| A | B |
|---|
| Dominant | allele- trait expressed, Captical letter (ex. B) |
| Recessive | allele- trait masked, lowercase letter (ex.b) |
| Heterozygous | 1 dominant allele, 1 recessive allele, called Hybrids or Carriers (ex. Bb) |
| Hybrids | offspring that are the result of two gentically different parents |
| Homozygous | 2 identical alleles called true breeding (ex. BB or bb) |
| Purebreds | offspring that are the result of two gentically similar parents |
| Phenottype | physical characteristic or trait (ex. tall) |
| Genotype | genetic makeup of the chromosome itself (BB, Bb, or bb) |
| Test Cross | The crossing of an organism, with an unknown genotype, to a homozygous recessive organism (tester) |
| Genetics | Study of heredity |
| Heredity | Set of characteristics passed from parent to child |
| Who was Gregor Mendel | Austrian monk (1822), high school teacher and gardener |
| What did Mendel do? | Bred pea plants and observed their patterns of inheritance. Known as the "Father of Genetics" |
| SPECIFICALLY what did Mendel do? | Took plants true breeding (if self-pollinated, would make identical offspring) and prevented self-pollination; crossed parent plants (P generation) with different characteristics to look at the offspring (F1 geeration)= seed shape, seed color, seed coat color, pod shape, pod color, flower position, and plant height; offspring called hybrids (got two different alleles) |
| Why did Mendel do this? | So he had a single variable controlled experiment to eliminate error. |
| Principle of Unit Characters | Biological inheritance is determined by "facotors" (genes) passed from 1 generation to the next and had contrasting "forms" (alleles). This states that individual pass "information" on as individual traits |
| Priciple of Dominance | Some "forms" are dominant and others are recessve. An organism with a particular form f a trait will always exhibit that form of the trait. |
| Law of Segregation | Saw that recessive traits would dissapear in the F1 generation but reappeared in the F2 generation. Hypothesized that each unit character separates into different sex cell. |
| Law of Independent Assortment | Remembered that factors segregate at random. Found that factors also segregate according to change. Found that certain factors were not associated with each other in their inheritance |
| Punnett Square | Gene combinations that might result from a genetic cross can be determined by this |
| One trait: | Monohybrid cross |
| Two traits: | Dihybrid cross |
| Three traits: | Trihybrid cross |
| Test cross | With homozygous recessive phenotypes, you can easily determine the genotype (e.g. both small letters like bb or zz). However, the Homozygous Dominant (BB and ZZ) and Heterozygous Dominant (Bb and Zz) are the same phenotype. |
| How is a test cross performed? | When you cross an unknown dominant phenotype with a known recessive phenotype and study the offspring |
| When is it a homozygous dominant genotype? | If all offspring show the dominant phenotype |
| When is it the heterozygous dominant genotype | If any (just one) of the offspring show the dominant phenotype |
| What is a Dihybrid Cross? | Determines the probability of genetic outcomes for Two traits instead of ONE |
| What is a Monohybrid Cross? | Single Trait cross |
| How are Dihybrid Crosses Possible? | Mendel Concluded that due to the Law of Independent Assortment different traits are not linked and have equal probabilit of showing up in offspring (ex. Tall purple plants, Tall White plant, short purple plants, and short white plants |
| What will dominance do? | It will skew the ratios, but all of these outcomes are POSSIBLE! |
| Mendel's Laws of Heredity | Law of Independent Assortment: each pair of alleles segregates into gametes independently; 4 sets of gametes are produced in equal probability YR, Yr, yR, yr; only true for genes on certain chromosomes |
| How to do a Dihybrid Cross: #1 | Figure out the alleles; identify what the trait/letter is dominant (B-Black fur); identifu what trait/letter is recessibe (b-Brown fur) |
| How to do a Dihybrid Cross: #2 | Draw your box (16 squares for dihybrids!) |
| How to do a Dihybrid Cross: #3 | Determine the possible gametes (sex cells) that could be made form the parents; you should have four combinations (For AaBb: AB, Ab, aB, ab); the letters should be all differnt for each combination (Yr or Ab) |
| How to do a Dihybrid Cross: #4 | Label each side of the Box, Plug and Chug!; put the same letters together again (AABb); Make sure to put dominant alleles First (AaBb) |
| How to do a Dihybrid Cross: #5 | Determine your possible Genotypes! (1/16 bbrr, etc) |
| How to do a Dihybrid Cross: #6 | Determine your possible Phenotypes (1/16 brown wrinkled, etc) |
| What are some alleles? | neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes |
| What special rules must be used for cases of complex inheritance? | uncomplete dominance; codominance; multiple alleles, lethal alleles, polygenic traits; also sex-linked inheritance |
| Incomplete dominance | Neither allele is dominant, the heterozygous phenotype is somewhere in between the two homozygous phenotypes (example: four o'clock flowers) |
| Codominance | Both alleles are dominant, both alleles appear in the phenotype seperately; each allele produces both types of protein, so they both appear (example: a black chicken mating with a white chicken will create an erminette chicken |
| Multiple Alleles | In a population, there might be more than 2 alleles for one single gene; any individual cannot have more than 2 alleles, even if many more exist in their gene pool; one from mother and one from father (ex. laborador coat color, mouse coat color,human blood types) |
| Blood Typing | Human blood works of a system of Codominance with the AB blood type and multiple alleles due to three alleles, A, B, and O |
| Who is Charles Drew? | Famous for his blood preservation methods |
| Lethal Alleles | Difies Mendel's laws of 3:1 because one fot he genotypes results in a lethal (deadly) Phenotype; also called pseudodominance, ex. sickle cell anemiz0offspring that gets C1C1 will die immediately from blood disorder but lethal alleles still persist because skip a generation because they are heterozygous |
| Polygenic Traits | Instead of a trait being controlled by a single pair of homologous chromosome, some traits are controlled by several genes; get more of a bell shaped curve or diversity (ex: skin color, hair color, etc.) (ex. AaBBCcddEe) |
| Poly=, Genic= | Poly=many, genic=genes |
