Heredity and Inheritance - What are traits and how are they passed from parent to offspring? Structure of DNA - What does DNA look like and how does it copy itself? Protein Synthesis - What role does DNA play in constructing proteins in our cells? Mutations - What happens when there is a change in the structure of DNA? Study of Genetics- starting with the outside (physical appearance) and moving inside (genes)
Genetics- study of genes Heredity- how traits are passed from parent to offspring Inheritance- receiving alleles from both parents
Lab Investigation: What are traits? 1. PTC paper test (taster or not taster) 2. Hairline (widows peak or straight) 3. eye shape ( almond or round) 4. eyelash length ( long or short) 5. tongue rolling ( roll or not) 6. thumb ( hitchhiker's or straight) 7. lip thickness ( thick or thin) 8. hair texture ( curly, straight, wavy) 9. inter-eye distance (close- set, far-set or medium-set) 10. lip protusion ( protruding, slightly protruding, or nonprotuding)
Traits Outside (physical apperance) = phenotype ex: long eyelashes Inside (genes) = genotype ex: EE or Ee The "E" is known as an allele . So, two alleles come together to form a genotype, and how this is expressed (what it looks like) is called a phenotype.
The genotype determines the phenotype because of the rule of dominance and recessive. For example: Plant height (tall or short) Dominance is represented by a capital allele, such as T. Recessive is represented by a lower case allele, such as t. Two alleles make up a genotype, such as Tt. This genotype would be expressed as a tall plant because the capital T is present and it takes over and hides the lower case t, the recessive allele.
Mendel looked at several different traits of pea plants: stem length, seed shape, seed color, pod shape, pod color, flower position, seed coat color, flower color Mendel and his Pea Plants
This is what Mendel observed in stem height: Pure-bred tall plant Pure-bred short plant P generation Both offspring are tall plants Next generation of offspring is 3 tall plants and 1 short plant
This is what he observed in flower color: Crossed a purely purple flower with a purely white flower All offspring had purple flowers Next generation of offspring had 3 purple and 1 white
Punnett Squares: What is the probability of getting offspring with a particular genotype? Flower Color P= dominant p = recessive P P p p
Complete Dominance - What Mendel observed. If you have a genotype that is heterozygous/hybrid, the dominant allele will hide the recessive allele and the dominant trait will be expressed (phenotype). Example: Flower Color Pp is a heterozygous genotype, but the dominant allele (P) is purple and it will hide the recessive allele, therefore the phenotype (physical appearance) of the plant will have purple flowers.
Co-Dominance - If you have a genotype that is heterozygous/hybrid, both traits will be expressed (phenotype). Example: Flower Color F P F W is a heterozygous genotype, with both a dominant purple allele and dominant white allele present, therefore the phenotype of the plant would be purple with white marks or white with purple marks.
Incomplete Dominance - If you have a genotype that is heterozygous/hybrid, both traits will be expressed (phenotype) as a blend of the two alleles. Example: Flower Color F P F W is a heterozygous genotype, with both a dominant purple allele and dominant white allele present, therefore the phenotype of the plant would be a blend/mix of the two colors; lavender flower color.
Co- Dominance for Skin Color ( green + pink ) Incomplete Dominance for Body Type (Medium)
Example: Two parents have 3 children. One child has a chronic disease, one child is a carrier, and the other is normal. The gene for this particular disease is found on recessive alleles. Child #1 Genotype = gg Child #2 Genotype = Gg Child #3 Genotype = GG Child #1 Phenotype = afflicted with disease Child #2 Phenotype = carrier of disease Child #3 Phenotype = normal What is a carrier?
Blood Typing: A, B, AB, and O Both A and B are dominant and O is recessive. How are blood types different? Physical structure of the blood cell Rh factor- positive or negative blood due to the proteins that make up the blood cells
Sex-Linked Traits All chromosomes are numbered except sex chromosomes. They are called X and Y. XX = female XY = male Traits can be carried on these sex chromsomes and be passed from parent to offspring.
Hemophilia and Red-Green Colorblindness are sex-linked traits X H X h = female carrier X H Y= male normal X H X H = female normal X h Y = male hemo X h X h = female hemo X C X C = female normal X C Y = male normal X C X c = female carrier X c Y = male colorblind X c X c = female colorblind