General Science: Chapter 21

Steps of replications

1. An enzyme, DNA gyrase, separates each side of the double helix. 2. Another enzyme, helicase, unwinds the double helix. 3. Several small proteins temporarily bind to each side and keep the sides separated. 4. An enzyme complex, DNA polymerase, walks down the DNA strands and adds new nucleotides to each strand. The nucleotides pair up: adenine (A) with thymine (T) and guanine (G) with cytosine (C). 5. A subunit of the DNA polymerase proofreads the new DNA. 6. An enzyme, DNA ligase, seals up the fragments into long continuous strands. 7. The new copies automatically wind up again.

A mutation in DNA can affect the amino acid sequence because it affects the code found in _____. A) mRNA B) tRNA C) the nucleus D) rRNA

A

Based on the original sequence, ACTTGAC, which of the following answer choices includes a transition mutation? A) ACTTGGC B) ACTTTAC C) ACTTCAC D) ACTTGTC

A

How does the structure of DNA make replication easy? A) The double helix unzips and each side serves as a template for the other. B) The helix is twisted apart and put back together. C) The single helix comes apart to allow new molecules in. D) The double helix is snipped open and new molecules are tucked in.

A

What are the steps for replication? A) Separation, unwinding, adding new nucleotides, sealing of new strands, winding up into new double helices B) Separation, winding, deleting of nucleotides, unsealing of old strands, unwinding C) Adding new nucleotides to the end of the existing double helix D) Adding old nucleotides in the middle of new single helices

A

What does DNA stand for? A) Deoxyribonucleic acid B) None of the answers are correct C) Deoxyribonucleic adenine D) Deoxyribonucleic arterine

A

What kind of mutation causes sickle-cell anemia? A) missense B) insertion C) silent D) nonsense

A

Which of the following modi cations of this DNA sequence, ACTGAC, would be considered a frameshift mutation? A) ACCTGAC B) AGTGAC C) ACTGAT D) ACAGAC

A

_____ mutations result in a longer DNA strand. A) Insertion B) Transversion C) Transition D) Deletion

A

Missense mutation

A point mutation that changes a codon to indicate a different amino acid

Mutagens

An environmental agent that causes a muttion

An example of a transversion mutation is _____. A) A thymine substituted a cytosine. B) A guanine substituted for a thymine. C) A cytosine substituted for a thymine. D) An adenine substituted for a guanine.

B

Do all cells replicate at the same rate? A) Yes, cells have to replicate on the same schedule or the organism will change. B) No, some cells replicate constantly; some do for a while, then stop; others stop, but are able to start up again. C) Yes, cells are cells. D) No, some cells live longer than others.

B

How do mutagens cause mutations? A) By increasing vulnerability to predators B) By increasing the likelihood of a replication error C) By decreasing the immune response D) By decreasing the likelihood of finding food

B

How would a shift in the reading frame likely alter the resulting protein? A) Any alteration to the reading frame would prevent the protein from being formed. B) The protein would be greatly altered because multiple amino acids would be miscoded. C) The protein would be only slightly altered because a single D) amino acid would be miscoded. E) The protein would be not be altered because the reading frame does not affect the resulting protein.

B

The best term to describe the incorporation of a random mistake into the DNA sequence at a specific point is _____. A) A chromosomal mutation B) A point mutation C) A base insertion D) A base deletion

B

Which of the following is the process of decoding RNA as instructions for building an amino acid chain? A) the central dogma B) translation C) transcription D) the gene E) protein synthesis

B

Which of the following statements is true? A) Oswald Avery did not have evidence that DNA is the molecule of heredity. B) With three billion base pairs in humans, each person has a unique DNA sequence. C) Only Watson and Crick were awarded the Nobel Prize in 1962. D) DNA is organized in a straight ladder design.

B

Which type of mutation results in an incomplete polypeptide because of an early stop signal? A) silent B) nonsense C) missense D) insertion

B

Transitions

Base substitution that swap purine for another purine or a pyrimidine for another pyridine

A type of point mutation that alters the length of the DNA strand is _____. A) An transversion. B) A transition. C) A deletion. D) A base substitution

C

DNA consists of four different nitrogenous bases, which are: A) Guanine, adenine, thymine and ribonucleic B) Guanine, adenine, uracil and cytosine C) Guanine, adenine, thymine and cytosine D)Guanine, deoxynucleic, thymine and cytosine

C

How does a frameshift mutation in the gene coding for the enzyme, hexosaminidase A, result in Tay-Sachs disease? A) The mutation does not alter production of the enzyme. B) The mutation results in over production of the enzyme. C) The mutation results in incorrect synthesis of the enzyme. D) The mutation prevents synthesis of the enzyme.

C

Mutagens are typically found _____. A) in the air B) in the ground C) in an organism's environment D) in an organism's food

C

The deletion of a base in the DNA strand will _____. A) Not alter the mRNA but will result in the removal of the subsequent amino acid. B) Result in the deletion of a base in the mRNA strand and the removal of the subsequent amino acid. C) Result in the deletion of a base in the mRNA strand and a modification to the subsequent amino acid. D) Not alter the mRNA strand but will result in a modification to the subsequent amino acid.

C

The eleventh amino acid of protein X should be serine, however due to a mutation it now has the amino acid alanine in that position. Which type of mutation could have caused this change? A) Silent B) Insertion C) Missense D) Nonsense

C

Which of the following is the process of transferring genetic information from DNA to RNA? A) translation B) the central dogma C) transcription D) the gene E) protein synthesis

C

Which type of mutation does NOT change the overall function of the protein? A) nonsense B) missense C) silent D) insertion

C

Why do people try to protect their skin from ultraviolet radiation? A) UV radiation always causes mutations. B) UV radiation causes tanning. C) UV radiation is a mutagen. D) UV radiation comes from the environment.

C

Why is DNA replication necessary? A) To alter the course of evolution B) To express specific characteristics of all organisms C) To pass on genetic information to new daughter cells D) To delete genetic information

C

What is the result of a frameshift mutation

Can change the whole sequence if an insertion or deletion is not a factor of 3 or can cause a nonsense mutation if it yields three stop codons

What is the result of a silent mutation

Can result in no change in the sequence or change

What is the result of missense mutation

Change the polypeptide and overall function of the protein

The Central Dogma is a framework used to represent which of the following? A) The flow of RNA to DNA B) The flow of protein to RNA C) The flow of protein to RNA to DNA D) The flow of genetic information from DNA to RNA to protein

D

What happens when mistakes occur in replication? A) All of the mistakes alter the genetic information carried by DNA. B) Proofreading misses most of the mistakes. C) Proofreading doesn't have anything to do with replicating DNA. D) Proofreading corrects most of the mistakes by removing and replacing the mismatched nucleotides.

D

What is the term for a distinct section of DNA that codes for one protein? A) transcription B) RNA C) translation D) gene E) chromosome

D

When can a genetic mutation get passed down through successive generations? A) When it makes the organism healthier B) When it makes the organism faster C) When it makes the organism stronger D) When it doesn't cause significant harm to the organism's ability to survive and reproduce

D

Which enzyme checks DNA for errors? A) DNA helicase B) RNA primase C) RNA polymerase D) DNA polymerase

D

Which of the following scientists are credited with discovering the structure of DNA? A) Oswald Avery and James Watson B) Frederick Griffth and Oswald Avery C) Maurice Wilkins and Oswald Avery D) James Watson and Francis Crick E) Frederick Griffth and Francis Crick

D

Which type of mutations can result in a frameshift? A) Nonsense and insertions B) Nonsense and missense C) Missense and deletions D) Insertions and deletions

D

The following concepts led to the hypothesis that DNA has a double helix structure: I. The ratio of A:T is 1:1. II. The ratio of G:C is 2:1 III. DNA strands are antiparallel A) II and III B) I, II and III C) I and II D) II E) I and III

E

Which of the following terms encompasses all the cellular activities involved in building protein molecules? A) transcription B) protein exocytosis C) translation D) protein hydrolysis E) protein synthesis

E

Bases for DNA

Guanine, adenine, thymine, and cytostine

What happens when DNA is not replicated correctly

It will get corrected, stop dividing, or self destructs

Who developed the double helix model

James Watson and Francis Crick

Frameshift mutation

Mutation caused by an insertion or deletion, which causes a shift in the translational reading frame

What is a silent mutation

Point mutation that has no overall effect on a protein's function

Nonsense mutation

Point mutation that turns one codon into a stop codon

What is the result of nonsense mutation

Results in early termination of a polypeptide (never completed)

Transverison

Swtitch purine with a pyrimidine or vice versa

Heart, muscles, and the brain replicate at what rate

Through rounds

How are base substitutions further categorized

Transitions and transverisons

Which base substitution happens more often and why

Transversions because there are two ways for it to happen. Transition only have one way.

Reading frame

Way of dividing the mRNA into codons and focusing on one codon at a time

Skin replicates at what rate

When they get a cue (injury)

When do mutations commonly happen

While a new DNA molecule is being formed through replication not the original strand

Name three mutagens

X-rays, extreme heat, and chemicals

Replication fork

Y shaped junction where double stranded DNA is separated into two single strands

How is each strand organized

antiparallel

Fingernails and bone marrow replicate at what rate

constantly

Point mutation

smaller and typically affects one or two bases