Bio – Week 3 – Lecture 1 – 17/3/25
Oligonucleotide = (polymer of 10-50 nucleotides, usually synthetically produced) - *the
prefix ‘oligo’ come from the Greek word meaning ‘a few’ i.e. a small but not specific number
DNA structure: = deoxyribose sugar RNA = ribose sugar
Two families of nitrogenous bases:
- Cytosine, thymine and uracil are smaller chemical structures (single ring) Pyrimidine
- Adenine and guanine are larger chemical structures (double ring structure) purine
T, A, G, C in DNA and U, A, G, C in RNA
DNA polarity: 5’ (5 prime) end and 3’ (3 prime) end
- Carbons in the sugar component are identified as 1’, 2’, 3’, 4’, 5’
- 5’ end of a single DNA strand as the 5’ carbon at the “end”
- 3’ end has 3’ carbon at the “end”
How we identify “ends” and direction/orientation -> two strands run antiparallel (opposite
orientations).
- The two strands in DNA run antiparallel
- Enzymes that make nucleic acids can only work in a
certain direction (DNA replication; transcription), e.g all
processes such as transcription only go one way.
Double helix:
- Two strands of DNA, held together by H-bonds
Complementary base parining:
- A (adenine) pairs with T (thymine)
- G (guanine) pairs with C (cytosine)
- From the sequence AGCT on one strand we can determine the
other strand which would result to be TCGA
- Different base sequences can encode different proteins/
different biological functions.
Complementary base pairing rule:
Purine (adenine and Guanine)
Pyrimidine (cytosine, thymine and uracil)
Purine + purine = too wide
Pyrimidine + pyrimidine = too narrow
Purine + pyrimidine = width consistent with X-ray data.
Oligonucleotide = (polymer of 10-50 nucleotides, usually synthetically produced) - *the
prefix ‘oligo’ come from the Greek word meaning ‘a few’ i.e. a small but not specific number
DNA structure: = deoxyribose sugar RNA = ribose sugar
Two families of nitrogenous bases:
- Cytosine, thymine and uracil are smaller chemical structures (single ring) Pyrimidine
- Adenine and guanine are larger chemical structures (double ring structure) purine
T, A, G, C in DNA and U, A, G, C in RNA
DNA polarity: 5’ (5 prime) end and 3’ (3 prime) end
- Carbons in the sugar component are identified as 1’, 2’, 3’, 4’, 5’
- 5’ end of a single DNA strand as the 5’ carbon at the “end”
- 3’ end has 3’ carbon at the “end”
How we identify “ends” and direction/orientation -> two strands run antiparallel (opposite
orientations).
- The two strands in DNA run antiparallel
- Enzymes that make nucleic acids can only work in a
certain direction (DNA replication; transcription), e.g all
processes such as transcription only go one way.
Double helix:
- Two strands of DNA, held together by H-bonds
Complementary base parining:
- A (adenine) pairs with T (thymine)
- G (guanine) pairs with C (cytosine)
- From the sequence AGCT on one strand we can determine the
other strand which would result to be TCGA
- Different base sequences can encode different proteins/
different biological functions.
Complementary base pairing rule:
Purine (adenine and Guanine)
Pyrimidine (cytosine, thymine and uracil)
Purine + purine = too wide
Pyrimidine + pyrimidine = too narrow
Purine + pyrimidine = width consistent with X-ray data.
