chapter five part two Flashcards
what are lipids
hydrophobic molecules that don’t mix with water
element composition of lipids
C,H, and some O
- mostly hydrocarbon/nonpolar regions
composition of fats
glycerol molecule, 3 fatty acids
covalent bonds in nucleic acids
phosphodiester
covalent bond in lipids
ester linkages between glycerol and fatty acids
fatty acids
have long carbon skeleton (16-18) C at one end is part of carboxyl group
- contains carboxyl and methyl groups
traicylglycerol
(triglyceride)
fat molecule w/ 3 fatty acids
- “cyl” = fatty acid
saturated fats
have all the hydrogen it can hold
unsaturated fats
has one or more double bonds
- creates kink in tail
- liquid at room temperature
uses of fats
energy storage, cushions vital organs
phospholipid composition
glycerol molecule, 2 fatty acids, 3rd hydroxyl group
what are phospholipids a major component of?
cell membranes
- hydrophobic tail
- hydrophilic head
steroids
lipids characterized by 4 fused rings in carbon skeleton and a functional group
cholesterol
precursor of many steroids
what is cholesterol good for?
component of animal cell membranes, synthesizes hormones
proteins
biologically functional molecule made up of polypeptides and chains of amino acids
how abundant are proteins in a cell?
50% of dry mass
functions of proteins
(STERCDHS)
- storage
- transport
- enzymatic
- receptor
- contractile
- defense
- hormone (communication)
- structural support
storage protein ex.
casein protein of milk stores amino acids
transport protein ex.
hemoglobin transports oxygen
enzymatic protein ex.
digestive enzymes catalyze hydrolysis in bonds of food
receptor protein ex.
neuromuscular junction
contractile protein ex.
actin and myosin responsible for contraction of muscles
defense protein ex.
protection against disease, antibodies help destroy viruses
hormone (communication) protein ex.
insulin causes tissues to take up glucose
structural support protein ex.
keratin (hair), silk fibers
enzymes
protein that regulates metabolism by acting as catalyst
catalysts
chemical agents that selectively speed up chemical reactions w/o being consumed
- lowers energy of activation
polypeptides
polymer of amino acids
amino acids
building blocks of proteins
how many different amino acids total?
20
what does an amino acids consist of?
- amino group
- carboxyl group
- hydrogen atom
- variable group (R)
all attached to C
4 types of amino acids
- nonpolar
- polar
- asidic
- basic
nonpolar AA
hydrophobic side chain
polar AA
hydrophilic side chain
acidic AA
negative side chain
basic AA
positive side chain
what are amino acids held together by?
peptide bonds
- made via dehydration reaction
4 levels of protein structure
primary, secondary, tertiary, quaternary
primary protein structure
linear chain of amino acids held together by peptide bonds
secondary protein structure
regions stabilized by hydrogen bonds between atoms of polypeptide backbone
- alpha helix
- beta pleated sheets
alpha helix
coil held together by H-bonding between every 4th AA
beta pleated sheet
2+ segments of polypeptide chain connected by H-bonds
- core of globular proteins
tertiary protein structure
3D shape stabilized by interactions between side chains
- hydrophobic interactions
- hydrogen bonds
- disulfide bridges
hydrophobic interactions in tertiary structure
AA w/ hydrophobic side chains usually end up in clusters at core or protein out of contact w/ water
disulfide bonds in tertiary structure
covalent bonds where 2 cysteine monomer (w/ sulfhydryl groups) are brought close together
quaternary protein structure
when protein consists of 2+ polypeptide chains
- collagen
- hemoglobin (globular protein)
denaturation
breakdown of protein shape
causes of denaturation
pH, salt concentration, high temperature, chemicals that break H-bonds
chaperonins
assist new proteins to fold/assemble into native shape
