HBiolSheet 1_2A
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1. Decide if each of the following statements about DNA replication is True or False. If the statement is False, rewrite the statement in your jotter, providing the correct word to replace the word underlined in the statement.
a. During DNA replication hydrogen bonds between bases break.
b. During the formation of a new DNA molecule, base pairing is followed by bonding between deoxyribose and bases.
c. As a result of DNA replication, the DNA content of a cell is halved.
2. The flowchart below describes steps in the process of DNA replication.
a) In your jotter, describe what happens at Step 2 and Step 4.
b) Other than the original DNA strand and free DNA nucleotides, give one substance needed for DNA replication.
c) State the importance of DNA replication to cells.
3. The diagram below shows the first two nucleotides in a DNA strand.
a) Which nucleotide, 1 or 2 is the 3’ end, and which is the 5’ end of this strand of DNA? Explain your answer.
b) To which end of the DNA molecule will new nucleotides be added when the strand of DNA above has new nucleotides added to it?
c) What type of bond is bond A?
d) A full DNA molecule consists of two DNA strands. Describe two ways in which the second strand of this DNA molecule will differ from the one drawn here.
4. The genome of a typical bacterium contains about 5 x 106 base pairs and can be replicated in 20 minutes. The human genome is larger (3 x 109 base pairs); yet the entire human genome can be replicated in 5 hours.
a) How many times larger is the human genome compared with the bacterial genome?
b) At what rate (in base pairs per minute) is the bacterial genome replicated?
c) How long would it take to replicate the human genome at this rate?
d) According to the text, at what rate (in base pairs per minute) is the human genome replicated?
e) How many times faster is the human genome replicated?
f) Explain how the replication of the human genome can occur so much faster.
5. The diagram below shows part of a DNA molecule during replication.
a) Identify parts X and Y.
b) Name bases 1 and 2.
c) With reference to a DNA molecule, what does the term, anti-parallel mean?
d) A DNA molecule contains 1500 guanine bases and 2000 adenine bases. How many deoxyribose sugar molecules does this DNA molecule contain?
