2.3 DNA

Question 1

What are nucleic acids

Answer 1

Large polymers formed by many nucleotides linked together in a chain and contain the elements: C, H, O, N, P

Question 2

What is the roles

Answer 2

Storage + transfer of genetic info + Synthesis of polypeptide

Question 3

What is the structure

Answer 3

• Contains a Phosphate group that’s acidic & negative
• Pentose sugar containing 5 carbons
• Nitrogenous base containing 1 or 2 carbon rings in structure

Question 4

What are the 2 types

Answer 4

DNA
RNA

Question 5

What is the differences between them

Answer 5

DNA: The sugar is called Deoxyribose (Has 1 less H)
RNA: The sugar is called Ribose

Question 6

Pyrimidines

Answer 6

The smaller bases which contain single carbon ring structure (T&C)

Question 7

Purines

Answer 7

The larger bases which contain double carbon ring structure (A&G)

Question 8

Role of RNA

Answer 8

Plays essential role in the transfer of genetic information from DNA to the proteins that make up the enzymes + tissues of the body

Question 9

What bond joins nucleotides together

Answer 9

Phosphodiester

Question 10

Steps to DNA extraction

Answer 10

1. Grind sample using mortar & pestle to break cell wall
2. Mix sample with detergent which breaks down cell membrane releasing cell contents to solution
3. Add salt to break down hydrogen bonds between DNA & water molecules
4. Add protease enzyme breaks down proteins associated with DNA in nuclei
5. Add ethanol which causes DNA to precipitate out the solution
6. The DNA should be seen as white strands forming between the layer of sample & layer of alcohol. The DNA can be picked up by stirring rod

Question 11

After protein synthesis what happens to protein molecules

Answer 11

RNA molecules are degraded in the cytoplasm. The phosphodiester bonds are hydrolysed and the RNA nucleotides are released + reused

Question 12

What is semi-Conservative repliaction

Answer 12

for DNA to replicate. The double Helix structure must unwind and then separate into two strands, so the hydrogen bonds holding the complementary bases together must be broken.

Free DNA nucleotides will then pair with their complementary basis which have been exposed as a strength are separate.

Hydrogen bonds are formed between them.

The new nucleotides join to the adjacent nucleotides with the phosphodiester bond.

Question 13

what is the roles of enzymes in replication

Answer 13

DNA replication is controlled by enzymes, a class of proteins that act as catalysts for biochemical reactions.

Enzymes are only able to carry out their function by recognising and attaching to specific molecules or parts of the molecule

Before replication can occur, the unwinding and separating of the two strands of the DNA double Helix is carried out by enzyme DNA helicase, it travels along the DNA backbone, catalysing reactions that break the hydrogen bond between complementary base pairs as it reaches them. This can be thought as the strand of unzipping new line

Free nucleotide spare with the newly exposed basis on the template strands during the unzipping process, a second enzyme, DNA polymerase, catalyses the formation of first four dice to bonds between these nucleotides.

Question 14

what is mutation

Answer 14

Random & spontaneous errors in the DNA bases

Question 15

What is the degenerate code

Answer 15

The degenerate code refers to the fact that multiple codons or sets of three nucleotides can code for the same amino acid during protein synthesis.

This is due to their being more codons than amino acids.

Question 16

What happens in transcription

Answer 16

• DNA is contained in a double-membrane called the nuclear envelope to protect it from being damaged by cytoplasm
• Chromosomal DNA molecule it too large to leave through nuclear pores and must make a shorter version of itself
• The section of gene that is needed unwinds & unzips using DNA Helicase which breaks the hydrogen bonds
• The 2 strands are separated and the first (5’ to 3’) is called the sense strand and contains the correct coding for the amino acid sequence. The other strand (3’ to 5’) is called the template / antisense strand
• Free RNA nucleotides that are complementary to the bases attach to the template strand and RNA polymerase binds them together and forms phosphodiester bonds
• There is no Thymine, so Adenine is paired with Uracil
• This completed strand is called mRNA and de-attaches itself from the template strand and leaves through nuclear pores and travels to ribosome in the cytoplasm

Question 17

what happens in translation

Answer 17

In ribosomes there is ribosomal RNA. (rRNA)

This is important in maintaining the structural stability of the protein synthesis sequence and plays a biochemical role in catalysing the reaction.

After leaving the nucleus, the mRNA binds to a specific site on the small subunit of a ribosome. The ribosome holds mRNA in position while is decoded or translated into a sequence of amino acids. This is known as translation

Transfer RNA (tRNA) Is necessary for the translation of mRNA. It is composed of a strand of RNA folded in such way that three bases, called the anticodon, are at one end of the molecule. This anticodon will bind to a complementary codon on mRNA following the normal base pair rules. The tRNA molecules carry an amino acid corresponding to that codon.

When the tRNA anticodon binds to the complementary codon along with the mRNA, the amino acids are brought together in the correct sequence to form a primary structure of the protein coded for by the mRNA.

Question 18

What 3 activities do cells require energy for

Answer 18

Synthesis
Transport
Movement

Question 19

what is the structure of Adenosine Triphosphate (ATP)

Answer 19

An ATP molecule is composed of a nitrogenous base. A pentose, sugar and three phosphate groups.

The base is always adenine, and the sugar is ribose.

Question 20

How is energy released

Answer 20

In a condensation reaction one of the phosphate groups is removed to from ADP (Adenosine diphosphate)

Question 21

Chemical Equation

Answer 21

ATP + Water = Inorganic Phosphate + ADP + Energy

Question 22

What is phosphorylation

Answer 22

the energy released in the breakdown of these fats & carbohydrates in cellular respiration is used to create ATP. This occurs by reattaching A phosphate group to an ADP molecule. T

Question 23

Properties of ATP

Answer 23

Small- Move easily into and out of cells

Water soluble- energy requiring processes happening aqueous environments.

Contains bond between phosphates with intermediate energy- large enough to be useful for cellular reactions, but not so large that energy is wasted as heat.

Releases energy in small quantities- quantities also suitable to more cellular needs, so that energy is not wasted as heat.

Easily Regenerated- can be recharged with energy.