Chapter 2 Flashcards
What happens during Mitosis?
1 progenitor cell divides into 2 genetically identical daughter cells
-2n–>2n
What type of cell does mitosis happen in?
somatic cells
What happens in meiosis?
1 progenitor cell divides into 4 daughter cells, in which only have half of the gene content of the mother cell
-2n–>1n
What type of cell does meiosis happen in?
germline cells: eggs, sperm/pollen
What is a controlled genetic cross?
a cross where the parental genotypes are known
What is a characteristic of using pure-breeding strains in experimental crosses?
they consistently produce the same phenotype even after many generations of crossing
What are discrete traits?
when each single trait has two forms(dichotomous) that are easily distinguishable and that have no intermediate forms
what is a reciprocal cross?
made when the same crosses are made but from different sexes
what is a test cross?
made when a plant is crossed with the recessive pure-breeding parent, which can help determine the genetic make-up (genotype) of individuals
What ratio of gametes is found in a diploid (homozygous recessive) monohybrid (heterozygous) testcross?
1:1
What is the trait shown by the F1 offspring?
the dominant phenotype
What is the trait that is not apparent in the F1 offspring?
the recessive phenotype
What did mendel find when the F1 pea plants were crossed?
75% had the dominant trait, but the recessive trait reappeared in the other 25%
what is a monohybrid cross?
when an F1 individual is crossed with another F1 individual(both are heterozygous)
what was the phenotypic ratio of the F2 phenotypes/when a diploid monohybrid is selfed?
3:1
What was the theory of particulate inheritance?
Mendel’s theory that plants carry two discrete hereditary units for each trait; a plant receives one of these in the egg and the second in pollen
What genotypic ratio is predicted for the F2 generation produced by the monohybrid cross?
1:2:1
What is the Law of Segregation?
alleles separate during meiosis
What is Autosomal inheritance?
refers to transmission of traits carried on autosomes, chromosomes found in both males and females
What is a pedigree?
a family tree, and is a way of tracing the inheritance of traits in humans and some animals
What trait is commonly expressed in every generation?
autosomal dominant traits
What are 5 ways of identifying autosomal dominant inheritance?
- Affected individuals have at
least one affected parents. - Both males and females are
affected in equal numbers, and
both sexes transmit the trait
equally. - When only one parent is affected,
about half the offspring will be affected. - Two unaffected parents will have
unaffected children. - Two affected parents can have
unaffected children.
What are 5 ways to identify autosomal recessive inheritance?
- Affected individuals are often
born to unaffected parents. - Both males and females are
affected in equal numbers, and
both transmit the trait equally. - When both parents have the
trait, all children will have the trait. - The trait is often not seen in every
generation. - If the trait is rare in the population,
then the unaffected parents of affected
individuals are more likely to be related.
what is chromosomal sex?
the presence
of sex chromosomes associated
with males and females
what is phenotypic sex?
he internal
and external morphology
found in each sex
In mammals, what is sex determined by?
the presence or absence of the Y chromosome
Which gender is heterogametic sex in mammals, and which is homogametic sex?
males are heterogametic sex and females are homogametic
What are 4 characteristics found in a X-linked recessive pedigree?
- More males than females
have the traits because of
hemizygosity - If a male with the recessive trait
mates with a homozygous
dominant female, all progeny will
have the dominant phenotype - Mating of male with the
recessive trait with a carrier
female will produce offspring of
which half will have the trait - Mating of a homozygous recessive female
with an unaffected male produces males
with the trait and carrier females
What are 3 characteristics found in a X-linked dominant pedigree?
- Affected males mated to a normal
female (homozygous recessive) transmit the trait to all daughters but none of the sons - The trait will be equally frequent in males and females, but some crosses are biased toward having affected female offspring.
- Heterozygous females mated with a normal male passes on the trait to half the progeny of each sex.
Characteristics of Y-linked inheritance?
-the y chromosome is transmitted in a male-to-male fashion
-pseudoautosomal because their inheritance resembles autosomal inheritance in that there are two copes→one x and one y
What was The Blending Theory of Inheritance?
previous thought that viewed traits in offspring as a mixture of the parental traits
what is monohybrid another word for?
heterozygous
what is diploid another name for?
homozygous recessive
What is wild-type another name for?
homozygous dominant
