Chapter 12 Flashcards
(18 cards)
Genetics
The study of heredity
Heredity
The delivery of characteristics from parent to offspring
Gregor mendel and his experiment
Austrian monk teacher and in charge of the monastery garden, worked with pea plants
Dominant alleles
A gene that is always expressed and hides others
recessive allele
A gene that is only expressed when a dominant allele isnt present.
segregation
during the formation of gametes (sex cells) the alleles segregate or separate
Homozygous
organisms with 2 identical alleles. true breeding for a particular trait. Ex: TT or tt.
Heterozygous
Organism with 2 different alleles. True breeding for a particular trait
Phenotype
physical characteristics. Ex TT Tt have the same phenotype… both tall.
Genotype
Genetic makeup. Ex: TT and Tt have different genotypes.
Propability
The likelihood that a particular event will occur. Ex: flipping a coin. There are 2 sides so chances of getting heads or tails is equal to 1/2 or 50%. Flip a coin 3 times whats the probability that the coin will land heads up every time? 1/2x1/2x1/2=1/8 Past outcomes do not affect future ones.
Punnett squares
Used to predict and compare the genetic variations that will result from a cross. The predicted ratio for genetic cross is 3:1 so 3 dominant to 1 recessive.
Independent assortment
The random sorting of chromosomes during meiosis, leading to diverse combinations of genes in gametes. Inheritance of one trait is not determined by the inheritance of another trait.
Incomplete dominance
Cases in which one allele is not completely dominant. Offspring is blending of the parental traits. Ex: red x white= pink.
codominance
Both alleles contribute to the phenotype. The alleles of the parents appear together in the phenotype of the offspring. Ex: red x white= white spotted.
Multiple alleles
Genes that have more than 2 alleles. Does not mean that an individual can have more than 2 alleles just that more that 2 alleles exist in the population. Ex: human blood types, A, B, AB, O
Polygenic traits
Traits produced by the interaction 2 or more genes. Different combinations of alleles for the genes produced many different phenotypes. Ex: human skin color, eye color height
Meiosis
If a cell wants to make a duplicate of itself it first must copy its DNA (part of a chromosome) result in reproductive cells (sperm, eggs, etc) part of each parent is carried to the four new cells. Phases are meiosis and meiosis II.
