Smallest unit of an element
What is the composition of an atom?
Made up of three basic subatomic particles
- Protons – positively charged
- = Atomic Number
- Neutrons – neutrally charged
- Electrons – negatively charged particles, circulating around nucleus.
Where can electrons be found in the atom?
They can be found revolving around the nucleus in energy levels called shells.
These are the electrons found in the outer shell
- Participate in chemical reactions
- Atoms most stable when the outermost shell is full
Interactions of valence electrons that hold atoms together.
- Hydrogen (Sort of)
Two or more atoms bound together by chemical bonds
Two or more atoms share pairs of valence electrons
- Nonpolar Covalent Bond
- Polar Covalent Bond
Nonpolar Covalent Bond
Atoms share electrons equally
Polar Covalent Bond
- Unequal sharing of electrons
- Unequal charge between different regions of the molecule
One atom gives electrons to another so that both have filled valence shells.
Generates ions – atoms or molecules with unequal numbers of protons and electrons.
What attraction is experienced in ionic bonds?
Strong electrostatic attraction between oppositely charged ions
Weak attraction between polar molecules; the (–) end of one polar molecule is attracted to the ( + ) end of another polar molecule.
For what is hydrogen bonding responsible?
- Water surface tension
- Water capillary action
- Shape of proteins
- DNA structure
What are some of the characteristics of water?
- Polar molecule
- Good solvent (ionic and polar substances dissolve in it)
- Can form hydrogen bonds
What defines something as hydrophobic versus hydrophilic?
- Substances that dissolve in water are called hydrophilic.
- Substances that do not dissolve in water are called hydrophobic.
These are solutes that release H+ when mixed with water
- ↑ [H+]
- Acidic Solution
These are solutes that bind H+ when mixed with water
- ↓ [H+]
How do you quantify acidity or alkalinity of a solution?
For this, you would use the pH rating system.
- pH = log[H+]
Scale on the system goes from 0 - 14, with neutral pH rated as a 7 in the scale.
Very large molecules
- Nucleic Acids
Macromolecules come in distinct structures and functions.
Sugars & Starches (Plant)
Molecules that contain hydrogen, oxygen, and carbon 1:2:1 ratio
- General Formula = CnH2nOn (e.g. glucose – C6H12O6)
Function = major source of energy in body
What are the three classifications of carbohydrates?
- Basic Unit
- One carbon ring
- Two monosaccharides joined by a covalent bond
- Polymer of Glucose
- Glycogen, Starch, Fiber
Starch is a plant product formed by the bonding together of thousands of glucose subunites into long chains.
Glycogen, sometimes called animal starch, is similar to starch, but more highly branched.
Plant material containing substances such as cellulose, lignin, and pectin, which are resistant to the action of digestive enzymes.
Includes: Fats, Oils
Contain compounds that are not soluble in water (hydrophobic compounds)
These are the fats and oils in the body
- 3 Fatty Acids
- Glycerol Backbone
Types of Fatty Acids:
Saturated Fatty Acids
Fatty acids in which carbon atoms within the hydrocarbon chain are joined by a single covalent bonds so that each carbon atom can also bond with 2 hydrogen atoms.
Unsaturated Fatty Acids
Fatty Acids that contain a number of double covalent bonds within the hydrocarbon chain so that each carbon atom can bond with only 1 hydrogen atom.
Contain a phosphate group (PO4) instead of third fatty acid.
Amphipathic = possess both polar and nonpolar ends
- Lowers surface tension of water
- Enables hydrophobic substances to be suspended in polar solvents
Basic Backbone of four interlocking carbon rings
Different functional groups attached to basic structure
- Sex Steroids
Precursor for other steroid hormoens, regulation of cell membrane fluidity.
Hormone produced by adrenal glands.
Hormones produced by gonads (testosterone, estradiol)
A type of fatty acid
Function as communication molecules between cells
Variety of roles in body
- Inflammation Regulation
- Regulate Hormones
- Control Cell Growth
Diverse in structure and function
Amino acids = building blocks
Basic Structure of Amino Acid:
- Amino Group
- Carboxyl Group
- A Functional side-chain
- Specific for each AA
Amino Acid Side Chains
Functional group differentiates 20 different AA
Side chains interact with each other
- Give protein shape
How are proteins made?
Formed from polypeptides – molecule consisting of many amino acids joined by peptide bonds.
Sequence of amino acids in a polypeptides chain
Formation of helix or sheet shape in a protein chain
Due to hydrogen bonds dorming between peptide bond regions
Twisting and folding of a single polypetide chain
Due to chemical interactions involving the amino acid side-chains
Bonding and interactions of multiple polypeptides.
How many levels of proteins structures are there?
Four levels of protein structure:
- Primary Structure
- Secondary Structure
- Teritary Structure
- Quaternary Structure
Building blocks for nucleic acids
Composed of a five-carbon sugar, a phosphate group, and nitrogenous base.
Sugars are deoxyribose (DNA) or ribose (RNA).
Similar to DNA (polymer of nucleotides)
- Usually single-stranded
- Different sugar (ribose)
- Different Nitrogen Base (uracil instead of thymine)
Sometimes proteins are combined with other molecules to become functional
- Glycoprotein = Protein + Carbohydrate
- Ex: Cell Membranes
- Lipoprotein = Protein + Lipid
- Carrier molecules in blood
Give examples of the function of proteins in the body
Structural: collagen fibers in connective tissues; keratin in skin
Enzymes: assist every chemical process in the body
Antibodies: part of the immune system
Receptors: receive communication from other cells for regulation of cell activity.
Carriers: across cell membranes or in blood.
Sugar = deoxyribose
Double Helix = two strands linked together by hydrogen bonds between nitrogenous bases
Complementary base pairing between strands:
- Adenine binds to thymine
- Guanine binds to cytosine