Chapter Three: Macromolecules Flashcards
Most macromolecules are _____
polymers
What is a polymer?
a long chain of smaller molecules called monomers, joined by covalent bonds
Polymers are made through _____, polymers are broken through ______.
Condensation
Hydrolysis
What are carbohydrates/polysaccharides
General Formula: Cn(H20)n
Small sugars, long polymers of sugars
Monosaccharides
smallest sugars (3C to 6C)
Disaccharides
two monosaccharides linked by covalent bonds
Oligosaccharides
3-20 monosaccharides
Polysaccharides
hundreds or thousands of monosaccharides (ex. starch, glycogen, cellulose)
Glucose
Formula: C6H12O6
Aldehyde on one end reacts with Hydroxyl on the other to form a ring
Monosaccharides are joined together by _______
glycosidic linkages
Cellulose is _____, Starch is ____, and Glycogen is ____
linear, branched, highly branched
Polysaccharide branching is determined by __________
monomer bonding patterns
Function of Carbohydrates
cell energy, carbon skeletons for many other molecules, cell recognition signals, extracellular signals
What are nucleotides?
monomers that can be joined in chains or be reversibly attached to other types of cell molecules (proteins)
What are nucleic acids?
polymers of nucleotides; DNA and RNA
What composes a nucleotide?
Pentose sugar, phosphate group, nitogenous base
What are the two types of bases in nucleotides
Single ring pyrimidines (C,T,U) and double ring purines (A,G)
RNA has _______ and DNA has ______
ribose
deoxyribose
Where is the phosphate attached on Deoxyribose and ribose
Carbon 5
How do two nucleotides join?
the phosphate of one reacts with the OH group on the carbon 3 of the other.
Which bases pair in DNA
T pairs with A
C pairs with G
The 3 end pairs with the 5 end of the opposite strand
the amounts of purines present is ______ the amount of purimidines present
equal
How are nucleotides of each chain joined
strong covalent bonds
paired chains are associated by __________ bonds. This is called ______
hydrogen
complementary base pairing
A-T/U pairs have _____ hydrogen bonds, G-C pairs have ____ hydrogen bonds
2
3
Different shapes of RNA
double-stranded or single-stranded; can form intramolecular base pair bonds with itself, folding to make complex double-stranded shapes
Which strand has Uracil, which has Thymine?
RNA has Uracil, DNA has Thymine
DNA replication
Two complete copies of DNA are made; one is transcribed into RNA
Functions of DNA
carries information for the organism’s structures and functions, reproduces itself, copies specific segments of info into RNA
Other functions of nucleotides (besides DNA and RNA)
ATP, GTP
What is ATP
energy transducer in biochemical reactions
What is GTP
energy source in protein synthesis
Different types of protiens
Enzymes, Structural/motor, signal/regulatory, receptor, transport, defensive, storage
Enzymes
catalytic molecules
How many kinds of amino acids are found in proteins?
20
How are amino acids linked?
peptide bonds
What are joined amino acids called?
polypeptides
Titin
a huge protein (34,000 AAs) that adds flexibility to muscle fibers
Thyrotropin
a short (3 AAs) polypeptide that controls secretion of thyroid hormone
Three amino acids with positive charges
Arginine (R), Histidine (H), Lysine (K)
Two amino acids with negative charges
Aspartic acid (D), Glutamic acid (E)
What do hydrophilic amino acids with polar but uncharged side chains form?
Hydrogen bonds
What are 5 hydrophilic amino acids with polar but uncharged side chains
Serine (S), Threonine (T), Asparagine (N), Glutamine (Q), Tyrosine (Y)
7 AAs with nonpolar hydrophobic side chains
Alanine (A), Isoleucine (I), Leucine (L), Methionine (M), Phenylalanine (F), Tryptophan (W), Valine (V)
What does Proline (P) do?
Can cause a kink or turn in a folded protein
What does Glycine (G) do?
Can fit in tight corners in a folded protein
What does Cysteine (C) do?
Can form a S-S bridge with another Cys
How does synthesis of proteins occur?
by condensation reactions between amino acid monomers; they fold into specific reproducible shapes as a result of the AA composition and order
Where are additional AA groups joined?
to the C-term
What is a C-term?
a monomer with a carboxyl group
What is an N-term?
The AA with a NH3+
Primary Structure
the linear sequence (order from N-term to C-term and composition) of AAs
Secondary Structure
regular, repeated pattern in different regions of the AA chain that arise from hydrogen bonding between AAs
Tertiary Structure
three-dimensional shape that arises from interactions (ionic, h-bonds, or hydrophobic) between R groups
Quaternary Structure
association of two or more polypeptides to form the functional protein (not present in all proteins)
Two types of secondary structure
alpha helix, beta pleated sheet
alpha helix
right-handed coil resulting from hydrogen bonding between N-H groups on one AA and C=O groups on another
beta pleated sheet
two or more polypeptide chains are aligned; hydrogen bonds form between the chains
What is primary structure stabilized by?
peptide bonds
What is secondary structure stabilized by?
hydrogen bonds
What is tertiary structure stabilized by?
hydrogen bonds, disulfide bridges, van der waals, ionic bonds
What does quaternary structure result from?
the interaction of subunits by hydrophobic interactions, van der Waals, ionic bonds, and hydrogen bonds
What is protein stability?
the tendency of a protein to maintain a native conformation
What is a disulfide bridge?
Formed by the terminal -SH group of cysteine reacting with another cysteine side chain
What factors after protein fold?
acidity, pH, protein fold
What does heat or high concentrations of polar molecules disrupt?
hydrogen bonds
What does pH changes disrupt?
ionic bonds between acidic and basic side chains
What does high concentration of polar solutes disrupt?
hydrogen bonding
What can an increase in salinity do?
cause protein denaturation
What is denaturation?
loss of 3D structure that is sufficient to cause loss of function
What do enzymes do?
lower the activation energy in almost all chemical reactions in cells, increasing the rate of reactions
What are some characteristics of enzymes?
are not altered by reactions, bring reactants together and increase their free energy, highly specific for their substrates (due to 3D structure)
What changes a protein’s function?
binding characteristics – ligand binding, binding affinity
Ligand
molecule or ion that binds to another molecule
What is ligand binding?
ligand binding is specific and involves several weak bonds, making a strong interaction
What is binding affinity
the strength of an interaction
Binding can cause a _________ which affects protein function. Define.
conformational change – change in shape
Cofactors
nonprotein molecules or inorganic ions that some proteins require in order to function (includes coenzymes and ATP)
Proteolysis
some long proteins must be shortened by breaking a peptide bond by hydrolysis.
Why does proteolysis occur?
So a protein can be synthesized but not activated until the appropriate time and location
What is an enzyme-substrate complex held together by?
hydrogen bonds, electrical attraction, covalent bonds
What is induced fit
An enzyme changing shape when bound to a substrate (but it always returns to it’s original form)
Do enzymes change final equilibrium? ∆G?
No
No
T/F an enzyme uses only one mechanism to catalyze a reaction?
F; an enzyme can use more than one
How does an enzyme catalyze reactions?
induce strain in the bonds of substrates, orienting the substrates to react, or charge polarization
metabolic pathway
series of reactions in which the product of one reaction is a substrate for the next
Enzyme-catalyzed reactions are often part of _____ pathways
metabolic
What do catabolic pathways do?
break down molecules into smaller molecules and release energy
What do anabolic pathways do?
synthesize complex molecules from simplier ones
When is the max reaction rate reached?
when all the enzymes are bound to substrate
what are inhibitors?
naturally occurring (and man-made) molecules that bind to the enzyme and slow reaction rates
Competitive inhibitors
compete with the natural substrate for binding sites (concentration-dependent)
Noncompetitive inhibitors
bind to the enzyme at a different site and alter the active site (they often function as metabolic regulators)
Reversible inhibitors
bonds noncovalently to the enzyme
Irreversible inhibitor
covalently bonds to side chains of the enzyme – permanently inactivates the enzyme
What is allosteric regulation?
Non-substrate molecules bind to a site other than the active site (the allosteric site) – noncompetitive inhibition
T/F Allosteric regulation can activate or inactivate enzymes
True
Reaction rates of _____________ are sensitive to small changes in substrate concentration
allosteric enzymes
Phosphorylation
a phosphate group is added by a protein kinase; in hydrophobic regions of the enzyme, the altered AA may induce a change to interact with hydrophilic regions
Which protein removes phosphate groups from proteins
phosphatases
T/F Phosphorylation is reversible process
True
T/F every enzyme functions best at the same temperature and pH
False
What is a lipid
a hydrophobic, mostly nonpolar covalent bond, structurally varied in size and arrangement of atoms
Triglycerides
lipid; glycerol and 3 fatty acids
Phospholipids
lipid; glycerol, 2 fatty acids, phosphate
Carotenoids
lipid; hydrocarbon chains with a terminal ring
steroids
lipid; have 4 ring structures
T/F lipids are considered polymers
F; many lipids are considered macromolecules but not polymers
Describe fatty acids
amphipathic; has carbons on it’s tail that can be joined by single or double bonds
amphipathic
having opposing chemical properties
saturated fatty acids
no double bonds between carbons – saturated with H atoms
unsaturated fatty acids
some double bonds in the carbon chain
What is a monounsaturated fatty acid?
one double bond
What is a polyunsaturated fatty acid?
more than one
What type of fatty acid is bent? Why?
Unsaturated, because of double bonds
Why fatty acid can be packed closest together?
Saturated fatty acids, because they are straight and unsaturated fatty acids are bent
What is glycerol
An acid
What are the three parts of a phospholipid?
A hydrophilic head, phosphate, glycerol, hydrocarbon chains
Phospholipid Bilayer
Hydrophobic tails pack together and the phosphate-containing heads face outward, where they interact with water
What is a lipoprotein
A single spherical layer of phospholipids, in conjunction with embedded proteins, that transport lipids in aqueous environments
What are waxes?
long, nonpolar chains that are very hydrophobic and make good barriers
What are steroid hormones?
lipid-based chemical signals
What are vitamins?
Small molecules that are not synthesized by the body and must be acquired in the diet
What are the functions of fats?
energy storage, insulation, cell membranes, pigments, hormones, vitamins
