CHE 430 HW FCs

Why is there a start codon on mRNA?

Group of answer choices

It establishes the reading frame

So that the first amino acid is always Met

To distinguish it from tRNA or rRNA

To distinguish between 5’ and 3’ ends of the mRNA

It establishes the reading frame

The genetic code is

Group of answer choices

The rules for base-pair formation

The assignment of amino acids to RNA codons

What DNA polymerase uses to replicate DNA

The sequences in DNA

The assignment of amino acids to RNA codons

What is the purpose of RNA polymerase in the replication fork of DNA?

Group of answer choices

To begin making proteins

To prevent errors in replication

To make RNA to be translated

To make a primer for the use of DNA polymerase

To make a primer for the use of DNA polymerase

What is the main point of PCR?

Group of answer choices

To determine who your ancestors were

To amplify miniscule (trace) amounts of DNA

To convince you to give large sums of money to genetic consultants

To determine which drugs work best for an individual’s condition

To amplify miniscule (trace) amounts of DNA

What is the primary role for tRNA?

Group of answer choices

It serves as the primer in DNA replication

To transmit genetic information for a protein’s primary structure

To deliver an amino acid to a ribosome during translation

To form the structural basis of the ribosome

To deliver an amino acid to a ribosome during translation

DNA uses the principle of base complementarity in its structure.  Which is the correct set of bases?

Group of answer choices

AU/GC

AC/GT

GC/AT

AT/GC

AT/GC

Restriction enzymes

Group of answer choices

Are helpful in determining the genetic code

Bind to specific DNA sequences to direct cutting of DNA at or near that site

Are RNA-specific enzymes that cut RNA at specific sites

Restrict the ability of DNA to replicate or be transcribed

Bind to specific DNA sequences to direct cutting of DNA at or near that site

A certain human gene was shown to have only 80% of its DNA sequence identical to that of an ape, but its corresponding protein sequence has 95% identity.  How this is possible?

Group of answer choices

None of these

It’s due to redundance (degeneracy) in the genetic code

Must be due to a mistake in sequencing

Because RNA is not similar enough to DNA

It’s due to redundance (degeneracy) in the genetic code

In our cells, the DNA within a given gene mostly has regions of non-coding potential interspersed among regions that provide information to make a protein.  The initial RNA transcripts in the nucleus therefore have many more bases than needed – these extra regions (introns) are removed through the process of

Group of answer choices

Splicing

Capping

Mutagenesis

Translation

Splicing

DNA sequencing is a very rapid process dependent (in most popular approaches) on the inability of DNA polymerase to recognize

Group of answer choices

Methylated bases in the template strand

A given restriction site

A U instead of an A on the template strand

The 3’ -H atom replacing an -OH in dideoxynucleotides

The 3’ -H atom replacing an -OH in dideoxynucleotides

Which of these agents are likely to introduce mutations into DNA?

Group of answer choices

Polycyclic aromatic hydrocarbons

Oxidizing agents

Ionizing radioactivity

High energy electromagnetic radiation

All of these

All of these

The process of translation uses up an enormous amount of energy.  One place this is clear is in

Group of answer choices

Trial and error of identifying the correct tRNA, through the hydrolysis of GTP

The hydrolysis of ATP in making all the different types of RNA

ATP hydrolysis in moving the huge ribosome from codon to codon

ATP hydrolysis during formation of the mRNA used in translation

Trial and error of identifying the correct tRNA, through the hydrolysis of GTP

Which of the following possible covalent modifications of proteins is used to regulate aspects of their function?

Group of answer choices (could be more than one)

Protease digestion

Phosphorylation

Binding of an effector molecule

Acetylation

Protease digestion

Phosphorylation

Acetylation

What is the point of having a number of enzymes activating each other, such as in the blood clotting cascade and other cascades?

Group of answer choices

This slows the response, to make it more manageable

This improves the response in both time and effect

This uses the least amount of energy

This produces a larger number of outcomes

This improves the response in both time and effect

In many examples of changing enzymes to modify their activity, the effect is readily reversible.  What is by far the main reason this is useful for systems that the enzyme finds itself in?

Group of answer choices

To undo mistakes they may have made

For rapid response response to meet changing needs of the organism

To maintain equilibrium

Reversible processes consume the least amount of energy

For rapid response response to meet changing needs of the organism

What sort of modification would be the least likely (by far) to be reversible?

Group of answer choices

Proteolytic cleavage

Carboxylation

Phosphorylation

Effector binding

Proteolytic cleavage

Many proteases (and some other enzymes) contain an active site with specific amino acids to do the actual hydrolyses they carry out. A likely set of such amino acids would be:

Group of answer choices

Tyr-Phe-Trp

Ser-His-Asp

Asn-Lys-Ala

Leu-Trp-Cys

Ser-His-Asp

Lipids contain esters.  Many lipases are digestive enzymes which hydrolyze ester bonds in dietary lipids.  The products of these enzymes are long-chain carboxylic acids (fatty acids) and an alcohol, usually glycerol. One such lipase is known to have a critical histidine in its active site.  Propose a likelu role for this histidine based on models you have looked at in this class.

Group of answer choices

The His is an acid acting directly on the carbonyl group in the lipid.

The His is positively charged, so is a great nucleophile.

The His acts as a base to convert an alcohol group into a -O^- nucleophile.

The His binds to a metal ion to guide it to attack the lipid directly.

The His acts as a base to convert an alcohol group into a -O^- nucleophile.