Ap- Bio 14 and 15 review questions

A poly-A sequence is added at the ___

3' end of a transcrpit in the nucleus

If the rate of replication in a particular prokaryote is 900 nucleotides per second, how long would it take to make two copies of a 1.2 million base pair genome?

44.4 min

What type of nucleic acid material is analyzed the most frequently in forensics cases?

Nuclear chromosomal DNA

Where are the RNA components of ribosomes synthesized?

Nucleolus

What are Okazaki fragments, and how they are formed?

Okazaki fragments are short stretches of DNA on the lagging strand, which is synthesized in the direction away from the replication fork.

What is not one of the proteins involved during the formation of the replication fork?

Origin of replication

Which feature of promoters can be found in both prokaryotes and eukaryotes?

TATA box

The ends of the linear chromosomes are maintained by what?

Telomerase

Where is uracil found?

mRNA

In prokaryotic cells, ribosomes are found in/om the _____

Cytoplasm

Which enzyme is only found in prokaryoric organisms?

DNA gyrase

Who was the first person to isolate the material that came to be known as nucleic acids?

Fredrich Miescher

What is the name of the method developed by Fred Sanger to sequence DNA?

dideoxy chain termination

If the sequence of the 5' to 3' strand is AATGCTAC, then they complementary sequences has which sequence?

3'-TTACGATG-5'

How many nucleotides are in 12 mRNA codons?

36

In which direction does DNA replication take place?

5' to 3'

What would be the consequence of a mutation in a mismatch repair enzyme? How would this affect the function of a gene?

Mismatch repair corrects the errors after the replication is completed by excising the incorrectly added nucleotide and adding the correct base. Any mutation in a mismatch repair enzyme would lead to more permanent damage.

What are the effects of point mutations on a DNA strand?

Mutations can cause a single change in an amino acid. A nonsense mutation can stop the replication or reading of that strand. Insertion or deletion mutations can cause a frame shift. This can result in nonfunctional proteins.

What does the enzyme primase synthesize?

RNA primer

The experiments by Hershey and Chase helped confirm that DNA was the hereditary material on the basis of the finding of what?

Radioactive phosphorus was found in the cell

Meselson and Stahl's experiments proved that DNA replicates by which mode?

Semiconservative

Peptide bond synthesis in prokaryotic translation is catalyzed by ______

ribosomal RNA

The sequence that signals the end of transcription is called the_____

terminator

What processing step enhances the stability of pre-tRNAs and pre-rRNAs?

Methylation

If a prokaryotic cell is replicating cell is replicating nucleotides at a rate of 100 per second, how fast would a eukaryotic ell be replicating nucleotides?

10 per second

If DNA of a particular species was analyzed and it was found that it contains 27 percent A, what would be the percentage of T?

27%

What is the best way to compare and contrast prokaryotic and eukaryotic DNA replication?

A prokaryotic organism's rate of replication is 10 times faster than that of eukaryotes. Prokaryotes have a single origin of replication and use five types of polymerases, while eukaryotes have multiple sites of origin and use 14 polymerases. Telomerase is absent in prokaryotes. DNA pol I is the primer remover in prokaryotes, while in eukaryotes it is RNase H. DNA pol III performs strand elongation in prokaryotes and pol δ and pol ε do the same in eukaryotes.

Which pre-mRNA processing step is important for initiating translation?

Adding the 7- methylguanosine cap

The DNA of virus A is inserted into the protein coat of virus B. The combination virus is used to infect E. coli. The virus particles produced by the infection are anaylzed for DNA and protein. What results would you expect?

DNA and protein from A

Describe the structure and complementary base pairing of DNA.

DNA is made up of two strands that are twisted around each other to form a helix. Adenine pairs up with thymine and cytosine pairs with guanine. The two strands are antiparallel in nature; that is, the 3ʹ end of one strand faces the 5ʹ end of the other strand. Sugar, phosphate, and nitrogenous bases contribute to the DNA structure.

Which enzyme is most directly responsible for the main process of producing a new DNA strand?

DNA pol III

During proofreading, which enzyme reads the DNA?

DNA polymerase

Compare and contrast the roles of DNA polymerase I and DNA ligase in DNA replication.

DNA polymerase I removes the RNA primers from the developing copy of DNA. DNA ligase seals the ends of the new segment, especially the Okazaki fragments.

What is the flow of information for protein synthesis according to the central dogma?

DNA to mRNA to protein

The AUC and AUA codons in mRNA both specify isoleucine. What feature of the genetic code explains this?

Degeneracy

Which feature distinguishes eukaryotic transcription from bacterial transcruption?

Eukaryotic transcription and translation do not take place at the same time

Which enzyme initiated the splitting of the double DNA strand during replication?

Helicase

Explain the events taking place at the replication fork. If the gene for helicase is mutated, what part of replication will be affected?

Helicase separates the DNA strands at the origin of replication. Topoisomerase breaks and reforms DNA's phosphate backbone ahead of the replication fork, thereby relieving the pressure. Single-stranded binding proteins prevent reforming of DNA. Primase synthesizes RNA primer which is used by DNA polymerase to form a daughter strand. If helicase is mutated, the DNA strands will not be separated at the beginning of replication.

In eukaryotes, what is DNA wrapped around?

Histones

At what stage in the transciption of a eukaryotic gene would TFII factors be active?

Initiation

If the b protein is missing, will a prokaryotic gene be terminated?

It depends on the gene

Which portion of a chromosome contains Okazaki fragments?

Lagging Strand

How did the scientific community learn that DNA replication takes place in a semiconservative fashion?

Meselson and Stahl experimented with E. coli. DNA grown in 15N was heavier than DNA grown in 14N. When DNA in 15N was switched to 14N media, DNA sedimented halfway between the 15N and 14N levels after one round of cell division, indicating 50 percent presence of 14N. This supports the semiconservative replication model.

What is often the first amino acid added to a polypeptide chain?

Methionine

A woman has deceloped skin cancer and she is pregnant. She is worried that her child will be born with the cancer she has while carrying her baby. Should she be worried?

No, the mutations causing the cancer are in somatic cells, not reproductive germ cells.

Which polymerase is responsible for the synthesis of 5s rRNA?

Polymerase III

What is the difference in the rate of replication of nucleotides between prokaryotes and eukaryotes?

Prokaryotes are 10 times faster

Compare and contrast the similarities and differences between eukaryotic and prokaryotic DNA.

Prokaryotes have a single, circular chromosome, while eukaryotes have multiple, linear chromosomes. Prokaryotes pack their chromosomes by super coiling, managed by DNA gyrase. Eukaryote chromosomes are wrapped around histone proteins that create heterochromatin and euchromatin, which is not present in prokaryotes.

Which molecule does not contain genetic information?

Protein

Which answer best explains why radioactive sulfur and phosphorus were used to label bacteriophages in the Hershey and Chase experiments?

Protein was labeled with radioactive sulfur and DNA was labeled with radioactive phosphorus. Phosphorus is found in DNA, so it will be tagged by radioactive phosphorus.

Nucleotide excision repair often is employed when UV exposure causes the formation of what?

Pyrimidine dimers

Which subunit of the E. coli polymerase confers specificity to transcription?

Sigma

Which type of point mutation would have no effect on gene expression?

Silent

What prevents the further development of a DNA strand in Sanger sequencing?

The addition of dideoxynucleotides

How can Chargaff's rules be used to identify different species?

The amount of adenine, thymine, guanine, and cytosine varies from species to species and is not found in equal quantities. They do not vary between individuals of the same species and can be used to identify different species.

What happens when a dideoxynucleotide is added a deceloping DNA strand?

The chain is not extended any further

How do the linear chromosomes in eukaryotes ensure that their ends are replicated completely?

The ends of the linear chromosomes are maintained by the activity of the telomerase enzyme.

Which set of results was found in Meselson and Stahl's experimetns?

The original chromosome was split and half went to each duplicate

Why are the -10 and -35 regions of prokaryotic promoters called consenus sequences?

They are similar in all bacterial species.

What is bacterial transformation?

Transformation is a process in which external DNA is taken up by a cell, therby changing morphology and physiology

Explain Griffith's transformation experiment. What did he conclude from them?

Two strains of S. pneumoniae were used for the experiment. Griffith injected a mouse with heat-inactivated S strain (pathogenic) and R strain (nonpathogenic). The mouse died and S strain was recovered from the dead mouse. He concluded that external DNA is taken up by a cell that changed morphology and physiology.

What are introns?

Untranslated DNA sequences in a gen

The DNA double helix does not have what?

Uracil

What is a purine?

a double-ring structure with a six-membered ring fused to a five-membered ring

Which molecule in the central dogma can be compared to a disposable photocopy of a book kept on reserve in the library?

mRNA

Which type of point mutation would result in the substitution of a stop codon for an amino acid?

nonsense