chapter 14 Flashcards
What is a character?
distinct heritable features; genes
What is a trait?
character variants; alleles
Give an example of a character used by Mendel that has two traits.
Answer could be any of the following: Flower color, flower position, seed color, seed shape, pod shape, pod color, stem length
What are characters and traits in modern terminology?
Characters are genes, traits are alleles
Describe Mendel’s four-point hypothesis
1) Alternative versions of genes account for variations in inherited characters
2) For each character, an organism inherits two alleles, one from each parent
3) If the two alleles at a locus differ, then one (the dominant allele) determines the organism’s appearance, and the other (the recessive allele) has no noticeable effect on appearance
4) Law of Segregation: the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes
What is a monohybrid cross?
A cross between two individuals that are heterozygous for one gene
What is a dihybrid cross?
A cross between two individuals that are heterozygous for two genes
State the law of segregation.
The two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes
State the law of independent assortment.
Each pair of alleles segregates independently of each other pair of alleles during gamete formation
In Mendel’s experiment, what is meant by the P, F1, and F2 generations? Which generation is entirely homozygous? Which is entirely heterozygous? Which is both?
P = parent; F1 = first generation; F2 = second generation. P is homozygous. F1 is heterozygous. F2 is both.
In which stage in meiosis do the alleles for character segregate during gamete formation?
Anaphase 1
In what stage of meiosis does independent assortment of chromosomes occur?
Metaphase 1
Complete dominance
when phenotypes of the heterozygous and dominant homozygote are identical
Incomplete dominance
the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties
Codominance
two dominant alleles affect the phenotype in separate, distinguishable ways
Compare the inheritance pattern of dominant and recessive inherited disorders.
Recessively inherited disorders show up only in individuals homozygous for the allele whereas expression of dominant disorders only requires one copy of the allele
What is a carrier?
heterozygous individuals who carry the recessive allele but are phenotypically normal
true breeding
a homozygous individual
hybrid
a heterozygous individual
alleles
the alternative versions of a gene
dominant
the allele that determines the organism’s appearance
recessive
the allele that has no noticeable effect on appearance unless the organisms is homozygous
homozygous
the two alleles at a particular locus are identical
heterozygous
the two alleles at a locus differ
phenotype
physical characteristics
genotype
genetic makeup
heritable feature
character that can be passed down to offspring
locus
location of a gene on a chromosome
