AP Bio chap 17 & chap 20 quiz

The reason for using Taq polymerase for PCR is that A) it is heat stable and can withstand the temperature changes of the cycler. B) only minute amounts are needed for each cycle of PCR. C) it binds more readily than other polymerases to primer. D) it has regions that are complementary to primers. E) All of these are correct.

A

Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double-stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA. A) 2, 1, 4 B) 1, 3, 2, 4 C) 3, 4, 1, 2 D) 3, 4, 2 E) 2, 3, 4

A

Which of the following statements about mutations is false? - An addition mutation results in an added base in the DNA sequence. - A knock-out mutation results in a total absence of the mutated protein. - Addition and deletion mutations disrupt the primary structure of proteins. - A deletion mutation results in the loss of a base in the DNA sequence.

A knock-out mutation results in a total absence of the mutated protein.

During which step in the PCR cycle do primers form bonds with a single-stranded template? - Denaturation. - All of these steps. - Extension. - Annealing.

Annealing.

A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using A) RNA polymerase to transcribe the gene. B) a restriction enzyme to cut the gene into shorter pieces. C) reverse transcriptase to reconstruct the gene from its mRNA. D) DNA polymerase to reconstruct the gene from its polypeptide product. E) DNA ligase to put together fragments of the DNA that code for a particular polypeptide.

C

Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme? A) AAGG TTCC B) AGTC TCAG C) GGCC CCGG D) ACCA TGGT E) AAAA TTTT

C

If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred? - Addition - Deletion - Addition and deletion - No mutation

Deletion

Which of the following is used to make complementary DNA (cDNA) from RNA? A) restriction enzymes B) gene cloning C) DNA ligase D) gel electrophoresis E) reverse transcriptase

E

What are restriction enzymes?

Enzymes that cut a DNA molecule at a particular place

During which step in the PCR cycle are nucleotides used? - Denaturation. - All of these steps. - Extension. - Annealing.

Extension.

What creates sticky-stranded ends?

If the cuts made by the restriction enzyme are staggered

What are frame-shift mutations?

Insertion/deletion of a base

What is the effect of a nonsense mutation in a gene? - It introduces a premature stop codon into the mRNA. - It alters the reading frame of the mRNA. - It prevents introns from being excised. - It changes an amino acid in the encoded protein. - It has no effect on the amino acid sequence of the encoded protein.

It introduces a premature stop codon into the mRNA.

Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)? - One addition and one deletion mutation. - One addition and two deletion mutations. - One deletion mutation. - One addition mutation.

One addition and one deletion mutation.

Each of the following options is a modification of the sentence THECATATETHERAT. Which of the following is analogous to a single substitution mutation? - THERATATETHECAT - THECATARETHERAT - CATATETHERAT - THECATATTHERAT - THETACATETHERAT

THECATARETHERAT

Each of the following options is a modification of the sentence THECATATETHERAT. Which of the following is analogous to a frameshift mutation? - THERATATETHECAT - THECATARETHERAT - CATATETHERAT - THECATATTHERAT - THETACATETHERAT

THECATATTHERAT

If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein? - Two. - None. - One. - Three.

Two

In the 1920s Muller discovered that X-rays caused mutation in Drosophila. In a related series of experiments, in the 1940s, Charlotte Auerbach discovered that chemicals - she used nitrogen mustards - have a similar effect. A new chemical food additive is developed by a cereal manufacturer. Why do we test for its ability to induce mutation? - We want to make sure that it does not emit radiation. - We worry about its ability to cause infection. - We want to prevent any increase in mutation frequency. - We want to be sure that it increases the rate of mutation sufficiently. - We worry that it might cause mutation in cereal grain plants.

We want to prevent any increase in mutation frequency.

What are point mutations?

When a base is replaced

What information can not be obtained from the sequence of a gene? - Amino acid sequence of the protein. - Effects of mutation on gene function. - Whether the gene is methylated. - Relationship between two species.

Whether the gene is methylated.

Which of the following DNA mutations is the most likely to be damaging to the protein it specifies? - a codon deletion - a codon substitution - a point mutation - a base-pair deletion - a substitution in the last base of a codon

a base-pair deletion

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 2 nucleotides - a deletion of a codon - a substitution of the first nucleotide of a GGG codon - a substitution of the third nucleotide in an ACC codon - an insertion of a codon

a deletion of a codon

Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene? - a base substitution at the beginning of the gene - a base substitution at the end of the gene - a frameshift deletion at the beginning of the gene - a frameshift deletion at the end of the gene

a frameshift deletion at the beginning of the gene

Which of the following modifications is least likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis? - neutralizing the negative charges within the DNA fragment - decreasing the length of the DNA fragment - altering the nucleotide sequence of the DNA fragment - increasing the length of the DNA fragment - methylating the cytosine bases within the DNA fragment

altering the nucleotide sequence of the DNA fragment

Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to - cut the plasmid with enzyme X and then insert the gene into the plasmid. - cut the plasmid twice with restriction enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X. - cut the plasmid with restriction enzyme X and insert the fragments cut with Y into the plasmid. - cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme. - insert the fragments cut with X directly into the plasmid without cutting the plasmid.

cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.

A frameshift mutation could result from - a base deletion only. - deletion of three consecutive bases. - either an insertion or a deletion of a base. - a base substitution only. - a base insertion only.

either an insertion or a deletion of a base.

Bacteria containing recombinant plasmids are often identified by which process? - using radioactive tracers to locate the plasmids - producing antibodies specific for each bacterium containing a recombinant plasmid - examining the cells with an electron microscope - exposing the bacteria to an antibiotic that kills cells lacking the resistant plasmid - removing the DNA of all cells in a culture to see which cells have plasmids

exposing the bacteria to an antibiotic that kills cells lacking the resistant plasmid

Restriction fragments of DNA are typically separated from one another by which process? - gel electrophoresis - electron microscopy - PCR - centrifugation - filtering

gel electrophoresis

Which of the following separates molecules by movement due to size and electrical charge? - gene cloning - DNA ligase - gel electrophoresis - restriction enzymes - reverse transcriptase

gel electrophoresis

In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel. - acidic ... basic - negative ... positive - basic ... acidic - long ... short - positive ... negative

negative ... positive

To produce a DNA fragment that contains the whole gene and has two sticky ends, where must the enzyme's restriction sites be located? - outside the gene on only one side, but not inside the gene - both inside the gene and outside the gene - inside the gene but not outside the gene - outside the gene on both sides, but not inside the gene

outside the gene on both sides, but not inside the gene

Which of the following statements about mutations is false?

repear

The unpaired nucleotides produced by the action of restriction enzymes are referred to as _____. - sticky ends - base sequences - single strands - restriction fragments - ligases

sticky ends