Inheritance Flashcards
Gregor _______ studied pea plants when studying heredity because they could produce _______, there are many variates, they are small and easy to grow, and can self-_______ or be cross-_______
Mendel, hybrids, fertilize, fertilized
Mendel’s experimental method was in three stages: Produce _______-_______ strains for each trait he was studying; _______-_______ two of these strains having alternate forms of a trait (and perform _______ crosses); Allow the _______ offspring to _______-_______ for several generations
true-breeding, cross-fertilize, reciprocal, self-fertilize
A _______ _______ is used to study only two variations of a single trait
Monohybrid cross
Mendel produced true-breeding pea strains for _______ traits
seven
The _______ generation is where offspring are produced by crossing two true-breeding strains
F1
Visible trait in the F1 generation was referred to as _______
dominant
The alternative trait in the F1 generation was called _______
recessive
In Mendel’s F1 generation with the pea plants, there were no plants with _______ characteristics of parents produced, meaning there was no _______ inheritance
intermediate, blending
How is the F2 generation produced?
The self-fertilization of F1 plants
Although masked in the F1 generation, the _______ trait reappeared among some F2 individuals
recessive
Mendel found always about a _______:_______ ratio of dominant : recessive traits in the _______ generation
3:1, F2
Mendel discovered that instead of 3:1 dominant : recessive in F2, the ratio is actually __ _______-_______ dominant : __ _______-_______-_______ dominant : __ _______-_______ recessive
1 true-breeding, 2 non-true-breeding, 1 true-breeding
Mendel’s 5-element model:
- Parents transmit discrete _______ (_______)
- Each offspring individual receives what?
- Not all copies of a gene are _______
- Alleles remain _______ - no _______
- Presence of _______ does not guarantee _______
factors (genes), one copy of a gene from each parent, identical, discrete, blending, allele, expression
_______ - Alternative form of a gene
Allele
_______ - two of the same allele
Homozygous
_______ - different alleles
heterozygous
_______ allele - expressed
Dominant
_______ allele - hidden by dominant allele
Recessive
_______ - Two alleles for a gene segregate during gamete formation (one from each parent) and are rejoined _______ _______ during fertilization
Segregation, at random
A _______ _______ is used to study two variations of two traits in a single cross
Dihybrid cross
The F1 generation of a dihybrid cross chows only the _______ _______ for each trait
dominant phenotypes
A dihybrid cross produces what ratio?
9:3:3:1
For the dihybrid cross Rr Yy x Rr Yy the 9:3:3:1 ratio would be (_______):(_______):(_______):(_______)
(R_ Y_):(R_ yy):(rr Y_):(rr yy) - where an underscore represents a dominant or recessive allele
In a dihybrid cross, the alleles of each gene are _______ _______
independently assorted
In a dihybrid cross, the _______ of different allele pairs is independent - for example seed shape is independent of seed color
segregation
The independent alignment of different homologous chromosome pairs during _______ _______ leads to the _______ _______ of the different allele pairs
metaphase I, independent segregation
A _______ is used to determine the genotype of an individual with an unknown phenotype
testcross
In a testcross you always cross the unknown genotype with what?
a homozygous recessive
_______ _______ _______: The probability that either of two mutually exclusive events occurs is the sum of their individual probabilities
Rule of addition
When crossing Pp x Pp, the probability of producing Pp offspring is what? Why
Probability of obtaining Pp (1/4) PLUS probability of obtaining pP (1/4) = 1/2
_______ _______ _______: Probability of two independent events both occurring is the product of their individual probabilities
Rule of multiplication
When crossing Pp x Pp, what is the probability of obtaining pp and why?
Probability of p from father: 1/2; probability of p from mother: 1/2; probability of pp = 1/2 x 1/2 = 1/4
_______ _______ refers to different phenotypes from the same genotype due to environmental conditions
phenotypic plasticity
_______ _______ refers to a range of possible phenotypes across genotypes
Continuous variation
Often a phenotype is the result of an accumulation of contributions by multiple _______, and these traits show continuous variation and are referred to as _______ _______
genes, quantitative traits
_______ _______ _______ (H^2) is the fraction of phenotypic variation due to underlying genetic variation
Broad sense heritability
_______ _______ _______ (h^2) is the fraction of phenotypic variation due to additive genetic variance
Narrow sense heritability
_______ refers to an allele hat has more than one effect on the phenotype
Pleiotropy
_______ _______ is where the heterozygote is intermediate in phenotype between the two homozygotes
Incomplete Dominance (like pink flowers)
_______ is where a heterozygote shows some aspect of the phenotypes of both homozygotes
Codominance (like type AB blood)
Human ABO blood demonstrates both _______ and _______ _______.
Codominance, multiple alleles
In human ABO blood, there are three alleles of the I gene (__, __, and __). The first two are _______ to the 3rd, but _______ to each other
I^A, I^B, i, dominant, codominant
_______ is when the action of one gene obscures the effects of another gene
Epistasis
When working with the fruit fly, T.H morgen discovered a _______ male fly with _______ eyes instead of red. He crossed this male fly with a normal red-eyed female
mutant, white
When Morgan crossed the mutant white-eyed fly with a normal red-eyed female, all of the F1 _______ had what?
progeny, red eyes (dominant trait)
When Morgan crossed the F1 females and F1 males, the F2 generation contained what?
Both red and and white-eyed flies, but all white-eyed flies were male
A _______ of an F1 female fly with a _______-_______ male showed the viability of _______-_______ females
testcross, white-eyed, white-eyed
Morgan concluded that the eye color gene resides on the _______ _______ _______
female X chromosome
Traits determined by sex chromosome genes are _______-_______
sex-linked
_______ _______ are a pair of dissimilar chromosomes that still pair during meiosis and mitosis
Sex chromosomes
Sex determination in Drosophila is based on the number of _______ _______
X chromosomes
_______ _______ varies across organisms: It is based on the presence of a Y chromosome in humans. In birds the male has two Z chromosomes and females are ZW.
Sex determination
Humans have _______ total chromosomes. 22 pairs are _______, and 1 pair are _______ _______
46, autosomes, sex chromosomes
In organisms with XY sex-determination, few genes from the __ chromosome are expressed.
Y
Human males have __ chromosomes
XY
Human females have __ chromosomes
XX
Certain genetic diseases affect _______ to a greater degree than _______
males, females
_______ _______ ensures equal expression of genes from sex chromosomes even though the number of chromosomes is different between the sexes
Dosage compensation
In mammal female cells, 1 X chromosome is randomly inactivated and is highly condensed into a _______ _______
Barr body
Females heterozygous for genes on the X chromosome are _______ _______
genetic mosaics
Some exceptions to the chromosome theory: _______ and _______ contain genes and these don’t follow the chromosomal theory of _______
Mitochondria, chloroplasts, inheritance
Genes from mitochondria and chloroplasts are often passed to the offspring by the mother, called _______ _______
maternal inheritance
_______ _______ exchanges alleles
Crossing over
If crossover occurs, parental alleles are recombined producing _______ gametes
recombinant
The result of the Creighton and McClintock experiment was that _______ recombinant progeny also have _______ recombinant chromosomes
genetically, physically
The conclusion of the Creighton and McClintock experiment was that a physical exchange of _______ _______ accompanied _______ _______
genetic material, genetic recombination
The distance between genes is proportional to the frequency of _______ events
recombination
recombination frequency = _______ _______ / _______ _______
recombinant progeny / total progeny
1% recombination = 1 _______ _______ = 1 _______
map unit (m. u.), centimorgan (cM)
Odd numbers of cross over events (1, 3, etc.) produce _______ _______, while no crossover or even numbers of crossovers (0, 2, etc.) produce _______ _______
recombinant gametes, parental gametes
_______ analysis is used to track inheritance patterns in families
Pedigree
_______ is the failure of homologues or sister chromatids to separate properly during meiosis
Nondisjunction
_______ is the gain or loss of a chromosome, and is the result of nondisjunction. _______ is the loss of a chromosome, and _______ is the gain
Aneuploidy, Monosomy, Trisomy
Autosomes __ and __ can survive to adulthood
21, 22
Trisomy __ (_______ _______) is where a human has a full 3rd chromosome
21, down syndrome
_______ of sex chromosomes can produce individuals with somewhat abnormal features, but often reach maturity.
Nondisjunction
Some examples of nondisjunction of sex chromosomes: XXX - triple-X females; XXY - males (_______ syndrome); XO - females (_______ syndrome); OY - _______ zygotes; XYY - males (_______ syndrome)
Klinefelter, Turners, nonviable, Jacob
