Yale Bowles' DNA STRUCTURE (Part II)

DNA STRUCTURE A

100

Genetic information is stored in the ________ of a DNA molecule.

nucleotides

200

The two strands of DNA have to be temporarily separated from each other; this job is done by a special enzyme, called?

 helicase

300

What are the building blocks on DNA?

1. Deoxyribonucleotides
2. Fatty acids
3. Ribonucleotides
4. Amino acids

Deoxyribonucleotides

400

Each strand of a parent DNA molecule serves as the template for __________ in a daughter molecule, the parental and daughter strand _______.

a complementary strand, bond

500

DNA replication is catalyzed by a type of enzyme called

 DNA polymerase

DNA STRUCTURE B

100

In _______________, the parental DNA remains together, and the newly formed daughter strands are together.

conservative replication

200

The leading strand grows continuously and the lagging strand is put together with short pieces called ________

Okazaki fragments.

300

The ____________ method suggests that each of the two parental DNA strands acts as template for new DNA to be synthesized.

semi-conservative

400

The enzyme helicase ________.

separates the 2 DNA strands of the double helix

500

During DNA replication many enzymes work together to help produce 2 DNA strands from the original strand of DNA. If DNA polymerase were to stop working what would be the result?

Responses

• The Okazaki fragments of the lagging strand would stay fragments because they would not be joined together.
• The original DNA strand would never have been unzipped and therefore DNA replication would not be able to take place.
• No new nitrogenous bases would be added to the DNA strands.
• There would be no RNA primer formed to attach to the template strand.

No new nitrogenous bases would be added to the DNA strands.

DNA STRUCTURE C

100

The _________suggests that each of the two parental DNA strands act as a template for new DNA to be synthesized

semi-conservative method

200

 A_________ is required to initiate synthesis, which is then extended by DNA polymerase as it adds nucleotides one by one to the growing chain.

 primer

300

_________, the DNA pol reads the newly added base before adding the next one, so a correction can be made.

proofreading

400

Nucleotide excision repair occurs when ________.

enzymes cut a DNA strand on each side of an incorrect base

500

We now know that DNA replication is semi-conservative. What does this mean?

Responses

• This means that during DNA replication the parental strand unzips and both halves of the strand are used as a template for replication. The end result is two strands of DNA which contain half of the parental DNA and half of new DNA.
• It means that when DNA is replicated one strand of DNA consists solely of parental DNA and the other strand is completely new
• It means that after DNA replication only half of the original DNA strand is replicated and the other half is not.
• It means that segments of the parental DNA strand are conserved, and new segments are intertwined between them.

during DNA replication the parental strand are split i (or unzipped) in two and are used as a template for replication.

DNA STRUCTURE D

100

 ___________is catalyzed by a type of enzyme called DNA polymerase

DNA replication

200

____________needs an “anchor” to start adding nucleotides: a short sequence of DNA or RNA that is complementary to the template strand will work to provide a free 3′ end. This sequence is called a primer.

DNA polymerase

300

 In E. coli, after replication, the nitrogenous base adenine acquires a ___________ group.

methyl

400

In which direction does DNA replication take place?

Responses

• 3′–5′3′–5′ 
• both 5′–3′ and 3′–5′ at once
• 5′–3′5′–3′ 

5′–3′

500

Mismatch repair occurs when ________

a single nucleotide is replaced after DNA replication is complete

DNA STRUCTURE E

100

True/False: DNA replication requires an enzyme.

True. Most biological reactions rely on the enzyme to speed up the reaction.

200

 another type of repair mechanism, ____________ , enzymes replace incorrect bases by making a cut on both the 3′ and 5′ ends of the incorrect base.

nucleotide excision repair,

300

Newspapers, magazines, and publishing firms hire editors to proofread for mistakes. What enzyme is responsible for proofreading our DNA and what happens if a mistake is made?

DNA polymerase is used to proofread our DNA and if it makes a mistake, then cancer can occur.

400

Meselson and Stahl used "heavy" ________ in their replication studies because ________.

nitrogen, it is present in nucleotides

500

Genetic information is stored in the sequence of nucleotides of a ___________.

DNA molecule