chapter 2 chemistry Flashcards
elements that make up body mass
oxygen, carbon, hydrogen, and nitrogen
planetary model
outdated, general orbit of electrons,
orbital model
current model, grey electron cloud, used to predict probable region of electron
orbitals
regions around nucleus where electrons are most likely to be found
atomic number
number of proteins in atom also indirectly number of electrons
mass number
mass of protons and neutrons together
isotopes
structural variations that differ in number of neutrons for elements
atomic weight
average of mass numbers of isotopes
radioisotopes
atoms decompose into more stable forms
radioactivity occurs when
alpha, beta, or gamma particles are ejected from nucleus
molecule
two or more atoms held together by chemical bonds
compound
2 or more different kinds of atoms bonded together
mixtures
two or more compounds physically intermixed
three types of mixtures
solutions, colloids, suspensions
solution
homogenous mixture, transparent, sea water or air
cant see path of light
solvent
present in greatest amount, usually liquid, being dissolved in
solute
what is being dissolved, smaller amounts
colloids
heterogeneous, translucent, milky, larger particles but dont settle out, gelatin
suspensions
heterogenous mixtures with large particles, visible, tend to settle out, sand water
mixtures vs compounds
mixtures` no chemical bonds, can be seperated physically, hetero or homo
compounds- seperated only by breaking bonds, homo
electron farthest from nucleus
greatest potential energy, most likely to interact
stable atoms
outermost energy level full, unreactive, contains 8 electrons
if outermost energy level contains less than 8 electrons
tend to gain, share, or lose electrons to achieve stability
octet rule
atoms interact in a manner to have 8 electrons in their outer most energy level
types of chemical bonds
ionic, covalent, hydrogen
ions
formed by transfer of valance shall electrons
anions
negative charge, gained electrons
cations
positive charge, lost electrons
ionic bond
chemical bond between atoms formed by transfer of electron
covalent
shared valance electrons
nonpolar
equally shared electrons, balanced
polar
unequal sharing of electrons,
electronegative
6 or 7 valance electrons, attract electrons
electropositive
atoms with few electrons, lose electrons
hydrogen bonds
very weak, but essential to allow for reactions at body temp
sysnthesis
A + B = AB
Always involve bond formation
Anabolic (vs. catabolic)
decomposition reaction
AB = A + B Hydrolysis is an example of this type. Reverse synthesis reactions Involve breaking of bonds Catabolic
exchange reactions
AB + C = AC + B
Also called displacement reactions
Bonds are both made and broken
part of reactant molecules change partners to produce differnet products
oxidized
electron donor, loses electron
reduced
electron acceptor, gains electron
exergonic
release energy, products have less energy than reactants
endergonic reactions
gain energy, products have more energy than reactants
reversibility
All chemical reactions are theoretically reversible
chemical equilibrium
Chemical equilibrium occurs if neither a forward nor reverse reaction is dominant
why are Many biological reactions are essentially irreversible
due to
Energy requirements
Removal of products
how to increase rate of chemical reactionS
increase temp
decrease size
increase concentration of reactant
add catalysts
inorganic compounds
do not contain carbon, water, salt, acid, base
organic compounds
Contain carbon (except CO2 and CO, which are inorganic)
Unique to living systems
Include carbohydrates, lipids, proteins, and nucleic acids
many are polymers
dehydratin synthesis
Monomers are joined by removal of water
hydrolysis
monomers are broken by addition of water
water properties
high heat capacity high vaporization heat polar solvent properties reactivity cushioning
acids
proton donors, release h
bases
proton acceptors, oh,
ph
measures concentration of h ions
neutralization
when acids and bases mix to form water and salt
buffers
mixture of compounds that resist ph changes
strong acids
disociate completely and irreversibly in water
weak acids
do not disociate completely
carbohydrates
Sugars and starches
Contain C, H, and O [(CH20)n]
Three classes
three carb classes
Monosaccharides
Disaccharides
Polysaccharides
carbohydrate functions
Major source of cellular fuel (e.g., glucose) Structural molecules (e.g., ribose sugar in RNA)
monosaccharides
Simple sugars
(CH20)n
fructose, ribose, gluctose
disaccharides
Double sugars
Too large to pass through cell membranes
sucrose, lactose, maltose
polysacchatides
Polymers of simple sugars, e.g., starch and glycogen
Not very soluble
large
lipids
Contain C, H, O (less than in carbohydrates), and sometimes P
Insoluble in water
main types of lipids
Neutral fats or triglycerides
Phospholipids
Steroids
Eicosanoids
Triglycerides
Neutral fats—solid fats and liquid oils
Composed of three fatty acids bonded to a glycerol molecule
triglycerides main functions
Main functions
Energy storage
Insulation
Protection
Saturated fatty acids
Single bonds between C atoms; maximum number of H
Solid animal fats, e.g., butter
straight chain
Unsaturated fatty acids
One or more double bonds between C atoms
Reduced number of H atoms
Plant oils, e.g., olive oil
bent chains
Phospholipids
Glycerol + two fatty acids and a phosphorus (P)-containing group
hydrophillic polar head, hydrophobic nonpolar tails
part of all cell membranes
steroids
lipids
Steroids—interlocking four-ring structure
Cholesterol, vitamin D, steroid hormones like testosterone / estrogen
Eicosanoids
Many different ones
Derived from omega fatty acids
Prostaglandins, thromboxanes, leukotrines
positive feedback loop
Lipoproteins
Transport fats in the blood
proteins
Polymers of amino acids (20 types)
Joined by peptide bonds
Contain C, H, O, N, and sometimes S and P
r groups
makes amino acids differnet
protein primary structure
The sequence of amino acids forms the polypeptide chain.
protein secundary structure
form helix spirals and zigzag sheets which are held together by hydrogen bonds
protein tertiary structure
secundary molecules are folded up to form a compact globular molecule held together by intramolecular bonds.
quaternary structure
Two or more polypeptide chains, each with its own tertiary structure,
combine to form a functional protein
fibrous proteins
Fibrous (structural) proteins
Strandlike, water insoluble, and stable
Examples: keratin, elastin, collagen, and certain contractile fibers
globular proteins
Globular (functional) proteins
Compact, spherical, water-soluble and sensitive to environmental changes
Specific functional regions (active sites)
Examples: antibodies, hormones, molecular chaperones, and enzymes
Molecular Chaperones (Chaperonins
Ensure quick and accurate folding and association of proteins
Promote breakdown of damaged or denatured proteins
Help trigger the immune response
Produced in response to stressful stimuli, e.g., O2 deprivation
Enzymes
Biological catalysts
Lower the activation energy, increase the speed of a reaction
some enzymes consist of
Apoenzyme (protein)
Cofactor (metal ion) or coenzyme (a vitamin)
substrate
substance on which enzyme acts
Nucleic Acids
DNA and RNA
Largest molecules in the body
Contain C, O, H, N, and P
Building block = nucleotide, composed of N-containing base, a pentose sugar, and a phosphate group
Deoxyribonucleic Acid (DNA)
Four bases:
adenine (A), guanine (G), cytosine (C), and thymine (T)
Double-stranded helical molecule in the cell nucleus
Provides instructions for protein synthesis
Replicates before cell division, ensuring genetic continuity
Ribonucleic Acid (RNA)
Four bases:
adenine (A), guanine (G), cytosine (C), and uracil (U)
Single-stranded molecule mostly active outside the nucleus
Phosphorylation:
Terminal phosphates are enzymatically transferred to and energize other molecules
Such “primed” molecules perform cellular work (life processes) using the phosphate bond energy
