Molecular Components of Cells

Study Notes

Cells contain thousands of different molecules
Many chemical elements are found in cells
The four most abundant atoms are C, H, O, and N, representing about 96% of the atoms in most living organisms
Other elements like P, Ca, S, Cl, Na, K, Mg comprise about 4% of the atoms.
Trace elements (like Cu, Zn, Se, I, Mo) exist in very low concentrations.
Water (H₂O) makes up about 70% of a bacterium's weight

Water: The most abundant component in cells, comprising 65% to 80% of animal or plant cells respectively.
Water's polarity allows it to form hydrogen bonds with other molecules
These hydrogen bonds are crucial for many cellular processes including hydrolysis, photosynthesis, thermal regulation.
Mineral Salts: Dissolved in water, they dissociate into ions (e.g., sodium chloride, potassium chloride, magnesium sulfate).
lons' balance is crucial for many cellular functions including membrane permeability, cell division, enzyme activity and muscle contraction
Important roles in nerve signaling, muscle contraction, and enzyme activity.

Organic compounds are composed of C, H, O, N, and sometimes S, P.
There are four main classes: proteins, carbohydrates, lipids, and nucleic acids.
Vitamins are also organic compounds.
Many organic molecules are involved in major cellular processes
These molecules are named metabolites, and the collection of them is the metabolome

Proteins are the largest and most diverse molecules in cells, composing 55-85% of the cell's dry weight
Proteins are made up of amino acids linked together by peptide bonds
There are 20 different amino acids
Diverse sequences of amino acids result in varied functions
Proteins perform diverse functions: structure, catalysis, transport, etc.
Proteins also play crucial roles in communication between cells, immune responses, and energy conversion in muscle activities.

Proteins play important roles in communication between cells, immune responses, and energy conversion in muscle activities.
Proteins are crucial for almost all functions in cells and organisms.