Life at the cellular level 1- molecules Flashcards
Define the major elements used to construct human biomolecules?
H, C, N, O. 99% of our bodies are this
What seven elements are required in large amounts for human biomolecules?
Na, Mg, K, Ca, P, S, Cl.
What 12 other elements are required in small amounts?
Mn, Fe, Co, Ni, Cu, Zn, Mo, Se, I.
(Usually form critical interactions in proteins, e.g. Fe in haemoglobin)
How many bonds do H, O, N , C make?
1,2,3,4
How is a molecule formed?
When atoms share electrons (or lose or gain electrons) and they stick together (covalent bond) they form molecules. Two or more elements bonded together = molecule.
What are the important functional groups?
Amino- NH3
Carboxyl-COOH
Hydroxyl-OH
Phosphate-H2PO4
Why can’t biomolecules have many different configurations?
Many biomolecules contain a double bond between carbon atoms (C=C) which is rigid (no freedom of rotation). They can therefore only interconvert between the two by breaking and re-forming bonds (energetically expensive!)
Functional groups and their effect on molecules?
Groups of elements that attach to these carbon structures are called “functional groups” and confer specific chemical properties to the molecule. Biomolecules can contain more than one functional group.
What configurations do biomolecules take?
cis/trans
Cis- Groups on the same side of the double bond
Trans-Groups on opposite sides of the double bond.
Why is configuration of biomolecules important? Rhodopsin example
Rhodopsin is a protein embedded in the (rods of the) retina of the eye that is bound to retinal. On exposure to light the configuration of retinal alters (from cis-retinal to trans-retinal) and this alteration stimulates nerves cells in the optic nerve to send messages to the brain where we “see”.
What is configuration?
the fixed arrangement of atoms in a molecule
What is conformation?
the spatial arrangement of groups that can have different positions in space due to the freedom of rotation of single bonds
What are the 5 chemical reactions of life?
Redox reactions
Making and breaking C-C bonds
Internal rearrangements
Group transfers
Condensation and hydrolysis reactions
OILRIG?
Oxidation Is Loss (of electrons)
Reduction Is Gain (of electrons)
What is oxidising agent and what is reducing agent?
The oxidising agent is what becomes reduced itself and a reducing agent becomes oxidised itself.
Redox in the context of NAD+ AND NADH?
NADH a reducing agent (which becomes oxidised itself to NAD+ as it reduces other compounds)
NAD+ is an oxidising agent (which becomes reduced itself as it oxidises other compounds)
Condensation?
two smaller molecules combine to form a larger molecule and in doing so release water
Hydrolysis?
breaking a large molecule into smaller units using water
Describe protein structure?
Proteins are long chains of amino acids (polypeptides are chains of amino acids as well but shorter than proteins).
The amino group of one amino acid reacts with the carboxyl group of another to form a peptide bond.
A molecule of water is lost (condensation) as each bond is form.
Describe structure of nucleic acid?
These form the core structure of DNA and RNA.
Nucleic acids are polymers of nucleotide (phosphate group attached to a sugar and a nitrogenous base) monomers linked by 3’,5’-phosphodiester bonds.
What sugar is in RNA compared to DNA?
RNA- ribose
DNA- deoxyribose
What are the nitrogenous bases?
Pyrimidines- Cytosine, Thymine (in DNA) , Uracil ( in RNA)
Purines- Adenine and Guanine
Difference between RNA and DNA?
RNA is single stranded nucleic acid
DNA is double stranded nucleic acid
Describe structure of lipids (fats and oils)?
Lipids (fats and oils) consist mainly of repeating units of fatty acids (FAs), which are long chains of C and H.
Saturated, monosaturated, unsaturated fatty acids?
Saturated-ALL bonds are single
Monosaturated- ONE double bond
Polyunsaturated-more than one double bond
How do double bonds affect fatty acid structure?
The more unsaturated the fatty acid (the more double bonds in the chain) the more fluid the fatty acid.
This has important implications for cell membranes, which are largely composed of fatty acids.
Describe structure of Triacylglycerides ?
Also called triglycerides or fats.
Glycerol + 3 fatty acid chains.
The fatty acid chains can be the same (simple triacylglycerides) or mixed (2 or more different fatty acids).
Describe structure of phospholipids?
Glycerol + 2 fatty acid chains + phosphate group.
Describe structure of sterols?
Sterols are structural lipids present in cell membranes.
They have an steroid nucleus – 4 fused rings
Explain how cholesterol is important sterol?
Essential component of cell membranes (role in membrane fluidity and reduces the permeability of the cell membrane).
Precursor to steroid hormones and fat soluble vitamins (A, D, E).
