Study Questions #2 Flashcards
September 4-7
What are hydrophobic interactions, and why are they important for living organisms?
Hydrophobic molecules are nonpolar. Hydrophobic interactions are two nonpolars interacting. Water excludes these molecules and forces them to associate together. This is how the final shapes of biopolymers.
Why do water and oil separate after you shake them up?
Water pushes oil away because it can’t hydrogen bond with oil.
What is a mole (to a chemist)?
quantity of a chemical that contains avogadro’s number of molecules(easier to weigh molecules than count them)
What is pH and why is it important to living organisms?
Power of Hydrogen. Measures how acidic something is. most reactions in the body have an optimal pH at which they operate best so pH must remain constant. pH= -log[H]
What is the difference in [H+] between a solution whose pH is 5 and a solution whose pH is 8?
- 10 fold increase between each pH.
What is a buffer?
minimizes changes in pH. A H+ resvoir donating or receiving as needed to keep pH constant.
Why is life based on carbon?
carbon can be assembled into large macromolecules; forms backbone of these molecules. Carbs, Lipids, Proteins, Nucleic acids
What is a functional group (in organic chemistry) and why are they so important?
groups of atoms that confer certain chemical properties
List the 7 most important functional groups in biological molecules.
hydroxyl(-OH), Sulfhydryl(-SH), Carbonyl(C=O),phosphate(-PO4), Carboxyl(-COOH), methyl(-CH3), Amino(-NH2)
What is a macromolecule, and what features do all macromolecules have in common?
large molecule; polymer of similar polar units
What types of macromolecules do you find in living organisms?
monomers- monosachharide,amino acid,fatty acid and glycerol, nucleotides Polymer-polysaccharide,fat,protein,nucleic
What is a dehydration reaction?
when two monomers bond together through the loss of a water molecule
What is an anabolic reaction?
Builds larger molecules from smaller molecules
What is a hydrolytic reaction?
when water is added to a polymer to split it apart
What is a carbohydrate, and what functions do carbohydrates perform?
Sugars. Store energy, structural, signaling
Why are carbohydrates good for storing energy?
large number of C-H bonds
What is an isomer?
Compound with same structural formula, but arranged differently
What is the difference between a structural isomer and a stereoisomer?
Structural- functional groups on different C Stereoisomer- functional groups attached to same carbon but in a different orientation.
What is a transport dissacharide?
disaccharides made by plants to keep sugars from being broken down as they pass through the plant. Maximizes the amount of sugar that is stored in the root
What is the difference between starch, glycogen and cellulose?
All are glucose polymers.
difference between alpha and beta- when glucose forms a ring the OH group is either below(alpha) or above(beta) the plane of the ring.
starches- glucose joined by 1-4 alpha links (C1 bonds to C4 of next glucose) (coil in water because glucoses bond to each other instead of water- makes them insoluble- slows hydrolysis)
glycogen- branched starch from animals- branches by 1-6 alpha links, this makes it soluble
cellulose- glucose joined by 1-4 beta links(glucose alternate C6 up then C6 down)- forms chains instead of coils- glucose hydrogen bond adjacent chains- beta 1-4links makes it hard to digest
Why is starch insoluble in water?
Its nonpolar and forms coils.
What is carbo-loading and how does it work?
strategy used by athletes
maximizes storage of glycogen in the muscles as a source of energy
diet night before race; fruits, vegetables, whole wheat and grains
Why is it so much harder to digest cellulose then starch?
Cellulose is formed from beta glucose and few organisms have the enzyme to break it down
Why do beans give you gas?
beans contain roffinase sugars with alpha galactose 1-6 links that humans cannot digest easily; bacteria can ferment the sugar giving off CO2 gas
What are proteins and what functions do they perform?
polymers of amino acids; structural, energy storage, catalysts(enzymes), signaling, transporter, defense(antibodies)
What are amino acids and what are the five groups of amino acids.
building blocks of proteins; 20 different; ionizable; polar, but uncharged ; nonpolar; aromatic; special function
Why do we say that proteins are made of “N to C”
proteins are made n to c. link amino of one amino acid to COOH of chain; amino is nose, carboxyl is tail. Dog sled example: the second dog’s nose is attached to the first dog’s tail.
Why is the structure of a protein so important?
structure determines function
What is the difference between the primary and secondary structure of protein?
primary structure is the amino acid sequence of a protein; secondary structure is when the primary structure hydrogen bonds to itself between amino and carboxyl groups to form alpha helix and beta pleated sheets.
What is the difference between the secondary and tertiary structure of protein?
secondary structure is when the primary structure hydrogen bonds to itself between amino and carboxyl groups to form alpha coils and beta sheets; tertiary structure is when water bends secondary structure due to interactions with R groups.
What is the quaternary structure of a protein?
Quaternary structure is final shape of protein with two or more subunits (polypeptide chains or chains of amino acids)
What is a motif, and what is a domain and how do they differ (when talking about protein structure)?
motif- combo of secondary structures- can’t function independently(ex: key on keyboard)- used to infer functions of unknown proteins
domains- structurally independent units- connected by single polypeptide chain- fold and function independently- many proteins have several domains
Why do proteins fold into their tertiary structure?
interactions with water and R groups; push nonpolars to middle; pull hydrophilic amino acids outward
What types of bonds help proteins maintain their tertiary structure?
hydrogen bonds with water, between N to C of backbone between R groups
Ionic bonds between acids and bases R groups
Vanderwaals interactions
Disulfide bridges between cysteine residues
Why do proteins fold into their final structure faster than we expect?
chaperonins help; temperature, pH, [salt], and nonpolar solvents also affect how fast they fold
What are nucleic acids?
polymers of nucleotides
What are the functions of DNA?
stores genetic information in its sequence of nucleotides
What are the functions of RNA?
retrieves information
What are nucleic acids made of?
Nucleotides, which are composed of a sugar, a phosphate group, and a nitrogen containing base
What are the two kinds of bases found in nucleic acids?
pyrimidines, purines
What bases do you find in DNA and what bases do you find in RNA?
A,C,T,G - DNA; A,C,U,G- RNA
What functions do bases serve in nucleic acids?
order of bases stores genetic information
What is the primary structure of a nucleic acid?
Code of nucleotides
Why do we say that nucleic acids are made 5’ to 3’?
phosphodiester bonds link PO4 on 5’C to 3’OH at end
Why do we care that nucleic acids are made 5’ to 3’?
- 2 DNA form double helix- hydrogen bonds between bases link them, Strands go opposite ways, each strand is the reverse and complement to the other
What are the main differences between DNA and RNA?
- Single and Double Strand
- U instead of T
- deoxyribose sugar and ribose sugar
What holds the backbone of nucleic acid together?
sugar and phosphate
What is the third degree structure of of a DNA molecule?
double helix
What holds the two strands of a DNA molecule together?
hydrogen bonds
Why can’t RNA form a double helix?
RNA is single stranded, ribose too big and bulky
Why does RNA adopt complicated shapes?
sequence of bases (A,U,C,G). gives it shape to interact with other molecules, allows catalytic activity
What is a ribosome?
a biological catalyst made of RNA
Why do most biologists believe that RNA became before DNA?
Rna came first, RNA synthases are older than DNA synthases, DNA evolved to protect genome because it is a more chemically stable compound
Why does Benedict’s reagent react with glucose but not with starch?
Glucose is a reduced sugar, benedict’s reacts with a free aldehyde group; however starch is not a reduced sugar and has no free aldehyde group
Why does iodine stain starch but not glucose?
iodine fits between coils of starch but glucose itself has no coils
Why does Bradford’s reagent detect proteins?
reacts with amino groups
Why does the Sudan dye detect lipids?
It is hydrophobic
Why does diphenylamine detect DNA but not RNA?
reacts with deoxyribose
Why did some amino acids travel farther up the TLC plates than others?
some are more attracted to solvent than silica gel on the TLC plate
