April 4th (256-263) Flashcards
Chromosome theory of inheritance
formed by Sutton and Boveri; asserts that the hereditary factors called genes are located on chromosomes.
Heredity
meaning inheritance of the transmission oft traits from parents to offspring.
trait
any characteristic of an individual, ranging from height to the primary structure of a particular membrane protein.
Blending inheritance
claimed that the traits observed in a mother and father blend together to form the traits observed in their offspring. As a result, an offspring’s traits are intermediate between the mother’s and father’s traits. false
Inheritance of acquired characters
claimed that traits present in parents are modified, through use, and passed on to their offspring in the modified form. false
model organism
a species that is used for research because it is practical (available in many recognizable traits, control mating for ex) and because conclusions drawn from studying it turn out to apply to many other species as well.
self-fertilization
a flower’s pollen falls on the female reproductive organ of that same flower.
cross-fertilization or cross
Mendel prevented self fertilization by cutting off the male reproductive organs before any pollen formed so he could transfer pollen from the plants that he wanted to w/ a brush.
phenotype
the observable traits of an individual, such as the shape of a pea seed.
gene
a hereditary factor that influences a particular trait
allele
a particular form of a gene.
genotype
a listing of the alleles in an individual.
homozygous
having two of the same allele.
heterozygous
having two different alleles.
dominant allele
an allele that produces its phenotype in heterozygous and homozygous form.
recessive allele
an allele that produces its phenotype in homozygous form.
pure line
individuals of the same phenotype that, when crossed, always produce offspring with the same phenotype (meaning they are homozygous for the gene in question).
hybrid
offspring from crosses between homozygous parents with different genotypes.
reciprocal cross
a cross in which the phenotypes of the male and female are reversed compared with a prior cross.
testcross
a cross between a homozygous recessive individual and an individual with the dominant phenotype but an unknown genotype.
x-linked
referring to a gene located on the X chromosome. (different patterns of inheritance in males and females)
y-linked
referring to a gene located on the Y chromosome. (determine male-specific development).
autosomal
referring to a gene located on any non-sex chromosome (an autosome) or a trait determined by an autosomal gene. (Mendel only studied these)
Mendel’s first experiments
consisted of crossing pure lines that differed in one trait (round vs. wrinkled seeds)
parental generation
adults initially used in an experiment
progeny/F1 generation
the offspring of the parental generation
monohybrid cross
mating between parents that each carry two different genetic determinants for the same trait.
dominant alleles and recessive alleles
dominant doesn’t mean a higher fitness and recessive doesn’t mean a lower fitness.
dominant and recessive only identify which phenotype is observed in an individual carrying two different genetic determinants for a given trait.
particulate inheritance
proposed by Mendel after first 2 hypotheses didn’t hold: heredity determinants maintain their integrity from generation to generation. Instead of blending together, they act as discrete entities or particles.
principle of segregation
to explain the reappearance of the recessive phenotype and the characteristic 3:1 ratio of phenotypes in F2 individuals, Mendel reasoned that the two members of each gene pair must segregate into different gamete cells during the formation of eggs and sperm so therefore each gamete contains one allele of each gene.
genetic model
refers to a set of hypotheses that explains how a particular trait is inherited; these hypotheses are sometimes referred to as Mendel’s rules.
