Module 1 - Nucleic acids

Question 1

What are nucleic acids?

Answer 1

Large molecules contained in the nucleus of cells

Question 2

What are the 2 types of nucleic acids and what are they important for?

Answer 2

DNA and RNA are both polymers made up of nucleotides. They are found in living organisms both necessary for building proteins, essential for the functioning of cells.

Question 3

What specifically is DNA important for?

Answer 3

Holding and storing genetic information which contains the instructions for growth and development of organisms

Question 4

What specifically is RNA important for?

Answer 4

Transfer the genetic code found in the DNA out of the nucleus to the ribosomes in the cytoplasm. Ribosomes read RNA in a process called translation.

Question 5

What are the key components of a DNA nucleotide

Answer 5

A phosphate group, A deoxyribose sugar with a H atom at carbon 2. Nitrogenous bases ( C, A, G, T)

Question 6

What are the key components of RNA nucleotides?

Answer 6

A phosphate group, a ribose sugar with a OH at carbon 2 and nitrogenous bases (C, A, G, U)

Question 7

Why is their a OH atom in RNA at carbon 2 rather than H atom?

Answer 7

This makes RNA more susceptible to hydrolysis which is why RNA is the transport molecule with a shorter molecular lifespan.

Question 8

What types of nitrogenous base is Adenine and Guanine?

Answer 8

Purines that have a double-ring structure.

Question 9

What types of nitrogenous base is Cysteine, Thymine and Uracil

Answer 9

Pyrimidines that have a single-ring structure

Question 10

What are the type of bonds formed between a phosphate group and a pentose sugar?

Answer 10

Phosphodiester bonds

Question 11

Between what components do the phosphodiester bonds form?

Answer 11

One phosphodiester bond will form between a phosphate group and carbon 5 in the pentose sugar of one nucleotide and then another bond formed between carbon 3 and a phosphate group of another nucleotide

Question 12

What is the sugar-phosphate backbone?

Answer 12

This is when the phosphate group and pentose sugar create an alternating pattern as a result of a phosphodiester bond.

Question 13

Describe simply the structure of DNA

Answer 13

DNA molecules are made up 2 polynucleotide strands lying side by side that turn in opposite directions (antiparallel)

Question 14

What does antiparallel strands mean?

Answer 14

This means that one polynucleotide chain has 3’ carbon and a 5’ carbon end. The other polynucleotide chain has a 5’ carbon end and a 3’ carbon end.

Question 15

Hydrogen bonding within the DNA molecules.

Answer 15

The 2 polynucleotide chains holding the DNA molecule is held together through hydrogen bonds between the nitrogenous bases.

Question 16

Describe the complementary bases between the nitrogenous bases. State how many hydrogen bonds formed.

Answer 16

Adenine (A) always pairs with Thymine (T) forming 2 hydrogen bonds
Guanine (G) always pairs with Cysteine (C) forming 3 hydrogen bonds

Question 17

Describe simply the structure of RNA

Answer 17

RNA is a single-stranded molecule containing Uracil instead of Thymine as a complementary base.

Question 18

What is semi-conservative replication?

Answer 18

The process where DNA is copied

Question 19

What is the importance of retaining one original DNA strand

Answer 19

It ensures genetic continuity meaning it ensures new cells produced during cell division inherit all their genes from parent cells.

Question 20

What enzymes unwinds the double helix in semi-conservative replication?

Answer 20

Helicase which breaks down hydrogen bonds between DNA strands leaving 2 single strands of polynucleotides.

Question 21

What are new polynucleotide strands in DNA made from during semi-conservative replication?

Answer 21

They are made from free nucleotides that are attracted to the exposed DNA bases by pairing

Question 22

Which enzyme then rebuilds the new double helixes

Answer 22

Polymerase which catalyses condensation reactions to form new strands.

Question 23

What happens at the end of semi-conservative replication?

Answer 23

Original and new strand are joined together through hydrogen bonds between nitrogenous bases.

Question 24

Describe a brief outline of the history of DNA research.

Answer 24

1800s - DNA was discovered
1953 - Molecular structure of DNA was discovered
Future - Future discoveries

Question 25

What are free nucleotides useful for in DNA replication?

Answer 25

These free nucleotides have 3 phosphates which activate the nucleotides to be used in DNA replication.

Question 26

What is the role of polymerase enzyme in DNA replication?

Answer 26

Synthesis new DNA strands from the template strands by catalysing condensation reactions between the deoxyribose sugar and phosphate groups of adjacent nucleotides creating the sugar-phosphate backbone.

Question 27

What does DNA polymerase do with the remaining 2 phosphate groups?

Answer 27

Cleaves (breaks down) them and uses the energy to make phosphodiester bonds.

Question 28

What makes virus pairing different to eukaryotic pairing?

Answer 28

The complementary bases are not equal which means that bases to do not pair up so the DNA is single-stranded.

Question 29

Which polynucleotide chain can DNA polymerase bind to and why?

Answer 29

5’ to 3’ chains because DNA polymerase can only add nucleotides to 3’ ends of a polynucleotide.