4.2 DNA and Protein Synthesis

Question 1

Genome:

Answer 1

The complete set of genes in a cell (including those in the mitochondria and chloroplasts).

Question 2

Proteome:

Answer 2

The full range of proteins that a cell can produce (coded for by the cell’s DNA/genome).

Question 3

Transcription:

Answer 3

Production of mRNA from DNA, in the nucleus.

Question 4

Translation: def

Answer 4

Translation is the process by which the genetic information stored in RNA is translated into a sequence of amino acids to form a protein.

Question 5

Similarities of tRNA and mRNA:

Answer 5

Both single strand polynucleotide strand.

Question 6

Contrast:

Answer 6

1. tRNA is folded into ‘clover leaf shape’ whereas mRNA is linear.
2. tRNA has hydrogen bonds between paired bases and mRNA doesn’t.
3. tRNA is a shorter fixed length whereas mRNA is longer, variable length.
4. tRNA has an anticodon, mRNA has codons.
5. tRNA has an amino acid binding site, mRNA.

Question 7

How mRNA is formed by transcription in eukaryotic cells?

Answer 7

1. Hydrogen bonds between DNA bases break.
2. Only one DNA strand acts as a template.
3. Free RNA nucleotides align next to their complementary bases on the template strand.
4. RNA polymerase joins adjacent RNA nucleotides.
5. This forms phosphodiester bonds via condensation reactions.
6. Pre-mRNA is formed and this is spliced to remove introns, forming mature mRNA.

Question 8

How mRNA is different from eukaryotic and prokaryotic cells?

Answer 8

1. pre-mRna produced in eukaryotic cells wheres mRNA is produced directly in eukaryotic cells.
2. Genes is proks do not contain introns so no splicing in prokaryotic cells.

Question 9

Translation:

Answer 9

1. mRNA attaches to ribosomes
2. tRNA anticodons bind to complementary mRNA codons;
3. tRNA brings a specific amino acid;
4. Amino acids join by peptide bonds;
5. Amino acids join together with the use of ATP;
6. tRNA released after amino acid joined to polypeptide
7. The ribosome moves along the mRNA to form the polypeptide

Question 10

Role of ATP:

Answer 10

1. Hydrolysis of ATP to ADP + Pi releases energy.
2. Amino acids join to tRNAs and peptide bonds form between amino acids.

Question 11

Role of tRNA:

Answer 11

1. Attaches to a specific amino acid in relation to its anticodon.
2. tRNA anticodon complementary base pairs to mRNA codon, forming hydrogen bonds.
3. 2 tRNAs bring amino acids together so peptide bond can form.

Question 12

Role of Ribosomes:

Answer 12

1. mRNA binds to ribosome
2. Allows tRNA with anticodons to bind.
3. Catalyses formation of peptide bond between amino acids (held by the tRNA molecule)
4. Moves along (mRNA to next codon)/ translocation.