molecular components of cells Flashcards
how many elements are found in living cells, and how are they distributed?
27
C N O H -> 96%
S K P Cl Ca Mg -> 4%
B F Mn Fe Co Cu Zn I -> <1%
what are the four classes of organic compounds?
carbohydrates, lipids, proteins, nucleic acids
what are the properties of water?
- most abundant (70%, 80%, 65%)
- differs among diff cell types (least in bones)
- electrically neutral
- polar
- forms hydrogen bonds
what do the properties of water mediate?
- solubilisation of molecules (by negative poles of oxygen)
- hydrolysis
- photosynthesis
- thermal regulation
- providing aqueous medium for metabolism
- lubrication function that permits diffusion of cell components
define hydration
it’s when mineral salts are dissolved in water and ionised, and each ion entity is surrounded by water molecules
what three conditions are essential for most physiological phenomena?
balance of concentration of diverse ions + acid-base equilibrium + osmotic pressure
what are some examples of physiological phenomena that adhere to the three conditions?
- membrane permeability
- cell division
- muscle contraction
- enzymatic activity
- intracellular signaling
- generation & propagation of nerve impulses
how is the activity of certain enzymes/proteins attributed to certain metal ions?
- calcium aids in the release of neurotransmitters into the synaptic cleft, and allows for muscle contraction
- iron is crucial for oxygen transport by hemoglobin and oxidation-reduction reactions catalysed by cytochromes
give examples of insoluble mineral salts. where are they found?
calcium carbonate, calcium phosphate, and silicium. they are mostly found in rigid structures like skeletons and animal shells.
define a metabolite
an intermediate or end product of metabolism
define a metabolome
a set of metabolites
are vitamins considered a fifth class? why or why not?
vitamins are not considered a fifth class since they do not form a homogenous independent class; i.e., some vitames (A, E, D) are derived from lipids, while others (C) from carbohydrates. the only common thing between them is that they are needed at low concentrations.
what percentage of dry weight do proteins make up?
proteins are the most abundant compound found in cells (they range from 55-85% of dry weight)
define a protein
proteins are unbranched amino acid polymers whose sequences are determined by genetic information carried by genes
what are the functions of a protein?
- determine cell structure and shape (ex. proteins of cytoskeleton)
- perform almost all physiological functions
- responsible for molecular identity of cells (ex. HLA, blood types)
- responsible for morphology of organisms (ex. skin colour, hair colour, size)
- all crucial physiological processes (expression of genetic information, DNA replication)
- involved in storage and transportation of:
- ions and molecules (pumps and channels in membrane)
- macromolecules (cytoskeleton and nuclear pore proteins)
- electrons (proteins in mitochondria/chloroplast)
- intercellular communication (many hormones)
- immunity (antibodies are proteins)
- progression of cell cycle and mitosis
- convert chemical energy (ATP) into mechanical energy in muscles for movement
- necessary for senses
how do we calculate the different possible variations of a polypeptide chain based on its length?
20^n, n=length in aa
what are the properties of amino acids?
- amphoteric
- composed of C, H, N, O (+sometimes S in 2 cases)
- made up of an amino group, carboxyl group, R-side chain, chiral C alpha
- only L-stereoisomers
- all soluble in water
there are 20 amino acids. how many are synthesised by our body? what about the other ones?
11 by our body, 9 supplied by our diet