Genetics and Heredity Ch. 7A Vocab Heredity: the passing of traits from parents to offspring (kids) Genetics: the study of how traits are inherited through the interaction of alleles Genetics Inherited Traits Eye color, nose shape, and many other physical characteristics are some of the traits inherited from parents to the offspring An organism is a collection of traits, all inherited from the parents How are traits passed on? two genes traitEach parent has two genes for a trait. These specific genes are called alleles. During Meiosis, the alleles for different traits are mixed up and separated randomly to insure that the offspring will be a genetically diverse individual Genes are passed on once Meiosis and fertilization takes place Gregor Mendel Father of GeneticsGregor Mendel is known as Father of Genetics Austrian Monk Worked with garden peas at a monastery Noticed and studied patterns in plant traits & people He was the first to use the mathematics of probability to explain heredity He was also the first to trace one trait through several generations Alleles Alleles are different forms of a trait that a gene may have EEx of a Trait: EYE COLOR EEx of a allele: blue eyes, green eyes, hazel and brown Alleles are represented b bb by various letters of the alphabet T, t, R, r, W, w, B, b Pattern of Inheritance patterns of inheritanceSome traits are expressed in an organism through different patterns of inheritance One pattern is know as Dominant and Recessive Dominant Traits Dominant traitDominant trait the trait that will physically be seen in an organism Capital letters are used to represent Dominant alleles. When these alleles are present, they take over or show Only requires one of the alleles present in the genotype to show up in the appearance Dominant Traits:, W -widows peak, F- freckles, G 6 fingers?! Recessive Traits Recessive traitRecessive trait: trait that hides in the background or is NOT always physically seen Recessive alleles are represented by Lowercase letters and are the weaker of the alleles two Rec. trait will only appear when theres two recessive alleles Recessive Traits: w -no widows peak, f - no freckles, d 5 fingers Genetic Cross crossA cross is the deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent Genotype and Phenotype GenotypeGenotype: inherited combination of alleles Actual genes Example: Bb, Ll PhenotypePhenotype: the organisms physical appearance What the organism looks like Blue eyes, brown hair, smooth chin Purebred and Hybrid Purebred: an organism that has two alleles that are the SAME Also called homozygous Ex: bb, TT, DD Hybrid: an organism that has two DIFFERENT alleles for a trait Also called heterozygous Ex: Bb, Tt, Dd Punnett Squares Punnett Squares visually gene/allele combinationsPunnett Squares are used to visually show all possible gene/allele combinations of a cross for ONE offspring (organism) Probability Probability: chance that an event will occur After solving Punnett squares, questions will often ask you to predict the probability of one of the traits. Ex: Whats the chance of a child having a smooth chin? Expressed like so: 0%, 25%, 50%, 75%, or 100% (0/4) (1/4) (2/4) (3/4) (4/4) End Notes More about Punnett Squares later Sex linked traits If a gene is found only on the X chromosome and not on the Y chromosome, it is said to be a sex linked trait. Because the gene controlling the trait is located on the sex chromosome, sex linkage is linked to the gender of the individual. The result is that females will have two copies of the gene while males would only have one. Sex linked traits cont. If the gene is recessive, then males only need one such recessive gene to have the sex linked trait rather than the normal two recessive genes for non sex linked traits. This is why males exhibit some traits more frequently than females. Examples of Sex linked traits Red-green colorblindness Male Pattern baldness Hemophilia Duchenne Muscular Dystrophy Red-green colorblindness genotypes Normal vision male-X C Y o Colorblind male-X c Y o Normal vision female-X C X C Normal vision female (carrier)-X C X c Colorblind female-X c X c Normal Vision father X Colorblind Mother Dad genotype: Mom genotype: Normal vision father x normal vision mother (no colorblindness in her family) Dad genotype: Mom genotype: Human Genome Project Completed in 2003, the Human Genome Project (HGP) was a 13-year project coordinated by the U.S. Department of Energy and the National Institutes of Health Some of the project goals were: identify all the approximately 20,000-25,000 genes in human DNA determine the sequences of the 3 billion chemical base pairs that make up human DNA store this information in databases Ethical Issues Discussion: What is the line between medical treatment and enhancement?