Biochem EX1 - Nucleotides Flashcards Preview

Fall 2015 > Biochem EX1 - Nucleotides > Flashcards

Flashcards in Biochem EX1 - Nucleotides Deck (14)

Which major nitrogenous bases are purines? Which are pyrimidines?

Purines = Adenine, Guanine   

Pyrimidines = Cytosine, Thymine


Can you tell the chemical structure of a purine from a pyrimidine (which has a “double-ringed” structure)?

Single ring = Pyrimidine   

Double ring = Purine


What four bases are normally found in deoxyribonucleic acids (DNA)? What four bases are normally found in ribonucleic acids (RNA)?

DNA = Adenine, Guanine, Thymine, Cystine            

RNA = Adenine, Uracil, Cytosine, Guanine


What are the three components of a nucleotide?

Sugar, Nitrogenous Base, Phosphate group


Can you tell the chemical structure of a nucleotide from a nucleoside (which nucleotide component is not found in nucleoside)?

The nucleoside lacks the phosphate group.


Can you tell the chemical structure of a ribonucleotide from a deoxyribonucleotide (which has an oxygen that is not present in the other)?

The ribonucleotide has an oxygen at the 2' carbon that the deoxyribonucleotide is missing.


What is the modification of a normal base found in DNA that affects gene expression? What is a nucleotide that is not found in DNA or RNA that is important in energy metabolism? Are there other bases and nucleotides we haven’t discussed in class yet (Hint-the answer is yes)?

Phosphorylation of a DNA base affects gene expression. ATP is a nucleotide not found in DNA or RNA that is important in energy metabolism.


What is the biochemical mechanism that enables coffee-drinking students to remain wakeful for longer periods of cramming?

Adenosine receptor suppression


What biological role do adenosine triphosphate (ATP) and guanosine triphosphate (GTP) have after being cyclized at their phosphates to form cAMP or cGMP?

They both serve as "second messengers" in the cell to allow signaling from receptors on the cell membranes to the inside of the cell.


What is the difference between a nucleotide and a nucleic acid?

Nucleotides are the subunit that is polymerized (connected into a long chain) to make nucleic acids (DNA and RNA).


Why is it said that the two strands of DNA run “antiparallel”?

Because the 5' end of one strand faces the 3' end of the other.


How many hydrogen bonds are there between an A-T pair, and how many between a G-C pair.

A-T has 2 hydrogen bonds            

G-C has 3 hydrogen bonds


What happens to DNA when it is exposed to temperatures of 94oC during a polymerase chain reaction (PCR) procedure?

The helix is broken and the strands separate.


A nucleoside often makes a more useful drug than a nucleotide because a nucleoside

A. has a phosphate and a nucleotide does not.

B. does not have a phosphate, while a nucleotide does.

C. is roughly half the size of a nucleotide.

D. is roughly double the size of a nucleotide.

E. can incorporate into RNA and DNA and a nucleotide cannot.

C) is roughly half the size of a nucleotide.