DNA Replication Lecture and Questions

DNA REPLICATION

DNA REPLICATION

→DNA makes two exact copies of
itself

→ The copies are then passed
along to new cells

WHY does DNA need
to replicate?

This ensures that each daughter cell gets a copy of the genome, and therefore, successful inheritance of genetic traits.

Multiple Choice

Why does DNA replicate?

• ensures that there is not a copy of genetics, so the inheritance of genes do not occur.

• ensures that each daughter cell gets a copy of the genome and successful inheritance of genetic traits

• Does not copy genes

WHEN in the cell’s life cycle
(think
back to mitosis) does the DNA
replicate?

Multiple Choice

When in the cell's life cycle does DNA Replicate?

• S Phase

• M phase

• Prophase

REPLICATION PROCESS

1. UNZIP!
• DNA Helicases (enzymes)- unwind the DNA

molecule and break the weak hydrogen bonds

– The two sides of DNA unwind and

separate.

• each side will serve as a template for a

new/ opposing strand of DNA

• Replication fork (2) – points at which the 2 sides

(strands) of DNA separate

Multiple Choice

What is the first step in DNA Replication?

• Proofread

• Duplicate

• Unzip

Multiple Choice

Within the Replication process, what UNWINDS the DNA molecule and break the hydrogen bonds?

• Replication Fork

• DNA Helicase

• Proofread

REPLICATION PROCESS

2. DUPLICATE!
DNA polymerase (another enzyme)binds (adds)

new nucleotides to old (original/exposed)
nucleotide sequence.

• Move in different/ opposite directions up and

down original strands of DNA

Multiple Choice

What is the second phase in the replication process?

• Unzip

• Replication Fork

• Duplicate

REPLICATION PROCESS

3. Proofread
DNA polymerases checks the two copies

of DNA for mistakes (mutations)

Multiple Choice

What is the 3rd step of the Replication Process?

• Proofread

• Duplicate

• Unzip

Multiple Choice

True or False: Proofread checks copies of DNA for mistakes.

• True

• False

MUTATIONS

● ANY changes in a nucleotide sequence

(order or pairing or nitrogen bases)

● Are NOT always harmful- mutations can

create genetic diversity & drive evolution!

● Causes:

○ Viruses
○ Chemicals
○ UV radiation
○ Extreme temperatures

Multiple Choice

An example of a cause of mutations is/are________________

• stomach Ulcers

• The common cold

• viruses

Multiple Choice

True or False: Mutations are ALWAYS Harmful and create genetic separation.

• True

• False

Multiple Choice

What are mutations?

• When the nucleotide sequence remains the same

• Changes in a nucleotide sequence

• When the nucleotides split

Final result

• Two identical copies of DNA
• One side is new, one side is old

Multiple Choice

The final result of DNA Replication produces: _____________

• 3 identical copies

• 4 identical copies

• no copies are made

• 2 identical copies