Biochemistry

Question 1

Ground state

Answer 1

All the electrons in an atom are in the lowest available energy levels

Question 2

Excited state

Answer 2

When an atom absorbs energy, it’s electrons move to a higher energy level

Question 3

Isotopes

Answer 3

Atoms of one element that vary only in the number of neutrons in the nucleus; all isotopes of the same element are identical because they have the same number of electrons in the same configuration

Question 4

Half life

Answer 4

Decay rate of radioactive isotopes

Question 5

Radioisotope

Answer 5

Radioactive isotopes

Question 6

Radioactive iodine

Answer 6

Can be used to diagnose and treat certain diseases of the thyroid gland

Question 7

Tracer

Answer 7

Ex. Radioactive carbon

Can be incorporated into a molecule and used to trace the path of carbon dioxide in a metabolic pathway

Question 8

Bond

Answer 8

Formed when two atomic nuclei attract the same electron/s

Energy is released when a bond is formed because atoms acquire a more stable configuration by bonding. They form a completed outer shell. Energy must be supplied to break a bond

Question 9

Ionic bond

Answer 9

Result from the transfer of electrons

Question 10

Anion

Answer 10

An atom that gains electrons (a negative ion)

Question 11

Cation

Answer 11

An atom that loses an electron (a positive ion)

Na+, Ca++, and CI- ions are all necessary for normal nerve function

Question 12

Covalent bonds

Answer 12

Form when atoms share electrons

Question 13

Molecule

Answer 13

The resulting structure of a covalent bond

Question 14

Nonpolar bond

Answer 14

When electrons are shared equally between two identical atoms; this is the type of bond found in diatomic molecules, such as H2 and O2

Question 15

Polar covalent bond

Answer 15

When electrons are shared unequally; this is the case between any two different atoms such as between atoms of carbon and oxygen in CO2

Question 16

Hydrophilic

Answer 16

“Water loving”; polar substances dissolve in water, known as the “universal solvent”

Question 17

Hydrophobic

Answer 17

“Water hating”; applies to nonpolar substances, which will dissolve in lipids; since the plasma membrane is a phospholipid bilayer, only nonpolar substances can dissolve through it; large polar molecules must travel across a membrane in special hydrophilic (protein) channels

Question 18

Water

Answer 18

Asymmetrical and highly polar; positive hydrogen, negative oxygen; the strong hydrogen attraction that water molecules have for each other is responsible for the special characteristics of water that are important for life on earth; high specific heat/heat of vaporization; strong cohesion tension

Question 19

Hydrogen bonding

Answer 19

The positive hydrogen of one molecule is attracted to the negative oxygen of an adjacent molecule

Question 20

Transpirational-pull cohesion tension

Answer 20

The means by which water moves up a tall tree from the roots to the leaves without the expenditure of energy; as one molecule of water is lost from the leaf by transpiration, another molecule is drawn in at the roots

Question 21

Capillary action

Answer 21

Results from the combined forces of cohesion and adhesion

Question 22

Spring overturn

Answer 22

When floating ice melts in the spring, becomes denser and sinks to the bottom of the lake, causing water to circulate throughout the lake

Oxygen from the surface is returned to the depths and nutrients released by the activities of bottom dwelling bacteria during winter are carried to the upper layers of the lake

Question 23

pH

Answer 23

A measure of the acidity and alkalinity of a solution; pH less than 7 is acidic, greater than 7 is basic, 7 is neutral

The value of the lH is the negative log of the hydrogen ion concentration in moles per liter

Question 24

Buffers

Answer 24

How biological systems regulate their pH; works by either absorbing excess hydrogen ions or donating hydrogen ions when there are too few; the most important buffer in human blood is the bicarbonate ion

Question 25

Isomer

Answer 25

Organic compounds that have the same molecular formula but different structures and therefore different properties

Question 26

Structural isomer

Answer 26

Differ in the arrangement of their atoms

Question 27

Cis-trans isomers

Answer 27

Differ only in spatial arrangement around double bonds, which are not flexible like single bonds

Question 28

Enantiomers

Answer 28

Molecules that are mirror images of each other; called the L- (left-handed) and D- (right handed) versions; all amino acids in cells are left handed

Question 29

Carbohydrates

Answer 29

Used for fuel and as building materials; quick energy

Question 30

Monosaccharides

Answer 30

C6H12O6
Glucose, galactose, fructose
(Isomers of each other)

Question 31

Disaccharide

Answer 31

C12H22O11

Two bonded monosaccharides