Topic 1---B: More biological Molecules- 1. DNA and RNA

Question 1

What are DNA and RNA both types of?

Answer 1

Nucleic acids (polymer) to nucleotides (monomer)

Question 2

What does DNA stand for?

Answer 2

Deoxyribonucleic acid

Question 3

What is DNA used for?

Answer 3

• It’s used to store your genetic information (instructions needed to grow and develop from a fertilised egg to a fully grown adult)

Question 4

What does RNA stand for?

Answer 4

Ribonucleic acid

Question 5

What is RNA main functions?

Answer 5

Transfer the genetic info from the DNA to the ribosomes

Question 6

What are ribosomes?

Answer 6

• They are the body’s ‘protein factories’
• They read the RNA to make polypeptides (proteins) in a process called translation.

Question 7

What are ribosomes made from?

Answer 7

RNA and proteins

Question 8

What is the nucleotide structure?

Answer 8

• Pentose sugar (sugar with 5 carbon atoms)
• Phosphate group
• Nitrogen- containing organic base (contains carbon)

Question 9

How do nucleotides join together and what do they form?

Answer 9

• Nucleotides join together via a condensation reaction between the phosphate group of one nucleotide and the pentose sugar of another.
• They form polynucleotide strands
• This forms a phosphodiester bond (consisting of the phosphate groups and 2 ester bonds).

Question 10

Sugar-phosphate backbone

Answer 10

Chain of phosphates and sugars

Question 11

What is DNA structure?

Answer 11

• Double helix structure
• Formed from 2 polynucleotide strands which wind around each other to form a spiral
• They are made up of lots of nucleotides joined together in a long chain
• DNA molecules are really long and coiled up very tightly so a lot of genetic information can fit into a small space in the cell nucleus.

Question 12

DNA nucleotide structure

Answer 12

• Phosphate group
• Pentose sugar (deoxyribose)
• Nitrogen containing organic base (A,T,C,G) 1 of 4

Question 13

What are the four possible bases on a DNA nucleotide?

Answer 13

• Adenine (A)
• Thymine (T)
• Cytosine (C)
• Guanine (G)

Question 14

How do two DNA polynucleotide strands join together?

Answer 14

By hydrogen bonds between the bases

Question 15

What does complementary base pairing mean and what are they in DNA?

Answer 15

-Each base can only join with one particular partner
Adenine always joins with Thymine (AT)
Guanine always pairs with Cytosine (CG)
So there are always equal amounts of each.

Question 16

How many hydrogen bonds form between AT?

Answer 16

2 Hydrogen bonds

Question 17

How many hydrogen bonds form between CG?

Answer 17

3 Hydrogen bonds

Question 18

What does anti-parallel mean?

Answer 18

Strands in opposite directions to one another (two polynucleotide strands are anti-parallel)

Question 19

RNA nucleotide structure

Answer 19

• Pentose sugar (ribose)
• Phosphate group
• Nitrogen containing organic base (AU CG) 1 of 4

Question 20

Differences between RNA and DNA structure

Answer 20

• Sugar in a RNA nucleotide is ribose sugar but the sugar in a DNA nucleotide is deoxyribose
• Uracil replaces thymine as a base so it always pairs with adenine in RNA (AU) but (AT) in DNA
• RNA strands are much shorter than most DNA polynucleotides
• In RNA the nucleotides form a single polynucleotide strand not a double one like DNA.
• RNA is single-stranded but DNA is double-stranded

Question 21

How is the DNA double helix formed

Answer 21

• 2 polynucleotides join together by hydrogen bonds between complementary base pairs
• A with T and C with G
• 2 hydrogen bonds form between AT and 3 hydrogen bonds form between CG
• By the anti-parallel strands twisting around eachother