DNA Structure and Replication

What part (s) of the nucleotides make up the rungs or steps of the DNA "ladder"?

• sugar 
• nitrogenous bases
• phosphate
• sugar and nitrogenous bases

What parts of the nucleotide make up the sides or backbone of the DNA "ladder"?

• Phosphate and sugar

• Sugar

• Phosphate

• Nitrogenous base

Do the 2 strands of DNA run parallel (the ends of the strands match) or antiparallel (the ends of the strands are opposites)?

• Parallel
• Antiparallel

When one nucleotide contains adenine, what type of base is the adenine attached to on the opposite nucleotide strand?

• Adenine
• Guanine
• Cytosine
• Thymine

When one nucleotide contains cytosine, what type of base is the cytosine attached to on the opposite nucleotide strand?

• Guanine

• Adenine

• Thymine

• Cytosine

The strands of DNA are held together by hydrogen bonds between the bases.  How many bonds connect adenine and thymine?

• 1
• 2
• 3
• 4

The strands of DNA are held together by hydrogen bonds between the bases.  How many bonds connect cytosine and guanine?  

• 1
• 2
• 3
• 4

What are the complementary bases on the strand: ATCCAG ?

• ATCCAG
• CGTTCT
• TAGGTC
• TAGGAG

What is the role of DNA helicase?

• To lay down nucleotides

• To keep the DNA strands open

• To break open or unwind and separate the DNA strands

T/ F : Replication is known as semi-conservative because half the original molecule is kept and the other half is new.

• True
• False