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What are some functions of lipids?
Form membranes (barriers), serve as fuel (hydrocarbon chains rich in energy), serve as signal (lipid derivatives used to transmit signals)
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What are some properties of lipids?
Dual chemical properties, hydrophobic and hydrophilic
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Lipids have hydro (phobic/philic) heads and hydro (phobic/philic) tails
- Hydrophilic heads
- Hydrophobic tails
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What purpose do bilayers serve?
Membranes compartmentalize cells and separate the outside from the inside of the cell
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What is a membrane?
A lipid bilayer
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What types of membrane proteins are there?
Transmembrane and membrane associated proteins
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Why can membranes be selectively permeable?
Influenced by the presence of proteins associated with the membrane
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What are some examples of selective permeability in membranes?
Channels, pores, transporters, receptors
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What do prokaryotic cell membranes lack?
Intracellular membranes. Only possess inner (plasma) membrane, cell wall, and outer membrane
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What are organelles?
Found in eukaryotic cells and they are membrane-enclosed compartments
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What purpose do organelles serve?
Biochemical functions are sequestered in organelles
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Where is cytoplasm?
Surrounded by plasma membrane, but not enclosed by any intracellular membranes
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How is the cytoplasm organized?
Cytoskeleton (series of structural filaments)
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What does the rough ER do?
Has ribosomes attached and involved in processing new proteins
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What does the smooth ER do?
lacks ribosomes and plays variety of roles like detox in the liver
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What is Tay-Sachs Disease
Results from defect in lysosome function and leads to muscle weakness, dementia, and early childhood death
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What is exocytosis? Give examples.
- Proteins deposited outside of the cell.
- Hormones such as insulin, antibodies, digestive enzymes, neurotransmitters
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What is exocytosis?
Bringing biomolecules into cells
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What is an endosome?
Structure that forms when the plasma membrane invaginates and buds off
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What is familial hypercholesterolemia?
Defective endocytosis of cholesterol from the blood leads to high blood cholesterol levels and heart attacks
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What is phagocytosis?
Large amounts of material can be taken into the cell
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What is Brownian Movement?
Movement of a molecule or ion along a random path
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What permits dynamic interactions between molecules?
Weak bonds
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What does Brownian Movement of water do?
Diffusion of biomolecules throughout cells, within organisms, and within the environment
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List stabilizing forces in molecules in order from strongest to weakest?
Covalent bonds, electrostatic interactions, hydrogen bonds, Van der Waal interactions, hydrophobic interactions
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What does the polarity of water account for?
Water's ability to dissolve biochemical molecules
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What is Coulomb's Law?
- The energy of an electrostatic interaction between two charges: E=kq1q2/Dr
- D=1 in vacuum and 80 in H2O
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How does water affect electrostatic interactions?
Weakens them
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What do Hydrogen bonds form between?
- Electronegative atom and hydrogen atom
- F-H
- O-H
- N-H
- **Lengths of H bonds are longer than covalent bonds
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What accounts for the cohesiveness of water?
Water is very polar and H-bonds between water molecules cause cohesiveness
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How does water affect H-bonded molecules?
Water disrupts hydrogen bonds between two molecules by competing for the H-bonding capability
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What molecules can interact in Van der Waals interactions?
Nonpolar, uncharged biomolecules
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What causes Van der Waals interactions?
Fluctuation and asymmetry of electrons in atoms causing fleeting dipoles
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What interactions are DNA strands held together by?
H-bonds and Van der Waals interactions
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Why is it important that the bonds between DNA strands aren't strong?
DNA needs to be able to be broken apart by enzymes so the genetic information can be accessed in replication and transcription
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How many H-bonds are between A-T and C-G?
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What is the hydrophobic effect?
Spontaneous clustering of hydrophobic molecules in water
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What is the advantage of having nonpolar molecules stick together when immersed in water?
More disorder of water (because less used to make a solvent cage) has increased entropy and is energetically favorable
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What does it mean to be amphipathic and what are the results in aqueous environments?
Having both hydrophilic and hydrophobic properties. In water, phospholipids form membranes
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What is pH a measure of? What is it defined as?
The H+ concentration in a solution. pH=-log10 ([H+])
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Acid/base: Which is the proton donor and which is the proton acceptor?
- Acid: proton donor
- Base: proton acceptor
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What is gastric esophageal reflux disease (GERD)?
Pathological condition that results when the esophagus is exposed to the acid of the stomach
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What is Ka and how does it deal with acid ionization?
Equilibrium constant/acid dissociation constant. The larger the Ka, the stronger the acid
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What is the Henderson-Hasselbalch equation?
 - Relates the pH and the ratio of base to acid. Used to determine the dissociation of an acid at a particular pH value.
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When pH=pKa . . .
[A-]=[HA]
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When pH>pKa . . .
A- predominates
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When pH<pKa . . .
HA predominates
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What is the buffer?
An acid-base conjugate pair that resists changes in pH of a solution
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What pH is a buffer most effective?
Near its pKa value
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What does it mean to be mono/di/triprotic?
The conjugate acid-base pairs can release 1/2/3 protons
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What are functional groups?
Array of atoms that have distinctive chemical properties
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