Ch. 2 - Chemical Level of Organization Flashcards
In an atom, the number of protons is ______ to the number of electrons
equal
What is the difference between the atomic number and mass number of an atom?
ATOMIC - number of protons (electrons too in an atom) in nucleus
MASS - sum of protons and neutrons in nucleus
What is a radioactive isotope?
Decay of nucleus gives off particles and energy; can cause DNA mutations
*difference in number of neutrons
What is the valence of an element?
The number of electrons necessary to complete outer shell; corresponds to # of cov bonds an element can form
if shell is not filled: chemically reactive!
if shell is full: chemically inert (e.g. noble glasses)
What is the difference between a compound and a molecule?
Compound: substance containing 2 or more different elements; can be broken in to diff types of atoms
Molecule: 2 or more atoms sharing e; involve covalent bonds
4 Properties of Water
*H-bonds give rise to such properties!!
- Highly cohesive; creates surface tension
- High heat capacity
- Expands upon freezing
- Versatile solvent - due to polarity
What are buffers?
Accept [H+] if too much or donate H+ if not enough in a solution; maintain pH at constant (not always neutral!) level
e.g. H2CO3 (carbonic aid) breaks down into HCO3 + H+
Catabolic pathways…
…release energy (exergonic) by breaking down complex molecules into simpler compounds
Anabolic pathways…
—require energy (endergonic) to build complex molecules from simple ones
How do enzymes function in chemical reactions?
Enzymes act as catalysts to speed up rxn rate by lowering activation energy
Difference between dehydration synthesis and hydrolysis?
Dehydration - links monomers into polymers by removing water
Hydrolysis - breaks down polymers into monomers by adding water
Function and properties of carbohydrates?
- Cn H2n On structure
- many -OH groups
- provide energy to cells
- polar covalent bonds, hydrophilic
C/C glycogen, starch, and cellulose
- All made up of glucose monomers
Glycogen - energy storage of animals
Starch - energy storage of plants, less compact/unbranched
Cellulose - structural polysaccharide in plants; linked differently
Why are lipids hydrophobic?
Made of nonpolar, hydrophobic molecules (usually hydrocarbons which are not made via dehydration synthesis)
3 important types of lipids
Triglyceride, phospholipids, steroids
Composition and function of a triglyceride?
Made of glycerol and 3 fatty acids; energy storage
- identity depends on type of F.A. it contains (differ in # of C, amount and position of double bonds)
Saturated vs. Unsaturated FA
S - no double bonds (straight chain), solid/dense at room temp; derived from animals
US - one or more double bonds (causes kinks), liquid at room temp; derived from plants
Cis vs. Trans Unsaturated FA
CIS - found in nature; liquid at room temp.
TRANS - mimic sat. FA (straight structure/pack well), processed
Properties of Phospholipids
- similar to fats, but replace 1 FA with a phosphate group
- amphipathic
- forms bilayers; basis of cellular membranes!
Properties of steroids
- lipids with carbon skeletons bent to form 4 fused rings
- all made from cholesterol as starting molec
e.g. hormones (estrogen, cortisol), vitamins
Functions of proteins?
give structure, regulate processes, provide protection, transport substances, act as substances
What are amino acids?
- Monomers of proteins
- all have amino base, carboxyl acid group, hydrogen
- differ by side chains (R groups)
What are the 4 levels of protein structure?
Primary - linear
Secondary - alpha helix and beta pleated sheets
Tertiary - 3D shape formed via R group interactions
Quaternary - multiple polypeptides
What causes denaturation?
Changes in pH, temperature, salt concentration, and other env factors
- causes loss in protein’s native structure; biologically inactive
Describe enzyme specificity
Due to enzyme shape (lock and key); shape of substrate and active site are complementary
What are nucleotides? Discuss structure.
- Monomers of nucleic acids
- all have P group, pentose sugar, and nitrogenous base
Compare and contrast pyrimidines and purines
- all nitrogenous bases
PYRIMIDINE - 1 ring; C, T, U
PURINE - 2 rings: A, G
How are the 2 strands in DNA held together?
via H-bonds, create double helix
What are the 3 types of RNA?
transfer RNA
ribosomal RNA
messenger RNA
How does ATP power cellular work?
via phosphorylation
- when hydrolyzed into ADP + P, energy is released
