Protein synthesis

Question 1

Describe the process of transcription (8 steps)

Answer 1

DNA helicase unwinds DNA double helix
by breaking the hydrogen bonds between the base pairs and strand seperates
Only one strand acts as a template.
Free RNA nucleotides align next to their complementary bases on the template strand and form temporary hydrogen bonds (uracil replaces thymine).
RNA polymerase joins the adjacent nucleotides together by forming phosphodiester bonds in a condensation reaction.
RNA polymerase reaches stop codon, mRNA (prokaryotes) or pre-mRNA (eukaryotes) detaches from DNA.
This forms pre-mRNA in eukaryotic cells and mRNA in prokaryotic cells.
Then the pre-mRNA is spliced (introns removed) to form mRNA.

Question 2

Describe the process of translation (8 steps).

Answer 2

1. mRNA attaches to ribosomes after leaving nucleus through cytoplasm
2. tRNA anticodons bind to complementary mRNA codons
3. tRNA brings a specific amino acid
4. Amino acids join by peptide bonds between 2 amino acids- requires ATP
5. Amino acids join together with the use of ATP - by condensation reaction
6. tRNA released after amino acid joined to polypeptide
7. continue until stop codon
8. The ribosome moves along the mRNA to form the polypeptide

Question 3

antibodies - specific protein

Answer 3

1- proteins - with variable regions

2- that bind specifically to antigens on pathogens.

3- this specific binding neutralizes pathogens and marks them for destruction by immune cells, such as phagocytes.

4- The importance of antibodies lies in their role in adaptive immunity, providing targeted defence against infections and contributing to long-term immunity through memory cells.

Question 4

What is the first step of protein synthesis?

Answer 4

Transcription

Question 5

What enzyme unwinds the DNA double helix during transcription?

Answer 5

DNA helicase

Question 6

What does DNA helicase break to unwind the DNA?

Answer 6

Hydrogen bonds between the base pairs

Question 7

Which strand acts as a template during transcription?

Answer 7

Only one strand

Question 8

What aligns next to their complementary bases on the template strand?

Answer 8

Free RNA nucleotides

Question 9

What replaces thymine in RNA?

Answer 9

Uracil

Question 10

What enzyme joins adjacent nucleotides together during transcription?

Answer 10

RNA polymerase

Question 11

What type of bonds does RNA polymerase form between nucleotides?

Answer 11

Phosphodiester bonds

Question 12

What happens when RNA polymerase reaches the stop codon?

Answer 12

mRNA (prokaryotes) or pre-mRNA (eukaryotes) detaches from DNA

Question 13

What is formed in eukaryotic cells after transcription?

Answer 13

Pre-mRNA

Question 14

What is formed in prokaryotic cells after transcription?

Answer 14

mRNA

Question 15

What process occurs to form mRNA from pre-mRNA in eukaryotic cells?

Answer 15

Splicing (introns removed)

Question 16

What is the first step of translation?

Answer 16

mRNA attaches to ribosomes after leaving the nucleus

Question 17

What binds to complementary mRNA codons during translation?

Answer 17

tRNA anticodons

Question 18

What does tRNA bring during translation?

Answer 18

A specific amino acid

Question 19

How do amino acids join together during translation?

Answer 19

By peptide bonds

Question 20

What is required for the formation of peptide bonds?

Answer 20

ATP

Question 21

What type of reaction occurs when amino acids join together?

Answer 21

Condensation reaction

Question 22

What happens to tRNA after the amino acid is joined to the polypeptide?

Answer 22

tRNA is released

Question 23

What continues until a stop codon is reached during translation?

Answer 23

The joining of amino acids

Question 24

What does the ribosome do during translation?

Answer 24

Moves along the mRNA to form the polypeptide