3.4.2 DNA & Protein Synthesis

Question 1

(DNA & Protein Synthesis) What is a genome?

Answer 1

Genome is the complete set of genes in a cell, including any mitochondrial / chloroplast genes.

Question 2

(DNA & Protein Synthesis) What is a proteome?

Answer 2

Full range of proteins produced by the genome.

Question 3

(DNA & Protein Synthesis) What is a cell proteome?

Answer 3

Proteins produced by a specific cell as a result of which genes are switched on / off.

Question 4

(DNA & Protein Synthesis) Is DNA a double or single polynucleotide chain?

Answer 4

Double.

Question 5

(DNA & Protein Synthesis) Is mRNA a double or single polynucleotide chain?

Answer 5

Single.

Question 6

(DNA & Protein Synthesis) Is tRNA a double or single polynucleotide chain?

Answer 6

Single.

Question 7

(DNA & Protein Synthesis) Describe the size of DNA, in comparison to mRNA/tRNA.

Answer 7

Largest molecule of the three.

Question 8

(DNA & Protein Synthesis) Describe the size of mRNA, in comparison to DNA/tRNA.

Answer 8

Molecule is smaller than DNA, but larger than tRNA.

Question 9

(DNA & Protein Synthesis) Describe the size of tRNA, in comparison to DNA/mRNA.

Answer 9

Smallest molecule of the three.

Question 10

(DNA & Protein Synthesis) Is DNA’s pentose sugar ribose or deoxyribose?

Answer 10

Deoxyribose.

Question 11

(DNA & Protein Synthesis) Is mRNA’s pentose sugar ribose or deoxyribose?

Answer 11

Ribose.

Question 12

(DNA & Protein Synthesis) Is tRNA’s pentose sugar ribose or deoxyribose?

Answer 12

Ribose.

Question 13

(DNA & Protein Synthesis) What are the organic bases in DNA?

Answer 13

Adenine, guanine, cytosine, thymine.

Question 14

(DNA & Protein Synthesis) What are the organic bases in mRNA?

Answer 14

Adenine, guanine, cytosine, uracil.

Question 15

(DNA & Protein Synthesis) What are the organic bases in tRNA?

Answer 15

Adenine, guanine, cytosine, uracil.

Question 16

(DNA & Protein Synthesis) Where in the cell is DNA found?

Answer 16

Mostly found in the nucleus.

Question 17

(DNA & Protein Synthesis) Where is the cell is mRNA manufactured and found?

Answer 17

Manufactured in the nucleus, but found throughout the cell.

Question 18

(DNA & Protein Synthesis) Where is the cell is tRNA manufactured and found?

Answer 18

Manufactured in the nucleus, but found throughout the cell.

Question 19

(DNA & Protein Synthesis) Describe the quantity of DNA.

Answer 19

Quantity is constant for all cells of a species (expect gametes).

Question 20

(DNA & Protein Synthesis) Describe the quantity of mRNA.

Answer 20

Quantity varies from cell to cell and with a level of metabolic activity.

Question 21

(DNA & Protein Synthesis) Describe the quantity of tRNA.

Answer 21

Quantity varies from cell to cell and with a level of metabolic activity.

Question 22

(DNA & Protein Synthesis) How chemically stable is DNA?

Answer 22

Chemically very stable.

Question 23

(DNA & Protein Synthesis) How chemically stable is mRNA?

Answer 23

Less stable than DNA or tRNA, individual molecules are usually broken down in cells within a few days.

Question 24

(DNA & Protein Synthesis) How chemically stable is tRNA?

Answer 24

Chemically more stable than mRNA, but less stable than DNA.

Question 25

(DNA & Protein Synthesis) What does the sequence of nucleotide bases on the DNA determine?

Answer 25

The sequence of nucleotide bases in the production of mRNA.

Question 26

(DNA & Protein Synthesis) Detail the process of transcription (DNA to mRNA).

Answer 26

An enzyme starts to unwind and separate the DNA strands at the start of a gene.

This exposes the nucleotide bases on in the strands including the template (coding) strand.

Free, activated RNA nucleotides undergo complementary base pairing, through hydrogen bonding, with the bases on the template strand only.

A to T, U to A, C to G, G to C

RNA polymerase forms phosphodiester bonds between the RNA nucleotides forming a single stranded polynucleotide called messenger RNA (mRNA).

Question 27

(DNA & Protein Synthesis) What does the sequence of triplets (codons) on the mRNA determine?

Answer 27

The order of amino acids in a polypeptide chain.

Question 28

(DNA & Protein Synthesis) Detail the process of translation (mRNA to polypeptide chain).

Answer 28

Ribosome attaches to a start codon (AUG) and the beginning of the mRNA…

A tRNA with the complementary anticodon (UAC) pairs with the codon on the mRNA through complementary base pairing.

The tRNA is attached to a specific amino acid (Methionine)

Ribosome move over by one codon allowing the next tRNA to bind.

A peptide bond is formed between the two amino acids (peptidyl transferase enzyme / ATP)

Ribosome moves over by one codon and the process continues as the next amino acid is added to the elongating chain.

The process stops when the ribosome meets a STOP codon.

The polypeptide chain starts to fold into its tertiary structure.

Question 29

(DNA & Protein Synthesis) Any gene mutation that alters the DNA genetic code. What could this have consequences for?

Answer 29

The structure of the polypeptide it encodes for.

Question 30

(DNA & Protein Synthesis) How does transcription differ between eukaryotes and prokaryotes: Prokaryotes.

Answer 30

DNA of genes have no proteins and no introns so the mRNA produced can be directly translated into an amino acid chain / polypeptide (protein).

Question 31

(DNA & Protein Synthesis) How does transcription differ between eukaryotes and prokaryotes: Eukaryotes. (3)

Answer 31

Transcription in the nucleus produced precursor mRNA (introns + exons)

Enzymes remove introns through splicing to form mature mRNA

Mature mRNA leaves the nucleus via a nuclear pore and can be translated at a ribosome.