71 terms

Gen Bio 2: Chapter 3 Lecture Notes


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Organic molecules formed when (Blank) atoms covalently bond to other (Blank) atoms to form carbon backbone
C forms (Blank) covalent bonds (has four valence electrons)
(Blank) can bond with large number of elements
C-C bonds are (Blank), but can be (Blank)
Strong, Broken
Molecules with same molecular formulas, but different atom arrangement and properties
Structural isomers
Differ in bonding arrangement of atoms
Geometric isomers
Differ in spatial arrangement of atoms
Properties of organic molecules
-Start with hydrocarbon
- non polar, hydrophobic and insoluble in water
-Replace H's with functional group(s)
- group of atoms that determines chemical behavior of molecules
Functional Groups
-Hydroxyl: OH
-Carbonyl: C=O
-Carboxyl: COOH
-Amino: NH2
-Phosphate: PO4H2
-Sulfhydryl: SH
Hydroxyl: OH
Polar and hydrophilic
Carbonyl: C=O
Polar and hydrophilic
Carboxyl: COOH
-Weakly acidic: COO-
-Ionic or polar
-Part of amino acids
Amino: NH2
-Weakly basic: NH3+
-Ionic or polar
-Part of amino acids and nucleic acids
Phosphate: PO4H2
-Weakly acidic: PO4^2-
- Hydrophilic
-Ionic or polar
-Part of nucleic acids and some lipids
Sulfhydryl: SH
-Part of some amino acids
Large biological molecules
Most macromolecules are polymers: long chains of monomers
-Monomers covalently bonded through condensation (dehydration) reactions to form polymers
-Polymers degraded to monomers by hydrolysis reactions
-Energy and structure
-Contain C,H, and O (1:2:1 rato)
-One sugar unit of 3-7 atoms
-Often form rings in solution
-Two monosaccharides covalently bonded by glycosidic linkage
-Hydrolyzed to monosaccharides during digestion
-Many repeating monosaccharides
Energy storage polysaccharides:
-Strach: glucose polymer in plants
-stored in amyloplasts
-Glycogen: glucose polymer in animals
-Stored in liver and muscle cell
Structural Polysaccharides
Cellulose, Chitin
Glucose polymer in plant cell walls, insoluble
Glucosamine polymer, OH group replaced by NH2, cell walls of fungi, exoskeleton of arthropods
-Energy storage, cell membranes, and hormones
-Consist mainly of C and H atoms
-Few O atoms
-Usually hydrophobic and insoluble in water
-Main storage fats
-Glycerol + three fatty acids
-Fatty acid: long, unbranched hydrocarbon with COO- at one end
-Joined by ester linkages
Saturated Fatty Acids
-C atoms are "saturated" with H atoms
-Contain maximum number of H atoms
-Fats high in saturated fatty acids usually solid at room temperature
Unsaturated Fatty Acids
-Include C=C double bonds
-not fully saturated with H atoms
-Fats with high proportion of unsaturated fatty acids usually liquid at room temperature
One C=C double bond
More than one C=C double bond
-Form cell membranes
- one end hydrophilic, other end hydrophobic
-Organic group + phosphate group + glycerol + 2 fatty acids
-Orange and yellow plant pigments involved in photosynthesis
-5-C isoprene unit
-Animals convert carotenoids to vitamin A
-Molluscs, insects and vertebrates covert vitamin A to retinal for vision
-Carbon atoms arranged in 4 attached rings
-monomer: 5-C isoprene unit
-Cholesterol, bile salts, some hormones
Complex (Blank) are made form amino acids
All amino acids have the same basic structure
-Central C bonded to amino group (-NH2), carboxyl group (-COOH) and R group
Proteins exist in (Blank) form at cellular pH
How many common amino acids are in proteins?
Classification based on properties of R group
-Non polar and hydrophobic
-Polar and hydrophilic
-Acidic and hydrophilic
-side chain with ionized carboxyl group
-Basic and hydrophilic
-side chain with ionized amino group
Essential amino acids cannot be synthesized by (Blank) precursors and must be obtained from diet
Nine essential amino acids for humans, T or F?
Carboxyl group of one amino acid covalently bonds to amino group of another amino acid by a peptide bond, T or F?
Multiple amino acids
Two amino acids form what?
Primary structure
-Linear sequence of amino acids in polypeptide chains
-Determines final portion conformation and therefore function
Some regions of a polypeptide chain exhibit secondary structure formed by (Blank)
hydrogen bonding
-Polypeptide chain forms helical coil
-Confers elasticity to proteins
Beta-pleated sheet
-Between different regions of polypeptide chain or between adjacent polypeptide chains
-Confers strength to proteins
Tertiary Structure
Overall shape of an individual polypeptide chain, determined by interactions among R groups
Quaternary Structure
Two or more polypeptide chains folded together; maintained by hydrogen bonds, ionic bonds, hydrophobic interactions, and/or disulfide bridges; Some proteins are comprised of only one polypeptide and do not have quaternary structure
Amino acid sequence dictates folding, but some proteins require molecular chaperones, T or F?
Denaturation occurs when protein loses its 3-D conformation, T or F?
Nucleic Acid Function
Store and transmit hereditary information and determine which proteins a cell makes
DNA(deoxyribonucleic acid)
-Composes genes
-Stores information for protein and RNA sequence
RNA (ribonucleic acid)
-Intermediate between DNA and proteins
-Directly participates in protein synthesis
-Ribozymes are biological catalysts
Polymers of nucleotides
Nitrogenous base + 5-C sugar + phosphate group(s)
Nitrogenous bases
-Double ring purines
-Adenine, guanine
-Single-ring pyrimidines
-Cytosine, thymine (Only in DNA), uracil (Only in RNA)
5-C sugar
Ribose (RNA) or deoxyribose (DNA)
Nucleotides joined by (Blank) linkages
Phosphate group covalently linked to (Blank) of adjacent nucleotide
Single stranded
Double stranded
Strands of DNA
Joined by hydrogen bonds between nitrogenous bases
ATP (adenosine triphosphate)
-Adenine + ribose + 3 phosphate groups
-Primary energy molecule
-Donates energy to other molecules by transferring phosphate group
-GTP plays similar role
NAD+ (nicotinamide adenine dinucleotide)
-Electron transfer molecule in biological oxidation and reduction reactions
A compound contains hydroxyl groups as its predominant functional group. Which of the following statement is true concerning this compound?
A) It lacks an asymmetric carbon, and it is probably a fat or lipid.
B) It should dissolve in water.
C) It should dissolve in a nonpolar solvent.
D) It won't form hydrogen bonds with water.
E) It is hydrophobic.
B) It should dissolve in water
2. Which two functional groups are always found in amino acids?
A) ketone and methyl
B) carbonyl and amino
C) carboxyl and amino
D) amino and sulfhydryl
E) hydroxyl and carboxyl
C) carboxyl and amino
3. Amino acids are acids because they always possess which functional group?
A) amino
B) carbonyl
C) carboxyl
D) phosphate
E) hydroxyl
C) carboxyl
4. A carbon skeleton is covalently bonded to both an amino group and a carboxyl group. When placed in water it:
A) would function only as an acid because of the carboxyl group.
B) would function only as a base because of the amino group.
C) would function as neither an acid nor a base.
D) would function as both an acid and a base.
E) is impossible to determine how it would function.
D) would function as both an acid and a base.
5. Which functional groups can act as acids?
A) amino and sulfhydryl
B) carbonyl and carboxyl
C) carboxyl and phosphate
D) hydroxyl and aldehyde
E) ketone and amino
C) carboxyl and phosphate