Nucleotide and DNA Structure

Question 1

What 5 elements are nucleic acids made up of? (5)

Answer 1

• Carbon
• Hydrogen
• Oxygen
• Nitrogen
• Phosphorus

Question 2

What two types of nucleic acids are there (state their full names)? (2)

Answer 2

• DNA (deoxyribonucleic acid)
• RNA (ribonucleic acid)

Question 3

What monomers make up nucleic acids? (1)

Answer 3

Nucleotides

Question 4

What are nucleotides made up of? (3)
What symbols do you use when drawing a diagram of a nucleotide? (3)

Answer 4

• A phosphate (circle)
• A pentose sugar (pentagon)
• A base (rectangle)

Question 5

Draw a simple diagram of 2 nucleotides bonded together (4)

Answer 5

Include:
- 2 phosphates
- 2 pentose sugars
- 2 bases
- phosphodiester bond between the phosphate and the carbon on the pentose sugar

Question 6

How do nucleotides bind together ? (1)
What bond do they form? (1)
Where do they form a bond between each nucleotide? (2)

Answer 6

• Nucleotides bond together via a condensation reaction
• which forms a phosphodiester bond
• between the phosphate group of one nucleotide
• and a carbon of the pentose sugar of another nucleotide

Question 7

Each strand of DNA is joined by bases.

Name the 4 bases and their complementary base pairs (2) and the mnemonic used to remember them (2) .

Answer 7

• Adenine pairs with Thymine
• Cytosine pairs with Guanine
• Apples grow on Trees
• Cars park in Garages

Question 8

What does complementary base pairing tell us about the number of bases in each DNA molecule? (2)

Answer 8

• There will always be an equal amount of A and T
• and an equal amount of C and G

Question 9

Summarise in one line what DNA and RNA do (2)

Answer 9

• DNA holds genetic information
• RNA transfers the genetic information to ribosomes

Question 10

What two things form ribosomes? (2)

Answer 10

• RNA
• Proteins

Question 11

Give 3 differences between RNA and DNA (6)

Answer 11

• DNA is made up of 2 polynucleotide strands whereas RNA is made up of one polynucleotide strand
• DNA nucleotides have the bases ATCG but in RNA, thymine is replaced by uracil
• DNA contains deoxyribose sugars whereas RNA contains ribose sugars

Question 12

What bond holds the bases of 2 strands together? (1)

Answer 12

Hydrogen bonds

Question 13

In DNA, the double-helix is the structural backbone. What is made up of? (2)

Answer 13

• Phosphates
• Pentose sugars

Question 14

What 2 structural features make DNA a stable structure? (2)

Answer 14

• The phosphodiester backbone protects the chemically reactive bases inside of the double helix
• The hydrogen bonding between the bases of the strands –> the more there are the more stability there is

Question 15

Is there an equal amount of hydrogen bonding between the bases? (2)

Answer 15

• No
• There are more hydrogen bonds between cytosine and guanine compared to adenine and thymine

Question 16

What are some adaptations of DNA that make it useful? (5)

Answer 16

• Its a stable structure - so it can pass down information to another generation without change
• Hydrogen bonding - Easy to break for DNA replication and protein synthesis
• Extremely large - holds a lot of genetic information
• Double-helix structure - protects the bases from outside chemical and physical forces
• Base-pairing - Allows DNA replication and to transfer information as mRNA

Question 17

Who discovered the structure of hydrogen bonding with DNA molecules? (1)

Answer 17

Watson and Crick