Lab 2 Quiz Flashcards
What is a polar covalent bond?
Covalent bonds form by the sharing of electrons. In a polar covalent bond, shared electrons spend significantly more time orbiting one nucleus than the other (molecule is still neutral). Examples: oxygen and hydrogen
What is a nonpolar covalent bond?
Covalent bonds form by the sharing of electrons. In a nonpolar covalent bond, shared electrons spend equal time around each nucleus. This is the strongest of all chemical bonds. Examples: carbon and carbon
What is an ionic bond?
An ionic bond is the attraction of a cation to an anion. The middle strength bond. Easily broken in water. Example: sodium (Na+) and Chlorine (Cl-) are attracted to each other and form sodium chloride (NaCl)
What is a hydrogen bond?
A weak attraction between a slightly positive hydrogen atom in one molecule and a slightly negative oxygen or nitrogen atom in another. Strength in numbers. It is not a true bond, but an attraction. Typically seen in water.
Define ion, cation, and anion and list examples of each .
An ion is a charged particle with unequal numbers of protons and electrons (example, sodium chloride). A cation (sodium) gives up electrons and acquires positive charge. An anion (chlorine) gains electrons and acquires and negative charge.
Examples:
- Cations: calcium, magnesium, sodium, potassium, hydrogen, manganese
- Anions: Chlorine, phosphate, some proteins
What is surface tension and its significance?
The cohesion of water at its surface, which forms an elastic layer called the surface film and is held together by a force call surface tension. (think of water drops hanging off a faucet or traveling in rivulets down a window). This demonstrates water’s powerful cohesion (tendency to stick to itself).
What are the differences between adhesion and cohesion as it relates to water?
Water molecules cling to each other. This is called cohesion (this creates surface tension in water). Adhesion is the concept of different types of molecules being able to stick together.
How do substances dissolve in water? Define solute, solvent, and solution.
A solution consists of particles of matter called the solute mixed with a more abundant substance (usually water) called the solvent. In a solution, the solute is small and dissolved in the solvent–usually is clear, like urine.
What substances mix with water?
Since water is polar, it will only mix with polar substances. It will mix with polar molecules, hydrophilic molecules, molecules with ionic bonds, and proteins.
What substances mix with lipids?
Lipids are nonpolar. They will mix with nonpolar molecules, hydrophobic molecules, and other lipids.
Define denaturation.
Denaturation is a drastic change in a protein which occurs due to conditions such as extreme heat or pH (example: cooking an egg and the egg white/albumen turns from clear and runny to opaque and stiff). It is sometimes reversible, but usually permanently destroys protein function.
What are the locations and functions of the proteins in the human body?
Location: EVERYWHERE! They are the secondmost abundant thing in the body to water.
Function:
- structure (Keratin gives strength to skin, hair, and nails) collagen in bones and teeth
- communication (some hormones used to communicate are proteins),
- membrane transport (they may govern what passes through cell membranes or act as barriers)
- catalysis (catalyst for metabolism)
- recognition and protection (immune system),
- movement (proteins change shape repeatedly and are foundational to movement)
- cell adhesion (bind cells, keep tissues together, reproduction, immune cells fight disease)
What substances can easily pass through the phospholipid bilayer?
Anything that is hydrophobic–nonpolar molecules, hydrophobic molecules, and lipids.
List the four groups of organic molecules and their monomers.
- proteins (amino acids)
- carbohydrates (monosaccharides)
- lipids (triglycerides have glycerol and 3 fatty acids, phospholipids have glycerol, two fatty acids, and a phosphate head)
- Nucleic acids (nucleotides)
Define dehydration synthesis.
How monomers join together to become a polymer. Hydroxyl (-OH) group is removed from one monomer and a hydrogen (-H) from another, producing –and releasing–water as a byproduct. The two monomers are then joined by a covalent bond.
Define hydrolysis.
The opposite of dehydration synthesis. A water molecule ionizes into OH- and H+. A covalent bond linking one monomer to another is broken, the OH- is added to one monomer and the H+ to another (all digestion consists of hydrolysis reactions).
What are the unique characteristics of proteins?
A protein is a polymer of amino acids (there are 20 which make 1000 to infinite combinations). They are made of peptides, which is any molecule composed of two or more amino acids joined by peptide bonds.
Structure–
- Primary sequence of amino acid (joined by peptide bonds)
- Secondary–alpha helix or beta sheet (formed by hydrogen bonding)–not all have this!
- Tertiary–folding/coiling due to interactions with groups and surrounding water (not all have this!)
- Quaternary–two or more polypeptide chains
What are the unique characteristics of lipids?
A lipid is a hydrophobic organic molecule, usually composed of carbon, hydrogen, and oxygen, with a high ratio of hydrogen to oxygen. There are five primary types: fatty acids, triglycerides (three fatty acids and glycerol), phospholipids (two fatty acids, glycerol, and phosphate head), eicosanoids, and steroids.
What are the locations and functions of lipids in the body?
Lipids are found in the cell membrane, hormones, fat soluble vitamins, fat cells, brain, and blood.
Functions:
- aid in fat digestion and nutrient absorption
- chemical messengers between cells
- involved in blood functions
- source of energy, energy storage
- cushion organs
- insulation
What is the arrangement of phospholipids in the plasma membrane?
The tail of the phospholipids face each other and the heads face away from each other. These form a phospholipid bilayer. The tail is hydrophobic, meaning hydrophilic structures cannot pass through.
