BIOL 111 Chapter 5

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Macromolecules

Functional Groups play vital roles

Monomer: HO—(X)—H

Polymers: made of many monomers

Dehydration removes 2H and O to join monomers together (Removes H₂O)
Hydrolysis breaks polymers back into monomers by adding H₂O back

Tuesday, September 7, 2010

BIOL 111 Review Chapter 1-5

Assignment: from eLearning

Most hydrocarbon macromolecules are hydrophobic

Molecule	Function(s)
Carbohydrates	Store energy; structural
Lipids	Store energy; structural; hormones (signaling)
Proteins	Widely varied (Table 5.1)
Nucleic acids	Instructions for building and reproduction

Carbohydrates

Monosaccharides

a monomer

EX: glucose, fructose, ribose

General formula: (CH₂O)_n
Linear and ring forms
Numbered carbons

Disaccharides

Two monosaccharides linked via glycosidic linkage (dehydration reaction that bonds Carbon to Oxygen: —C—O—C—)

Used for fast energy

Examples:

Maltose = glucose + glucose (1-4 linkage)
Sucrose = glucose + fructose
Lactose = glucose + galatose

Polysaccharides

Polymers of monosaccharides

Energy storage and structures

Storage:
- Starch: plants; stored in chloroplasts
- Glycogen Animals
Structural:
- Cell walls = cellulose; LONG parallel strands held together by hydrogen bonds
- Exoskeletons = chitin; modified structure helps hold it in hydrogen bonds

Lipids

All are hydrophobic

Fats

EX: saturated/unsaturated fats

Two components: Glycerol + 3 fatty acids
Linked via ester linkages (Carbon double bonds to one oxygen and single bonds to another)
formed by dehydration synthesis

Saturated: all opportunities to form a bond between H and C have been filled Unsaturated: Double bond between two carbons in hydrocarbon chain, so structure is bent

Phospholipids

3 components: Phosphate group + Glycerol + 2 fatty acids
2 layers form cell membranes: phospholipid bilayer
Hydrophilic head, hydrophobic tails

Steroids

EX: Cholesterol

4 carbon rings
Structure does not change
hydrophobic; goes in and out of cell membranes easily

Proteins

VERY diverse structures functions (Once again, see Table 5.1)
Amino acid is monomer form of protein
20 Amino Acids: KNOW which amino acids are polar (hydrophilic), non-polar (hydrophobic), basic, or acidic

Proteins are made out of polypeptides, which are polymers made from amino acids joined by dehydration reaction that creates a peptide bond.

Backbone formed: H—[N—C—C]—[N—C—C]— . . . —[N—C—C]—OH Head/Beginning is amino end: +H₃N

Amino Acids

Only 20 different types: Figure 5.17

Structure of an Amino Acid

α carbon has 4 bonds:

↑ R-group (differs for each amino acid)
→ Carboxyl Group: —COOH
↓ Hydrogen
← Amino Group: NH₂—

Structures and Folding

When completed, proteins fold into 3D shapes based on hydrogen bonds, electronegativity, hydrophilia/hydrophobia, etc.

Chaperonins (chaperone proteins) assist in folding process: protein goes in; cap goes on; container changes shape; encapsulated protein folds; cap comes off; folded protein released.

Shape can accept certain other molecular structures (like a puzzle piece):

enzymes will change shape when it accepts molecules to allow bonding to occur easier.
antibodies will bind to certain proteins found in viruses and bacteria

primary structure: The actual order/sequence of amino acids when protein is stretched out
secondary structure: α helix or β pleated sheet; interactions between backbone atoms; β pleated sheets like to line up side-by-side because of hydrogen bonds between amino acids
tertiary structure: Interactions between R-groups; Hydrogen bonds, Hydrophobic interactions and van der Walls interactions; Disulfide bridge; Ionic bonds
quaternary structure: Interactions between separate polypeptide chains/strands (i.e. between separate proteins)

Hemoglobin is formed from four separate polypeptides of two different proteins: 2 α chains and 2 β chains

Denaturation

disruption of protein structure

heat disrupts H-bonds
pH disrupts ionic bonds
chemicals disrupt ionic, disulfide, and hydrogen bonds
nonpolar organic solvent turns inside-out

Sickle-cell anemia is caused by mutation in primary structure of hemoglobin that prevents hemoglobin from folding properly (leaves hydrophobic region exposed, which causes bad molecules to crystalize into unusable shapes

Thursday, September 9, 2010

Nucleic Acids

Storage and transmission of hereditary information: job is to store amino acid sequences for building structure and reproduction

Two types:

deoxyribonucleic acid (DNA)

Double-helix structure; used for storage inside chromosomes in nucleus

ribonucleic acid (RNA)

single strand of nucleic acids

Used to carry information to ribosomes for protein synthesis:

DNA → RNA → protein

Monomer (Nucleotide)

Nucleoside is the following components without phosphate group

pentose sugar "platform"
- deoxyribose (found in DNA; no-oxygen-ribose) OR
- ribose (found in RNA) (OH on Carbon #2 instead of just H)
Nitrogenous bases attached to pentose:
- Pyrimidines (one carbon ring)
  - Cytocine (C; matches to G)
  - Thymine (T; in DNA; matches to A)
  - Uracil (U; in RNA; matches to A)
- Purines (two carbon rings)
  - Adenine (A; matches to T or U)
  - Guanine (G; matches to C)

Polymer (Polynucleotide)

Monomer nucleic acids linked by phosphate group on Carbon #5 via phosphodiester bonds (dehydration synthesis)

Sequence goes 5' → 3' (Carbon #5 bonds to Carbon #3)

DNA monomers held together by hydrogen bonds