Lecture 4: Fundamentals of Life I: Molecules

Question 1

what are the CHNOPS elements?

Answer 1

carbon
hydrogen
nitrogen
oxygen
phosphorous
sulfur

Question 2

why is carbon the basis of life?

Answer 2

main backbone of most biological structures including amino acid glycine- hence ‘carbon- based’ life

the energy it takes to link with the CHNOPS atoms is quite similar, and once linked they are quite stable

also a wide range of double and triple bond configurations

result is the capacity to form chains with complex branching and networks of rings

millions of possible ‘organic’ compounds can be formed

Question 3

what are the 4 classes of biological molecules, and give example of what they are used for?

Answer 3

proteins (structural support, enzymes)

sugars (structural support, energy)

lipids (membranes and energy)

nucleic acids (information storage)

Question 4

what is chirality?

Answer 4

when a molecule/ ion can’t be superposed on its mirror image by any rotations or changes

amino acids are chiral, except for glycine

Question 5

what makes water a suitable solvent for life?

Answer 5

readily dissolves many ions

large heat capacity and range (0 to 100 C)

cosmically abundant

Question 6

what makes ammonia another possible suitable solvent for life?

Answer 6

readily dissolves many chemicals

less viscous than water

quite high heat of vaporisation and heat capacity

Question 7

why isn’t silicon the basis for life?

Answer 7

can make chained compounds and hybrid oregano-silicon compounds

readily forms very stable compounds in presence of oxygen

although- forms unstable compounds with other elements compared to methane