biology chapter 9 test review

what is genetics?

the scientific study of heredity

who was gregor mendel?

-"father of modern genetics"

-monk

-1st person to analyze patterns of inheritance through pea plants

-developed the basic principles of genetics

what is heredity?

the transmission of traits from one generation to the next

what is a character?

a heritable feature that varies among individuals, such as hair color

what is a trait?

variant of a character, such as brown or black hair

what are true-breeding varieties?

plants that produce offspring of the same variety when they self-pollinate

what are hybrids?

offspring from a cross between 2 true-breeding varieties?

what is the P generation?

parent generation

what is the F1 generation?

hybrid offspring of the P generation

what is the F2 generation?

offspring of the F1 generation

what is a monohybrid cross?

a cross between individuals that differ in only one character

what are alleles?

different versions of the same gene

what does homozygous mean?

when both copies of the alleles are identical

what does heterozygous mean?

when the alleles are different

what is a dominant allele?

the allele that determines appearance

what is a recessive allele?

the allele that has no noticeable effect on the organism's appearance

what are gametes?

sex cells

what is the law of segregation?

when allele pair separates during gamete formation (meiosis)

what is a punnet square?

a chart used to show possible combinations of gametes and offspring from a cross

what is a phenotype?

an organism's physical appearance, what they look like

what is a geneotype?

an organism's genetic makeup

what is a dihybrid cross?

the crossing of parental varieties that differ in 2 characters

what was the result of Mendel's dihybrid cross?

it showed that each pair of alleles segregates independently of the other during gamete formation (law of independent assortment)

what is a test cross?

mating between an individual with a dominant phenotype (but unknown genotype) and a homozygous recessive individual

what is a pedigree?

a family tree showing genetic traits and their history within that family

what is a wild-type trait?

traits seen most often in nature

what is a carrier?

individuals that appear normal because they have a copy of a dominant allele, but also have a copy of the recessive allele

what is inbreeding?

mating of close relatives, which often causes recessive genetic disorders to become more common

what is incomplete dominance?

when hybrid offspring have an appearance between the phenotypes of the parents

what is codominance?

when both alleles are expressed in the phenotype

what is an example in humans of codominance?

blood types ex: type AB

what is pleiotropy?

the impact of 1 gene on more than 1 character, ex: sickle cell is a disease but also gives immunity to malaria

what is polygenic inheritance?

the additive effect of 2 or more genes on a single phenotype, ex: skin color

what are linked genes?

genes located close together on the same chromosome that tend to be inherited together

what can crossing over cause?

-separate liked alleles (genes)

-produce gametes with recombined chromosomes

-produce offspring with recombined phenotypes

Sex chromosomes can influence the ___________ of certain traits.

inheritance

what are sex-linked traits?

any gene on a sex chromosome (mainly on the X chromosome because it's bigger)