Genetics Test#1

X-linked Dominant

- Affected males pass the trait to all daughters and no sons - Affected females (if heterozygous) pass the trait to half their sons and half their daughters - Does not skip generations

Y-Linked

- All male offspring of an affected male are affected

Autosomal Recessive

- Appear equally in males and females - Tend to skip generations - More likely to appear among progeny of related adults (kissing cousins)

Autosomal Dominant

- Appear equally in males and females - does not skip generations - unaffected person does not pass it on

X-linked Recessive

- Appears more frequently in males - Affected male doesn't pass trait onto sons - Can pass the allele onto daughters who are unaffected and passes to sons that are affected -Unaffected indiv do not pass on the trait

What are some of the differences between RNA and DNA?

- Nucleotides contain RIBOSE - Includes uracil instead of thymine - RNA usually single-stranded

Genetic Linkage

- The closer two loci are on a chromosome, the less they assort independently - Multiple genes are inherited as a unit

Steps of Scientific Hypothesis Testing

1) Biological question 2) Model 3) Hypothesis 4) Data Collection 5) Statistical Test 6) Interpretation 7) Evaluation 8) Revise & Repeat

Name the Four Levels of Complexity in nucleic acid structure

1) Nucleotides ( A,T,G,C) 2) Single Strand 3) Double Helix 4) 3-dimensional folding of double helix

Chromosomal Sequences

1. Synthesize RNA and cellular proteins 2. Replication of chromosomes 3. Proper segregation of chromosomes 4. Compaction of chromosomes

Assume that long fingers are a recessive trait with 80 penetrance. Two people heterozygous for long fingers mate. What is the probability that their first child will have long fingers?

1/4 * 80% = 20%

A piece of double-stranded DNA has 100 base pairs. How many complete turns can this double helix make?

10 complete turns

Approximately how much DNA is wrapped around an octomer of histones?

146 base pairs

Describe chromosome number in meiosis II in humans.

1N -> 1N

In which kind of cell can mitotic crossover not occur?

1n

How many copies of H2A, H2B, H3, and H4 are present in each nucleosome?

2 copies of each

Synteny

2 or more genes on same chromosome

Arrange the following events in the proper order in which they occur during meiosis I. 1 = Separation of homologous chromosomes 2 = Synapsis 3 = Crossing-over 4 = Independent assortment

2, 3, 4, 1

If a piece of DNA is 50,000 base pairs long and the average linker is about 54 base pairs, how many nucleosomes would be present?

250

A nucleus is 4 μm in diameter. Its DNA is composed of a million base pairs. Approximately how much does it need to be condensed in order to fit inside the nucleus? 30-fold 100,000-fold 1 million-fold 3 million-fold

3 million-fold

Which order of atoms correctly describes the backbone of a DNA strand?

3'C-O-P-O-5'C

A piece of double-stranded DNA has 100 base pairs. What is the length of the piece of DNA?

34 nm

How many chromosomes are present in a human primary oocyte? How many chromatids?

46; 92

Genes A and B are 10 mu apart. A man has an AB/ab genotype. His father was AB/AB. He marries a woman who is ab/ab. What is the likelihood they will have an Ab/ab child?

5%

A diploid cell has 10 chromosomes. Answer the following questions about this cell. 1. How many chromosome pairs are in the cell? 2. Following mitosis how many cells will be produced? 3. How many chromosomes will each cell have after mitosis?

5, 2, 10

Garden peas have 1n number of seven chromosomes, therefore they have ___________ linkage groups when they are diploid.

7

What is the correct order of stages in the cell cyle A) G1, S, prophase, metaphase, anaphase B) S, G1, prophase, metaphase, anaphase C) prophase, S, G1, metaphase, anaphase D) S, G1, anaphase, prophase, metaphase

A

What is Chargaff's rule?

A + G = C + T

What is a homolog?

A set of one maternal and one paternal chromosome that pair up within a cell during meiosis (Ex. recitation 4 drawings)

A trait that appears to be dominant in one sex but recessive in the other is called.....

A sex influenced trait

The ABO Blood types in humans are controlled by one gene with 3 alleles. Is it possible for a couple to produce progeny with all four blood types? If so which of the following would describe their phenotypes?

A x B

A son has the blood-type B (IBi). The father of this boy is known to be blood type AB. In order for the son to donate blood to his mother, what must be the mother's genotype? A) IBi B) IAi C) IAIB D) ii

A) IBi

Autosomal recessive traits often appear in pedigrees in which there have been consanguine mating, because these traits: A) tend to skip generations B) appear only when both parents carry a copy of the gene for the trait, which is more likely when the parents are related C) usually arise in children born to parents who are unaffected D)

B

Mendel's work was critical for a number of reasons but what differentiated his work the most was... A) that he used peas. B) that he applied statistical analyses to his results. C) that he was a priest. D) that he kept careful records of what he did

B

Neutralizing their positive charges would have which effect on the histone proteins A)they would bind the DNA tighter B) they would seperate from the DNA C) they would no longer be attracted to each other D)They would cause supercoiling of the DNA

B

Diploid Cells have A) two chromosomes B) two sets of chromosomes C) one set of chromosomes D) Two pairs of homologous chromosomes

B & D

DNA supercoiling in bacterial chromosome

Bacterial chromosomal DNA is negatively supercoiled Negative supercoiling has 2 major effects 1. Helps in compaction of the chromosomes 2. Creates tension that may be released by DNA separation

If Very, Macleod, and McCarty had found that samples of heat-killed bacteria treated with RNase and DNase transformed bacteria, but samples treated with protease did not, what conclusion would they have made? A) Protease carries out transformation B) RNA and DNA are the genetic materials C) Protein is the genetic material D)RNase and DNase are necessary for transformation

C

A son has the blood-type A (IAi). The father of this boy is known to be blood type AB. Which of the following is not a possible genotype for the mother? A) IAi B) ii C) IAIB D) IBi

C) IAIB

The antiparallel nature of DNA refers to: A) its charged phosphate groups B) the pairing of bases on one strand with bases on the other strand C) the formation of hydrogen bonds between bases from opposite strands D) the opposite direction of the two strands of nucleotides

D

Which of the following events takes place in meiosis ll, but not in meiosis l? A) crossing over B) contraction of chromosomes C) separation of homologous chromosomes D) separation of chromatids

D

Which is the most complete and accurate definition of epistasis? A) An inheritance pattern where a 9:3:3:1 ration is found in the F2 generation B) An inheritance pattern where the observed genotypic ratios differ from expected ratios C) An inheritance pattern where two genes affect a single trait D) An inheritance pattern in which the alleles of one gene mask the phenotypic effects of different gene

D)

Rosalind Franklin used X-Ray diffraction to study wet DNA. What did her data suggest about the structure of DNA?

DNA is a helical structure that is not a single strand and consists of about 10 base pairs per complete turn.

You have crossed a red-eyed female to a red-eyed male. What outcome from your cross would indicate that the female was heterozygous? Equal proportions of white-eyed males and red-eyed males Equal proportions of white-eyed females and red-eyed females All females with red eyes Equal proportions of red-eyed males and red-eyed females

Equal proportions of white-eyed males and red-eyed males

Which of the following represents the highest level of chromosome condensation? Radial loop domain 30 nm fibers Double helix Nucleosome Heterochromatin

Heterochromatin

What aspect of the sugar is unique to RNA?

It contains an OH group on the number 2' carbon of the pentose sugar.

Gain of Function Mutation

Mutation gives protein new function, can be associated with too much protein expression

Dominant-Negative Mutations

Mutation results in protein that counteracts wild-type

Why is an individual with blood type O considered a universal donor?

Neither the A or B antigens are present on type O red blood cells

Which of the following represents the lowest level of chromosome condensation? Radial loop domain 30 nm fibers Heterochromatin Nucleosome Euchromatin

Nucleosome

If a person is blood type O and needs a transfusion, which of the following blood types could act as a donor? B O A AB

O

Where do the largest strands of DNA occur in a gel electrophoresis?

On the bottom

Haploinsufficiency

One functioning gene copy is not enough to produce wild-type phenotype - Heterozygote Results in Abnormal Phenotype (Polydactyly)

Allele

One of two or more alternative forms of a gene

If the ura2 and arg3 genes were closely linked, which type of asci is most likely from a mating of ura2-arg3 haploids and ura2+-arg3+ haploids?

PD

Assuming that the ura2 and arg3 genes assort independently, which types of asci are most likely to be found in equal proportions from a mating between ura2-arg3 and ura2+-arg3+ haploids?

PD and NPD

incomplete dominance

Phenotype of a heterozygote is intermediate (falls within the range) between the phenotypes of the two homozygous. - example, an Rr heterozygote may be pink, whereas the RR and rr homozygotes are red and white.

Complete Dominance

Phenotypes of a heterozygous is the same as the phenotype of a homozygous

Codominance

Phenotypes of the heterozygote includes the phenotypes of both homozygotes

What is the backbone of DNA made up of?

Phosphates & Sugars

What are the 7 true breeding strains Mendel found in his pea plants

Seed color Seed shape Seed coat color Pod color Pod shape Flower position Stem length

What is an SNP?

Single Nucleotide Polymorphism- single nucleotide difference seen between members of the same species

Pseudoautosomal Inheritance

Some genes are located on both X & Y chromosomes - They are inherited in the same manner as autosomal genes

A single strand of RNA with sequence 5'-UGAAUUGCAUCGGCAAUUGG-3' has the potential to form which structure? Bulge loop Internal loop Stem loop Multi branched loop

Stem loop

What 2 probability rules does the binomial expansion equation combine?

Sum & Product Rule

Probability

The likelihood of the occurrence of a particular event Number of times an event occurs/ total number of events

When looking at linkage in haploid eukaryotes, the following types of asci suggest linkage is occurring between two genes.

The number of parental ditypes greatly exceeds the number of nonparental ditypes.

What is the structural difference between the sugar found in RNA and the sugar found in DNA?

The presence of a 2' hydroxyl

product rule

The probability that two or more independent outcomes will occur is equal to the product of their individual probabilities.

Mendel's law of segregation

The two copies of a gene segregate (or separate) from each other during transmission from parent to offspring.

Sex-Influenced Inheritance

Trait is dominant in one sex, recessive in other

What are X-linked traits

Traits linked to the X chromosome XX= female

Mendel's law of independent assortment

Two different genes will randomly assort their alleles during the formation of haploid cells

Product Rule

Used to Predict the Occurrence of Independent Events - To the calculate the probability of two or more independent events happening together MULTIPLY the individual probabilities.

The Sum rule

Used to predict occurrence of mutually exclusive events - To the calculate the probability of at least one of two or more independent events happening together ADD the individual probabilities.

genetic recombination

When an offspring receives a combination of alleles that differs from those in the parental generation

Wild- Type VS mutant alleles

Wild Type - Most prevalent alleles - One or several Genetic Polymorphism - Typically code for properly functioning protein Mutant - Uncommon alleles - Typically don't express a properly functioning protein (Loss of Function mutation) - Often recessive (Not Always)

How could you distinguish between an autosomal recessive trait with higher penetrance in males and X-linked recessive trait

X-linked recessive traits are only passed from sons to mothers, not from fathers

gain-of-function mutations

a mutation that causes a gene to be expressed in an additional place where it is not normally expressed or during a stage of development when it is not normally expressed.

dominant-negative mutations

a mutation that produces an altered gene product that acts antagonistically to the normal gene product. Shows a dominant pattern of inheritance.

incomplete penetrance

a pattern of inheritance in which a dominant allele does not always control the phenotype of the individual.

overdominance

an inheritance pattern in which a heterozygote is more vigorous than either of the corresponding homozygotes.

Epistasis

an inheritance pattern where one gene can mask the phenotypic effects of a different gene.

Chargaff's Rules

any cell of all organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases (A + T) < > (C + G)

In which of the following will you not be able to determine if a particular allele is dominant or recessive?

bacteria

Monoecious

both male and female parts

loss-of-function alleles

defective copy of a gene

If your P > 0.05

do not reject - Data consistent with predicted ratio

In males the hen-feathered phenotype is __________ and cock-feathered phenotype is ____________.

dominant; recessive

A Barr body (an inactive X chromosome in female mammals) is an example of euchromatin. constitutive heterochromatin. facultative heterochromatin. a metaphase chromosome.

facultative heterochromatin.

genetic polymorphism

more than one wild-type allele occur in a population

When topoisomerase adds turns in a right-handed direction....

positive supercoils are added

mutant alleles

random mutations occur in populations and alter preexisting alleles.

9:3:3:1

ratio expected outcome when a plant that is heterozygous for both genes is allowed to self-fertilize

If your P < 0.05

reject - Data do not match predicted ratio

Which direction would you turn Z-DNA to introduce negative super coils?

right

In genetic linkage, what does the distance between two loci tell you?

the closer two loci are on a chromosome the less likely they assort independently

norm of reaction

the effects of environmental variation on an individual's traits.

A male cat and a female cat produce a litter of kittens. Which criteria of genetic material is represented? transmission information replication replication

transmission

Lethal Alleles

• Typically result in death, Usually recessive • Occur in essential genes - Those required for survival. 1/3 of all genes (~7000) • Many cause death very early in development