Life at a Cellular Level 2 Flashcards
What elements do we need large amounts of each day?
- H2
- C
- N2
- O2
- Na
- P
- S
- Cl2
- K
- Ca
What are the four lightest atoms?
- Hydrogen
- Oxygen
- Nitrogen
- Carbon
What kind of bonds can C form?
- Single bonds (H)
- Single and double bonds (O, N)
- Single, double and triple bonds (C)
What defines biomolecular function?
-Functional groups of atoms that involve bonds between carbon and other groups of atoms
Why is the polarity of C bonds critical to functionality?
- C-C and C-H are relatively stable as they share e equally
- C-O and C-N or C- functional group bonds are highly polar which alters the C bond reactivity
Configuration
The fixed arrangement of atoms in a molecule
What is function also dependent on?
The arrangement of groups on the molecule
How can molecules which contain C=C be arranged?
It is a rigid conformation so only 2 arrangements:
- Cis
- Trans
- It is only possible to interconvert between the 2 by breaking and reforming bonds
C can act as a chiral centre. What are the two forms of chiral C?
- Laevo (left handed)
- Dextro (Right handed)
- Only way to rotates is to break and reform bonds
What kind of amino acid are all proteins made from?
L-amino acids
Conformation
The precise arrangement of atoms in a molecule
What do bonds that can rotate allow?
Many different conformations which are inter-convertible without breaking and re-forming covalent bonds
What dictates how freely bonds can rotate?
Interactions of groups around the C-C bond
What are the 5 chemical reactions of life?
- Redox reactions
- Making and breaking C-C bonds
- Internal rearrangements
- Group transfers
- Condensation and hydrolysis
What is oxidation?
Loss
What is reduction?
Gain
What usually occurs in biological redox reactions?
2 e’s (and 2 protons) are gained or lost
What is an example of making/breaking C-C bonds.
Cleavage of glucose in the glycolysis pathway
What is an example of internal rearrangements?
In glycolysis, before the sugar splits
What is an example of a group transfer?
In glycolysis phosphate group is transferred
What is an example of condensation/hydrolysis?
The sub-units of proteins, polysaccharides and nucleic acids are all joined by condensation and broken by hydrolysis reactions
What are proteins?
Polymers of amino acid monomers linked by peptide bonds
What are nucleic acids?
-Polymers of nucleotide monomers linked by 3’,5’-phosphodiester bonds
What are the 2 types of nucleic acid?
- Pyrimidines (flat single rings)-C,T,U
- Purines (flat, double rings)-A, G
What allows DNA to form the double helix?
Flat planar structure of bases
Describe the bonds between bases.
- A to T= 2 bonds
- C to G= 3 bonds
Describe the structure of RNA.
Single stranded
What is retovir?
A nucleotide analogue
What is Zidovudine?
- Also known as AZT
- Is an analogue of the thymine nucleotide found in DNA
What are polysaccharides?
Polymers of sugar monomers linked by glycosidic bonds
What is D-glucose?
- Monomer unit of starch and glycogen
- Reducing sugar
Why is D-glucose termed a reducing sugar?
- The linear form has an aldehyde group which can oxidised
- If this is oxidised then the other reactant would be reduced, so glucose is a reducing sugar
How are glucose polymers formed?
By the condensation reaction between 2 glucose monomers
How is a reducing end formed?
- In glucose polymers, a monomer is linked to another which locks it in the cyclic form.
- This continues until all the monomer are locked in cyclic from apart from the end monomer
What do lipids usually contain?
One or more long chain fatty acids
Why is oil a liquid?
It is unsaturated
Why is lard solid?
It is almost exclusively saturated.
Why is butter soft?
It is a mixture of saturated and unsaturated
What are 2 classes of lipids?
- Triacylglycerides
- Phospholipids
Describe Triglycerides.
- Storage lipids
- Non-polar
- 3 fatty acid chains linked to glycerol
Why are phospholipids polar?
They have a head group attached to the glycerol
