Genetics Flashcards
What is a character?
a heritable feature that varies among individuals
ex. flower color
what is a trait
each variant for a character such as purple or white colors
What is a genetic cross
the mating of haploid gametes
what is the P generation
The parents used in a cross are part of the parental generation they are both true-breeding
What is the F1 generation
the offspring of the P generation. They are a product of hybridization
What is the F2 generation?
Offspring of the F1 generation
What is true-breeding
plants that produce offspring of the same variety when they self-pollinate
What is hybridization
The mating of two contrasting, true-breeding varieties
What is the genotype
genetic makeup
what is the phenotype
the physical expression of the genotype
whats the relationship of phenotype and genotype
an organisms phenotype may not always reveal its genetic composition because of dominant and recessive alleles
If two alleles at a locus differ, which one determines the appearance and which has no effect?
the dominant allele determines the organism’s appearance
the recessive allele has no effect on appearance
what does the law of segregation state?
the two alleles for a heritable character (on homo chromos) separate during meiosis and end up in different gametes
What is a homozygote
an organism with two identical alleles for a character
What is a heterozygote
an organism that has two different alleles for a gene
the dominant allele in this controls the phenotype
are dominant alleles always the most common
no
What is a monohybrid
individuals that are heterozygous for one character (Aa)
what is a monohybrid cross
the cross between heterozygotes
Aa x Aa
What is cystic fibrosis
a recessive human genetic disease (heterozygotes do not show the disease and are carriers)
What is a test cross
it is used to distinguish between homozygous dominant and heterozygote genotypes
if any offspring display the recessive phenotype, the mystery parent must be heterozygous
What is a dihybrid and how is it produced
the crossing of two two-breeding parents differing in two characters produces dihybrids in the F1 generation
dihybrids are heterozygous for both characters
What are dihybrid crosses
crosses that involve two traits
what does the law of independent assortment apply to
genes on different chromosomes
what is true about the inheritance of genes located near eachother on the same chromosome
they are inherited together
what are the extensions to mendelian genetics
incomplete dominance/co-dominance
multiple alleles
pleiotropy
incomplete dominance
when alleles are not completely dominant or recessive
the phenotype is an intermediate between the two parents
multiple alleles
when a gene has more than two alleles (ex. blood type)
pleiotropy
when a gene produces multiple phenotypes
what is codominance
two dominant alleles affect the phenotype in separate distinguishable ways
both alleles are dominant and both phenotypes are expressed
most genes exist in populations
with more than two allelic forms
what are Y-linked genes
involved in male determination and development
Which chromosome are sex linked human disorders carried on?
X chromosome
What are human sex-linked disorders due to and who does it affect?
they are often due to recessive alleles and they mostly affect males since they only have 1x chromosome
What are carriers
carriers express the normal trait phenotypically but are heterozygous for the recessive allele
who is a carrier of X-linked recessive traits?
Only females because they have two X chromosomes and can be heterozygous for the allele
what is polygenic
a trait affected by multiple genes
what does it mean to be multifactorial
it means that a phenotypic character is influenced by multiple genes and environmental factors
what is epistasis
the phenotypic expression of a gene at one locus alters the gene at a second locus
