Exam 1 Flashcards
Lectures 2-6
What is the size order?
eukaryotic cells>prokaryotic cells>viruses>macromolecules>atoms
What are atoms?
building blocks of life
What is the structure of an atom?
nucleus - protons and neutrons
orbiting nucleus - electrons in orbitals
What is an ion?
atoms or molecules with a net + or - electrical charge
Ionic bonds
two oppositely charged ions associate
one atom gives up 1+ electrons to another atom
does NOT include partial charges
Covalent bonds and types
when atoms share electrons; 2 types
1. nonpolar: electrons shared equally
2. polar: electrons shared unequally
Electronegativity
how strongly an atom attracts electrons
<0.5 = nonpolar covalent bond
>=0.5 = polar covalent bond
What are the important functions of water?
- biochemical reactions require an aqueous environment
- means of transport (ex. plant)
- resistant to temp. change; acts as a temp. buffer in organisms and ecosystems
What is the chemistry of water?
- polar w/ two polar covalent bonds
- can form hydrogen bonds
- liquid at room temp. b/c water molecules hydrogen bond w/ each other
What is a partial charge?
when there are 2 different electronegativities, the more electronegative atoms pull electrons closer
hydrogen bond
attraction between 2 atoms already in other chemical bonds - one is a hydrogen (𝛿+) and the other is an electronegative atom (𝛿-)
polar molecules
hydrophilic: water-loving
non-polar molecules
hydrophobic: water-fearing
ex. lipids, fats
amphipathic
molecules that are polar and nonpolar
acid
donates protons (H+) so more acid, higher proton concentration
base
accepts protons (H+) so more base, lower protein concentration
pH scale
0 (very acidic), 7 (neutral), 14 (very basic)
pH = 7 neutral [H+] = [OH-]
pH < 7 acidic [H+] > [OH-]
PH > 7 basic [H+] < [OH-]
What is the relationship between proton concentration and pH?
- pH = -log[H+] so inverse
- 1 unit change in pH = 10 fold change in H+ concentration (ex. 5 to 7 is -100)
- units: mol/L
macromolecules
polymers
polymers
large molecules of subunits called monomers; covalent bonds link monomers
condensation reaction
link monomers together to form a polymer; water is taken out