Exam 2 Flashcards
(24 cards)
Artificial selection
the purposeful control of mating by choosing parents for the next generation.
How was Mendel different from scientists before him
- He studied garden peas; each pea had both male and female organs which allowed self or cross fertilization
- He studied discrete traits
- He collected and perpetuated lines of peas that bred true (pure-breeding)
- He made reciprocal crosses
- He studied inheritance in a quantitative manner
- He was a good experimentalist
Self-fertilization (selfing)
Fertilization in which both egg and sperm come from the same plant or animal; mendels peas self-fertilized since they had both egg and pollen within the same plant/flower and they would self-fertilize because of proximity
How did Mendel cross-fertilize
Mendel removed the male sex organs from the flowers of one plant (to prevent selfing) and then brushed pollen from another plant onto the female organs of the first plant
Discrete traits
an inherited trait that exhibits an either/or status (that is, purple versus white flowers). Synonymous with discontinuous trait.
Continuous traits
Opposite of discrete traits; has intermediates (height, skin color,etc)
Pure breeding
organisms that produce offspring with specific parental traits that remain constant from generation to generation; synonymous with true-breeding (lines); these lines are also called inbred
Inbred
describes individuals or a population of organisms produced by matings of close genetic relatives; inbreeding results in homozygosity (plants with white flowers only produce white flowers, etc)
Antagonistic pairs
Constant but mutually exclusive alternatives (purple vs white flower or yellow vs green seeds)
Hybrids
offspring of genetically dissimilar parents; often used as synonym for heterozygotes (yellow and green parents, round and wrinkled, etc)
What are reciprocal crosses and what did they prove in mendel’s experiments
Reversed characteristics of male vs female when crossing thus controlling whether a trait was transmitted via egg or sperm (use pollen from purple flower to fertilize egg of white flower and then use pollen from white flower to fertilize egg of purple flower); proved that two parents contributed equally to inheritance since the progeny of reciprocal crosses were similar
Parental (P) generation
individuals whose progeny in subsequent generations will be studied for specific traits.
Monohybrid crosses
crosses between parents that differ in only one trait.
Gene
a specific segment of DNA in a discrete region of a chromosome that serves as a unit of function by encoding a particular RNA or protein.
Monohybrid
individuals having two different alleles for a single trait.
Mendel’s law of segregation
Mendel’s first law, which states that the two alleles for each trait separate (segregate) during gamete formation and then unite at random, one from each parent, at fertilization.
Product rule
the probability of two or more independent events occurring together is the product of the probabilities that each event will occur by itself (fertilization to make egg and sperm are independent events)
Sum rule
the probability that any of two or more mutually exclusive events will occur is the sum of their individual probabilities (punnet square demonstrates)
Test cross
(1) a cross used to determine the genotype of an individual showing a dominant phenotype by mating with an individual showing the recessive phenotype; and (2) a cross used to determine whether genes are linked and the distance (recombination frequency) between linked genes.
Dihybrid
an individual that is heterozygous at two different genes.
recombinant types
phenotypes reflecting a new combination of alleles that occurred during gamete formation.
Parental types
phenotypes that reflect a previously existing parental combination of alleles that is retained during gamete formation.
What were the parental types in mendels peas
Yellow round or green wrinkled
