AP Biology Review

In a nucleosome, the DNA is wrapped around

histones

In the polymerization of DNA, a phosphodiester bond is formed between a phosphorate group of the nucleotide being added & which of the following atoms or molecules of the last nucleotide in the polymer?

the 3' OH

which of the following molecules are required for the process of translation?

mRNA,tRNA, and rRNA

the spontaneous loss of amino groups from adenine in the DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

nuclease, DNA Polymerase, DNA ligase

E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

one low-density and one intermediate-density band

Semiconservative replication involves a template what is the template?

one strand of the DNA molecule.

which of the following types of cells are affected most by telomere shortening?

only eukaryotic cells

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

several transcription factors

Thymine makes up 28% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be guanine?

22%

A particular triplet of bases in the template strand of DNA is 5' - AGT - 3'. What would be the corresponding codon for the mRNA that is transcribed?

3' - UCA - 5'

which of the following sequences of nucleotides are possible in the templates strand of DNA that would code for the polypeptide sequence Phe-Leu-IIe-Val?

3' -AAA-GAA-TAA-CAA-5'

which of the triplets below is possible anticodon for a tRNA that transports proline to a ribosome?

3'-GGC-5'

Rank the following one-base point mutations with respect to their likelihood of affecting the structure of the corresponding polypeptide (from most likely to least likely) 1.Insertion mutations deep within an intron. 2. substitution mutation at the third position of a codon in an exon. 3. substitution mutation at the second position of a codon in an exon. 4. Deletion mutation within the first exon of the gene.

4, 3, 2 , 1

Use this model of a eukaryotic transcript to answer the following question. E = exon and I = intron 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Which components of the previous molecule will also be found in mRNA in the cytosol?

5' - UTR E1 E2 E3 E4 UTR - 3'

At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' CCTAGGCTGCAATCC 5' An RNA primer is formed starting at the underlined T of the template. Which of the following represents the primer sequence?

5' ACGUUAGG 3'

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?

8%

In an analysis of the nucleotide composition of a molecule of DNA, which of the following combinations of base pairs will be found?

A + C = G + T

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?

A + G = C + T

Which of the following Statements is the most current Descriptions of a gene?

A DNA sequence that is expressed to for, a functional product; either RNA or polypeptide.

Which of the following DNA mutations is most likely to damage the protein it specifies?

A base-pair deletion

which of he following processes occurs in eukaryotic gene expression?

A cap is added to the 5' end of he mRNA.

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?

A deletion of two nucleotides

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following statements to be true?

A gene from an organism can be theoretically be expressed by any other organism.

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. What is the result of this type of mutation?

A polypeptide missing an amino acid

Which of the following characteristics would you expect of a eukaryotic organism that lacks the enzyme telomerase?

A reduction in chromosome length in gametes.

During the elongation phase of translation, which site in the ribosome represents the location where a codon is being read?

A site

Which of the following processes occurs when termination of translation takes place?

A stop codon is reached

which of the following effects might be caused by reduced or very little active telomerase activity?

Cells maintain normal functioning

A particular triplet of bases in the coding sequence of DNA is AAA. the anticodon on the tRNA that binds the mRNA codon is...

AAA

which one of the following structures, if missing, would usually prevent translation from starting?

AUG codon

post-translational modifications of proteins may include which of the following processes?

Addition of carbohydrates to form a glycoprotein

For a science fair project, 2 students decided to repeat Hershey & Chase experiment, with modifications. They decided o radioactively label the nitrogen of the DNA, rather than the phosphate and two to five nitrogen atoms. Thus, labeling the nitrogen atoms would provide a stronger signal than labeling the phosphates. why wont this experiment works?

Amino Acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA & proteins.

Codons are three-base sequences in mRNA that specify the addition of a single amino acid to the growing protein chain during translation. How do eukaryotic codons and prokaryotic codons compare?

Codons are a nearly universal language among all organisms.

Hershey & Chase set out to determine what molecule served as the unit of inheritance. They completed a series of experiments in which E. Coli was infected by a T2 virus. which molecular component of the T2 virus actually ended up inside the cell?

DNA

Which of the following facts did Hershey & Chase make use of in trying to determine whether DNA or protein is the genetic material?

DNA contains phosphorus, whereas protein does not.

Suppose you are provided with an actively dividing culture of E. Coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?

DNA in both daughter cells would be radioactive.

DNA contains the template needed to copy itself, but it has no catalytic activity in cells. What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed during DNA replication?

DNA polymerase

In E. Coli, Which enzyme catalyzes the elongation of a new DNA strands in the 5' to 3' direction?

DNA polymerase 3

Why does a new DNA strand elongate only in the 5' to 3' direction during DNA replication?

DNA polymerase can add nucleotides only to the free 3' end.

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 the pre-existing strand, and the strands are antiparallel.

The lagging strand is characterized by series of short segments of DNA (Okazaki fragments) that will be joined together to form a finished lagging strand. the experiments that led to the discovery of Okazaki fragments gave evidence for which of following ideas?

DNA polymerase is an enzyme that synthesizes leading and lagging strands during replication only in one direction.

In DNA replication, the resulting daughter molecules contain one strand of the original paternal DNA and one new strand. what is the explanation for this phenomenon?

DNA replication is semiconservative.

which of the following investigators was (were) responsible for the discovery that in DNA from any species, the amount of thymine, and the amount guanine equals the amount of cytosine?

Erwin Chargaff

Which of the following statements describes the process of transformation in bacteria?

External DNA is taken into a cell, becoming part of the cells genome.

An original section of DNA has the base sequence AGCGTTACCGT. A mutation in this DNA strand results in the base sequence AGGCGTTACCGT. This change represents _____.

Frame-shift mutation

Which of he following characteristics of eukaryotic telomeres cause them to replicate differently than the rest of the chromosomes?

Gaps left at the 5' end of the lagging strand template.

Which of the following statements correctly describes Srchibald 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.

which of the following statements correctly describes the structure of chromatin?

Heterochromatin is highly condensed, whereas euchromatin is less compact.

which of the following statements accurately describes one characteristics of histones?

Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.

which of the following molecular characteristics cause histones to bind tightly to DNA?

Histones are positively charged, and DNA is negatively charged.

which of the following structural characteristics is most critical for the association between histones and DNA?

Histones are positively charged.

Which of the following processes correctly describes alternative RNA splicing?

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

How does the enzyme telomerase meet the challenge of replication the ends of the linear chromosomes?

It catalyzes the lengthening of telomeres, compensating for the shortening that occur during replication without telomerase activity.

Which of the following statements correctly describes the effect a nonsense mutation would have on a gene?

It introduces a premature stop codon into the mRNA.

Which of the following statements correctly describes a ribozyme?

It is an RNA with catalytic activity.

Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine, and cytosine forms hydrogen bonds with guanine. What is the significance of the structural arrangement?

It permits complementary base pairing.

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

Its joins okazaki fragments together.

What performed classic experiments that supported the semiconservative model of DNA replication?

Meselson and Stahl

Once researchers identified DNA as the molecule responsible for transmitting heritable traits, they asked how information was transferred from the DNA in the nucleus to the site of proteins synthesis in the cytoplasm. Which of the following statements correctly describes the mechanism of information transfer in eukaryotes that accomplishes this task?

Messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm, where protein synthesis takes place.

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3'

Met-Ser-Ser-Leu-Ser-Leu

In his transformation experiments what phenomenon did Griffith observe?

Mixing a heat-Killed pathogenic strain of bacteria with a living non-pathogenic strain can convert some of the living cells into pathogenic form.

The genetic code is redundant. What is meant by this statements?

More than one codon can specify the addition of the same amino acid.

Which of following statements supports the one gene-one enzyme hypothesis?

Multiple antibody genes can code for different related proteins, depending on the splicing that takes place post- transcriptionally.

In E. Coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin of replication. Which of the following events would you expect to occur as a result of this mutation?

No replication fork will be formed.

In E. Coli, to repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?

Nuclease, DNA polymerase, DNA Ligase

Which of the following lists represents the order of increasingly higher levels of organization of chromatin?

Nucleosome, 30-nm chromatin fiber, looped domain.

how might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene?

Only a Single amino acid could change, because the reading frame would be unaffected

a heat-killed, phosphorescent (light-emitting) strain of bacteria is mixed with a living, non-phosphorescent strain. Further observation of the mixture show that some of the living cells are now phosphorescent. Which of the following observations would provide the best evidence that the ability to phosphorescent is a heritable trait?

Phosphorescence in descendants of the living cells.

Which of the following statements accurately describes the differences between DNA replication in prokaryotic & DNA replication in eukaryotes?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

What would be the consequence of a mutation in a bacterial cell that produces a defective aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNAs with the anticodon AAA?

Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

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

RNA polymerase 2

Which of the following statements best describes the termination of transcription in prokaryotes?

RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

What is the function of the enzyme topolsomerase in DNA replication?

Relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix.

After the first replication was observed in their experiments testing the nature of DNA replication, Meselson & Stahl could be confident of which of following conclusion?

Replication is Semi-conservative.

In DNA Replication in E. Coli, the enzyme primase is used to attach a 5 to 10 base ribonucleotide strand complementary to the parental DNA strand. The RNA strand serves as a starting point for the DNA polymerase that replicates the DNA. If a mutation occured in the primase gene, which of the following results would you expect?

Replication would not occur on either the leading or lagging strand.

which of the following statements about RNA processing is correct?1

Ribozymes may function in RNA splicing.

It became apparent to Watson & Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information. Which of the following characteristics of DNA is responsible for this?

Sequence of Bases

in eukaryotic cells, transcription cannot begin until...

Several Transcription factors have bound to the promoter.

Which of the following types of molecules help to hold the DNA strands apart while they are being replicated?

Single - strand DNA binding Proteins.

In his work with pneumonia-causing bacteria and mice, Griffith found that...

Some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic.

telomere shortening puts a limit on the number of times a cell can divide. research has shown that telomerase can extend the life span of cultured human cells. how might adding telomerase affect cellular aging?

Telomerase eliminates telomere shortening and retards aging.

what is meant by the description "antiparallel" regarding the two strands that make up DNA double helix?

The 5' to 3' direction of one strand runs counter 5' to 3' direction of the other strand.

Which of the following statements correctly describes the difference between ATP & the nucleotides used during DNA synthesis?

The Nucleotides have the sugar deoxyribose; ATP has the sugar ribose.

researchers found a strain of E. Coli bacteria that had mutations rates one hundred times higher than normal. Which of the following statements correctly describes the most likely cause of these results?

The Proofreading mechanism of DNA polymerase was not working properly.

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight, & mutations to the DNA in their skin cells are left uncorrected. Why are the mutations not corrected in individuals with this disorders?

The disorder causes cells to be unable to repair thymine dimers.

Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA during DNA replication?

The leading strand is synthesized in the same direction as the movement of the replication fork, & the lagging strand is synthesized in the opposite direction.

In the structural organization of many eukaryotic genes, individual exons may be related to which of the following?

The various domains of the polypeptide product.

In E. Coli, what is the function of DNA polymerase 3?

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

Which of the following processes occurs in prokaryotes but not in eukaryotes?

Transcription and translation occur simultaneously.

which of the following statements is true about protein synthesis in prokaryotes?

Translation can begin while transcription is still in progress

Hershey and Chase used a DNA-based virus for their work. How might the results have been different if they had used an RNA virus?

With an RNA virus, radioactive RNA would have been in final pellet.

A single base substitution mutation is least likely to be deleterious when the base change results in _____.

a codon that specifies the same amino acid as the original codon.

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the

binding of the anticodon to the codon and the attachment of amino acids to tRNAs

the elongation of the leading strand during DNA synthesis...

depends on the action of DNA polymerase.

What is the function of the release factor during translation on eukaryotes?

it binds to the stop codon in the A site in place of a tRNA.

which of the following statements correctly describes the function of a signal peptide?

it helps target a protein to the ER.

which of the following statements accurately describes the structure of a eukaryotic chromosomes?

it is a single linear molecule of double-stranded DNA plus proteins.

which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes?

it is the recognition site for the binding of a specific transcription factor.

which of the following properties is associated with a protein that will be secreted from a eukaryotic cell?

its signal sequence must target it to the ER after which it goes to the golgi.

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. when you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. one class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). which two classes of DNA do these different samples represent?

leading strands and Okazaki fragments

According to the central dogma, what is the intermediate molecule involved in the flow of information in a cell that should go in the blank? DNA --> _______----> Proteins

mRNA

Which of following molecular structures contain codons?

mRNA

in a healthy eukaryotic cell, the rate of the DNA repair is typically equal to the rate of DNA mutation. when the rate of repair lags behind the rate of mutation, what is a possible fate of the cell?

the cell can be transformed into cancerous cell

If a cell were unable to produce histone proteins, which of the following results would be more likely effect on the cell?

the cell's DNA could not be packed into its nucleus.

what are telomeres?

the ends of the linear chromosomes

Which of the following statements correctly describes the difference between the leading strand and the lagging strand in DNA replication?

the leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in the 5' yo 3' direction.

in an experimental situation, a student researcher inserts an mRNA molcule into a eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the following processes would you expect her to find to have occurred?

the molecule is digested by enzymes because it is not protected at the 5' end.

How does the primary transcript in the nucleus of a eukaryotic cell compare to the functional mRNA?

the primary transcript is larger then the mRNA.

how does the primary transcript in the nucleus of a prokaryotic cell compare to the functional mRNA?

the primary transcript is the same size as the mRNA.

In bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs which of the following statements explains this fact?

the rules for the base pairing between the third base of a codon and tRNA are flexible.

Which of the following processes is the first event to take place in translation in eukaryoties?

the small subunit of the ribosomes recognizes and attaches to the 5' cap of the mRNA.

which of the following characteristics is directly related to coding of a single amino acid during the process of translation?

the three-base sequence of mRNA.

Once a peptide has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next?

translocation