Chapter 2 The Chemistry of Life Flashcards
Matter
Anything that has mass and occupies space
Solid, liquid, gas
Chemistry
Study of matter and its interactions
Atoms
smallest unit of matter that retains original properties. made up of:
- Subatomic particles
Subatomic Particles
Protons, Neutrons, Electrons
Protons (p+)
In atomic nucleus
-Positively charged
Neutrons (n0)
In atomic nucleus, slightly larger than protons
-no charge
Electrons (e-)
Outside atomic nucleus
-negatively charged
Atomic Nucleus
Central core of atom
Neutral
Atoms are electrically neutral:
-no charge
- number or protons and electrons are equal.
Electron shells
-regions surrounding atomic nucleus
-where electrons exist
- 3 main electron shells
Some atoms may have more than 3 shells
1st electron shell
Closest to nucleus - 2 electrons
2nd electron shell
8 electrons
3rd electron shell
18 electrons, “satisfied” with 8
Atomic Number
number of protons in atomic nucleus; defines every element
Element
substance that cannot be broken down into simpler substance by chemical means. (on periodic table)
-Total number of protons predicts element
Periodic Table
List elements by increasing atomic numbers
4 Major Elements
Human body is made up of:
1. Hydrogen
2. Oxygen
3. Carbon
4. Nitrogen
5. 7 mineral elements and 13 trace elements
Mass Number
sum of all protons and neutrons in atomic nucleus
-Protons are at the bottom / next to element symbol
-Neutrons are on the top / next to element symbol
Isotopes
Atom with same atomic number (number of protons) but different mass number (number of neutrons)
Radioisotopes
Unstable isotopes. High energy or radiation released by radioactive decay, allows isotope to assume more stable form
Mixtures
Atoms of two or more elements physically intermixed without changing chemical of atoms
1.Suspensions
2. Colloids
3.Solutions
Suspension
Ex: blood in suspension
- Large, unevenly distributed particles
-Will settle out when left undisturbed
Generally a liquid mixed with solid
Colloids
Ex: milk
-Small, evenly distributed particles
-Will not settle out
Solutions
Ex: glucose in water
-extremely small, evenly distributed particles
-will not settle
- Solute
- Solvent
Solute
Substance dissolved
ex: sugar in water
Solvent
Substance that dissolves solute
ex: water
Chemical Bond
-Energy relationship or attractive force between atoms
-Formed when valence electrons of atoms interact
Molecule
formed by chemical bonding between two or more atoms of the same element
Compound
formed when two or more atoms from different elements combine by chemical bonding
-Contain both metal and nonmetal ions
Valence Electrons
Determine how an atom interacts with other atoms
Octet Rule
Atom is most stable when 8 electrons in valence shell
Duet Rule
Atoms with 5 or fewer electrons- atom is most stable when valence electron shell holds 2 electrons
Ionic Bond
(ions) Electrons are transferred from metal atoms to nonmetal atom:
-cations
-anions
Cations
Positively charged ion
-Metal loses one or more electrons
Anion
Negatively charged ion
-Nonmetal gains one or more electrons
Covalent Bonds
Strongest bond. two or more nonmetals share electrons
Electronegativity
Protons attract electrons
-increase from bottom left to upper right of periodic table (Fluorine is the most electronegative element)
Nonpolar Covalent Bonds
Two nonmetals in molecule:
-similar or identical electronegativities
-pull with equal force
Nonpolar molecules occur in 3 situations
-Atoms sharing electrons are same element
-Arrangement of atoms makes one atom unable to pull more strongly than another atom
-Bond between carbon and hydrogen
Polar Covalent Bonds
Two Nonmetals with
-different electronegativities
-share electrons unequally
-form polar molecules
Partially negative
Atom with higher electronegativity pulls shared electrons close to itself
Partially Positive
Atom with lower electronegativity , shared electrons are pulled toward other atom
Dipoles
Polar molecules with partially positive and partially negative ends
Hydrogen Bonds
Responsible for key property of water
- weak attractions between partially positive end of a one dipole and partially negative end of another dipole
Chemical Reaction
-Chemical bond is formed, broken, or rearranged
-Electrons are transferred between two or more atoms
Chemical Equation
- Reactants- starting ingredients, will undergo reaction
- Products- results of chemical reaction
Reversible Reactions
Proceed in either direction; denoted by two arrows in opposite direction
Irreversible Reactions
Proceed from left to right, denoted by single arrow
Energy
Capacity to do work or put matter into motion
- Potential
- Kinetic
Potential Energy
Stored, can be released later to do work
Kinetic Energy
Potential energy has been released or set in motion to perform work
-All atoms have kinetic energy (in constant motion)
3 Forms of Energy in Human Body
- Chemical
- Electrical
- Mechanical
Chemical Energy
in bonds between atoms; drives nearly all chemical processes
Electrical Energy
Generated by movement of charged particles or ions
Mechanical Energy
energy directly transferred from one object to another
Endergonic Reactions
require input of energy from another source; products contain more energy than reactants
Exergonic Reactions
release excess energy; products have less energy than reactants
Homeostasis
Breaking down molecules, converting energy in food to usable form and building new molecules
-Carried out by 3 types of chemical reactions:
- Catabolic
- Exchange
- Anabolic
Catabolic Reaction
(Decomposition reactions)
- large substance is broken down into smaller substances
-Usually exergonic- chemical bonds broken
AB - A + B
Exchange Reactions
One or more atoms from reactants are exchanged for one another
AB + CD - AD + BC
-example is oxidation reduction reaction
Oxidation Reduction reaction
(redox) Electrons and energy are exchanged instead of atoms
-Usually exergonic reactions- release more energy
Oxidized
Reactant that loses electrons
Reduced
Reactants that gains electrons
Anabolic Reaction
Small simple subunits united by chemical bonds, make large complex substances
- endergonic; fueled by chemical energy
A+B - AB
Activation Energy (Ea)
Energy required for all chemical reactions
Analogy
Activation energy must be supplied so that reactants reach transition states ( get to top of energy “hill”) to react and from products ( roll down hill )
Increase reaction rate by reducing Ea
- Concentration
- Temp
- Reactant properties
- Presence or absence of catalyst
Concentration
When it increases more reactant particles are present’ chance of successful collisions between reactants
Temperature
Raising temp of reactants increases kinetic energy of atoms; leads to more forceful and effective collisions between reactants
Properties
Size and Phase influence reaction rates:
-Smaller particles move faster
- Gaseous particles in gaseous phase have higher kinetic energy than solid or liquid
Catalyst
Increases reaction rate by lowering Ea
Enzymes
Biological catalysts; most are proteins
-Speed up reactions by lowering activation energy
–Highly specific for individual substrates
-Do not alter reactants or products
–Not permanently altered in reactions catalyze
Substrates
Substance that can bind to enzymes active site
Induced-fit Mechanism
Enzymes interaction with substrate
- Binding of substrate causes small shape change that brings substrate to transition state
- Reduces energy of activation; allows transition state to proceed to final product
Biochemistry
chemistry of life
Inorganic
compounds generally do not contain carbon bonded to hydrogen;
Ex: water, acid, bases and salts
Organic
compounds do contain carbon bonded to hydrogen
Ex: Carbohydrates, lipids, proteins, nucelotides
Water
H2O
Makes up 60-80% of mass of human body.
-Universal solvent
-High heat capacity – able to absorb heat without significantly changing temperature
*Carries heat with it when it evaporates
*Cushions and protects body structures because of relatively high density
*Acts as a lubricant between two adjacent surfaces (reduces friction)
H2O
-Oxygen pole- partially negative
Hydrogen pole- partially positive
Hydrophilic solutes
like dissolves like. can be dissolved in water
-polar covalent bonds and ionic compounds
Hydrophobic solutes
do not dissolve in water (oils and fats)
-nonpolar covalent compounds
Hydrogen ions (H+)
The study of acids and bases
Hydrogen Ions
Positively charged ions
Hydroxide Ions
Negatively charged ions
Acid
Hydrogen ion or proton donor:
-number of hydrogen ions increases in water when acid is added
-Higher number of hydrogen ion
Base (alkali)
Hydrogen ion acceptor
-binds free hydrogen ions in a solution
-number of hydrogen ions decreases in water when base is added
- lower number of hydrogen ion
pH scale
Range from 0-14
- hydrogen ion concentration of a solution
-pH = Log[H+]
- pH = 7 , solution is neutral; number of hydrogen ions and base ions are equal
-pH less than 7 is acidic; hydrogen ions out number base ions
-pH greater than 7 is basic or alkaline base ions out number hydrogen ions
Buffer
resists changes in pH; prevents large swings in pH when acid or base is added to solution
-major buffer is carbonic acid-bicarbonate buffer system
-Blood pH must remain within its narrow range
-most body fluids are slightly basic 7.35-7.45
Salt
any metal cation and nonmetal anion held together by ionic bonds
-Can dissolve in water to form cations and anions called electrolytes; capable of conducting electrical current
Monomers
single subunits combined to build larger structures (polymers)
Monomers & Polymers
Each organic compound in the body (carbo, lipid, protein and nucleotides) are made of of monomers and polymers
Dehydration synthesis
Links monomers together, makes molecule of water
Hydrolysis
catabolic reaction; uses water to break polymers into smaller subunits
Carbohydrates
Composed of carbon, hydrogen and oxygen
-Function primarily as fuel
types:
-Monosaccharides, disaccharides, polysaccharides
Monosaccharides
-Monomers from which all carbohydrates are made of
▪3 to 7 carbons each
▪Glucose, fructose, galactose, ribose, and deoxyribose are most abundant
Disaccharides
Formed by the union of two monosaccharides by dehydration synthesis
Polysaccharides
Many monosaccharides joined to one another by dehydration synthesis reactions
*Polysaccharides covalently bound to proteins or lipids form glycoproteins and glycolipids; various functions in bod
Glycogen
Storage polymer of glucose
-Mostly in skeletal muscle and liver cells
Lipids
Group of non-polar hydrophobic molecules (does not dissolve in water) composed primarily of carbon and hydrogen
Ex: fats and oils
Fatty acids
Lipid monomers
-4 to 20 carbon atoms; may have none, one, or more double bonds between carbons in hydrocarbon chain
Saturated fatty acids
Fatty acids – solid at room temperature
-NO double bonds between carbon atoms
-carbons are “saturated” with maximum number of hydrogen atoms
Monounsaturated fatty acids
Generally liquid at room temperature
-ONE double bond between two carbons in hydrocarbon chain
polyunsaturated fatty acids
Liquid at room temperature
-two or more double bonds between carbons in hydrocarbon chain
Omega 3 fats
Good
-Flaxseed oil and fish oil; cannot be made by humans; obtained in diet
–Polyunsaturated; positive effects on cardiovascular health
Saturated fats
Bad
-Animal fats; also in palm and coconut oils
–Overconsumption associated with increased cardiac disease risk
Trans fat
Ugly
-Produced by adding H atoms to unsaturated plant oils (“partially hydrogenated oils”)
–No safe consumption level; significantly increase risk of heart disease
Triglyceride
Three fatty acids linked by dehydration synthesis to modified 3-carbon carbohydrate,
Glycerol
storage polymer for fatty acids
Phospholipids
Glycerol backbone
-two fatty acid “tails” and one phosphate “head”i n place of third fatty acid
-vital to structure of cell membranes
Amphiphilic
Molecule with polar group (phosphate head) and non-polar group (2 fatty acid tails)
Steroids
(Lipids) non polar
-share four ring hydrocarbon structure called steroid nucleus
Cholesterol
(Lipid) steroid that forms bases for all other steroids
Proteins (amino acids)
-Two basic types: 1.Fibrous
2. Globular
-Four levels of complex protein structure: primary, secondary, tertiary, quaternary
amino and carboxylic acid
Fibrous Protein
Long rope-like strands; mostly non-polar amino acids; add strength and durability to structures
Globular Protein
Spherical or globe-like; mostly polar amino acids; function as enzymes, hormones, and other cell messenger
Primary structure
Amino acid sequence of polypeptide chain
Secondary Structure
One or more segments of primary structure folded in specific ways, held together by hydrogen bonds
–Alpha helix – coiled spring
–Beta-pleated sheet – Venetian blind
Tertiary Structure
Three-dimensional shape of peptide chain (twists, folds, and coils, including secondary structure); stabilized by hydrogen bonding
Quaternary Structure
linking together more than one polypeptide chain in specific arrangement; critical to FUNCTION of protein
Protein denaturation
Destroying protein’s shape by heat, pH changes, or exposure to chemicals
*Disrupts hydrogen bonding and ionic interactions that stabilize STRUCTURE and FUNCTION
Nucleotides
-Monomers of nucleic acids
Make up genetic material
Structure:
-Nitrogen base with hydrocarbon ring structure
–Five-carbon pentose sugar (ribose or deoxyribose)
–Phosphate group
Purines
Type of nitrogen base
-Double ringed molecule: adenine and guanine
Pyrimidines
Type of nitrogen base
-Single ringed molecule: cytosine, uracil, and thymine
Adenosine triphosphate (ATP)
Adenine attached to ribose and three phosphate groups
-main source of chemical energy in body
-Synthesized from ADP and phosphate group (Pi)
-ATP synthesis – highly endergonic reaction due to negative charges on phosphate groups
-Hydrolysis of bond is highly exergonic because ADP is more stable than ATP
-Not stored significantly by cells; entire supply exhausted in 60–90 seconds; cells must continually replenish ATP supply
DNA
(Nucleotide)
-Extremely large molecule in nuclei of cells; composed of two long chains that twist around each other to form double helix
*Contains genes – recipe (code) for protein synthesis (process to make every protein)
Structure of DNA
–Pentose sugar deoxyribose (lacks oxygen-containing group of ribose) forms backbone of strand; alternates with phosphate group
–Bases: adenine, guanine, cytosine, and thymine
- DNA exhibits complementary base pairing; purine A always pairs with pyrimidine T; purine G always pairs with pyrimidine C
- A = T (where = denotes 2 hydrogen bonds) and C ≡ G (where ≡ denotes 3 hydrogen bonds
RNA
single strand of nucleotides; moves between nucleus and cytosol; critical to making proteinsRNA contains pentose sugar riboseRNA contains uracil instead of thymine; still pairs with adenine (A = U)
Transcription
RNA copies recipe for specific protein
Translation
RNA exits nucleus to protein synthesis location
-directs making of protein from recipe
