chapter 4-Genetics Flashcards
what are Mendel’s 3 Laws?
- Inherited characteristics are controlled by factors known as genes
- One factor or gene masks the effect of another
- a pair of factors or genes separate or segregate during the formation of sex cells
what is a genotype?
The genes of an organism
what is a phenotype?
The visible traits of an organism
homozygous?
Two genes that are the same
ex. TT
heterozygous?
two different genes
ex.Tt
Gene?
A code of heredity
allele?
An alternate form of genes
ex.T= tall and t= short
mono hybrid cross?
A gene with contrastic traits
ex.Tt from TTxtt
dihybrid cross?
A hybrid that is heterozygous for alleles of two different genes
ex. TT tt x TT tt
multiple alleles?
three or more alternative forms of a gene that occupy the same place.
ex. Ee in a square of a Punnett square
Incomplete dominance?
blending of the dominant & recessive traits so that the third phenotype is something in the middle
ex. red x white = pink
What is probability?
the study of outcomes of events and occurrences
rule of independent events?
chance has no memory
product rule?
probability of independent events occurring simultaneously= product of these events occurring separately
ex. the chances of tossing heads after two tosses =1/2, but the chances of tossing it three times in a row=1/2x1/2x1/2=1/8
polygenic inheritance?
traits are inherited characteristics that are affected by one or more gene
pleiotropic genes?
genes that affect many characteristics
ex. sickle-cell anemia
chromosomal theory of inheritance?
- chromosomes carry genes
- paired chromosomes segregate during meiosis
- chromosomes assort independently during meiosis
- each chromosome contains many different genes
what is a somatic cell?
the cells of an organism except the sex cells
sex linked trait?
crontrolled by genes located on the sex chromosomes
ex.eye colour in Drosophilia controlled by X chromosome
zygotes?
a cell resulting from the Union of male and female sex cells
gene pool?
all of the genes that occur within a specific population
what is the Hardy Weinberg principle?
A principle indicating conditions under which allele and gene frequencies will remain constant from generation to generation
what are the 4 conditions in the Hardy Weinberg principle?
- Large populations
- no selection
- No net mutations
- No net migration
gene equilibrium?
the condition of an alleged or genes type in a gene pool where the frequency does not change from generation to generation
genetic drift?
the process in which allele frequencies in a population change randomly overtime because of chance
what did Mendel experiment on?
pea plants
codominance?
where in the offspring both dominant and recessive genes appear
ex.AB blood type
