AP Biology : Central dogma

Study concepts, example questions & explanations for AP Biology

varsity tutors app store varsity tutors android store

Example Questions

← Previous 1 3 4 5 6 7 8

Example Question #1 : Central Dogma

What is the result of a silent mutation?

Possible Answers:

A shift in the reading frame that results in a nearly completely different protein

Inclusion of a different amino acid

Early termination of translation

There is no change to the peptide product

Correct answer:

There is no change to the peptide product

Explanation:

As the name suggests, silent mutations are point mutations that actually have no visible effect on the protein. This is due to the degeneracy of the genetic code. Several codons actually insert the same amino acid. It is possible to mutate a codon so that it actually inserts the same amino acid. For example, if the codon UCU were mutated to UCG, it will still recruit the amino acid serine.

The other answers describe other types of mutations. Missense mutations are point mutations that result in the swapping of one amino acid for another. Nonsense mutations cause early termination. Frameshift mutations shift the reading frame of the codon sequence, severely altering the protein composition.

Example Question #1 : Central Dogma

Which of the following describes abortive initiation?

Possible Answers:

The inability of the initiation complex to form

Short cycles of RNA synthesis

RNA polymerase cannot bind to the promoter sequence

Arrest of transcription due to error

Correct answer:

Short cycles of RNA synthesis

Explanation:

Abortive initiation is the process by which RNA polymerase starts short cycles of RNA synthesis. During abortive initiation, RNA polymerase releases short RNA strands before the initiation complex leaves the promoter sequence. Abortive initiation is a common process in both eukaryotes and prokaryotes.

Example Question #1 : Central Dogma

If a DNA sequence is mutated from AGCTAA to AGCCTAA, what kind of mutation has occurred?

Possible Answers:

Deletion

Point mutation

Insertion

Substitution

Correct answer:

Insertion

Explanation:

An insertion mutation is a mutation due to an additional nucleotide base pair being added to a DNA sequence. In this case, a cytosine nucleotide has been inserted.

Example Question #1 : Central Dogma

If a DNA sequence is mutated from AGCTAA to AGCAAA, what type of mutation has occurred?

Possible Answers:

Substitution

Frameshift

Deletion

Insertion

Correct answer:

Substitution

Explanation:

A substitution mutation occurs when a base pair is exchanged for a different base pair. In this case, a thymine nucleotide has been substituted for an adenine nucleotide.

Example Question #2 : Central Dogma

If a DNA sequence experiences an insertion mutation, what consequence may this have on the DNA sequence?

Possible Answers:

Cause a frameshift mutation

Cause a point mutation

Cause a deletion

Prevent RNA polymerase from binding

Correct answer:

Cause a frameshift mutation

Explanation:

An insertion mutation that occurs where an amount of nucleotides that is not a multiple of three is added to a DNA sequence will shift the reading frame.

Example Question #2 : Central Dogma

If a DNA sequence is mutated from TCCGGA to TCGGA, what type of mutation has occurred?

Possible Answers:

Substitution

Insertion

Deletion

Point

Correct answer:

Deletion

Explanation:

A deletion mutation occurs when a base pair is removed from the DNA sequence. In this case, a cytosine nucleotide has been deleted.

Example Question #1 : Understand Steps Of Transcription

Histones are most closely linked to which of the following processes?

Possible Answers:

Eukaryotic cell division

Crossing over of genetic information

Synthesis of ATP in the nucleolus

Chromosome formation

Correct answer:

Chromosome formation

Explanation:

Histones are the packaging proteins on which long DNA molecules are coiled before mitosis. In this respect they are involved in cell division, but they are most closely linked to chromosome condensation. During interphase DNA is mostly packaged as euchromatin. Euchromatin is loosely packed and is capable of being transcribed, making it essential for protein synthesis and cell growth during the G1 and G2 phases. During mitosis the DNA condenses into tightly-packed heterochromatin in the form of chromosomes, which allow for cell division. The difference in packaging between euchromatin and heterochromatin comes from histone proteins. During chromosome formation, DNA becomes tightly wound around the histones to create the chromosome structure.

Example Question #2282 : Ap Biology

Which of the following proteins is essential for transcription?

Possible Answers:

Trypsin

DNA polymerase

Primase

RNA polymerase

Correct answer:

RNA polymerase

Explanation:

RNA polymerase is the protein that synthesizes an RNA complement to a gene. RNA polymerase binds the template DNA strand and recruits ribonucleotides to build a strand of heteronuclear RNA (htRNA). The htRNA then undergoes modification to become mature mRNA before exiting the nucleus into the cytosol for translation.

DNA polymerase and primase are essential for the replication of DNA. DNA polymerase recruits nucleotides to synthesize the daughter strand of DNA, and primase creates small RNA primers to recruit DNA polymerase to the replication fork. Trypsin is a protease that is not involved in transcription; it helps to digest proteins in the small intestine.

Example Question #2283 : Ap Biology

A researcher discovers a highly bizarre eukaryotic species whose mature mRNA do not contain poly-A tails. Which of the following proteins might this species also lack?

Possible Answers:

eIF4E

PABP

eEF1

eIF2

Correct answer:

PABP

Explanation:

PABP (poly-A-binding protein) binds to the poly-A tail in the 3' UTR of eukaryotic mRNA. It is likely that this species would not have a PABP homolog because it does not have a poly-A tail.

eIF4E binds to the 5' cap. eIF2 is responsible for bringing the first tRNA to the initiation complex. eEF1 is an elongation factor that helps bring tRNAs to the ribosome. 

Example Question #2284 : Ap Biology

What is the central dogma of molecular biology?

Possible Answers:

DNA, RNA, Protein

RNA, DNA, Protein

RNA, Protein, DNA

DNA, Protein, RNA

Protien, DNA, RNA

Correct answer:

DNA, RNA, Protein

Explanation:

Proteins are coded for by RNA, which is coded for by DNA. The central dogma of molecular biology is the general sequence for the flow of information in coding for a protein. An mRNA strand is created using the DNA strand as a template. This new strand of mRNA then leaves the nucleus and is used as a template for 3-pronged tRNA molecules carrying amino acids to create a chain, which will eventually create a protein.

The central dogma of molecular biology is the general sequence of DNA to RNA to protein.

← Previous 1 3 4 5 6 7 8
Learning Tools by Varsity Tutors