Chapter 5 - The Structure and Function of Large Biological Molecules Flashcards
what are the 4 macromolecules?
carbohydrates, lipids, proteins, nucleic acid
what are polymers? which macromolecules are polymers?
a long molecule consisting of many similar or identical building blocks linked by covalent bonds
carbohydrates, proteins, and nucleic acids
what kinds of bonds link polymers?
covalent
what are the building blocks of polymers?
monomers
what are enzymes? what do they do?
specialized macromolecules that speed up chemical reactions
help with making/breaking polymers
what is a dehydration reaction?
when monomers are connected by a reaction in which two molecules are covalently bonded to each other with the LOSS of a water molecule
each monomer contributes part of the water molecule that is released during the reaction (-OH from one, -H from the other)
what is hydrolysis?
polymers are disassembled into monomers by hydrolysis: the bond between monomers is broken by the ADDITION of a water molecule
what are examples of carbohydrates?
sugars: glucose, fructose, etc.
starch, cellulose
what are the monomers of carbohydrates?
monosaccharides (simple sugars)
what is the molecular formula of a carbohydrate? what functional groups does it contain?
multiple of the unit CH2O (H-C-OH)
carbonyl group (CHO) and hydroxyl groups (OH)
how many carbons are usually in a carbohydrate?
3-7 carbons in a chain
what is the function of carbohydrates?
major energy source for the cell!
they are storage structures structures for storing sugar in the cell
major nutrients/energy for cells (cellular respiration)
what are disaccharides?
double sugars linked by glycosidic linkage
what types of bonds link disaccharides? what are they?
a covalent bond between monosaccharides by dehydration
what are carbohydrate polymers called? what are they?
polysaccharides: polymers made of monosaccharides joined by glycosidic linkages
in what form do carbohydrates usually exist?
rings in aqueous solutions
what is the molecular formula for a molecule made by linking three glucose molecules together by dehydration?
C6H12O6 —> C18H32O16
because there’s only 2 places where water is released
what shape is starch?
helical
what shape is cellulose?
straight, never branched, OH groups can bond with other cellulose, most animals don’t have the enzyme to break it down
how is the function of polysaccharides determined?
determined by monomers and position of glycosidic linkage
what are the function of polysaccharides?
1) storage polysaccharides
2) structural polysaccharides
3) modification of proteins and phospholipids
4) glycosylation
what are storage polysaccharides?
- plants store starch: made of glucose monomers (amylose, unbranched, simplest form)
- animals store glycogen (amylopectin form, branched)
what are structural polysaccharides? examples?
organisms build strong materials from structural polysaccharides
- cellulose (polymer of glycose) is a component of the tough walls that enclose plant cells, insoluble fibers that surround the cell
- chitin is used by insects to build exoskeletons
- area that exists outside the cell is made of polysaccharides
what is glycosylation? what does it help with?
modification of protein and phospholipids by carbohydrates –> increases chemical diversity
what does gycosylation help with?
1) cell recognition:
important for immune system for recognition of cells
2) protein function/stability:
function/stability can rely on if it gets glycosylation
3) protein folding:
folding can depend on if it receives glycosylation
4) important for secreted proteins:
proteins that get made in the cell that need to be on the outside of the cell/are on the outside and it serves as a zipcode to let the cell know where it needs to go
are lipids polymers?
no, they aren’t big enough
are lipids hydrophobic or hydrophilic?
hydrophobic
lipids mix poorly, if at all, with water because mostly hydrocarbons and not very polar - water molecules hydrogen bond to each other and exclude the fats
3 types of lipids?
steroids, fats, phospholipids
what are fats constructed from? what kind of macromolecule are they?
they are lipids
a fat is constructed from two smaller molecules: glycerol and fatty acids
glycerol is an alcohol
hydrophobic!
what is a fatty acid?
a fatty acid has a long carbon skeleton (16-18 carbons)
COOH group
how is a fat made?
to make a fat: THREE fatty acids are joined to glycerol by an ester linkage (dehydration reaction between hydroxyl and carboxyl) = triacylglycerol
C-OH + CO-OH –> C-O-C=O bond it formed from the dehydration
C-O-C=O is the ester bond: 3 are formed, one for each dehydration!
look at the picture, it helps
what is a saturated fat?
no double bonds
as many hydrogen atoms as possible are bonded to the carbon skeleton = saturated!
makes uniform straight chain = stacks closely = solids at room temp
usually found in animals
what are unsaturated fats?
has one or more double bonds
almost all naturally occurring fatty acids have cis double bonds = kink in the chain –> don’t stack = liquid
usually found in plants
what do cis double bonds cause in fats (lipid)?
a kink in the chain = prevents them from stacking = liquid at room temperature
what is a hydrogenated fat?
means that the unsaturated fat has synthetically been converted to a saturated fat by adding hydrogen
recent studies have shown that this produces saturated fats and unsaturated fats with trans double bonds (trans fats)
what kind of fat causes health risks?
saturated fats!
what is a trans fat?
the result of partially hydrogenation
cis C = C bond are converted to trans C = C so the fat behaves like a saturated fats (solid at room temperatures)
what is the function of fats?
1) storage of energy (animals use adipose cells)
2) insulates body
what is a phospholipid?
only has TWO fatty acids attached to glycerol rather than three
the third hydroxyl group of glycerol is joined to a polar phosphate group
what does the third hydroxyl group of a glycerol bond to in a phospholipid?
a polar phosphate group
how does the behavior of the two heads of a phospholipid differ?
the hydrocarbon tails are hydrophobic and are excluded from water
the phosphate group attached to the head is hydrophilic —> when added to water they form bilayers
hydrophobic tails are turned in to each other to exclude water
polar heads are on outside of membrane towards water b/c they interact w/ H2O
what is the function of phospholipids?
important for membrane structure
phospholipids make up the aqueous side of the cell membrane
what are steroids?
steroids are lipids characterized by a carbon skeleton consisting of four fused rings
how are steroids distinguishable from one another?
by the chemical groups attached to the rings
what are examples of steroids?
signaling hormones
vitamins
cholesterol
what is cholesterol?
a steroid (lipid)
a crucial molecule in animals, common component of animal cell membranes, precursor from which other steroids are synthesized