Activity #2 | DNA and Chromosome Structure

Picture 2. This image is of two replication forks for a human X chromosome. In this image, red letters are RNA nucleotides and black letters are DNA nucleotides. The shapes with boxed numbers pointing to them represent enzymes in the DNA replication process, though their shapes are not true to shapes seen on molecular levels.

Quiz

Question

Based on Picture 2, how many places along the human X chromosome can replication start?

1 place

2 places

3 places

4 places

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Question

Looking at Picture 2, enzyme 2 is primase. When enzyme 3 starts working at the site that enzyme 2 is at, will enzyme 3 add to the G or to the U?

It adds to the G

It adds to the U

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Question

Enzyme 3 is building the leading strand for which replication fork in Picture 2?

The fork on the left

The fork on the right

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Question

Where would enzyme 2 go to work next?

It’ll stay where it’s at and build nucleotides until it gets to the other red nucleotides on the bottom strand

There are no more spots for it to work in

Top strand close to the left fork

Looks Good!

Picture 3: This image is of two replication forks for a human X chromosome. In this image, red letters are RNA nucleotides and black letters are DNA nucleotides. The shapes with boxed numbers pointing to them represent enzymes in the DNA replication process, though their shapes are not true to shapes seen on molecular levels.

Quiz

Question

Where will an Okazaki fragment get made in picture 3?

On the top left strand & bottom right strand

On the top right strand & bottom left strand

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Question

Are the DNA polymerase III’s in picture 3 building leading or lagging strands?

Leading

Lagging

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Question

How many places shown in this image can another DNA polymerase III work?

0

1

2

3

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Question

Where would enzyme 2 go to work next?

It’ll stay where it’s at and build nucleotides until it gets to the other red nucleotides on the bottom strand

There are no more spots for it to work in

Top strand close to the left fork

Looks Good!

Picture 4: This image is of two replication forks for a human X chromosome. In this image, red letters are RNA nucleotides and black letters are DNA nucleotides. The shapes with boxed numbers pointing to them represent enzymes in the DNA replication process, though their shapes are not true to shapes seen on molecular levels.

Quiz

Question

The enzymes labelled #1 will…

Build a strand of DNA nucleotides based on the template strand

Place RNA primers on the template strand

Remove the RNA nucleotides and replace it with DNA

Unzip the DNA

Seal the sugar-phosphate backbone

Looks Good!

Question

The enzymes labelled #3 will…

Build a strand of DNA nucleotides based on the template strand

Place RNA primers on the template strand

Remove the RNA nucleotides and replace it with DNA

Unzip the DNA

Seal the sugar-phosphate backbone

Looks Good!

Question

The enzymes labelled #4 will…

Build a strand of DNA nucleotides based on the template strand

Place RNA primers on the template strand

Remove the RNA nucleotides and replace it with DNA

Unzip the DNA

Seal the sugar-phosphate backbone

Looks Good!

Question

The enzymes labelled #5 will…

Build a strand of DNA nucleotides based on the template strand

Place RNA primers on the template strand

Remove the RNA nucleotides and replace it with DNA

Unzip the DNA

Seal the sugar-phosphate backbone

Looks Good!

Question

Where in your cells does picture 4 take place? Where in your body are these cells?

Nucleus; only the ovaries/testes

Nucleus and cytoplasm; only the ovaries/testes

Nucleus; everywhere

Trick question – this is actually in a test tube

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Question

What is made at the completion of the process shown in picture 4?

One double helix DNA strand

Two identical double helix DNA strands

Two new genetic combinations that are independently assorting

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