1.1 Chemistry in Living Systems Flashcards
Isotope
Elements with the same number of protons, different number of neutrons
Radioisotopes
Isotopes whose nuclei are unstable and decay spontaneously
Describe how radioisotopes decay
Neutron -> proton + electron + energy
Half-life
Time taken for 1/2 of the atoms in a sample to decay
Radiometric Dating
Method for determining age of geological or archeological specimen based on concentration and half-life of a particular radioisotope contained within it
How do scientists estimate how many years have passed since an animal died
Measure the ratio of C-12 and C-14
What happens to C-12 and C-14 when an animal dies
C-12 stays constant while C-14 continues to decay (decreases)
Radioisotope Tracing
- Radioisotope used to label molecules
- As radioisotope breaks down, it releases energy, which can be detected by nuclear imaging tech such as positron emission tomography (PET)
- Scientists trace the radioisotope as it moves in the body and undergo chem and physiological processes in organisms (DNA replication, aa transport)
Detecting Disease by Radioisotope Tracing
Through nuclear imaging tech, can learn about internal anatomy and functioning of specific organs, detect disease
Dangers of Radioisotopes
- Cellular and tissue damage
- Genetic mutations
- Radiation sickness
- Cell death
Intramolecular Forces (chemical bond)
Hold atoms together within a molecule
Ionic Bonds
Valence of one atom is transferred permanently to another atom
Cation
Atom that loses the electrons become positively charged
Anion
Atom that gains the electron and becomes negatively charged
Covalent Bond
Two atoms share one or more pairs of valence electrons
- Typically two non metals
- Strong bonds
Non polar covalent bonds
Equal sharing
Polar covalent bonds
Unequal sharing
Electronegativity
Atoms ability to attract electrons in a chem bond
- Two atoms with close value electronegativity = covalent
- Two atoms with far apart electronegativity = ionic
Polar molecules
- Contain polar bonds
- Non symmetrical molecules
- Partial neg and partial pos
Non polar molecules
- Straight and symmetrical molecule
- Effects of polar bonds cancel each other out
Dipoles
- Separation of charges within a molecule (b/c of unequal sharing)
- More electro pull closer to them
- Arrow points to neg charge
- No overall dispoles in non polar molecules
Four molecular shapes (orbitals)
- Linear
- Angular
- Pyramidal
- Tetrahedral
Why does molecular shape matter?
Biological molecules must recognize and interact with other molecules in the cell based on molecular shape and size
(enzymes, hormones, neurotransmitters)
Intermolecular Forces
Weak attractive forces between molecules or diff parts of same molecule
- Determine how molecules interact
- Responsible for some physical prop
- Easily broken down with energy
London Dispersion Forces
2 non polar molecules
- results from temp uneven distribution of electrons
- Weak!
Ion-dipole forces
polar molecule and ion
Dipole-dipole forces
two polar molecules
opposite dipoles attract
Hydrogen bonding
- Very strong dipole-dipole forces
- Exists between partial positive H and partial neg N, O or F polar molecule
- One hydrogen bond is weak, many is strong
List the 10 properties of water
- Polar covalent bond
- Solute
- Solvent
- High heat capacity
- Gas, liquid, solid
- Surface tension
- Density
- Capillary Action
- Cohesion
- Adhesion
Hydophillic Substances
Water soluble
Ionic and polar
How do ionic compounds dissolve?
Water molecules orient themselves so that partially neg oxygen atoms are facing cations from the ionic compound and partially positive hydrogen atoms are facing anions from the ionic compound
Hydrophobic
Water insoluble
Non polar substances
Amphiphilic Molecules
Have polar region and non polar region
- Will orient themselves to minimize contact that their non-polar regions have with water
Hydrophobic Effect
Hydrophobic molecules clump together to avoid water
Functional Group - Hydroxyl
OH
- found in carbs, proteins, na, lipids
- polar
Functional Group - Carbonyl
CHO, CO
- found in carbs, na
- polar
Functional Group - Carboxyl
COOH
- proteins, lipids
- polar
- acidic
- ionizes to release H+
Functional Group - Amino
NH2
- aa, proteins, na
- polar
- basic
- accepts h+
- Forms hydrogen bonds
Functional Group - Sulfhydryl
SH
- some aa, proteins
- polar
- forms disulphide bonds to stabilize protein structure
