Protein synthesis (nucleic acid), genetic code and codons & exons (exclusive)

Question 1

What are the 2 stages of protein synthesis?

Answer 1

Transcription - occurs in nucleus and involves DNA and mRNA
DNA strand is transcribed into mRNA
Translation - involves mRNA, tRNA and ribosomes
The process of amino acids being assembled together forming a polypeptide chain/protein

Question 2

Step 1 of transcription?

Answer 2

A molecule of mRNA is made in nucleus:
1. Hydrogen bonds between complementary bases break and DNA uncoils, separating the 2 strands
- Just like that one time in DNA replication

Question 3

Step 2 of transcription?

Answer 3

2. One of the DNA strands is used as a template to make the mRNA molecule
   - The template is called the antisense strand

Question 4

Step 3 of transcription?

Answer 4

3. Free nucleotides line up by complementary base pairing and adjacent nucleotides are joined by phosphodiester bonds thus forming a molecule of mRNA
   - Ig it rlly just be like DNA replication

Question 5

Step 4 of transcription?

Answer 5

4. the mRNA moves out of the nucleus through a pore and attaches to a ribosome in the cytoplasm which the next stage occurs (translation)

Question 6

Step 1 of translation?

Answer 6

Amino acids join together to form a polypeptide chain:
1. mRNA attaches to a ribosome and tRNA collects amino acids from the cytoplasm and carries them to the ribosome. tRNA is a single stranded molecule with a binding site at one end ∴ can only carry one type of amino acid, and a triplet of bases at the other
- We don’t know how it collects amino acids, but it just does type shi

Question 7

Step 2 of translation?

Answer 7

2. tRNA attaches itself to mRNA by complementary base pairing; two molecules attach to mRNA at a time

Question 8

Step 3 of translation?

Answer 8

3. The amino acids attached to 2 tRNA molecules are joined by a peptide bond, then tRNA molecules detach themselves from amino acids, leaving them behind
   - Seems like first person amino acid connecting thingy

Question 9

Step 4 of translation?

Answer 9

4. Process is repeated leading to a formation of a polypeptide chain until a stop codon is reached on mRNA, which ends the process of protein synthesis

Question 10

What does DNA stand for?

Answer 10

Deoxyribonucleic acid

Question 11

What’s the monomer and structure of DNA?

Answer 11

• A = phosphate = circle
• B = sugar (5 carbon pentose) = pentagon
• C = organic (nitrogenous) base = rectangle
  consists of 4 nitrogenous bases (adenine, thymine, guanine, cytosine)
• All connected by just a line

Question 12

What are the 4 nitrogenous bases classed as purines or pyrimidines for DNA?

Answer 12

• Purines = adenine & guanine
• Pyrimidines = thymine & cytosine [& uracil]
• 4 nucleotides possible for DNA

Question 13

What does RNA stand for?

Answer 13

Ribonucleic acid

Question 14

What are the 3 types of RNA?

Answer 14

They all use information from DNA for the construction of proteins but in slightly different ways
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)

Question 15

What’s the monomer and structure of RNA?

Answer 15

• A = phosphate = circle
• B = sugar (5 carbon pentose) = pentagon
• C = organic (nitrogenous) base = rectangle
  consists of 4 nitrogenous bases (adenine, uracil, guanine, cytosine)
• All connected by just a line

Question 16

What are the 4 nitrogenous bases classed as purines or pyrimidines for RNA?

Answer 16

• Purines = adenine & guanine
• Pyrimidines = uracil & cytosine
• 4 nucleotides possible for RNA

Question 17

What does ATP stand for?

Answer 17

Adenosine triphosphate

Question 18

What is ATP?

Answer 18

• The main energy currency of all cells
• A nucleotide
• Small water-soluble molecule

Question 19

Structure of ATP?

Answer 19

• A = adenine = Hexagon connected to pentagon
• B = ribose = pentagon
• C = phosphate = 3 circles connected but not touching (lines)
• All connected by lines, just like DNA/RNA

Question 20

How does ATP store/release energy?

Answer 20

• 3 phosphate groups = negatively charged ∴ repel each other
• Makes covalent bond linking them unstable (like a coiled spring)
• Each phosphate straining to break away from each other
• Bonds easily broken and release 30.6kJmol^-1 of energy

Question 21

Suggest why ATP is called the universal energy currency

Answer 21

Used by all organisms/species to provide energy for most biochemical reactions