Transcript H 2 O + + H 2 O

AP Bio Exam Review:
Biochemistry & Cells
Elements of Life
• 25 elements
• 96% : C, O, H, N
• ~ 4% : P, S, Ca, K & trace
elements (ex: Fe, I)
Hint: Remember CHNOPS
II. Atomic Structure
• Atom = smallest unit of matter that
retains properties of an element
• Subatomic particles:
Mass
Location
Charge
(dalton or AMU)
neutron
1
nucleus
0
proton
1
nucleus
+1
electron
negligible
shell
-1
Bonds
Covalent
Ionic
Hydrogen
All important to life
Form cell’s
molecules
Quick reactions/
responses
H bonds to other
electronegative
atoms
Strong bond
Weaker bond
(esp. in H2O)
Even weaker
Made and broken by chemical reactions
Weaker Bonds:
Van der Waals Interactions: slight, fleeting
attractions between atoms and molecules
close together
– Weakest bond
– Eg. gecko toe hairs + wall surface
1. Polarity of H2O
• O- will bond with H+ on a different molecule of
H2O = hydrogen bond
• H2O can form up to 4 bonds
H2O Property
Chemical
Explanation
Examples of
Benefits to Life
Cohesion
•polar
•H-bond
•like-like
↑gravity plants, trees
transpiration
Adhesion
•H-bond
•unlike-unlike
plants xylem
bloodveins
Surface Tension
•diff. in stretch
•break surface
•H-bond
bugswater
Specific Heat
•Absorbs & retains E
•H-bond
oceanmoderates
temps protect
marine life (under ice)
Evaporation
•liquidgas
•KE
Cooling
Homeostasis
•Polarityionic
Good dissolver
Universal Substance
4. Solvent of life
• “like dissolves like”
Hydrophilic
Hydrophobic
Affinity for H2O
Appears to repel
Polar, ions
Nonpolar
Cellulose, sugar, salt
Oils, lipids
Blood
Cell membrane
Acids and Bases
Acid: adds H+ (protons); pH<7
Bases: removes protons, adds OH-; pH>7
Buffers = substances which minimize changes
in concentration of H+ and OH- in a solution
(weak acids and bases)
• Buffers keep blood at pH ~7.4
• Good buffer = bicarbonate
Figure 3.9 The pH of some aqueous solutions
Functional Groups
Functional Group
Molecular Formula
Names & Characteristics
Draw an Example
Hydroxyl
-OH
Alcohols
Ethanol
Carbonyl
>CO
Ketones (inside skeleton)
Aldehydes (at end)
Acetone
Propanol
Carboxyl
-COOH
Carboxylic acids (organic
acids)
Acetic acid
Amino
-NH2
Amines
Glycine
Sulfhydryl
-SH
Thiols
Ethanethiol
Phosphate
-OPO32- / -OPO3H2
Organic phosphates
Glycerol phosphate
Monomers
•Small organic
•Used for building
blocks of polymers
•Connects with
condensation reaction
(dehydration
synthesis)
Polymers
Macromolecules
•Long molecules of
•Giant molecules
monomers
•2 or more polymers
•With many identical
bonded together
or similar blocks linked
by covalent bonds
ie. amino acid  peptide  polypeptide 
protein
smaller
larger
Dehydration Synthesis
(Condensation Reaction)
Hydrolysis
Make polymers
Breakdown polymers
Monomers  Polymers
Polymers  Monomers
A + B  AB
AB  A + B
+
+ H2O
+ H2O
+
I. Carbohydrates
• Fuel and building
• Sugars are the smallest carbs
 Provide fuel and carbon
• monosaccharide  disaccharide 
polysaccharide
• Monosaccharides: simple sugars (ie. glucose)
• Polysaccharides:
Differ in
 Storage (plants-starch, animals-glycogen)
 Structure (plant-cellulose, arthropod-chitin)
position &
orientation of
glycosidic
linkage
II. Lipids
A.Fats: store large amounts of energy
– saturated, unsaturated, polyunsaturated
B.Steroids: cholesterol and hormones
C.Phospholipids: cell membrane
– hydrophilic head, hydrophobic tail
– creates bilayer between cell and external
environment
Hydrophilic head
Hydrophobic tail
Four Levels of Protein Structure:
1. Primary
– Amino acid sequence
– 20 different amino acids
– peptide bonds
2. Secondary
– Gains 3-D shape (folds, coils) by H-bonding
– α helix, β pleated sheet
3. Tertiary
– Bonding between side chains (R groups) of amino acids
– H & ionic bonds, disulfide bridges
4. Quaternary
– 2+ polypeptides bond together
amino acids  polypeptides  protein
• Protein structure and function are sensitive to
chemical and physical conditions
• Unfolds or denatures if pH and temperature
are not optimal
IV. Nucleic Acids
Nucleic Acids = Information
Monomer: nucleotide
DNA
•Double helix
•Thymine
•Carries genetic code
•Longer/larger
•Sugar = deoxyribose
RNA
•Single strand
•Uracil
•Messenger (copies),
translator
•tRNA, rRNA, mRNA, RNAi
•Work to make protein
•Sugar = ribose
Comparisons of Scopes
Light
Electron
• Visible light passes through
specimen
• Light refracts light so
specimen is magnified
• Magnify up to 1000X
• Specimen can be
alive/moving
• color
• Focuses a beam of electrons
through specimen
• Magnify up to 1,000,000
times
• Specimen non-living and in
vacuum
• Black and white
Prokaryote Vs. Eukaryote
•
•
•
•
•
“before” “kernel”
No nucleus
DNA in a nucleoid
Cytosol
No organelles other
than ribosomes
• Small size
• Primitive
• i.e. bacteria
• “true” “kernel”
• Has nucleus and nuclear
membrane
• Cytosol
• Has organelles with
specialized structure
and function
• Much larger in size
• More complex
• i.e. plant/animal cell
Parts of plant & animal cell p 108-109
• Cells must remain small to maintain a large
surface area to volume ratio
• Large S.A. allows increased rates of chemical
exchange between cell and environment
Animal cells have intercellular junctions:
• Tight junction = prevent leakage
• Desomosome = anchor cells together
• Gap junction = allow passage of material
Cell Membrane
6 types of membrane proteins
Passive vs. Active Transport
• Little or no Energy
• Moves from high to low
concentrations
• Moves down the
concentration gradient
• i.e. diffusion, osmosis,
facilitated diffusion
(with a transport
protein)
• Requires Energy (ATP)
• Moves from a low
concentration to high
• Moves against the
concentration gradient
• i.e. pumps,
exo/endocytosis
hypotonic / isotonic / hypertonic
Exocytosis and Endocytosis transport large
molecules
3 Types of Endocytosis:
• Phagocytosis (“cell eating” solids)
• Pinocytosis (“cell drinking” fluids)
• Receptor-mediated
endocytosis
• Very specific
• Substances bind to
receptors on cell surface