Bio 011: Midterm 2

What was the surprising finding from Griffith's work with mice and pneumonia-causing bacteria in 1928

a heritable substance from heat killed pathogenic cells (S cells) transformed nonpathogenic (R cells) making them pathogenic and killed mice.

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

What is meant by the description "antiparallel" regarding the strands that make up DNA?

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

Which of the following DNA sequences is complementary to 5' TAGAC 3'?

5' GTCTA 3'

The copying of the information in DNA is efficient because

Each strand of a DNA molecule carries complementary information and can be used as a template during replication

Which of the following unwinds the helix to provide a single-stranded template for DNA polymerase to be able to build a complementary strand?

Helicase

Why is the lagging strand synthesized in a discontinuous fashion (multiple RNA primers and Okazaki fragments)?

DNA synthesis only occurs in a 5' to 3' direction, which causes lagging strand synthesis to "restart" as new 3' regions of template DNA become available

Which of the following best describes the function of telomerase at the telomere?

It adds new DNA to the 3' end of the template strand of DNA

The process that produces mRNA from DNA is called

transcription

What process enables a single gene to encode two or more polypeptides that are different in their amino acid sequence?

alternative splicing

Which of the following types of RNA is NOT produced in bacteria? rRNA, tRNA,mRNA

pre-mRNA

mRNA processing in eukaryotes (including 5' cap addition and splicing), occurs

in the nucleus

What mRNA sequence will be transcribed from this DNA template:

3' - TTCGGACTA - 5'

5' - AAGCCUGAU - 3'

A difference between bacterial and eukaryotic translation is

modifications to the 5' end of mRNA are required for ribosome binding only in eukaryotes

How many tRNAs will be used to translate this mRNA sequence into a polypeptide? 5' - CAAGACUGACGACCC - 3'

2

Formation of a peptide bond during translation elongation is catalyzed by:

Ribozyme activity of the ribosomal RNA

What recognizes the codons UAA, UAG, UGA in the ribosome "A" site?

release factor protein

RNA interference is a mechanism for silencing gene expression at the

post-transcriptional but pre-translational level.

Which of the following is NOT a general function of an non-coding RNA (ncRNA)?

encoding a polypeptide

non-coding RNAs are

RNA molecules that do not encode polypeptides

How does cAMP-CAP binding its target DNA sequence (the CAP site) affect lac operon transcription?

It enhances RNA polymerase binding to the promoter and increases the rate of transcription

To produce multiple proteins from a polycistronic mRNA, each translated region must have:

a ribosome binding site, a start codon, a stop codon

A mutation in the E. coli lacI gene causes expression of a Lac Repressor that cannot bind to its DNA target (the Operator). What would happen at the lac operon in this mutant when there is No Lactose and High Glucose

low levels of lac operon transcription

If lacI were mutated so that the Lac Repressor ALWAYS binds to the operator DNA sequence (regardless of small effector molecule levels), this would cause:

The lac operon would always be transcribed at very low rates, the levels of lactose and glucose would not matter

E. coli exposed to high levels of lactose and glucose (lactose high + glucose high) will transcribe the lac operon at a low rate because:

Glucose causes cAMP levels to decrease and cAMP is the small molecule effector required by CAP to acivate lac operon transcription

A common feature of all eukaryotic "core promoters" is:

a "TATA" sequence recognized by TFIID

Cell type-specific regulation of gene transcription typically requires:

Combinations of regulatory elements (enhancers and silencers) in the promoter region

The collagen gene is transcribed in fibroblast cells but is never transcribed in neurons. This differential transcription could be regulated by:

A transcription activator that is only expressed in fibroblasts and binds to an enhancer sequence in the collagen promoter

Chromatin remodelers can:

change the spacing between nucleosomes, so that more DNA is accessible to transcription factors

Which of the following statements about chromatin is TRUE?

Histones are a major component of chromatin