1.1 Chemistry in Living Systems

Question 1

Isotope

Answer 1

Elements with the same number of protons, different number of neutrons

Question 2

Radioisotopes

Answer 2

Isotopes whose nuclei are unstable and decay spontaneously

Question 3

Describe how radioisotopes decay

Answer 3

Neutron -> proton + electron + energy

Question 4

Half-life

Answer 4

Time taken for 1/2 of the atoms in a sample to decay

Question 5

Radiometric Dating

Answer 5

Method for determining age of geological or archeological specimen based on concentration and half-life of a particular radioisotope contained within it

Question 6

How do scientists estimate how many years have passed since an animal died

Answer 6

Measure the ratio of C-12 and C-14

Question 7

What happens to C-12 and C-14 when an animal dies

Answer 7

C-12 stays constant while C-14 continues to decay (decreases)

Question 8

Radioisotope Tracing

Answer 8

• 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)

Question 9

Detecting Disease by Radioisotope Tracing

Answer 9

Through nuclear imaging tech, can learn about internal anatomy and functioning of specific organs, detect disease

Question 10

Dangers of Radioisotopes

Answer 10

• Cellular and tissue damage
• Genetic mutations
• Radiation sickness
• Cell death

Question 11

Intramolecular Forces (chemical bond)

Answer 11

Hold atoms together within a molecule

Question 12

Ionic Bonds

Answer 12

Valence of one atom is transferred permanently to another atom

Question 13

Cation

Answer 13

Atom that loses the electrons become positively charged

Question 14

Anion

Answer 14

Atom that gains the electron and becomes negatively charged

Question 15

Covalent Bond

Answer 15

Two atoms share one or more pairs of valence electrons
- Typically two non metals
- Strong bonds

Question 16

Non polar covalent bonds

Answer 16

Equal sharing

Question 17

Polar covalent bonds

Answer 17

Unequal sharing

Question 18

Electronegativity

Answer 18

Atoms ability to attract electrons in a chem bond
- Two atoms with close value electronegativity = covalent
- Two atoms with far apart electronegativity = ionic

Question 19

Polar molecules

Answer 19

• Contain polar bonds
• Non symmetrical molecules
• Partial neg and partial pos

Question 20

Non polar molecules

Answer 20

• Straight and symmetrical molecule
• Effects of polar bonds cancel each other out

Question 21

Dipoles

Answer 21

• 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

Question 22

Four molecular shapes (orbitals)

Answer 22

1. Linear
2. Angular
3. Pyramidal
4. Tetrahedral

Question 23

Why does molecular shape matter?

Answer 23

Biological molecules must recognize and interact with other molecules in the cell based on molecular shape and size
(enzymes, hormones, neurotransmitters)

Question 24

Intermolecular Forces

Answer 24

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

Question 25

London Dispersion Forces

Answer 25

2 non polar molecules - results from temp uneven distribution of electrons - Weak!

Question 26

Ion-dipole forces

Answer 26

polar molecule and ion

Question 27

Dipole-dipole forces

Answer 27

two polar molecules opposite dipoles attract

Question 28

Hydrogen bonding

Answer 28

- 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

Question 29

List the 10 properties of water

Answer 29

1. Polar covalent bond 2. Solute 3. Solvent 4. High heat capacity 5. Gas, liquid, solid 6. Surface tension 7. Density 8. Capillary Action 9. Cohesion 10. Adhesion

Question 30

Hydophillic Substances

Answer 30

Water soluble Ionic and polar

Question 31

How do ionic compounds dissolve?

Answer 31

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

Question 32

Hydrophobic

Answer 32

Water insoluble Non polar substances

Question 33

Amphiphilic Molecules

Answer 33

Have polar region and non polar region - Will orient themselves to minimize contact that their non-polar regions have with water

Question 34

Hydrophobic Effect

Answer 34

Hydrophobic molecules clump together to avoid water

Question 35

Functional Group - Hydroxyl

Answer 35

OH - found in carbs, proteins, na, lipids - polar

Question 36

Functional Group - Carbonyl

Answer 36

CHO, CO - found in carbs, na - polar

Question 37

Functional Group - Carboxyl

Answer 37

COOH - proteins, lipids - polar - acidic - ionizes to release H+

Question 38

Functional Group - Amino

Answer 38

NH2 - aa, proteins, na - polar - basic - accepts h+ - Forms hydrogen bonds

Question 39

Functional Group - Sulfhydryl

Answer 39

SH - some aa, proteins - polar - forms disulphide bonds to stabilize protein structure