Higher Biology - Unit 1.2

​Unit 1.2

DNA Replication​

​​ The process

• DNA replication is the process in which DNA molecules can make identical copies of themselves

• A copy is needed for each daughter cell produced during cell division or mitosis

​Step one

The DNA is un​wound a and unzipped. The weak hydrogen bonds are broken by the en​zyme helicase

​Step two

​The primers bind to the 3' end of the leading strand, DNA polymerase will add the complementary nucleotides

​Step three

​Fragments of the DNA are joined together by the emzyme ligase. The DNA strand twists to form a double-helix​

​A 3D animation for visual understanding

https://youtu.be/2_-jSoSaaTA

Fill in the Blanks

Which enzyme breaks the weak hydrogen bonds during DNA replication

Fill in the Blanks

The DNA is unzipped and unwound. The .... ........ bonds are broken by the enzyme helicase

Fill in the Blanks

Primers bind to the template strands. The ... will add the complementary nucleotides

Fill in the Blanks

The DNA strands are joined together by ... and the 2 new strands twist to form a double helix

Fill in the Blanks

Name the complementary strand of nucleotides which attaches itself to the template strand

​P C R

​Polymerase chain reation

PCR is a ​ technique used by scientists to make millions of copies of the same DNA quickly and cheaply. The replicated DNA can then be taken and used for analysis and investigation

​P C R

The Process​

1. DNA is heated up between 92 and 98​°C (denatured)

2. Cooled between 50 and 65

3. Complementary Primers are added

4. ​Heated between 70 and 80°C and Polymerase is added

​P C R

Requirements​

• The original strand of DNA which needs amplified

• Complementary primers

• Thermal cycler

• Heat tolerant polymerase

• Supply of nucleotides

​P C R

Uses​

• Helps solve crimes

• Genetic tests

• Settle paternity suits

Fill in the Blanks

What property is the DNA polymerase required to have when used for PCR?

Multiple Choice

Which of the following is not a use of PCR?

• To identify criminals

• For genetic testing

• To exploit and replicate desirable traits in foods we consume

• To settle paternity suits

Multiple Choice

During PCR, which temperature range breaks the hydrogen bonds?

• 92 - 98°C

• 50 - 65°C

• 70 - 80°C

Multiple Choice

During PCR, which temperature range allows primers to bond?

• 92 - 98°C

• 50 - 65°C

• 70 - 80°C

Multiple Choice

During PCR, which temperature range allows heat resistant DNA polymerase to replicate the DNA?

• 70 - 80°C

• 92 - 98°C

• 50 - 65°C

Multiple Choice

Which of the following is not a requirement of PCR?

• A supply of nucleotides

• ATP

• Thermal Cycler

• Burette

​List of terms

DNA polymerase - Enzyme which adds complementary nucleotides to the template strand to form a new complementary strand

​

Primer - A short complementary strand ​of nucleotides that bounds to a target sequence at the 3 end of the template strand

​

Ligase - Enzyme that joins DNA fragments during DNA replication

​

Helicase - Enzyme which breaks the weak hydrogen bonds connecting the DNA bases

​

Thermal cycler - A device which automatically performs the clinical temperature changes required for PCR​

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Fill in the Blanks

What is the name of the device which automatically performs clinical temperature changes required for PCR

Multiple Choice

DNA polymerase

• Enzyme which adds complementary nucleotides to the template strand to form a new complementary strand

• A short complementary strand ​of nucleotides that bounds to a target sequence at the 3 end of the template strand

• Enzyme that joins DNA fragments during DNA replication

• Enzyme which breaks the weak hydrogen bonds connecting the DNA bases

Multiple Choice

Primer

• A short complementary strand ​of nucleotides that bounds to a target sequence at the 3 end of the template strand

• Enzyme that joins DNA fragments during DNA replication

• Enzyme which breaks the weak hydrogen bonds connecting the DNA bases

• Enzyme which adds complementary nucleotides to the template strand to form a new complementary strand

Multiple Choice

Ligase

• Enzyme which adds complementary nucleotides to the template strand to form a new complementary strand

  ​

• A short complementary strand ​of nucleotides that bounds to a target sequence at the 3 end of the template strand

  ​

• Enzyme that joins DNA fragments during DNA replication

• Enzyme which breaks the weak hydrogen bonds connecting the DNA bases

Multiple Choice

Helicase

• Enzyme which breaks the weak hydrogen bonds connecting the DNA bases

• Enzyme which adds complementary nucleotides to the template strand to form a new complementary strand

• A short complementary strand ​of nucleotides that bounds to a target sequence at the 3 end of the template strand

• Enzyme that joins DNA fragments during DNA replication

​END OF KEY AREA