4.2 - DNA and protein synthesis

Question 1

Define genome

Answer 1

complete set of genes in cell

Question 2

Define proteome

Answer 2

full range of proteins a cell is able to produce

Question 3

Describe the structure and features of messenger RNA (mRNA)

Answer 3

• linear, single-stranded
• ribose sugar
• AUCG bases
• moves from cytoplasm to nucleus
• codons
• more nucleotides than tRNA
• different mRNAs have different lengths

Question 4

Describe the structure and features of transfer RNA (tRNA)

Answer 4

• clover-leaf shape
• ribose sugar
• AUCG bases
• H bonds
• amino acid binding site
• anticodon
• moves from cytoplasm to nucleus
• all tRNAs are similar lengths

Question 5

What is transcription?

Answer 5

production of mRNA from DNA

Question 6

Where does transcription occur?

Answer 6

nucleus

Question 7

Describe the process of transcription

Answer 7

• helicase breaks H bonds between comp. DNA bases so 2 DNA strands separate
• only 1 DNA strand acts as a template
• free RNA nucleotides are attracted to exposed bases according to base pairing rule, forming comp. base pairs
• RNA polymerase joins adjacent mRNA nucleotides by phosphodiester bonds
• stops when stop codon is reached
• RNA polymerase moves away and DNA rejoins
• mRNA leaves nucleus via pore and attaches to ribosome in cytoplasm ahead of translation

Question 8

How does transcription end for prokaryotes vs eukaryotes?

Answer 8

prokaryotes: mRNA made
eukaryotes: pre-mRNA made, which is then spliced to remove introns to form mRNA

Question 9

What is splicing?

Answer 9

removal of introns from base sequence

Question 10

What is translation?

Answer 10

production of polypeptide from the sequence of codons carried by mRNA

Question 11

Describe the process of translation

Answer 11

• mRNA attaches to ribosome which finds start codon
• tRNA brings specific amino acid attached to its amino acid binding site to ribosome
• anticodon on tRNA binds to complementary codon on mRNA
• amino acids join by peptide bonds in condensation reaction using ATP
• tRNA molecules detach from amino acids
• ribosome moves along mRNA forming polypeptide chain until stop codon reached
  (2 molecules can attach to mRNA at a time)

Question 12

Name the type of bond between complementary base pairs in DNA, and between adjacent nucleotides

Answer 12

hydrogen bonds
phosphodiester bonds

Question 13

Describe the structure and features of DNA

Answer 13

• double helix
• deoxyribose sugar
• ATCG bases
• stays in nucleus

Question 14

What are ribosomes made up of?

Answer 14

RNA and protein