biology chapter 3 Flashcards
Hydrocarbons
Molecules consisting only of carbon hydrogen - stores energy
Carbon
Framework of biological molecules consists primarily of carbon bonded to
Carbon, O, S, N, P or H
Can form up to 4 single covalent bonds - very versatile - forms chains, branches, rings, tubes, balls, coils
Isomers
Molecules with the same molecular or empirical formula
Structural isomers
Structure of carbon skeleton is different
Stereoisomers
Same C skeleton but differ in how groups attached
Enatiomers
Type of stereoisomer
- Mirror image molecules
- chiral molecular- when C is bonded to 4 different molecular, these can rotate either to the left or to the right - D form and L form
- D sugars and L amino acids
Macromolecules
Polymers- built by linking monomers
Monomers- small similar chemical subunits
Dehydration synthesis
Formation of large molecules by the removal of water
Monomers are joined to form polymers
Hydrolysis
Breakdown of large molecules by the addition of water
Polymers are broken to monomers
Carbohydrates
Molecules with a ratio 1:2:1 of carbon, hydrogen, oxygen
Empirical formula CH2O
C-H covalent bonds much energy
- carbohydrates are good energy storage molecules
Examples: sugars starch glucose
Monosaccharides
Simplest carbohydrate- 3>6 C atoms
6 carbon sugars play important roles
Fructose is a structural isomer of glucose
Galactose is a stereoisomer of glucose enzymes. That act on different sugars can distinguish structural and strereoisomers of the basic six carbon skeleton
Disaccharide
2 monosaccharides linked together by dehydration synthesis
Used for sugar transport or energy storage
Enzymes for glucose don’t recognize it attached as a disaccharide
Linkage that is connected by glycosystic
Polysaccharides
Long chains of monosaccharides -linked through dehydration synthesis -glycosidic linkages Energy storage plant use as starch animals use glycogen Structural support plants use cellulose anthropods use as chitin Insoluble
Nucleus acids
Information molecules
Polymers- nucleus acid
Monomers- nucleotides
-sugar+ phosphate group+ nitrogenous base
-sugar is deoxyribose in DNA or ribose in RNA
Nitrogenous bases include
Purines: adenine and guanine
Pyrimidines: thymine, cytosine, uracil
Nucleotides connected by phosphodiester bonds- bonded by phosphate groups
DNA- 1 fewer oxygen
RNA-1 more oxygen
DNA
Encodes information for amino acid sequence of proteins
- sequences of bases
Double helix - 2 polynucleotide strands canine tend by hydrogen bonds
- base pairing rules a with t or y in RNA
C with G
Gene
Section of DNA that causes certain amino acids to bond in a certain a order = polypeptide
RNA
RNA similar to DNA except
-Contains ribose instead deoxyribose OH and C2
-contains uracile instead of thymine
Single polynucleotide strand, not helical
RNA I temples from DNA
RNA uses information in DNA to specify sequence of amino acids in proteins
Proteins functions
- Enzyme catalyst
- Defense
- transport
- Support
- Motion
- Regulation
- storage
Proteins
Proteins are polymers -composed of 1 or more long, unbranched chains of amino acids. -eAch chain is a polypeptide Amino acids are monomers Amino acid structure -central carbon atom -amino group - carboxyl group - single hydrogen - variable R group
Amino acids joined by dehydration synthesis
- peptide bond
.
4 levels of structure
Part one
The shape of a protien determines its function and the shape is determined by the amino acid sequence
- Primary structure - sequence of amino acids chain of amino acid= polypeptide chain
- Secondary structure- interaction of peptide R groups and the H in peptide backbone
4 levels of structure part 2
- Tertiary structure- final fold shape of a globular protein- hydrophobic exclusion - internal amino acids are non polar( hydrophobic) and are are driven into interior of the protein and the more polar and charged are on the surface of the folded polypeptide chain
- stabilized by a number of forces- ionic bonds, van. Der Walls forces, disulfide bridges , H bonds
- final level of structure for proteins consisting of only a single polypeptide chain
- quarterly structure- arrangement of individual chains (sub units) in a protein with 2 or more polypeptide chains
Lipids
Loosely defined group of molecules with one main chemical characteristic
High proportion of nonpolar C-H bonds causes the molecule to be hydrophobic
Ex- fats, oils ,waxes, and even some vitamins
High energy molecules
Fats
Triglycerides( triacylglycerol)
- composed of 1 glycerol and 3 fatty acids
-need not to be identical
-chain length varies
Saturated- no double bonds between carbon atoms
•higher melting point, animal origin
Unsaturated -1 or more double bond
-low melting point, plant origin
Trans fat- are artificially made with hydrogens