Nucleic Acids

Which one of the following proportions is true for DNA bases?

• Adenine = Cytosine

• Cytosine = Thymine

• Thymine = Adenine

• It depends on the DNA strand

Answer explanation

Remember Chargaff's complimentary base pairing: A=T and C=G

In DNA, thymine always pairs with ...

• any nitrogenous base

• adenine

• guanine

• cytosine

Answer explanation

Remember Chargaff's complimentary base pairing: A=T and C=G

Which of the following BEST describes a DNA molecule?

• double helix

• β-pleated sheet

• made of amino acids

• is ladder-like

Answer explanation

DNA has two strands which are spiraled, so it can be described as a double helix.

What is the name of the DNA monomer shown?

• Nucleotide

• Amino acid

• Triglyceride

• Phospholipid

Answer explanation

A nucleotide comprises of:

sugar, phosphate, base

Why is DNA important?

• It is a complicated molecule

• It's in everything

• It contains the code for the traits of all living things

• It makes something living

Answer explanation

The sequence of nitrogenous bases code for proteins, and as we know, proteins do all the work in living things.

What are the three components of a nucleotide?

• sugar, hydrogen, nitrogenous base

• sugar, oxygen, nitrogenous base

• sugar, phosphate group, nitrogenous base

• sugar, phosphate group, protein

Answer explanation

The sugar and the phosphate are the 'backbone' or sides of the 'ladder', and the nitrogenous bases are the 'rungs'.

What is DNA's basic job?

• to code for proteins

• to code for sugars

• to code for lipids

• to code for nucleic acids

Answer explanation

The sequence of nitrogenous bases code for the sequence of amino acids that are the primary structure of PROTEINS!

Which nitrogenous base pairs with which?

• A with T

  C with G

• A with C

  T with G

• A with G

  T with C

• A with A

  T with T

  G with G

  C with C

Answer explanation

Remember, the straight A pairs with the straight T, and the curly C pairs with the curly G.

The two strands of the DNA double helix are held together by what type of bond?

• hydrogen bonds

• peptide bonds

• covalent bonds

• ionic bonds

Answer explanation

DNA bases are held together by hydrogen bonds so that the code can be easily accessed.

If 20% of the nitrogenous bases in a DNA molecule are GUANINE, what percentage of the nitrogenous bases will be ADENINE?

• 30%

• 20%

• 60%

• 40%

Answer explanation

A bit of math here.....

20% G means 20% C, equalling 40%

The remaining 60% must have 30% A and 30% T