Lecture 5: Chemical Structure and Physiological Function

Question 1

electrons

Answer 1

move around the nucleus in orbitals grouped into shells; fill inner shells before outer (valence) shells.

Question 2

atom

Answer 2

most stable when its valence shell is filled. If an elements has one shell, it needs 2 electrons in that shell to be stable; if an element has 2+ shells, it needs 2 electrons in the inner shell and 8 in the outer to be stable.

Question 3

covalent bond

Answer 3

when two atoms share valence electrons so that each atom can be more stable (as a molecule).

Question 4

non polar covalent bond

Answer 4

equal sharing of valence electrons between atoms. ex: lipids

Question 5

polar covalent bond

Answer 5

unequal sharing of valence electrons between atoms. These bonds dissolve in water. ex: carbohydrates, nucleic acids

Question 6

electronegativity

Answer 6

strength at which an atom’s nucleus pulls electrons; increases from left to right along the periodic table.

Question 7

lipids

Answer 7

make up the cell membrane and serve as signaling molecules; contain carbon and hydrogen; non polar; hydrophobic. ex: hormones (cortisol, testosterone)

Question 8

cell membrane

Answer 8

lipid bilayer that separates the insides/outsides of the cell and only lets certain substances through (selective permeability).

Question 9

phospholipid

Answer 9

makes up the cell membrane and forms lipid bilayers in water; polar.

Question 10

hydrophilic

Answer 10

polar; the heads interact with each other, water, and other polar molecules.

Question 11

hydrophobic

Answer 11

non polar; the tails do not interact with anything.

Question 12

saturated lipid

Answer 12

hydrocarbon chains that consist of only single bonds between the carbons (less permeable).

Question 13

unsaturated lipid

Answer 13

hydrocarbon chains that have one or more double bond (kinks = more permeable).

Question 14

permeability

Answer 14

defines the rate of passive diffusion of molecules through the cell membrane depending on the charge and polarity of a molecule; must stay in a homeostatic range.