DNA and RNA

Question 1

DNA and its function

Answer 1

1. Deoxyribonucleic Acid

2. Stores genetic information

Question 2

RNA and its function

Answer 2

1. Ribonucleic Acid

2. Transfers genetic info from nuclues to ribosomes

Question 3

Similartities between DNA and RNA

Answer 3

1. Nucleic acids / nucleotides

2. Carry genetic info

Question 4

Nucleotide definition

Answer 4

Biological molecules (or monomers of DNA/RNA) consiting of

1. Pentose sugar - 5 carbon sugar
2. Nitrogen conatining organic base
3. Phophate group

Question 5

DNA nucleotide

Answer 5

DNA nucleotide consists of:

1. Pentose sugar - deoxyribose
2. Phosphate group
3. Nitrogen containing organic base (including A,T,C,G)

All DNA nucleotides have the same pentose sugar, phosphate group, however, they can have different nirtogen containing organic bases

Question 6

RNA nucleotide

Answer 6

RNA nucleotide consists of:

1. Pentose sugar - ribose
2. Phosphate group
3. Nitrogen containing organic base (Including A,U,C,G)

In RNA, thymine is swapped with uracil.

Question 7

Differences between DNA and RNA

are they asking for the differences between the polynucleotides or nucleotides?

Answer 7

1. The pentose sugar. DNA has deoxyribose, RNA has ribose
2. The nitrogen containing organic bases. In RNA, the nitrogen conaining organic bases are A,U,C,G. In DNA. they are A,T,C,G. Thymine is replaced with uracil
3. The function of RNA is to transfer genetic info from nucleus to ribosome. Function of DNA is to store genetic info

Question 8

Polynucleotide

Answer 8

1. This is a polymer of nucleotides (can be DNA or RNA nucleotides)
2. Formed in a condensation reaction between nucleotides
3. Phosphodiester bonds form between the nucleotides (between the phosphate group of one nucleotide and sugar of another nucleotide), phosphodiester bond consists of one phosphate group + 2 ester bonds
4. Water molecule removed per phosphodiester bond formed
5. The chain of sugars and phosphates in the polynucleotide chain is known as sugar phosphate backbone

Question 9

Sugar-phosphate backbone

Answer 9

1. Chain of sugars and phosphates in the polynucleotide chain

Question 10

Structure of DNA

Answer 10

1. DNA consists of two polynucleotide DNA strands
2. They are joined together by hydrogen bonds formed between the complementary base pairs
3. Adenine always pairs with thymine and cytosine always pairs with guanine
4. 2 hydrogen bonds form between A and T and 3 hydrogen bonds form between C and G
5. The two polynucleotide DNA strands are antiparalell, which means they run in opposite directions
6. These two strands twist around each other to form the DNA double helix

Question 11

Complementary Base Pairing Definition

Answer 11

1. One base pairs with only one other specific base. Adenine always pairs with thymine and cytosine always pairs with guanine. This means there is equal amounts of Adenine and thymine and equal amounts of cytosine and guanine

Question 12

DNA Replication

Answer 12

1. DNA replication occurs before cell division
2. This is to ensure each new cell produced has a full amount of DNA
3. DNA replicates by semi-conservative DNA replication
4. This means that half of the DNA strands in the new DNA molecule are from the original DNA molecule
5. This allows for genetic continuity - this means that genes from the parent cells are inherited into the new cells

Question 13

Genetic continuity definition

Answer 13

Genes from parent cells inherited into new cells produced by semi-conservatice cell division

Question 14

Process of semi-conservative DNA replication

Answer 14

1. The enzyme DNA helicase breaks the hydrogen bonds between the complementary base pairs holding the two DNA polynucleotide strands together. This causes the DNA double helix to uncoil. We end with 2 single DNA polynucleotide strands
2. Each of these original strands act as a template for each of the new strands. The bases are exposed on the original DNA strands. Free floating nucleotides attach to their complementary exposed bases via complemntary base paring. Adenine always pairs with thymine and cytosine always pairs with guanine
3. The nucleotides of the new DNA strand join together via a condensation reaction. A new DNA polynucleotide is formed. Phophodiester bonds are formed between the nucleotides (consists of one phosphate group and 2 ester bonds). Water molecule released per phosphodiester bond formed. This reaction is catalysed by DNA polymerase (DNA polymerase forms phosphodiester bonds)
4. Hydrogen bonds form between complementary base pairs between the 2 polynucleotide strands to hold them together. Between adenine and thymine, 2 hydrogen bns form and between cytosine and guanine, 3 hydrogen bonds form. The strands then coil around each other to form DNA double helix
5. The new DNA molecule contains one DNA polynucleotide strand from the original DNA molecule and one new DNA polynucleotide strand.

Question 15

Action of DNA polymerase

Answer 15

1. DNA double helix consists of two antiparallel DNA polynucleotide strands
2. Therefore, nucleotides are arranged differently, have different shape
3. DNA polymerase is an enzyme with an active site, with a specific tertiary structure
4. Only substrates with correct shape / specific shape / orientation can bind with active site of DNA polymerase and form E-S complexes