Chapter 3, 4, 5, 6, 7, 8, 9 and 17
Question 1 DNA sequencing and PCR-
Chapter 4, 5, 6, 7 and 8
Tutorial answers
Central dogma-
● All cells, from bacteria to humans, express their genetic information through the principle of
central dogma.
● The central dogma is essential for a gene's function. DNA needs to replicate itself to express its
information. The flow of information occurs from DNA to RNA (transcription), then RNA to protein
(translation).
● For many genes, RNA is the final product. Some RNAs fold into precise 3D structures that have
structural and catalytic roles in the cell. Roles of many noncoding RNAs still unknown
DNA replication-
● DNA direction and polarity- DNA has two antiparallel polarities, both strands are synthesised 5’ to
3’ (new strand runs 5’ -> 3’, old template strand 3’ -> 5’). This allows for easy removal of wrongly
inserted bases during proofreading by DNA polymerase- as when nucleotide is removed a new
nucleotide can be easily attached to the 3' -OH group. The triphosphate group of dNTP will
provide the energy for this incorporation. On 5’, this energy from cleavage of a high energy bond
is not possible and synthesis/ elongation will stop.
● DNA monomer nucleotide- nitrogenous base (A/T/G/C) + deoxyribose sugar + phosphate group.
During DNA synthesis phosphodiester bonds are formed between monomers while hydrolysing
the matching dNTP molecule. Energy for the formation of the covalent phosphodiester bond
comes from the substrate itself- hydrolysis of the substrate dNTP results in release of
pyrophosphate molecules (PPi) and the nucleotide base is incorporated into the sugar backbone.
,Chapter 3, 4, 5, 6, 7, 8, 9 and 17
● DNA replication is semi-conservative- old strand is used as a template to generate a new strand.
Therefore, every new DNA is a combination of an old strand and new strand.
,Chapter 3, 4, 5, 6, 7, 8, 9 and 17
DNA replisome-
Replication bubbles exist because replication starts at replication origin sites-
DNA polymerase works as a dimer. Topoisomerase. Need to get more details.
, Chapter 3, 4, 5, 6, 7, 8, 9 and 17
● DNA polymerase synthesizes DNA from a double stranded “primer”.
Mistakes in DNA synthesis-
During DNA replication 1 in 105 bases is wrongly inserted.
a) Exonucleolytic proofreading-
● Mistakes can be restored by the proofreading activity of the DNA polymerase complex.
● The complex has a polymerization active site and an editing site- so the complex can go in 3’->5’
for editing/ exonuclease activity.
Question 1 DNA sequencing and PCR-
Chapter 4, 5, 6, 7 and 8
Tutorial answers
Central dogma-
● All cells, from bacteria to humans, express their genetic information through the principle of
central dogma.
● The central dogma is essential for a gene's function. DNA needs to replicate itself to express its
information. The flow of information occurs from DNA to RNA (transcription), then RNA to protein
(translation).
● For many genes, RNA is the final product. Some RNAs fold into precise 3D structures that have
structural and catalytic roles in the cell. Roles of many noncoding RNAs still unknown
DNA replication-
● DNA direction and polarity- DNA has two antiparallel polarities, both strands are synthesised 5’ to
3’ (new strand runs 5’ -> 3’, old template strand 3’ -> 5’). This allows for easy removal of wrongly
inserted bases during proofreading by DNA polymerase- as when nucleotide is removed a new
nucleotide can be easily attached to the 3' -OH group. The triphosphate group of dNTP will
provide the energy for this incorporation. On 5’, this energy from cleavage of a high energy bond
is not possible and synthesis/ elongation will stop.
● DNA monomer nucleotide- nitrogenous base (A/T/G/C) + deoxyribose sugar + phosphate group.
During DNA synthesis phosphodiester bonds are formed between monomers while hydrolysing
the matching dNTP molecule. Energy for the formation of the covalent phosphodiester bond
comes from the substrate itself- hydrolysis of the substrate dNTP results in release of
pyrophosphate molecules (PPi) and the nucleotide base is incorporated into the sugar backbone.
,Chapter 3, 4, 5, 6, 7, 8, 9 and 17
● DNA replication is semi-conservative- old strand is used as a template to generate a new strand.
Therefore, every new DNA is a combination of an old strand and new strand.
,Chapter 3, 4, 5, 6, 7, 8, 9 and 17
DNA replisome-
Replication bubbles exist because replication starts at replication origin sites-
DNA polymerase works as a dimer. Topoisomerase. Need to get more details.
, Chapter 3, 4, 5, 6, 7, 8, 9 and 17
● DNA polymerase synthesizes DNA from a double stranded “primer”.
Mistakes in DNA synthesis-
During DNA replication 1 in 105 bases is wrongly inserted.
a) Exonucleolytic proofreading-
● Mistakes can be restored by the proofreading activity of the DNA polymerase complex.
● The complex has a polymerization active site and an editing site- so the complex can go in 3’->5’
for editing/ exonuclease activity.
