AP BIO CHAPTER 6 TEST REVIEW

In which direction does DNA replication take place?

5' to 3'

What is the major challenge in the production of RNA in eukaryotes compared to prokaryotes?

exporting the mRNA across the nuclear membrane

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

semi-conservative

Cells make protein through translation. Organize the steps of translation in the correct order from start to finish.

-A tRNA molecules pairs with the corresponding mRNA codon. -mRNA is transported outside the nucleus. -Ribosomes bind to mRNA. -As the mRNA is read, the amino acids on each tRNA are linked. -The ribosome reaches the STOP codon and ends the process

Transcription is the beginning of protein synthesis. Some of the following sentences describe events that occur during the process of transcription in eukaryotes. Determine which sentences describe steps in the process of transcription, and then place them in the order that they occur.

-RNA polymerase separates the DNA into two strands -RNA polymerase adds complementary base pairs to form a strand of RNA -The RNA molecule (called a transcript) moves to the cytoplasm -RNA polymerase binds to DNA

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

23%

The genetic code is always read

3 bases at a time in the same direction

If the sequence of the 5' to 3' strand is AATGCTAC, then the complementary sequence has the following sequence:

3'-TTACGATG-5'

An organism's genome is 15% Thymine. How much Guanine is present? _%

35

How many nucleotides are in 12 mRNA codons?

36

How long would the amino acid sequence be that is translated from this mRNA strand: AUGGGCUACCGA ?

4

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

7-methylguanosine cap

Two scientists are both studying RNA. One scientist is studying RNA in mice, and the other is studying RNA in E. coli bacteria. Which of the following best describes how each scientist would use the genetic code and amino acid table?

Both scientists would use the same genetic code because in all organisms the code is read three bases at a time and in the same direction

A mutation has occurred in the DNA and in the mRNA for a gene. Discuss which would have a more significant effect on gene expression. Why?

Both will result in the production of defective proteins. The DNA mutation, if not corrected, is permanent, while the mRNA mutation will only affect proteins made from that mRNA strand. Production of defective protein ceases when the mRNA strand deteriorates

From which molecules are mRNA molecules transcribed?

DNA

Explain how the components of DNA fit together.

DNA is composed of nucleotides, consisting of a 5 carbon sugar, a phosphate, and a nitrogenous base. DNA is a double helical structure in which complementary base pairing occurs. Adenine pairs with thymine and guanine pairs with cytosine. Adenine and thymine form two hydrogen bonds and cytosine and guanine form three hydrogen bonds. The two individual strands of DNA are held together by covalent bonds between the phosphate of one nucleotide and sugar of the next. The two strands run antiparallel to each other.

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 anti-parallel in nature; that is, the 3' end of one strand faces the 5' end of other strand. Sugar, phosphate and nitrogenous bases contribute to the DNA structure

During proofreading, which of the following enzymes reads the DNA?

DNA polymerase

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

DNA polymerase can join new nucleotides only to the 3' end of a preexisting strand, and the strands are antiparallel

The main mechanism for repairing nucleotide errors in DNA is...

DNA polymerase proofreading

What is the initial mechanism for repairing nucleotide errors in DNA?

DNA polymerase proofreading

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

DNA to mRNA to protein

What is going on in this picture?

DNa is being transcribed into mRNA

Which of the following features distinguishes eukaryotic transcription from bacterial transcription?

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

Which of the following statements about epigenetic regulation is FALSE?

Histones protein charge becomes more positive when acetyl groups are added

What would be the consequence of a mutation in a mismatch repair enzyme? How will 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

If mRNA is complementary to the DNA template strand and the DNA template stand is complementary to the DNA non-template strand, why are base sequences of mRNA and the DNA non-template strand not identical? Could they ever be?

No, they cannot be identical because the T nucleotide in DNA is replaced with U nucleotide in RNA and AUG is the start codon

Which of the following molecules does not contain genetic information?

Protein

Explain why radioactive sulfur and phosphorous were used to label bacteriophages in the Hershey and Chase experiments.

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

The binding of what is required for transcription start?

RNA polymerase

Which of the following 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?

Radiolative phosphorus was found in the cell

Explain why half of DNA is replicated in a discontinuous fashion.

Replication of the lagging strand occurs in the direction away from the replication fork in short stretches of DNA, since access to the DNA is always from the 5' end. This results in pieces of DNA being replicated in a discontinuous fashion

Discuss the contributions of Francis Crick, James Watson, and Rosalind Franklin to the discovery of the structure of DNA.

Rosalind Franklin used X-ray diffraction methods to demonstrate the helical nature of DNA, while Watson and Crick formulated the double stranded structural model of DNA.

Discuss how mutations can increase variation within a population.

Substitution mutations may cause a different amino acid to be placed at a specific location, causing small changes in the protein. Frameshift mutations usually cause multiple amino acid changes, increasing chances that a new protein will form, leading to radically different characteristics in the offspring.

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 are not found in equal quantities. They do not vary between individuals of the same species and can be used to identify different species

A tRNA is chemically modified so that the amino acid bound is different than the one specified by its anticodon. Which codon in the mRNA would the tRNA recognize: the one specified by its anticodon or the one that matches the modified amino acid it carries?

The anticodon will match the codon in mRNA

You are looking at two fragments of DNA. Both have the sequence CATTCTG on one strand and GTAAGAC on the other. One of the fragments is exposed to UV light, the other is not. What will happen to the fragments and how might these mutations be repaired?

The fragment exposed to UV light contains thymine dimers. Thymines lying adjacent to each other can form thymine dimers when exposed to UV light. They can be repaired by nucleotide excision.

Which step in the transcription of eukaryotic RNA differs the most from its prokaryotic counterpart?

The initiation step in eukaryotes requires an initiation complex with enhancers and transcription factors. Also, the separation of the DNA strand is different as histones are involve

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

The original chromosome was split and half went to each duplicate.

Describe the semi-conservative model of DNA replication and explain how the structure of DNA affects how it is replicated.

The two strands of DNA unwind from each other, and each template synthesis of a new, complementary strand. So the results in two DNA molecules with one original strand and one new strand. The strucute makes it where DNA can only synthesis in a 5' to 3' direction.

Which of the following is true of epigenetic changes?

They allow movement of histones.

Describe how the model of DNA replication illustrates the function of topoisomerase.

Topoisomerase relieves the pressure that resutls from supercoiling by breaking and reforming DNA's phosphate backbone ahead of the replication fork

What is a purine?

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

RNA differs from DNA in that RNA has

a single strand and contains uracil

If glucose is absent but lactose is present, the lac operon will be:

activated

What are Autonomously Replicating Sequences (ARS)?

area of eukaryotic chromosomes that are equivalent to the origin of replication in E.coli

What do RNA and DNA have in common?

both contain four different nucleotides

Post-translational modifications of proteins can affect which of the following?

chemical modifications

What is meant by a recombinant DNA molecule?

chimeric molecules

Which of the following are involved in post-transcriptional control?

control of RNA splicing

Genetic recombination occurs by which process?

crossing over

In prokaryotic cells, ribosomes are found in/on the:

cytoplasm

What would be the outcome of a mutation that prevented DNA binding proteins from being produced?

decreased transcription because enhancers would not be able to bind to transcription factors

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

degeneracy

The elongation of the leading strand during DNA synthesis

depends on the action of DNA polymerase

Binding of an RNA binding protein will change the stability of the RNA molecule in what way?

either increase or decrease

Control of gene expression in eukaryotic cells occurs at which level(s)?

epigenetic and transcriptional, translational, and post-translational levels

Gene A is thought to be associated with color blindness. The protein corresponding to gene A is isolated. Analysis of the protein recovered shows there are actually two different proteins that differ in molecular weight that correspond to gene A. What is one reason why there may be two proteins corresponding to the gene?

gene was alternatively spliced

Individual genetic maps in a given species are ________.

genetically similar

What is genomics?

genomics is the study of entire genomes, including the complete set of genes, their nulcoetide sequence and orgaization, and their interactions within a spcies and with other species

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

helicase

In a nucleosome, the DNA is wrapped around

histones

In eukaryotes, what is DNA wrapped around?

histones

What would happen if the operator sequence of the lac operon contained a mutation that prevented the repressor protein from binding the operator?

in the absence of lactose, the lac operon will be transcribed

What would happen if the operator sequence of the trp operon contained a mutation that prevented the repressor protein from binding to the operator?

in the presence of tryptophan, the genes trpA-E will be transcribed

What will result from the binding of a transcription factor to an enhancer region?

increased transcription of a distant gene

How are GMOs created?

introducing recombinant DNA into an orgamism by an means

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

it depends on the gene

Which portion of a chromosome contains Okazaki fragments?

lagging strand

What is the first step in isolating DNA?

lysing the cells in the sample

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

methionine

Which amino acid is coded for by the codon with the RNA sequence AUG? Use either genetic code table.

methionine (met)

Where are the RNA components of ribosomes synthesized?

nucleolus

What are cancer-causing genes called?

oncogenes

What are positive cell-cycle regulators that can cause cancer when mutated called?

oncogenes

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

origin of replication

Which of the following are found in both DNA and RNA?

phosphate groups, guanine, and cytosine

What is required in addition to a genetic linkage map to build a complete picture of the genome?

physical map

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

polymerase 3

Which technique used to manipulate genetic material results in a significant increase in DNA or RNA fragments?

polymerase chain reaction

What is the final product of the process shown in the diagram below?

protein

What process transfers heritable material to the next generation?

replication

The peptide bond synthesis in prokaryotic translation is catalyzed by:

ribosomal RNA

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

sigma subunit

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

silent

The ends of the linear chromosomes are maintained by what?

telomerase

The sequence that signals the end of transcription is called the:

terminator

What are epigenetic modifications?

the addition of reversible changes to histone proteins and DNA

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 telmoerase enzyme

What do figures X and Y in the graphic illustrate?

transcription and translation in a prokaryotic cell(figure x) and a eukaryotic cell (figure y)

Ribosomes are tiny "factories" within cells that do all of the following EXCEPT

translate DNA into RNA

Identify the type of change that can occur in the DNA of a chromosome that is termed a chromosomal mutation.

translocation

What are introns?

untranslated DNA sequence in a gene

The DNA double helix has all of the following EXCEPT

uracil