Unit 2 - Molecules Flashcards
Hydrogen bonds
Weak bonds that form between the slightly neg. end and the slightly pos. end of two molecules. PLAYS A BIG ROLE IN BIOLOGY
When do polar covalent bonds occur?
When one nucleus has a slightly positive charge (larger nucleus attracts electrons more strongly so it develops a slightly neg. charge while the smaller nucleus has a slightly pos. charge)
Tell me about water
It’s a polar covalent molecule, it forms hydrogen bonds with itself (cohesion), it’s essential for life, and ice floats (it’s less dense than water)
What 6 biologically important functions does water perform?
- Regulates body temperature (has a high heat capacity) 2. Universal solvent (dissolves ionic + polar substances) 3. Transport medium (solutes, heat, etc) 4. Lubricant (joints) 5. Ampiphrotic (acts as both acid/base) 6. Cohesion/ Adhesion
Acid
Any substance which releases H+ when it dissociates (pH 0-7)
Base
Any substance which releases OH+ when it dissociates (pH 7-14)
Substances which resist small changes in pH
Buffers
Most biological systems require a pH scale near _____
Neutral (Ex. Blood : pH 7.4, a pH of 7.8 is fatal)
Oxidation
The loss of electrons or hydrogen atoms in a reaction (An element that loses electrons or H+ in a chemical reaction has been “oxidized”)
Reduction
The gain of electrons or H+ atoms in a reaction (The reactant which had gained atoms or H+ atoms has been “reduced”)
Another way to say natural selection
Differential survival
Polar covalent bonds must be _____ (structure/shape)
Asymmetrical
What 4 elements make up 99% of the mass of most cells?
C,H,O,N
The 4 levels of biomolecules
LEVEL 4: cell + organelles LEVEL 3: supramolecular complexes (chromosome, cell wall, plasma membrane) LEVEL 2: macromolecules (DNA, protein, cellulose) LEVEL 1: mononumeric units (nucleotides, amino acids, sugars)
3 cellular uses of biological molecules
Anabolism, catabolism, enzymes
Anabolism
When molecules are joined together to form a larger molecule, results in loss of water (BY DEHYDRATION SYNTHESIS)
Catabolism
when a molecule is broken down into two or more smaller molecules, results in addition of water (BY HYDROLYSIS)
Enzymes
A special class of proteins that speed up and initiate all chemical reactions in cells
Draw dehydration synthesis
Draw hydrolysis
What is an organic compound
A compound (that makes up living things) that consists of carbon and hydrogen atoms covalent my bonded to each other + other elements (CAN BE CALLED HYDROCARBONS) (Can form polymers by joining monomers)
What are the four groups of organic compounds
- carbohydrates - lipids - proteins - nucleic acids
What can Carbon do that makes it so essential (in organic compounds)
- form covalent bonds to as many as four other atoms - rotate freely around a single covalent bond - form a variety of structures
What’s a functional group
Atoms or groups of atoms that are attached to carbon backbones (provide distinct properties, such as solubility and chemical reactivity)
