Human Cells: Structure and Replication of DNA

Question 1

Genetic information is what?

Answer 1

Inherited

Question 2

DNA is a substance that does what?

Answer 2

Encodes the genetic information of heredity in a chemical language

Question 3

What is DNA?

Answer 3

A very long double-stranded molecule in the shape of a double helix

Question 4

Each strand of DNA is made up of what?

Answer 4

Chemical units called nucleotides

Question 5

A nucleotide is made up of what?

Answer 5

A deoxyribose sugar, a phosphate and a base

Question 6

Deoxyribose molecules have how many Carbon atoms?

Answer 6

Five Carbon atoms and are numbered 1 to 5

Question 7

The phosphate of one nucleotide is joined to what Carbon and linked to what other Carbon of the next nucleotide in the strand to form what?

Answer 7

Joined to Carbon 5
Linked to Carbon 3
To form 3-5 sugar-phosphate backbone

Question 8

What are the four different DNA bases called?

Answer 8

Adenine (A), Cytosine (C), Guanine (G) and Thymine (T)

Question 9

The nucleotides of one strand of DNA are linked to the nucleotides on the second strand through what?

Answer 9

Their bases - the bases form pairs that join the strands

Question 10

Bases pair in a complementary way, what are the complementary pairs?

Answer 10

Adenine pairs with Thymine

Guanine pairs with Cytosine

Question 11

Base pairs are held together by what?

Answer 11

Weak hydrogen bonds

Question 12

What is on each end of the sugar-phosphate backbone?

Answer 12

The 3’ end starts with a deoxyribose molecule and the 5’ end finishes with a phosphate

Question 13

The two strands of a DNA molecule run in opposite directions and are said to be what?

Answer 13

Antiparallel to each other

Question 14

The base sequence of DNA forms what?

Answer 14

The genetic code

Question 15

DNA molecules replicate before what?

Answer 15

Cell division

Question 16

What is replication?

Answer 16

The process by which DNA molecules can direct the synthesis of identical copies of themselves

Question 17

DNA replication requires what?

Answer 17

The original DNA strands to act as template strands, a supply of DNA nucleotides, the enzymes DNA polymerase and ligase, and ATP

Question 18

What happens prior to cell division?

Answer 18

DNA is replicated by the enzyme DNA polymerase

Question 19

DNA polymerase needs what to start replication?

Answer 19

Primers

Question 20

What is a primer?

Answer 20

A short complementary strand of nucleotides which binds to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides

Question 21

What does DNA polymerase do during replication?

Answer 21

Adds DNA nucleotides, using complementary base pairing, to the deoxyribose (3’) end of the new DNA strand which is forming

Question 22

How are the two template strands formed?

Answer 22

DNA is unwound and hydrogen bonds between complementary bases are broken

Question 23

DNA polymerase can only add DNA nucleotides in one direction from its 3’ end towards its 5’ end, what is the result of this?

Answer 23

The leading strand is replicated continuously and the lagging strand is replicated in fragments

Question 24

Fragments of DNA are joined together by what?

Answer 24

The enzyme ligase

Question 25

What is polymerase chain reaction (PCR)?

Answer 25

A laboratory technique for the amplification of DNA

Question 26

How does PCR amplify DNA?

Answer 26

Using complementary primers for specific target sequences

Question 27

In PCR what are primers?

Answer 27

Short strands of nucleotides which are complementary to specific target sequences at the two 3’ ends of the region of DNA to be amplified

Question 28

Repeated cycles of heating and cooling do what? What does a cycle of PCR double?

Answer 28

Amplify the target region of DNA.

The number of copies of a region of DNA

Question 29

DNA is heated to what to do what?

Answer 29

Heated to between 92 and 98 degrees Celsius to separate the strands

Question 30

It is then cooled to what to allow what?

Answer 30

Cooled to between 50 and 65 degrees Celsius to allow primers to bind to target sequences

Question 31

It is then heated to what to do what?

Answer 31

Heated to between 70 and 80 degrees Celsius for heat-tolerant DNA polymerase to replicate the region of DNA

Question 32

What are the applications of PCR?

Answer 32

It can amplify DNA to help solve crimes, solve paternity disputes and diagnose genetic disorders

Question 33

Macromolecules such as fragments of DNA from a source can be what?

Answer 33

Separated by gel electrophoresis