Chapter 2: Chemical Composition of the Body Flashcards
Matter
- Anything that takes up space and has mass (solid, liquid, gas)
- composed of elements
Element
- substance that can’t be chemically broken down into any simpler substance (i.e. oxygen, carbon, gold, helium)
- elements are composed of atoms
Subatomic particles
- protons: positive charge and in atoms nucleus
- neutrons: electrically neutral/no charge and in nucleus
- electrons: negative charge and orbit around nucleus
Atomic symbol
- letters of the atom
Atomic Number
- # of protons (bottom number in symbol)
Atomic Mass
- equals # of protons and neutrons
- top number in symbol
Isotopes
- different forms of an atom with same number protons, but different number neutrons (i.e. carbon-12, carbon-13, carbon-14)
Major elements of body
- 99.3%
- hydrogen 63%
- oxygen 26%
- carbon 9%
- nitrogen 1%
Remaining 0.7% of total atoms
- calcium
- phosphorus
- potassium
- sulfur
- sodium
- chlorine
- magnesium
Trace Elements
- less than 0.01% total atoms in body
- iron
- iodine
- copper
- zinc
- maganese
- cobalt
- chromium
- selenium
- molybdenum
- flourine
- tin
- silicon
- vanadium
Molecule
group of 2 or more atoms held together by energy
Compound
- molecule composed of 2+ elements (i.e. O2 or H2O)
- electrons contain energy and atoms always seek out their lowest energy state meaning a full outer shell of electrons
Energy shell levels
- 1st energy level = max 2 electrons
- 2nd energy level = max 8 electrons
- 3rd level = max 8 electrons
Lowest energy state
- outermost level needs to be completely filled in order to be a stable atom
- unstable elements seek out other unstable elements
Chemical Bond
- force holding 2 atoms together
Covalent Bonds
form when 2 atoms share a pair of electrons
Double Covalent Bond
form when 2 atoms share 2 pairs of electrons
Polar v Nonpolar
- atoms have different degrees of electronegativity (the power to attract electrons)
Polar covalent molecule
- unequal sharing of the electron pair between atoms
- unequal charge distribution of the molecule
Nonpolar covalent molecules
- equal sharing of electron pair
- equal charge distribution across the molecule
Ionic Bonds
- occurs as result of an electrical attraction between 2 ions
Ion
- a charged atom
- an atom in which the number or protons does not equal the number of electrons
Cations
positively charged ions
anions
negatively charged ions
electrolytes
the ionic forms of mineral elements because give electrical charge to solution
Hydrogen Bond
- form between polar molecules as a result of an electrical attraction between the positive end of one molecule and the negative end of another (i.e. H2O)
Strength of Chemical bonds (highest to lowest)
- covalent (share e-)
- ionic (opposite charge attraction)
- hydrogen (attraction of H to O or N)
- hydrophobic interactions/VanDerWaals ( attraction between nonpolar molecules when close together - NOT AN ACTUAL BOND)
Molecular shape
- contributes to ability of different molecules to form chemical bonds
- rotations of bonds can rearrange molecules 3-D shape and therefore its molecular function
free radicals
atom containing an unpaired (single) electron in its outermost orbital
- highly reactive
- oxidize other atoms
Formation of free radcal
- produced in certain cell types ~ used by certain leukocytes to destroy pathogens
- produced as a consequence of exposure to radiation or toxins
- -> cause DNA damage and are harmful to cells ~ associated with age-related disorders including cardiovascular, neural and eye diseases
- -> antioxidants are protective (i.e. vitamins C and E)
Aqueous solution
- chemical reactions in cells occur within an aqueous environment
- aqueous solution = water is solvent
Important Properties of water
- excellent solvent
- water has great capacity to absorb, store, and release heat
- water is adhesive and cohesive
- water molecules take part in many chemical reactions in the body
Excellent Solvent Property of Water
- dissolves more compounds in greater amounts than any other liquid
Solution
homogeneous mixture of 2+ kinds of molecules, atoms, or ions
Solute
dissolved substance
solvent
substance in which the solute dissolves
solute concentration
amount of the solute present in a unit volume of solution (g/L), (moles/L) –> 1M of solute per solution
like dissolves likes
- nonpolar solutes will be soluble in nonpolar solvents
- polar solutes will be solutes in polar solutes
hydrophilic substances
- dissolve in and interact with water (ions, and polar covalent molecules)
hydrophobic substances
- do not interact with water
- are poorly soluble or completely insoluble in water (nonpolar covalent molecules)
Water has a great capactiy to absorb, sore and release heat property
- high heat capacity and high heat of vaporization
- high specific heat (amount of energy required to raise the temperature of a substance by 1 degrees celcius
- water serves as a heat “buffer” = keeps internal temperature relatively stable
Water is adhesive and cohesive
- cohesion: water molecules cling together
- adhesion: water molecules adhere to surfaces
- facilitate flow of blood to blood vessels
Water molecules take part in many chemical reactions in the body property
- hydrolysis reaction
- dehydration reaction
- reactions are good for creating or breaking large organic molecules
hydrolysis reaction
covalent bond is broken when water is added to system
dehydration reaction
covalent bond is formed when water is removed between molecules
Acid
- molecule that dissociates in an aqueous solution releasing hydrogen ions (i.e. HCL –> H+ and Cl-)
- increase in H+ in solution = more acidic
Strong Acid
Completely Ionize in solution
Weak Acid
Incompletely ionize in solution
Base
a molecule that takes up hydrogen ions, or releases hydroxide ions (OH-) in an aqueous solution
- basic solution = alkaline solution
pH sclae
- based on -log[H+] of solution
- lower ph = more acidic, higher ph = more basic
- neutral solution = pH 7.0
- acidic solution = pH 7.0
- up to 14
pH importance
- cells function in a limited pH range (7.25-7.45) is normal range in human blood
- enzyme activity is affected by pH
- pH changes can cause protein and enzyme denaturation
- buffering systems in body function to keep pH in normal limits
Buffer
- chemical that takes up excess H+ or OH- from solution (or donates H+ to solution) to minimize changes in pH
Organic Molecules
- life is carbon-based
- organic molecules contain carbon and hydrogen
- each carbon atom can covalently bond to 4 other atoms
- hydrocarbons contain only carbon and hydrogen
Macromolecules
- polymers
- structure depends on monomer structure, number, 3-D organization or subunits
Polymers
- composed of smaller subunits called monomers
- synthesized by dehydration reactions, broken down by hydrolysis reactions
Function Group
- group of atoms attached to an organic molecule that gives it unique chemical properties
- specific combinations of atoms, always reacts the same way chemically
- often provide an electrical charge or polarity to the molecule, make a molecule hydrophobic or hydrophilic
4 classes of organic molecules in organisms
- carbohydrates
- lipids
- proteins
- nucleic acids
Carbohydrates
- simple and complex sugars; important to energy production and storage
Simple Sugars
- monosaccharides (monomer) –> most are pentoses or hexoses (i.e. glucose, fructose)
- disaccharides: 2 bonded monosaccharides –> i.e. lactose, maltose, sugar
Complex Sugars
- polysaccharides: many joined monosaccharides
- starch & glycogen: store energy. composed of thousands of glucose molecules linked together and differ in degree of branching
- cellulose & chitin: structural components
Lipids
- composed mostly of hydrogen and carbon atoms
- nonpolar and hydrophobic
- subclasses: triglycerides (fats&oils), phospholipids, steroids
Fats
- long-term energy storage and insulation in animals
Oils
- long-term energy storage in plants and their seeds
Phospholipids
- component of plasma membrane
Steroids
- component of plasma membrane (cholesterol) and sex hormones
Triglycerides and fats
- composed of 3 fatty acid molecules and 1 glycerol molecule
- 1 fat molecule = triglyceride
Saturated Fatty Acid
- all carbons are linked by single covalent bonds
Unsaturated fatty acid
- contain 1+ double bonds between carbon atoms
Monounsaturated
one double bond
polyunsaturated
more than one double bond
Cis fatty acid
both hydrogens are on the same side of the double-bonded carbons (most naturally occurring)
Trans fatty acid
hydrogens are opposite sides of the double bonded carbons
Eicosanoids
altered fatty acids derived from arachidonic acid that regulate certain cell functions
phospholipids
glycerol
2 fatty acids
phosphate group
nitrogen containing group
Amphipathic
important for phospholipid membrane
Steroids
- structure includes 4 interconnected rings of carbon atoms
- i.e. cholesterol, cortisol, testosterone, estrogen
Polypeptide
- polymers formed from amino acids joined by peptide bonds
- carbon, hydrogen, oxygen, nitrogen
- peptide has 50 amino acids
Amino Acids
- all have an amino group, a carboxyl group, and a varying side chain (R)
- 20 different naturally occurring amino acids
- proteins creating by dehydration reaction of amino acids
glycoproteins
one or more monosaccharides covalently attached to the side chains of specific amino acids
levels of protein structure
- primary, secondary, tertiary, quaternary
Primary structure
- amino acid sequence
- determines 2nd and 3rd structures
Secondary structure
- alpha helix
- beta pleated sheet
Tertiary structure
- conformation= 3D shape of molecule
- how folds in space
- critical to protein function!
Quaternary structure
only in proteins with one or more polypeptide subunits
Nucleic Acids
composed of chains of nucleotides
DNA
- deoxyribonucleic acid
- contains the sugar deoxyribose
- double-stranded (double-helix)
- genetic material
- nucleotides covalently bind to make DNA
- sugars&phosphates are the backbone
- adenine&thymine = 2H bonds
- cytosine&guanine = 3H bonds
RNA
- ribonucleic acid
- ribose
- single-stranded
- involved in converting the info in DNA to proteins
ATP
- adenosine triphosphate = energy currency of the cell
- receives energy from breakdown of carbs, proteins, and fats
- releases energy upon hydrolysis
- energy transfer
- *energy currency of cell**
Cells use ATP for:
- production and force movement
- active transport
- synthesis of organic molecules
