BIO 175 Exam 2

He discovered linkage

Morgan

You are doing a pyrosequencing experiment, which of the following are required?

-DNA fragments, DNA pol, and primers

What proteins are necessary during RNA replication?

-DNA polymerase III: adds nucleotides -DNA ligase: seals breaks on DNA -Helicase: break H bonds to make them split

He discovered the "transforming principle"

Oswald Avery

Which of the following causes a DNA fragment to be formed in the 5' to 3' direction?

Polarity causes DNA polymerase III can only add nucleotides to the 3' end of a DNA strand.

What protein is not necessary during RNA replication?

RNA polymerase-links ribonucleotides into growing RNA in transcription

You are studying a gene of interest using PCR and you want your amplified sequences to the really exact. How would you manipulate PCR conditions?

Raise the annealing temperature (so it doesn't separate)

strand of DNA that is complementary to AAATTG

CAATTT

In bacteria, what is the function of DNA polymerase III?

to add nucleotides to the 3' end of a growing DNA strand

In cats, an X-linked locus is responsible for fur color. There are two known alleles at this locus. One results in black fur color; the other results in orange fur color. A heterozygote animal has patches of orange and black fur (tortoiseshell). Which coat color phenotypes are expected from the cross of a black female and an orange male?

tortoiseshell females; black males

What might happen to DNA replication if each of the following enzymes was dysfunctional? Helicase, DNA polymerase III, DNA ligase, Primase, DNA polymerase I

-Helicase: won't unwind so replication wouldn't begin -DNA polymerase III: comp. strand not produced so no replication -DNA ligase: won't be "knit" together so "holes" in comp. strand -Primase: no primer so replication won't begin -DNA polymerase I: no primer degration so RNA left in complementary strand

Which of the following describes telomeres?

-contain repetitive DNA sequence -are important in cellular mechanism evolved to prevent shortening of chromosomes -in the form of heterochromatin -found at the ends of linear chromosomes

Heterochromatin has

-few expressed genes -condensed chromatin

RNA splicing serves all if the following functions:

-providing a diversity of transcriptions from the same sequence of DNA -quicker regulation of expressions at the post-transciptional level

What is true about DNA replication?

-the lagging strand is synthesized in short fragments, directed away from the replication fork -replication occurs in the 5' to 3' direction -the DNA must be denatured at the replication fork

RNA splicing serves all of the following functions excpet

-to turn off transcription at a pre-transcriptional level -in pre they can't splice before being made

What are the two types of splicing?

1. exons (code): retained 2. introns: removed

Map distance inferred from a test cross that yields 90% parental classes

10% recombinant classes, the genes are inferred to be 10 map units apart on the chromosome

A strand of DNA is 34% G, what percentage of T is present?

16%

A sample of double-stranded DNA contains 28% thymine. Approximately what percent of the nucleotides in this sample will be guanine?

22%

In birds, sex is determined by ZW chromosome inheritance. Males are ZZ and females are ZW. Within pigeon populations there is a recessive, Z-linked allele that is lethal in embryos. What is the expected sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a wildtype female?

2:1 male to female

Use this model of a eukaryotic primary transcript to answer the following question.E = exon and I = intron5′-UTR E1 I1 E2 I2 E3 I3 E4 UTR-3′If the primary transcript is processed and transported to the cytosol, which of the following molecules best represents the mRNA that will be produced?5′-UTR E1 E2 E3 E4 UTR-3′

5′-UTR E1 E2 E3 E4 UTR-3′

A sample of double-stranded DNA contains 42% cytosine. Approximately what percent of the nucleotides in this sample will be thymine?

8%

DNA strands are antiparallel. Which of the following statements defines "antiparallel"?

A 5' to 3' DNA strand is paired with the 3' to 5' DNA strand

Frederick Griffith heat-killed a culture of pathogenic bacteria. He split the sample and injected half of it into mice. The mice lived. He then mixed the other half with a living, nonpathogenic bacteria strain and injected the mixture into mice. The mice died. These results best support which of the following conclusions.

A substance had been transferred from pathogenic to nonpathogenic bacteria

Which of the following combinations of base pairs will be found in a molecule of DNA?

A+C=G+T

Wilson and Crick inferred this from the observations of Chargaff

A=T, and G=C

Rosalind Franklin's X-ray crystallography data suggested DNA is double stranded and has a uniform diameter. These observations can be used to rule out base pairing between two of the same nucleotide because ________.

An A-A pair is wider than a C-C pair

DNA replication is semi-conservative. This means that __________.

Both double strands have a newly created strand and an original template strand

Name of the DNA strand that has the DNA version of a transcripts sequence

Coding strand and template strand (non-coding)

Which of the following events will result in recombination between linked genes?

Crossovers between genes resulting in chromosomal exchange

Which prokaryotic polymerase is primarily responsible for filling in DNA nucleotides into the gap created by the removal of RNA primers?

DNA polymerase I

Which protein is responsible for the removal of the RNA primer from the 5' end of a lagging strand of DNA, and replacing it with DNA nucleotides?

DNA Polymerase I

Which of the following proteins in known for its ability to break hydrogen bonds?

DNA helicase

During DNA replication, an enzyme called DNA helicase "unzips" the molecule of double-stranded DNA. What is the most likely mechanism of DNA helicase?

DNA helicase breaks down the hydrogen bonds between the purines and pyrimidines

Oswald Avery and collaborators made this key discovery

DNA is the substance responsible for heredity and transformation in bacteria

Of the following DNA replication proteins, which one links the Okazaki fragments of the lagging strand?

DNA ligase

In bacteria, which of the following proteins is responsible for removing nucleotides from the RNA primer that is used for initiation DNA synthesis?

DNA pol I

In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5' → 3' direction?

DNA polymerase III

Which of the following statements underlies the reason why ddNTPs are used in sequencing?

DNA polymerases require a 3' OH group to add to a new nucleotide

What is the reverse complement of this DNA strand? AAGTCTTAC

GTAAGACTT

Which of the following statements correctly describes Archibald Garrod's hypothesis for how "inborn errors of metabolism" such as alkaptonuria occur?

Genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes

In his experiment, Griffith demonstrated...

Genetic information could be taken up by a cell from its environment, changing its characteristics (mice and heating)

Which of the following replication proteins is used to unwind the DNA double helix?

Helicase

Which of the following pairs of DNA replication proteins is responsible for unwinding the DNA double-helix and maintaining the separation of the DNA strands?

Helicase and single-strand binding protein (SSB)

Which of the following amino acids substitutions would you expect to disrupt protein function the most?

His replaced by Asp (positive replacing a negative charge)

Which of the following processes correctly describes alternative RNA splicing?

It can allow the production of proteins of different sizes and function from a single mRNA

Which of the most accurately describes the Beadle and Tatum experiment?

It led to the one gene one enzyme hypothesis

__________ is a protein that synthesizes RNA primers on __________ during DNA replication.

Primase . . . both the leading and lagging strands

Which of the following processes occurs as part of transcription?

RNA is synthesized

In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein?

RNA polymerase II

Enzyme responsible for transcription of mRNA

RNA polymerase where it will bind to a promotor (5' end)

In cats, an X-linked locus is responsible for fur color. There are two known alleles at this locus. One results in black fur color; the other results in orange fur color. A heterozygote animal has patches of orange and black fur (tortoiseshell). Which of the following explains the patches of color in female heterozygote cats?

Random X inactivation affects fur color

What is not true about DNA replication?

Replication occurs during prophase of mitosis: replication doesn't occur in mitosis and meiosis, but it will occur during everything else

Which of the following statements about RNA processing is correct?

Ribozymes may function in RNA slicing

A single DNA molecule (one double-helix) undergoes three rounds of replication. After the final replication is complete, how many of the DNA molecules present do not contain any part of the original template?

Six

What explanation makes sense for why calico cats are always female?

The calico pattern occurs as a result of barr body formation (extra tail, 2X chromosome and won't be expressed because its in barr body)

Which of the following statements regarding gene linkage is correct?

The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them

Which statement correctly describes the process of DNA replication?

The original molecule is separated and each daughter molecule will have one old DNA strand and a new DNA strand

Extra one of this chromosome causes Down Syndrome

Trisomy 21

Which aneuploidy would likely have the least significant effect on the individual?

Trisomy XYY

The only viable human monosomy

Turner Synfrome

Red-green color blindness is an X-linked recessive trait in humans. Two people with normal color vision have a son with colorblindness. Given this information, the genotypes of the parents are ________.

XNXn and XNY

A doubly heterozygous (dpy/+,unc/+) phenotypically wildtype worm is mated to a doubly homozygous dumpy (dpy/dpy), uncoordinated (unc/unc) worm. This cross produces the following numbers and phenotypic categories of offspring: 93 wildtype; 85 dumpy and uncoordinated; 88 dumpy but normal movement; 92 normal shape but uncoordinated

assort independently (1:1:1:1)

In Drosophila melanogaster, wing-size and body-color genes are linked. Vestigial wings and black body color are both recessive traits. A researcher crossed black-bodied, normal-winged females and gray-bodied, vestigial-winged males. The F1 were all gray bodied, normal winged. A test cross was performed with F1 females. The researcher calculated a map distance of 17 map units. Which of the following information is correct about the testcross progeny?

black-bodied, normal-winged flies plus gray-bodied, vestigial-winged flies= 17% of the total

Aneuoploidy

chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number

If two loci are genetically linked, it means

close enough together that they may not be separated during recombination

Which of the following is a reason that a new DNA strand elongates only in the 5' to 3' direction during DNA replication?

dehydration reactions require a free -OH group

What is the function of telomerase in embryonic cells?

extends the 3' end of DNA during replication

RNA is single stranded, can hydrogen-bond with other nucleic acids, and has functional groups that can function in catalysis. These characteristics support that RNA could have which of the following cellular roles?

forming peptide bonds

Which of the following outlines the order of enzyme action you would expect in replication of a section of DNA?

helicase, primase, DNA polymerase III, DNA polymerase I, ligase

"Transformation" in the context of molecular biology refers to

insertion of DNA into an organism that can result in a change in phenotype

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

joins Okazaki fragments together

3' OH of exon is linked to this after splicing

linked to 5' phosphate end of adjacent exon, forms a phosphodiester bond and results in the formation of a continuous mRNA molecule without intronic sequences

Which of the following RNA molecules is responsible for carrying the code that will be read at the ribosome in order to create a protein?

mRNA

Which of the following molecules carries information from DNA and directs incorporation of amino acids at the ribosome?

mRNA

Males are more often affected by X-linked traits than are females because...

males are hemizygous genes on the X chromosomes

In E. coli, a mutation in a gene called dnaB prevents the helicase from binding at the origin of replication. Which of the following events would you expect to occur as a result of this mutation?

no replication form will. be formed

Proposed by Beadle and Tatum

one gene, one enzyme

Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human X chromosome. The patients' muscles weaken over time because they have a lack or decreased levels of dystrophin, a muscle protein. Which of the following correctly predicts the probability of muscular dystrophy in female children?

one-half of the daughters of an affected man and a carrier woman would have this condition

DNA Pol III

produces DNA in the 5' to 3' direction on the leading strand

DNA sequence that determines the site of transcription initiation

promotor region that is toward the 5' of transcription start side

A catalyically-active RNA molecule

ribozymes

Which of the following characteristics of DNA allows it to carry a vast amount of hereditary information?

sequence of bases

Which of the following does NOT describe telomeres?

serve as primers for replication of the genome

Genotype of daughters of father who is red-green color blind and mother who is not a carrier for color blindness

sex linked recessive trait

ribonucleic acid-protein complex that mediates splicing

splicesome

Lowering the salt concentrations favors this DNA conformation

ssDNA GGATTCAGTGCT

When Thomas Hunt Morgan crossed red-eyes F1 generation flies to each other, the F2 generation included both red-and white-eyes flies, but all the white-eyes flies were male. Which of these best explains Morgan's result?

the gene involved is located on the X chromosome

Which of the following phrases correctly defines one genetic map unit?

the physical distance between two genes that results in a 1% frequency of recombination

Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA?

the primary transcript is larger than the mRNA

A recombination frequency of 50% indicates....

the two genes are far apart or on different chromosomes

A testcross performed with F1 dihybrid flies results in more parental-type offspring than recombinant-type offspring. Which of the following statements best explains this result?

the two genes are linked on the same chromosome

In the structure of many eukaryotic genes, individual exons parallel which of the following?

the various domains of the protein product