Topic 4: Central Dogma of Molecular Biology

Question 1

Describe definition and characteristics of genome, transcriptome, and proteome

Answer 1

• Genome: complete genetic composition of a cell or species (DNA) - same DNA in all of cells
• Transcriptome: set of all RNA molecules present in 1 cell or 1 individuals at 1 time - differs depending on subsets of genes being expressed, various cell types or stages of cells
• Proteome: set of proteins expressed - differs depending on subsets of genes being expressed and RNA being translated, various cell types or stages of cells

Question 2

Contrast chromosomes in prokaryotes and eukaryotes

Answer 2

Prokaryotes: circular chromosomes, quite small, few base pairs

Eukaryotes: linear chromosomes, big, wrapped around histone proteins –> nucleosomes condensed into chromatin

Question 3

Describe the human genome (pairs of chromosomes, copies of genes)

Answer 3

• 22 pairs of chromosomes (+ 1 pair of sex chromosome)
• 1 pair of copies of each gene (1 copy on 1 chromatid sister = allele)

Question 4

Identify and describe the overall roles of different types of RNA

Answer 4

• mRNA: messenger delivering coding region to make proteins
• Transfer RNA and ribosomal RNA: protein synthesis/translation
• MicroRNA and small nulcear RNA: regulatory roles

Question 5

At what rate is mRNA produced and after being used, what happens to them?

Answer 5

mRNA can be produced at different rates
Eg. gene A may be transcripted to many copies of mRNA –> many copies of proteins
gena B may –> just 1 mRNA –> 1 protein

Degraded via ribose after being used

Question 6

Explain the importance of amino acid sequence in determining the protein function

Answer 6

Amino acid sequence decides the structure of the protein which determines its functions

Question 7

What can proteins form to assist celluler functions?

Answer 7

Receptors, enzymes, hormones, growth factors, toxins, transporters and antibodies

Question 8

What is epigenetics?

Answer 8

Modifications to DNA without changing the DNA sequence can affect gene activity

Question 9

The genetic code is based on single, doublet or triplet code?
What is the implication of such coding?
What is the set of bases encoded an amino acid called? Its sequence/order?

Answer 9

Triplet code –> 64 base pairs –> redundancy in the code in which some amino acids can have more than 1 code

Set of 3 bases are called codon, quoted 5’ to 3’

Question 10

Identify the start codon

Answer 10

AUG

Question 11

What are stop codons?

Answer 11

Encode NO amino acid
Signal ribosomal RNA to stop making proteins

Question 12

What is the open reading frame?

Answer 12

Start to stop codon/ the part encodes the protein

Question 13

Identify and describe different types of DNA/RNA mutations and effects on protein synthesis

Answer 13

• Missense: 1 single amino acid is changed
• Nonsense: change in DNA –> stop codon
• Silent: mutation of coding region, BUT no effect on protein sequence
• Point: 1 single base pair is changed
• Insertion/Deletion: addition/removal of 1/more nucleotide base pairs/a piece of DNA
• Frameshift: insertion/deletion change reading frame