BIO130H1 Lecture Notes - Lecture 2: Cytosol, Endoplasmic Reticulum, Supersecondary Structure
BIO130H1(S) – Lecture 2 Thursday, January 11, 2018
NOTE: Structure and function are completely intertwined on a whole organism scale as well as
on a molecular scale.
Molecular Interactions
Those between individual molecules usually mediated by noncovalent attractions
oElectrostatic attractions
oHydrogen bonds
ovan der Waals attractions
oHydrophobic interactions
**Individually, very weak forces BUT can sum to generate strong binding between
molecules
Thus, within a molecule covalent attractions
Nucleic acid chains
1) DNA is synthesized from deoxyribonucleoside
triphosphate, otherwise known as dNTPs
2) RNA is synthesized from ribonucleoside triphosphates, or
NTPs
3) Nucleotides are linked by phosphodiester bonds
Base pairing
1) Holds the DNA double helix together
2) A – T
a. 2 H-bonds
3) G – C
a. 3 H-bonds
b. Harder to break apart than with 2 H-bonds
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BIO130H1(S) – Lecture 2 Thursday, January 11, 2018
RNA because of oxygen at 2’C
Strictly speaking, DNA is 2 molecules with
non-covalent attractions between them
However, some scientists say that
DNA is just 1 molecule composed of
2 strands
Three forces that keep DNA together:
(Forces that keep the 2 strands together)
1. Hydrogen bonds between bases
2. van der Waals attractions
a. the bases, and how they’re stacked, their covalent bonds and since their atoms
are at the right distance, so their flickering dipoles have that attraction
3. Hydrophobic interactions
a. Ring structured bases
DNA Structure
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find more resources at oneclass.com
BIO130H1(S) – Lecture 2 Thursday, January 11, 2018
Note: Most
protein/DNA contacts
are made in the major
groove because the
minor groove is too
narrow
Each phosphate carries
a negative charge,
making the entire DNA
backbone highly
charged and polar.
Review
1) The strands in a double helix are antiparallel
a. One strand is 5’ 3’ while its partner is 3’ 5’
2) What are the 2 ends of the DNA strand composed of?
a. 5’ = phosphate group (-PO4)
b. 3’ = hydroxyl group (OH)
NOTE: ‘high temperature’ in biology is typically 100°C, which is not high enough to break the
covalent bonds
The sequence of the 2 strands are complementary
Strands can be unzipped
The above process important for DNA replication (including PCR) and RNA synthesis
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find more resources at oneclass.com
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BIO130H1 Full Course Notes
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Document Summary
Note: structure and function are completely intertwined on a whole organism scale as well as on a molecular scale. Those between individual molecules usually mediated by noncovalent attractions: electrostatic attractions, hydrogen bonds, van der waals attractions, hydrophobic interactions. **individually, very weak forces but can sum to generate strong binding between molecules. Nucleic acid chains: dna is synthesized from deoxyribonucleoside triphosphate, otherwise known as dntps, rna is synthesized from ribonucleoside triphosphates, or. Ntps: nucleotides are linked by phosphodiester bonds. Base pairing: holds the dna double helix together, a t, 2 h-bonds, g c, 3 h-bonds, harder to break apart than with 2 h-bonds. Strictly speaking, dna is 2 molecules with non-covalent attractions between them. Note: most protein/dna contacts are made in the major groove because the minor groove is too narrow. Each phosphate carries a negative charge, making the entire dna backbone highly charged and polar.
