Ch 3: Proteins, Carbohydrates, and Lipids Flashcards
macromolecules
proteins, lipids, carbohydrates, and nucleic acids
proteins
made up of amino acids
aka protein, peptide, polypeptide
has many functions
amino acids
make up proteins
20 different types
polypeptide chain
single, unbranched, chain of amino acids
peptide bond
amino acids bond together covalently in a condensation reaction
condensation reaction
loss of H2O molecule
hydrophobic amino acids
hydrophobic if R groups don’t contain O or N
glycine (G): smallest amino acid
alanine(A): simplest with aliphatic R-group
Phenylalanine (F): simplest with aromatic R group
Hydrophilic amino acids
R group contains O or N
Lysine (K): pos charged
aspartate (D): neg charged
serine (S): -OH, hydroxyl group
exceptions to the rule
tyrosine and tryptophan
amino acids are often modified after translation
most common modification is phosphorylation,
occurs on the -OH group of serine, threonine, and tyrosine
isomers
molecules with the same chemical formula, but atoms are arranged differently
structural isomers
differ in how their atoms are joined together
primary structure
1˚
amino acid sequence
secondary structure
2˚
wavy structure
shape adopted by the amino acid backbone
alpha helix or B pleated sheet
tertiary structure
3˚
folded 3-D structure
Quaternary structure
4˚
how multiple proteins interact with each other
alpha helix
cork screw shaped
right handed
Has all (-C=O) pointing in the same direction (up)
Has all (-N-H)_ pointing in the opposite direction (down)
has all amino acids in parallel (N–>C)
has R groups that stick out
B strand
- Looks like a wavy noodle
- Has no handedness
- Has (-N-H) and (-C=O) in an amino acid unit pointing the same direction (both up or both down)
- Amino acid units alternate pointing up and down
- Anti parallel (N→C, C←N)
- R groups interact
Disulfide bonds
help hold together 3˚ and 4˚ structure
lipids
nonpolar and are almost completely hydrophobic
store energy
saturated fatty acids
no double bonds btw carbons; saturated with H atoms
unsaturated fatty acids
some double bonds in carbon chain
fatty acid structure
one end: carboxyl group (CO2-); hydrophilic
other end: (-CH2) hydrophobic
amphipathic
triglycerides
composed of a glycerol, 3 fatty acid chains, and an ester bond
fats and oils
fats are almost completely hydrophobic
animal triglycerides
contain saturated fatty acids: solid at room temp (fats)
plant triglycerides
contain unsaturated fatty acids: liquid at room temp (oil)
phospholipids
like triglycerides, except one of the glycerol hydroxyl groups is bonded to a phosphate, which is bonded to another organic molecule
have a hydrophilic, charged head and a hydrophobic tail
in water they form lipid bilayers
Carbohydrates
have the general formula: Cn(H2O)n
aka carbohydrate, saccharide, and sugar
end is ose
glucose
most common sugar and has 6 carbons
has two ring forms: alpha anomer and beta anomer
alpha anomer
has its hydroxyl group pointing down and it bumbs the hydroxyl group at C2
beta-anomer
has its hydroxyl group pointing up and there’s a hydrogen at C2 which is smaller
no bumping occurs
glyceraldehyde
3 carbons
ribose
5 carbons
6 carbons
galactose, fructose
disaccharides
galactose+glucose=lactose
glucose + fructose=sucrose
polysaccharides
cellulose
starch
glycogen
