Lecture 2: Matter The Stuff of Life: Part I: The Bonds of Life

Question 1

5 bonding types (attractive forces)

Answer 1

-ionic
-covalent
-metallic
-van der waals
-hydrogen bonding

Question 2

ionic bonding

Answer 2

the force of attraction between positively and negatively charged ions

most ionic compounds are crystalline solids at room temperature

typically very strong

they hold proteins or enzymes together

Question 3

covalent bonding

Answer 3

takes place between atoms with small differences in charge which are close to each other in the periodic table, or identical atoms

formed by sharing of outer shell electrons between atoms, rather than by electron transfer

this bonding can be attained if the two atoms each share one of the other electrons

help hold proteins together

Question 4

metallic bonding

Answer 4

metallic bonding is the type of bonding found in metal elements- not important for life

this is the electrostatic force of attraction between positively charged ions and delocalised outer electrons

Question 5

van der waals bonding

Answer 5

van der waals bonding shows inter- molecular forces between molecules

attraction between molecules is due to electric dipole forces between the atoms or molecules

this exists between all atoms and molecules

van der waals forces are of the order of 1% of the strength of a covalent bond

Question 6

hydrogen bonding

Answer 6

a hydrogen atom, having one electron, can be covalently bonded to only one atom

however, the hydrogen atom can involve itself in an additional bond with a second atom such as fluorine or oxygen

this second bond permits a hydrogen bond between two atoms or structures

hydrogen bonds hold DNA together

Question 7

strength of the bonds of lifes

Answer 7

strong- ionic, covalent, metallic

weak- van der waal, hydrogen

Question 8

what is an isotope?

Answer 8

atoms with different numbers of neutrons

Question 9

basic differences between ionic, covalent, hydrogen, and van der waals bonds

Answer 9

strong- ionic, covalent, metallic

weak- van der waals, hydrogen

important for life- ionic, covalent, van der waals, hydrogen

not important for life- metallic

Question 10

how are ionic and covalent bonds used by life in extreme environments?

Answer 10

covalent bonds very strong- thermal motion can’t break bonds allowing molecules to form

ionic bonds also typically very strong- bond energy much higher than energy causes by thermal motion

Question 11

what is the importance of hydrogen bonds in the structure of DNA?

Answer 11

hydrogen bonds hold DNA together

DNA replicated information by ‘undoing’ the hydrogen bonds