problem Mendelian Genetics3/25/2017Another Codominance ProblemExample: male Type O (ii) x female type AB (IAIB)iIAIBIAiIBi1/2 = IAi1/2 = IBicopyright cmassengale
32copyright cmassengale Mendelian Genetics3/25/2017CodominanceQuestion: If a boy has a blood type O and his sister has blood type AB, what are the genotypes and phenotypes of their parents?boy - type O (ii) X girl - type AB (IAIB)copyright cmassengale
33Thomas Hunt MorganDiscovered that females have XX chromosomes and males have XY by studying a fruit fly.Sex Chromosomes determine the sex of an organism.He discovered that the gene for eye color in fruit flies is a sex linked trait carried on the Y chromosome
34copyright cmassengale Mendelian Genetics3/25/2017Sex-linked TraitsTraits (genes) located on the sex chromosomesSex chromosomes are X and YXX genotype for femalesXY genotype for malesMany sex-linked traits carried on X chromosomeThe genes interact with other genes scattered throughout the genomecopyright cmassengale
35Blood Type Blood Type Antigen Antibody Can donate to Can receive from ABO