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
hydrolysis
break polymers back to monomers by breaking the covalent bonds; water is put in
carbohydrate (CH2O)n polymers
polymers: polysaccharides (ex. cellulose, starch, glycogen)
cellulose (definition, function, monomer, covalent bond, branching)
- definition: polymer of β-glucose monomers held together by β-linkages
- function: provides shape to plant cells
- monomer: β-glucose
- simple sugars
- monosaccharides (ex. glucose, fructose)
- covalent bond: β-linkages
- branching: linear
starch (function, monomer, covalent bond, branching)
- function: energy storage molecules (stores α-glucose) in plants and later broken down for energy
- monomer: α-glucose
- covalent bond: α-linkages
- branching: branched
glycogen (function, monomer, covalent bond, branching)
- function: energy storage molecules (stores α-glucose) in animals and later broken down for energy
- monomer: α-glucose
- covalent bond: α-linkages
branching: highly branched
α-glucose
polymers: starch and glycogen
monomers held together by α-linkages
function: energy storage molecules
What are the functions of proteins? (5)
- enzymes (speed up chemical reactions)
- signaling molecules (hormones/neurotransmitters)
- signaling receptors (cell signaling)
- movement (motor proteins)
- structural (cytoskeletal proteins, ECM)
What is the structure of amino acids?
amino group, carboxylic acid group, R-group, central or α-carbon, and a hydrogen
What differentiates one amino acid from another?
R-group: 20 different R-groups
What is the covalent bond that links amino acids together?
peptide bonds
What is the structure of a protein?
amino-terminus, amino acids, peptide bonds, carboxy-terminus
What is the function of DNA?
stores genetic information
What is the function of RNA?
expresses genetic information
structure of nucleotides
5-carbon sugar, nitrogenous base, 5’ phosphate group
DNA vs RNA nucleotide
DNA is H
RNA is OH
covalent bonds between nucleotides
phosphodiester
RNA definition
polymer of RNA nucleotides and has 1 sugar-phosphate backbone ‘single-stranded’
DNA definition
polymer of DNA nucleotides and has 2 sugar-phosphate backbones ‘double-stranded’
What glues the 2 strands of DNA together?
Hydrogen bonding between nitrogenous bases
2 types of lipids
- triglycerides
- phospholipids
triglyceride definition
definition: a form of stored energy for plants and animals
triglyceride structure
monomers:
* 1 glycerol (3-carbon molecule that’s the backbone of triglycerides)
* 3 fatty acids (a carboxylic acid group attached to a long hydrocarbon chain)
held together by ester bonds
glycerol
3-carbon molecule that’s the backbone of triglycerides
fatty acid
carboxylic acid group attached to a long hydrocarbon chain
ester bonds
bond a carboxylic acid group attached to an alcohol; hold together glycerol and fatty acid monomers
saturated fatty acid
all C-C bonds
long, straight chains saturated with hydrogens
pack well = solid (fats)
unsaturated fatty acid
C=C bonds
- to be involved in the double bond, each carbon has to give up a hydrogen
bends in fatty acid chain
don’t pack well = liquid (oils)
monounsaturated fatty acid
one C=C
polyunsaturated fatty acid
2 or more C=C
phospholipid definition
- definition: the primary component of plasma membranes
phospholipid monomers and bonds
a glycerol, 2 fatty acid chains, a phosphate group (same type of nucleotides)
covalent bonds: ester bonds
property of phospholipid and why
amphipathic b/c polar hydrophilic head and nonpolar hydrophobic tail
structure phospholipids form in an aqueous solution
- phospholipid bilayer is formed
- heads interact with aq environment outside the cell
- heads interact with aq environment inside the cell
