Worksheet 1 DNA REPLICATION Flashcards

1
Q

When should DNA be replicated?

A

Any time the cell needs to divide.

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2
Q

What life events would include DNA replication?

A

Growth, wound healing, regeneration, gamete production

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3
Q

Which enzyme acts first in DNA replication?
A. Helicase
B. Primase
C. Polymerase
D. Ligase

A

A. Helicase

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4
Q

Which enzyme(s) add(s) new DNA nucleotides to an existing strand? (Select all that apply.)
A. Primase
B. Ligase
C. Polymerase
D. Helicase

A

C. Polymerase

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5
Q

What is the difference between the leading strand and the lagging strand?

A

The leading strand goes in the 3’ to 5’ orientation, so it can be copied in a linear line. The lagging strand is in the 5’ to 3’ direction, so it must be copied in sections (in the opposite orientation) and those sections ‘glued’ together. Remember that DNA is always synthesized in the 5’ to 3’ direction.

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6
Q

TRUE or FALSE: Replication of the leading and lagging strands requires different enzymes.

A

FALSE

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7
Q

Why are there no Okazaki fragments on the leading strand?

A

Okazaki fragments are formed on the lagging strand so DNA can be synthesized in the essential 5’ to 3’ manner on the lagging strand.

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8
Q

Why is it important to replicate DNA without errors?

A

Because the sequence of DNA is what makes it do what it does.

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9
Q

What might happen if there were errors in DNA replication.

A

A mutation means a sequence change: in a somatic cell, this could lead to cancer;

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10
Q

What happens to the original template DNA after a round of replication?

A

It is paired with a newly synthesized DNA strand

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11
Q

Instead of Thymine, RNA has

A

Uracil

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12
Q
A
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13
Q

Draw a single nucleotide, labeling the phosphate, in the box to the right:

A

-

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14
Q

Draw and label a double-stranded segment of DNA with four nucleotides (arranged in two base pairs)

A

-

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15
Q

Draw and label a nucleosome

A
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16
Q

What are the functions of a nucleosome?

A

Nucleosomes allow the packing/supercoiling of DNA into chromosomes for easy separation in mitosis/meiosis. When DNA is wrapped around nucleosomes, it cannot be transcribed/translated so this allows genes to be turned “off”

17
Q

Describe what is meant by “Highly-repetitive DNA sequences” and list several functions of these sequences.

A

Nucleotide sequences in DNA that do not code for the production of proteins are also called introns. Repeating base letter patterns are 5-300 letters long (ex. AGAGAG) and build up mutations quickly without affecting organism (since they don’t code for traits) which makes them helpful for DNA fingerprinting. They also makeup telomeres, produce tRNA and rRNA and help promote or silence gene expression.