Chapter 2: Biochemistry

Question 1

Isotopes

Answer 1

Atoms of one element where the number of neutrons vary.

Question 2

Half-life

Answer 2

The rate of decay for some isotopes.

Question 3

Radioisotopes

Answer 3

Radioactive isotopes that can be used to diagnose and treat certain diseases of the thyroid gland. A good example is I-131.

Question 4

Tracer

Answer 4

Used to trace the path of a certain molecule, such as radioactive carbon.

Question 5

Bond

Answer 5

Formed when two atomic nuclei attract the same electrons. Making bonds releases energy, but breaking bonds requires energy.

Question 6

Ionic Bonds

Answer 6

Bonds that result from the transfer of electrons.

Question 7

Covalent Bonds

Answer 7

Bonds that result from atoms sharing electrons, which creates molecules.

Question 8

Hydrophilic

Answer 8

“Water-loving.” Refers to substances that are polar and can dissolve like (polar) substances.

Question 9

Hydrophobic

Answer 9

“Water-hating.” Refers to substances that are non polar and can only dissolve equally non polar substances.

Since the plasma membrance is a phospholipid bilayer, only non polar substances can easily pass through. Large polar molecules must use special hydrophilic channels.

Question 10

Properties of Water

Answer 10

• Water can make hydrogen bonds between other water molecules.
• Water is highly polar.
• Water has high specific heat, which means they resist changes in temperature and warm the nearby land.
• Water has a high heat of vaporization.
• Water is the universal solvent.
• Water has strong cohesion, such as capillary action and surface tension.
• Only substance where the solid is less dense than the liquid form.

Question 11

pH

Answer 11

Measure of the acidity and alkalinity of a solution. Calculate it using -log(H+ moles/L).

Question 12

pH of water, blood, and acid rain

Answer 12

Water: 7
Blood: 7.4
Acid rain: 1.5-5.4

Question 13

Buffers

Answer 13

Substances that resist changes in pH. Works by absorbing H+ ions or donating H+ ions when necessary.q

Question 14

Isomers

Answer 14

Organic compounds with the same molecular formula but different structures.

Question 15

Structural Isomers

Answer 15

Differing in the atom arrangement.

Question 16

Cis-Trans Isomers

Answer 16

Differing in the double bond arrangement.

Question 17

Enantiomers

Answer 17

Mirror images (L and D sides). For example, the L-dopa is effective against Parkinson’s, but D-dopa is useless.

Question 18

Macromolecules

Answer 18

Carbohydrates, lipids, nucleic acids, proteins

Question 19

Carbohydrates

Answer 19

Made from C, H, O. The ratio between H atoms and O atoms is always 2:1. Carbohydrates are often used for quick energy. There are three classes of carbohydrates: monosaccharides, disaccharides, and polysaccharides.

Question 20

Monosaccharides

Answer 20

Glucose, galactose, fructose.

Question 21

Disaccharides

Answer 21

Two monosaccharides glued together with the release of a water through dehydration or condensation.

glucose + glucose -> maltose + H2O
glucose + galactose -> lactose + H2O
glucose + fructose -> sucrose +H2O

Question 22

Hydrolysis

Answer 22

The breakdown of a compound by adding water.

Question 23

Polysaccharides

Answer 23

Macromolecules. They are polymers of carbohydrates and formed by many monosaccharides joined together through dehydration reactions.

Plants have cellulose (plant walls) and starch for storage, whereas animals have chitin (exoskeleton and cell walls) and “animal starch.”

Question 24

Lipids

Answer 24

Hydrophobic substances that include fats, oils, steroids, and waxes. Composed of 1 glycerol and 3 fatty acids.

Question 25

Fatty acid

Answer 25

A hydrocarbon chain with a carboxyl group at the end. They can be either saturated or unsaturated.

Question 26

Saturated Fatty Acid

Answer 26

• Solid at room temperature (example: butter).

- Only contains single bonds.

Question 27

Unsaturated Fatty Acid

Answer 27

• Liquid at room temperature (example: oil).

- Contains at least one double bond.

Question 28

Steroids

Answer 28

Composed of four lipid rings. Examples include cholesterol, testosterone, estradiol.

Question 29

Lipid Functions

Answer 29

• Energy storage.
• Upkeeping the structure of the cell membrane.
• Hormones.

Question 30

Phospholipids

Answer 30

Made of a hydrophobic tail and a hydrophilic head. When these make contact with the water, they self-form into a bilayer, with the heads facing the water and the tails towards the insides.

Question 31

Proteins

Answer 31

Functions:

1. Growth and repair.
2. Cell-cell signaling.
3. Enzymatic activity.
4. Homeostasis.
5. Movement.

Proteins are composed of amino acids joined together by peptide bonds, and have an amino group, carboxyl group, and an R group.

Question 32

Protein Structure

Answer 32

Primary, secondary, tertiary, quaternary.

Primary: single linear sequence of amino acids.
Secondary: the linear sequence begins to fold and coil due to hydrogen bonds, and can form either an alpha helix or beta pleated sheet.
Tertiary: the 3D shape of a protein that is created by the folding in of the secondary structure.
Quaternary: proteins that consist of more than one polypeptide chain.

Question 33

Denaturation

Answer 33

Unfavorable conditions for a protein can cause a protein to lose the strong intermolecular forces and its characteristic shape.

Question 34

Chaperonins

Answer 34

Proteins that assist in the folding of proteins.

Question 35

Prions

Answer 35

Misfolded proteins that can cause brain diseases.

Question 36

Nucleic acids

Answer 36

The two types of nucleic acid are RNA and DNA, which encode hereditary information.

Made up of nucleotides, which consist of a nitrogenous base, 5 carbon sugar, and phosphate group.

Question 37

Laws of Thermodynamics

Answer 37

1. Energy cannot be created or destroyed, only converted.

2. With more energy conversions, the universe become more disordered.

Question 38

Metabolism

Answer 38

Sum of all the chemical reactions that take place in the cells. Some reactions involve breaking down molecules (catabolism) and building molecules (anabolism).

Question 39

Characteristics of Enzymes

Answer 39

Enzymes are “globular proteins” and have a 3D (tertiary) shape. They are also substrate specific, and follow the induced-fit model, meaning the enzymes chances its shape slightly to fit the substrate.

Question 40

Competitive Inhibition

Answer 40

When some similar looking compounds look similar and “compete” for the same active site on the enzyme. This reduces the amount of product made from the enzymes, as well as limiting the substrates binding to the enzyme.

Question 41

Noncompetitive Inhibitors

Answer 41

Bind to a site distinct and separate from the enzyme’s active site.