MG : Mendelian Genetics

Which of the following would be true of a plant heterozygous for a single gene controlling flower color? (Assume complete dominance).
A) If crossed with another heterozygous plant, the majority of progeny will have the dominant flower color.
B) It will pr

A) If crossed with another heterozygous plant, the majority of progeny will have the dominant flower color.
DESCRIPTION: There will be roughly three times as many plants with the dominant flower color as plants with the recessive flower color.

The 3:1 phenotypic ratio observed among progeny of an F1 X F1 cross requires random union of gametes.
True or False

True - The 1:2:1 genotypic ratio represents relative probabilities of gamete combinations based on the assumption that gamete union is random.

What would be the best way to determine which of two alleles of a gene is dominant to the other?

Observe the relevant phenotype in the progeny that result from a cross between individuals from two different 'pure-breeding' lines.
DESCRIPTION: All progeny will be heterozygous for the trait in question and will display the phenotype that corresponds wi

How could a botanist best determine whether the genotype of a green-pod plant is homozygous or heterozygous?

Cross the green-pod plant with a yellow-pod plant.
DESCRIPTION: A cross between a plant of unknown genotype and one that is known to be homozygous recessive is called a test cross because the recessive homozygote tests whether there are any recessive alle

Determining Punnett Squares:
Dominant : Green (G)
Ressesive : yellow (g)
So, a Yellow plant is crossed with a Green plant....

Yellow = gg
Green = Gg or GG
Since you don't know weather or not your green plant is heterozygous or homozygous test Both:
1) Green being heterozygous:
gg X Gg = 50% Gg and 50% gg
(2 green and 2 yellow)
2) Green being homozygous:
gg x GG = 100% Gg
(4 gree

Suppose that the botanist carried out a "test cross" and determined that the original green-pod plant was heterozygous (Gg). Which of Mendel's findings does her test cross illustrate?

Law of segregation

Test Cross -

Is a way to explore the genotpye of an organism. Needed when the specific genotype of a single organism is not know.

During which part of meiosis do the two alleles of a gene separate?

Meiosis 1

During which phase does the separation of two alleles of a gene occur? (Assume no recombination)

Anaphase

Independent assortment explains _______.

Why a collection of meiotic products that includes gametes of genotype Ab will also include gametes of genotype AB in roughly the same proportion.

Because alignment of the chromosomes is _____________, the alignment that produces Ab is just as likely as the alignment that produces AB. Therefore, the two genotypes should both occur with equal frequency.

Random

Independent assortment occurs only in cells that are heterozygous for two genes (AaBb) and not in cells that are completely homozygous (AABB or aabb).
True or False

False - Independent assortment describes the random alignment of chromosomes. The Radom assortment of Heterozygous (AaBb) will be seen; however, the Random assortment of Homozygous (AABB) or (aabb) would not be as clearly seen, it still occurs.

Which of the following genotypes represents a gamete produced by a failure to segregate during meiosis in a cell of genotype AaBbCC ?

AaBC
This gamete contains two copies of gene "A". Proper segregation would have separated A from a and allowed only one copy per gamete.

Segregation during meiosis describes:

The genotype is separated and only one copy per gamete of each gene is allowed to carry on.
Example:
(AaBbCC) after undergoing segregation: You are left with
(aBC), (abC), or (ABC)
Only one form of each gene in the genotype.
Failure to, or incorrect segre

Which of the following phenomena is a consequence of Independent Assortment?

The phenotypic ratio among phenotypes produced from an F1 X F1 dihybrid cross is 9:3:3:1.
(The 9:3:3:1 ratio requires that the four gamete classes produced occur with equal frequency. This requires independent assortment.)

The 9:3:3:1 ratio exhibited in the F2 generation of a dihybrid cross is a genotypic ratio.
True or False

False

Genotypic Ratio -

Describes the number of times a genotype would appear in the offspring after a test cross.

A pea plant is heterozygous for two genes; one controlling height, one controlling color. The genotype is written PpTt. Based on the Law of Independent Assortment, approximately what proportion of the pollen produced by this plant should have the genotype

1/4
Why?
Two heterozygous genes Height (Pp) and Color (Tt)
So, Pp X Tt =
1/4 or 25% PT
1/4 or 25% Pt
1/4 or 25% pT
1/4 or 25% pt

Independent Assortment assumes that all genotypes produced through a Punnett Square or other method are _____________ likely

Equally

A couple has two boys and is expecting a third child. The probability that the third child will be a boy is �.
True or False

True - The probability of having a boy or a girl is 1/2. The sex of a previous child does not influence this probability.

What is the probability of a family with six children having three boys and three girls?

Probability = 20/64
Formulas:
P(n,x) = (nCx)
p^x
(1-p)^n-x
(nCx) = (n/x)
(n-1/x-1)
(n-2/x-2)
P = 1/2
n = 6
x = 3
(nCx) = (6/3)
(5/2)
(4/1) = 20
P(6,3) = (20)
1/2^3
(1-(1/2))^6-3
P(6,3) = 5/16 or 20/64

If three differently colored dice are rolled at the same time, what is the probability that a 6 will be the outcome on each one?

Probability 1/216
Dice 6 sides thus labeled (1-6)
so there is a 1/6 chance of rolling a 6 with one dice.
So, with three dice, multiple the odds (1/6) 3xs = (1/6)(1/6)(1/6) = 1/216
or (1/6)^3 = 1/216

You would like to know whether the progeny of a pair of mated fruit flies are distributed among the resulting four phenotypic classes in a 1:1:1:1 ratio. You perform a chi-square test and obtain a p value of 0.04. Assuming you have done the test correctly

The differences between the observed and expected counts are too large to be attributed to chance.
(It is on this basis (p< 0.05) that the decision to reject the hypothesis of a 1:1:1:1 ratio is made.)

Chi-Square formula

x2 = (sum of symbol) ((o - e)2 / e)
*o is the observed value for a given category
*e is the expected value for a given category
*(sum of symbol) means the summation of all calculated values for each category

The larger the number of total individual counts in a chi-square test, the higher the degrees of freedom (df).
True or False

False: Degree of Freedom increases with increasing n (number of categories), but not necessarily with increasing number of subjects.

The expected ratio of phenotypes among the progeny of a test cross is 1:1:1:1. Out of 200 total resulting progeny, 48 occur in one of the four phenotypic classes. Which means the Observed - Expected value = __________

The value of observed minus expected for this cell = -2.
(With a total of 200, the expected number in each cell when the predicted ratio is 1:1:1:1 = 50 (because, 200/50 = 4 and you have four 1's. The observed number is 48.)

Pedigree Analysis: If an individual has a genetic condition that neither parent has, then that condition must be ________________.

recessive

Pedigree Analysis: Dominant conditions require that every affected individual have at least one affected _____________.

parent

For dominant conditions:

1) Unaffected individuals are homozygous for the recessive, wild-type allele.
2) Affected individuals with only one affected parent are heterozygous.
3) Affected individuals with any unaffected children are heterozygous.
4) Affected individuals with two a

For recessive conditions:

1) Affected individuals are always homozygous recessive.
2) Unaffected children of an affected parent are always carriers (heterozygous).
3) Both parents of affected individuals must have at least one recessive allele.
4) If both parents are carriers, the

Assume that a black guinea pig crossed with an albino guinea pig produced 5 black offspring. When the albino was crossed with a second black one, 4 black and 3 albino offspring were produced. What genetic explanation would apply to these data?

Albino = recessive; black = dominant

The fundamental Mendelian process that involves the separation of contrasting genetic elements at the same locus would be called?

Segregation

Assuming complete dominance, a 3:1 phenotypic ratio is expected from a monohybrid sib or self-cross.
True or False

True

A 9:3:3:1 phenotypic ratio is expected from a dihybrid testcross.
True or False

False