genetics final

T/F: In bacteria, genes that encode enzymes that are in the same metabolic pathways are generally organized into operons.

True

What was the synthetic inducer used by Jacob and Monod and why was it used?

Isopropyl-β-D-thiogalactoside (IPTG) because it doesn't breakdown in the presences of β-galactosidase

Two environmental conditions have to be met for lactose metabolites (operon) to be expressed at the maximum level, what is one of those two conditions?

Glucose is absent

Researchers have identified \____ new genes for eye color in a study involving the genetic analysis of almost \__________ people across Europe and Asia. (Hint: write the numerical value without commas to receive full credit)

195000

Which of the following mutations is dominant over wild-type lacI+ in a partial diploid experimental cell?

lacI^S

In the lac operon in E. coli, a nonsense mutation in the \________ gene will likely result in a loss of β-galactosidase activity in the cell.

LacZ

Would the following bacteria genotype of the lac operon be repressed, inducible or constitutively on?

Repressed

cAMP binds to \__________ to maximize the expression of the lactose operon.

CAP

A lacO^C mutation is

constitutive.

What is one key difference between the lac operon and the ara operon?

One protein acts as the activator and the repressor in the ara operon.

Challenge: The E. coli pyr operon encodes enzymes required for synthesis of pyrimidines. It is only expressed when the cell is starved of pyrimidines. Early in the sequence of the operon, just downstream of the promoter, is a sequence containing inverted repeats. In silico predictions demonstrate that this sequence can form a hairpin by base-pairing. The repeat sequence is preceded by a short stretch of AT-rich DNA. What is a possible model for the regulation of the pyr operon?

This operon is regulated by a repressor that attaches in the AT-rich sequence of DNA and then creates a hairpin in the DNA so that polymerase cannot move past the hairpin.

Challenge: The fox operon, which has sequences A, B, C, and D (which may represent either structural genes or regulatory sequences) and it encodes enzyme 1 and 2. Mutations in sequences A, B, C, and/or D have the following effects, where a plus sign (+) indicates the enzyme is synthesized and a minus sign (-) indicates the enzyme is not synthesized.

Inducible

The Trp operon engages in two levels of control, Global and attenuated. In which level of control is it when expression is repressed when trp levels are high by the ribosomes ability to translate the mRNA?

Attenuated

Challenge: The fox operon, which has sequences A, B, C, and D (which may represent either structural genes or regulatory sequences) and it encodes enzyme 1 and 2. Mutations in sequences A, B, C, and/or D have the following effects, where a plus sign (+) indicates the enzyme is synthesized and a minus sign (-) indicates the enzyme is not synthesized.

B

What is another amino acid biosynthesis pathway that uses attenuation as a method of control similar to tryptophan.

Phenylalanine

Challenge: HDAC inhibitors are commonly used as mood stabilizers or in the treatment of neurodegenerative diseases. What effect would a HDAC inhibitor have on the target cells?

It would stop the removal of acetyl groups on lysine residues of histone tails.

Challenge question: How could the over expression of a transcription factor change the transcription of different genes in different cell types? (Select all possibilities)

- Different genes are transcribed in different tissue.

-Genes could be located in euchromatin in some cells but located in heterochromatin others which would alter transcription factors ability.

-The amounts of different genes are transcribed in different amounts in different tissue based off other transcription factors.

Clear plaques on a bacterial lawn (or agar plate) is associated with

lytic growth

T/F: Histone acetyltransferases are necessary for taking acetyl groups off of lysines.

False

What is the underlying reason that a lambda phage would need to switch from the lysogenic state to the lytic state?

To escape an endangered host cell (exposure to UV)

Challenge: A researcher has identified a eukaryotic mutant cell line that has reduced transcription of gene X relative to the parental cell line. The mutant cell line has a single point mutation in the entire genome. Where might the mutation be located (select all possibilities)?

Promoter

Promoter Proximal Regions

Cis regulatory modules

Bacteriophage blocks the lytic growth phase by cI binding to

operator sequences.

Bacteriophage lambda has a

circular genome.

Thought questions: Accumulating evidence suggests that epigenetic effects can be inherited across multiple generations. For example, the effects of a pregnant woman smoking can effect her children and her grandchildren. Similar observations is seen with fathers. Do you think that this adds to the moral responsibility of a mother and father?

Yes

Bacteriophages engage in two interactive cycles with bacteria. What are these cycles?

Lytic and lysogenic

\____ is the molecular decision maker for bacteriophage lytic vs lysogenic life cycle.

cII

T/F: SWI/SNF is a nucleosome remodeling complex found in eukaryotes.

True

Where do repressor proteins bind in eukaryotes?

Silencer

β-interferon encodes the anti-viral protein interferon, and it is normally switched off except in the case of viral infection. Which proteins are needed to turn on β-interferon?

SWI/SNF, enhancesome, GCN5, CBP, TBP, RNA pol II

Igf2, experiences maternal imprinting. What does this mean?

The mother's gene is silenced during gamete formation.

Barrier insulators are necessary for

block the spread of heterochromatin.

T/F: Genomic imprinting is the phenomenon in which a gene inherited from one of the parents is not expressed because both copies are not made of genomic DNA.

False

How are methyl groups associated with epigenetics?

Methyl groups provide a positive charge which allows for a tighter interaction/configuration with DNA.

Genes have two important functions: inheritance and expression. A single gene is found at a defined position called a

locus

Please select the correct genotype for the following pea plant: heterozygous purple flower plant that is true breeding tall (dominant) with wrinkled peas (recessive). Use P, T, and R for the nomenclature of the three genes, respectively.

P/p; T/T; r/r

\_________________________occurs when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant

Self-pollinating

F2 is short for

Filial 2 generation

What is the reason some peas are wrinkled?

A dysfunctional starch-branching enzyme

What are the types of gametes observed in the following cross: A/a x A/a

A and a

What is the expected genotypic ratio of the following cross: B/b x B/b

1:2:!

You cross a red heterozygous flower with a white homozygous flower and get the following progeny: 55 red and 45 white. You hypothesis that the plants are following Mendelian Genetics inheritance rules. Preform a chi-square analysis to test your hypothesis. What is your chi-square value?

1

You cross a red heterozygous flower with a white homozygous flower and get the following progeny: 65 red and 35 white. You hypothesis that the plants are following Mendelian Genetics inheritance rules. Preform a chi-square analysis to test your hypothesis. What is your chi-square value and do you reject your hypothesis or fail to reject it?

9; reject

Most mutant alleles do not function as well as the wt allele.

True

When two heterozygotes for a lethal allele are mated, one-fourth of their offspring will die.

True

You cross a red heterozygous flower with a white homozygous flower and get the following progeny: 55 red and 45 white. You hypothesis that the plants are following Mendelian Genetics inheritance rules. You preform a chi-square analysis to test your hypothesis. Do you

fail to reject your hypothesis

Degrees of freedom is the number of alleles minus one.

false

The white gene is Drosophila encodes a ATP transporter which uses energy (ATP) to move cargo across membranes. Flies with the dominant allele have red eyes and flies that are homozygous recessive have white eyes. The dominant allele is w+ the recessive allele is w. If you cross two heterozygous flies, what percentage of the progeny will be carriers of the recessive trait?

50%

A (An) \____________________ is a gene which in certain circumstances can transform a cell into a tumor cell.

Oncogene

Alleles are considered to by haplo-insufficient when

All the above- the biological process is dose sensitive.-it requires two functional alleles to carry out normal function.-an organism, that is heterozygous for a specific allele, is unable to complete a normal function and has a phenotype similar to a homozygous recessive organism.

In the multiple-allele series that determines coat color in rabbits, c+ encodes agouti, cch encodes chinchilla, and ch encodes Himalayan. Dominance within this allelic series is c+ \> cch \> ch. In a cross of c+/ch x c+/ch, what proportion of progeny will be chinchilla?

0%

Polydactyly is a condition that results in more that five digits on an individuals hands and/or feet. This condition is the result of a domainant allele. If two individuals with polydactyly have a child, what is the chance the child will be a boy and have polydactyly?

not enough information

If two individuals with brown eyes have four children, three have brown eyes and one with blue eyes. What is the chance that the parents of the four children are both homozygous?

0%

If two individuals with brown eyes have four children, three have brown eyes and one with blue eyes. What is the chance that one of the brown-eyed children is a carrier of the recessive trait?

66.6%

Co-dominance follows the same inheritance pattern as incomplete dominance.

false

If two flowers are cross, one red and one white, and all the resulting progeny flowers from this cross are both red and white, what is the most likely inheritance pattern?

co-dominance

If two flowers are cross, one red and one white, and all the resulting progeny flowers from this cross are all pink (intermediate), what is the most likely inheritance pattern?

Incomplete dominance

When two heterozygotes for a recessive lethal allele are mated, one-fourth of their offspring will die.

true

Pleiotropic genes contribute to

more than one phenotype.

If there are no interactions between two genes, A and B, and two heterozygotes (A/a;B/b) are mated to each other, what is the expected phenotypic ratio in the offspring?

9:3:3:1

The phenotypic ratio is altered if the genes interact with each other or exhibit a form of

epistasis

A dihybrid cross (A/a; B/b x A/a; B/b) yields 320 F2 offspring. How many are expected to be heterozygous for both genes ?

80

Deafness is caused by recessive mutations in any one of at least five genes. Two deaf individuals have nine children, all of whom have can not hear. Which of the following can you conclude?

The parents have mutations in the same gene.

When crossing 2 individuals with the following genotypes: A/a; B/b; C/c x A/a; B/b; C/c; what is the chance (likelihood) of obtaining a progeny that is homozygous dominant at all three loci?

1/64

\__________________ is the process by which organisms equalize the expression of genes between members of different biological sexes. Across species, different sexes are often characterized by different types and numbers of sex chromosomes.

Dosage Compensation

Which sex, male or female, is the homogametic sex in humans?

female

What is the best guess for inheritance pattern in the pedigree above? (squares highlighted more besides one circle)

X-linked recessive

One form of hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia marries a phenotypically normal woman whose father had hemophilia. What is the probability that they will have a daughter with hemophilia? (Note: In this problem, you must include the probability of having a daughter in your math of the final probability.)

1/4

Eye color is drosphilia is linked to the X-chromosome and red eyes is dominant to white eyes. If a female white-eyed fly is crossed to a red-eyed male fly, what would be the exprected ratio of progeny?

1 female red-eye fly : 1 male white-eye fly

What is the best prediction for inheritance pattern in the pedigree diagrammed above? (circles highlighted excecpt one square)

X-linked dominant

Reduced penetrance of the polydactyl gene is probably a result from a combination of genetic, environmental, and lifestyle factors, many of which are unknown. When a gene displays reduced penetrance, it means

the genetic trait is expressed in only a part of the population.

In sea turtles, sex is temperature dependent. What does this mean?

Sea turtles sex is determined by the temperature they were incubated at inside their eggs

In Drosophila, sex is determined by the number of

X chromosomes

Reduced penetrance of the polydactyl gene is probably a result from a combination of genetic, environmental, and lifestyle factors, many of which are unknown. When a gene displays reduced penetrance, it means

the genetic trait is expressed in only a part of the population.

Deafness is caused by recessive mutations in any one of at least five genes. Two deaf individuals have nine children, all of whom have normal hearing. Which of the following can you conclude?

The parents have mutations in different genes.

You cross a pure-breeding white flower with a pure-breeding red flower, and the offspring are white with red spots. This is an example of what type of inheritance?

Co-dominance

What is the purpose of pseudoautosomal regions?

The pseudoautosomal regions allow for homologous pairing during meiosis

The sex of birds and some insects is determined by a ZW chromosomal arrangement in which the males are the homogametic sex (ZZ) and females are hemizygous (ZW). Assume that a recessive lethal allele on the Z chromosome causes death of an embryo in birds. What sex ratio would result in viable offspring if a cross were made between a male heterozygous for the lethal allele and a normal female?

2:1 male to female

The Cape Verde Islands and the Galapagos Islands have very different species despite their very similar geological and climatic conditions. What did Darwin suggest explained these differences?

Species migration from nearby landmasses

Which phrase describes the process that led to the development of different beaks in Darwin's finches?

Adaptive radiation

Blunt beaks in finches in the Galapagos Islands are in the ancestral condition.

false

The entire DNA sequence of an organism can be determined, and different organisms have many differences in sequence between them. (There are many differences even between members of the same species.) What would be the best way for geneticists to find out which DNA regions were important for a particular trait difference - for example, beak shape in Darwin's finches?

Compare sequences between different finch species with different beak shapes.

In the first video (Chapter 1), Dr. Donze discussed sequence differences between lactose tolerant and lactose intolerant people. What was the reason for lactose intolerance that was discussed in class?

Mutations upstream of the lactase gene

In the phrase, 'ABC1 is involved in transcriptional regulation', ABC1 refers to a gene (DNA) and not a protein.

false

What type of protein controls when and where genes are expressed?

Transcription factor

Which of the following nucleic acid bases are found in DNA? Please select all that apply.

C,T,G,A

Scientists identified several DNA regions that potentially held the sequence that contributed to the different beak shapes in Darwin's finches. What was the next step used to determine which region might be responsible?

Sequences were compared to those from other animals to see if they contained genes that might be involved in beak development

What evidence does not supported the hypothesis that differences in the ALX1 gene were responsible for beak differences in Darwin's finches? (only one answer)

ALX1 was found in all the finch DNA sequences

The \_________ is the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

phenotype

Match the following items below.

- Not located in prokaryotes (4)

- Ribonucleic acid (2)

- Found in prokaryotes (3)

- deoxyribonucleic acid (1)

DNA (1)

RNA (2)

Naked DNA (3)

Nucleus (4)