chapter 15: mendelian inheritance

when does first-division nondisjuction occur?

metaphase 1

when does second-division nondisjuction occur?

metaphase 2

what is codominance?

multiple alleles can be fully expressed at the same time in a heterozygous individual

what is a recessive allele?

not expressed allele

this type of trait is influenced by more than one gene

polygenic

what are mendels laws?

principle of segregation and independent assortment

what is a gene?

segment of DNA that codes for a protein

what are variable number of tandem repeats?

short nucleotide sequences organized as tandem repeats

for a simple mendelian trait, a heterozygous (Pp) ____.

shows dominant phenotype

for a simple mendelian trait, a homozygous dominant (PP) ____.

shows dominant phenotype

for a simple mendelian trait, a homozygous recessive (pp) ____.

shows recessive phenotype

what happens in division nondisjuction?

some gametes have extra chromosomes and some gametes are missing chromosomes

what does the independent assortment of genes in different chromosomes reflect?

the fact that nonhomologous chromosomes can orient in either of two ways that are equally likely

what does the segregation of alleles reflect?

the separation of homologous chromosomes during anaphase 1 of meiosis

what happens in copy-number variation?

the size of the duplicated or deleted region can include one or more complete genes

what are polygenic traits?

traits controlled by two or more genes

what is the principle of independent assortment?

two copies of each gene segregate into gametes independently of the two copies of another gene

what is incomplete dominance?

unique heterozygous phenotype

how are single nucleotide polymorphism presented?

in large fractions of the population

what is the principle of segregation?

individuals inherit two copies of each gene

what is a locus?

location of a gene

where do genes come from in the principle of segregation?

1 from mother and 1 from father

suppose that, in humans, the ability to roll the tongue (R) is dominant to being unable to roll (r), and having freckles (F) is dominant to having no freckles (f). If a woman heterozygous for both traits married a man with no freckles who couldn't roll his tongue, what is the probability that they would have a freckled, tongue-rolling child?

1/4

how many individuals per 10,000 human live births have extra or missing chromosomes?

33

what are the early theories of transmission genetics?

hippocrates and darwin, aristotle, lamarck

what does homozygous mean?

homologous chromosomes carry the same alleles

what does heterozygous mean?

homologous chromosomes carry two different alleles for the same gene

conditions in which homologous chromosomes carry the same alleles:

homozygous

what is the different between a gene and an allele?

a gene is a segment of DNA that codes for a protein or RNA; alleles are alternate forms of a gene

what is a single nucleotide polymorphism?

a substitution of a single nucleotide at a specific position on the genome

what is a short tandem repeat polymorphism?

a type of microsatellite polymorphism that leads to different alleles by differing the number of repeated sequence

what is an allele?

alternative variations of a gene/trait

what is a phenotype?

an individuals observable traits

in mendel's peas, an individual that is heterozygous for seed color: a) has only one kind of allele for seed color b) has two different alleles for seed color c) will express the dominant allele d) will express the recessive allele e) has two different alleles for seed color and will express the dominant allele

b) has two different alleles for seed color c) will express the dominant allele

what is a dihybrid cross?

cross between 2 diploid parents but tracking two genes

what does a test cross determine?

determines the genotype of an individual that shows the dominant phenotype

what is polymorphism?

discontinuous genetic variation resulting in the occurrence of several different forms or types of individuals among the members of a singe species

what is a dominant allele?

expressed allele

according to the principle of segregation, a heterozygous plant with alleles Aa will produce:

gametes in the ratio of 1 A allele: 1 a allele

what is genetic variation?

genetic differences that exist among individuals in a population at a particular point in time

what is a genotype?

genetic makeup of an organism

if you crossed a true-breeding yellow-seed plant (AA) with a heterozygous yellow-seed plant (Aa), offspring

genotypes would be 1 AA: 1 Aa

a mutation in a pleiotropic gene ____.

has multiple phenotypic outcomes

an individual is heterozygous for a gene if: a) his or her mother is heterozygous for a gene b) his or her father is heterozygous for a gene c) he or she developed from a sperm and egg that carried different alleles d) he or she developed from a sperm and egg that carried the same allele e) only one allele is present in the population

he or she developed from a sperm and egg that carried different alleles