chapter 14: genetics Flashcards
what are transmission genetics?
deals with the way genetic differences among individuals are passed from generation to generation
what is a trait (characteristic)?
one or two or more detectable variants in a genetic character
what is a genotype?
the genetic makeup, or set of alleles, of an organism
what is a phenotype?
an organisms physical appearance, which is determined by its genetic makeup
what is hybridization (“basic cross”)
the mating, or crossing, of two true-breeding varieties
what does the term true-breeding mean?
referring to organisms that produce offspring of the same variety over many generations of self-pollination
why are garden peas a good organism for genetic study?
they have easily identifiable traits (ex. tall or short)
what is a character?
character: an observable heritable feature that may vary among individuals
what is a dominant allele? what is a recessive allele?
dominant allele: is always expressed (it’s either in a homozygous or heterozygous pair)
recessive allele: is only expressed when in a homozygous pair (ex. bb)
what does it mean to be heterozygous?
having two different alleles (ex. Pp)
are true-breeding plants heterozygous or homozygous?
homozygous
what does it mean to be homozygous?
having two identical alleles (ex. PP or pp)
what is a locus?
the location of a gene on a chromosome
what is the P generation? what is F1 and F2?
P generation: parental plants that were crossed
F1: the first filial hybrid (heterozygous) offspring, arising from a P generation cross
F2: second filial and offspring of F1
how did Mendel show that “blending” is not taking place?
when Mendel cross-pollinated one variety of purebred plant with another, the crosses yielded offspring that looked like either one of the parent plants, not a blend of the two
what is the law of segregation?
Mendel’s first law, stating that the two alleles in a pair segregate into different gametes during gamete formation
how do you test cross? what type of information does this give you?
cross an individual with a dominant phenotype to a homozygous recessive individual. this test can determine whether a dominant phenotype is homozygous or heterozygous for a specific allele.
what is the law of independent assortment?
Mendel’s second law, stating that each pair of alleles segregates independently of each other pair during gamete formation (this law only applies to genes/allele pairs located on different chromosomes or to genes that are very far apart on the same chromosome)
what is epistasis?
a gene at one locus affects the expression of a gene at another locus
what is pleiotropy?
the ability of a single gene to have multiple effects
what is polygenic inheritance?
two or more genes influence a phenotype (ex. height and eye color)
does the environment have an impact on phenotype?
yes, things such as temperature, oxygen levels, diet, and humidity can all affect phenotypes
what happens in recessive disorders?
recessive: in recessive disorders heterozygous individuals are carriers
who is Gregor Mendel? what organism did he use in his work?
was a biologist, who through his work with pea plants, discovered the fundamental laws of inheritance
