Exam #2 (2 & 6)

Question 1

Element

Answer 1

A substance that consists of only one kind of atom and cannot be separated into simpler parts by chemical methods; 92 are naturally occuring;

Question 2

4 Most Common Elements in Organisms

Answer 2

• Carbon
• Hydrogen
• Oxygen
• Nitrogen

Question 3

Atoms

Answer 3

The basic units of all matter

Question 4

Subatomic Particles Composing Atoms

Answer 4

• Neutrons: uncharged, found in the nucleus
• Protons: positively charged, found in the nucleus
• Electrons: negatively charged, form cloud around the nucleus

Question 5

Atomic Number

Answer 5

The number of protons in the nucleus

Question 6

Atomic Weight (Mass)

Answer 6

The sum of the number of protons and neutrons found in an atom

Question 7

Isotope

Answer 7

Forms of the same chemical element that differ in their number of neutrons; useful tools in biological research

Question 8

Molecule

Answer 8

Two or more atoms held together by chemical bonds

Question 9

Chemical Bond

Answer 9

Form when atoms lose, gain, or share the electrons in their outer shell to achieve the most stable state

Question 10

Ionic Bond

Answer 10

A strong chemical bond resulting from the attraction of positively and negatively charged ions; resulting product is called a salt

Question 11

Covalent Bond

Answer 11

Strong chemical bond formed by the sharing of electrons between atoms; share pairs of valence electrons

Question 12

Hydrogen Bond

Answer 12

Weak attraction between a positively charged hydrogen atom of one compound and a negatively charged atom of another compound; charges of the two atoms are due to polar covalent bonds

Question 13

Ion

Answer 13

An atom that gains or loses an electron; becomes positively or negatively charged

Question 14

Cation

Answer 14

Positively charged ion

Question 15

Anion

Answer 15

Negatively charged ion

Question 16

pH

Answer 16

Scale of 0 to 14 that expresses the acidity or alkalinity of a solution

Question 17

Buffer

Answer 17

Substances in a solution that acts to prevent changes in pH

Question 18

Macromolecules

Answer 18

Large molecules that contain 10s of atoms to billions of atoms; complex enough that life is usually necessary to make them
- organic: the molecules contain at least Carbon and Hydrogen

Question 19

4 Types of Macromolecules

Answer 19

• Carbohydrates: sugars, starch, glycogen, chitin, celluose, peptidoglycan (most composed of ringed molecules)
• Lipids: triglycerides, phospholipids, steroids
• Proteins: building blocks, enzymes
• Nucleic Acids: DNA, RNA

Question 20

Monosaccharides

Answer 20

Simple sugars; primary choice to make cellular energy (ATP)

Question 21

Polysaccharides

Answer 21

Carbohydrates that cells make to store energy in the form of a carbohydrate; glycogen in animals, cellulose in plants; chitin, cellulose, and peptidoglycan are complex carbohydrate molecules that cells use as building blocks of cell walls

Question 22

Triglycerides

Answer 22

Fat molecules that cells construct to store energy

Question 23

Saturated Fat

Answer 23

Fatty acid that contains no double bonds

Question 24

Unsaturated Fat

Answer 24

Fatty acid with one or more double bonds

Question 25

Phospholipids

Answer 25

Fat molecules that cells construct as building blocks for cell membranes and other membrane-bound organelles

Question 26

Steroids

Answer 26

Fat molecules that have four carbon rings connected to each other; cholesterol and some hormones

Question 27

Proteins

Answer 27

Made up of smaller amino acid molecules (20 different types); most made up of about 200 adjacent amino acids; conduct most of the cellular work and are used as building blocks for cell walls, cell membranes, flagella, cilia, and organelles; also used as enzymes that allow cells to create chemical reactions

Question 28

Nucleotides

Answer 28

Small molecules that make up nucleic acids

Question 29

Enzymes

Answer 29

Proteins that function as biological catalysts, facilitating the conversion of a substrate into a product; work on only one type of substrate; end is -ase

Question 30

Catalyst

Answer 30

Substance that speeds up the rate of a chemical reaction without being altered or depleted in the process

Question 31

Active Site

Answer 31

Small crevices on enzymes that allow a substrate to precisely bind to it

Question 32

Enzyme-Substrate Complex

Answer 32

The temporary binding of an enzyme and a substrate during which the activation energy is lowered for the reaction

Question 33

Cofactors and Coenzymes

Answer 33

Inorganic (minerals) and organic (vitamins); loosely attach to enzymes and complete the active site; without them, enzymes cannot function correctly and normal metabolism is impaired

Question 34

Environmental Factors That May Disrupt the Normal Shape and Function of Enzymes

Answer 34

- Temperature: speed up or slow down rate of reactions; denaturation at too high temps - Salt Concentration: most operate best at low concentrations - pH: best at values slightly above 7

Question 35

Allosteric Regulation

Answer 35

The temporary binding of regulatory molecules to the allosteric site of an enzyme; can make enzymes more or less reactive (starting or stopping a chemical reaction)

Question 36

Competitive Inhibition

Answer 36

An inhibitor molecule binds to the active site of an enzyme and prevents the true substrate from binding

Question 37

Non-Competitive Inhibition

Answer 37

An inhibitor molecule binds to the allosteric site of an enzyme and permanently changes the shape of the enzyme

Question 38

Metabolism

Answer 38

The sum of all chemical reactions that occur within a cell

Question 39

Anabolic Chemical Reactions

Answer 39

Chemical reactions in which smaller molecules are joined together to build larger molecules; typically require an input of energy; dehydration synthesis

Question 40

Catabolic Chemical Reactions

Answer 40

Chemical reactions in which larger molecules are broken apart into smaller ones; typically release energy; hydrolysis; release the energy stored within covalent bonds of macromolecules and produce ATP

Question 41

ATP (Adenosine Triphosphate)

Answer 41

A modified RNA nucleotide with three phosphate groups; the covalent bond attaching the last phosphate group is considered a high energy bond that a cell uses for energy

Question 42

REDOX (reduction-oxidation) Reactions

Answer 42

Transfer of electrons (and H+) from one molecule to another; one becomes reduced (gains) and one becomes oxidized (loses); always occur together

Question 43

NAD+ and FAD+

Answer 43

Molecules that act as electron acceptors in catabolic chemical reactions; one is reduced to NADH, the other is reduced to FADH2

Question 44

Glycolysis: Simplified Reaction

Answer 44

Glucose (6 carbons) + 2 ATP + 2 NAD+ + 10 enzyme mediated chemical reactions ----> 2 pyruvate (3 carbons) + 4 ATP + 2 NADH

Question 45

Steps of Glycolysis

Answer 45

- First step in the degradation of sugars - One glucose enters the pathway - Two pyruvate are produced at the end of the 10 step process - Four ATP are produced, two used to initiate reactions (2 ATP generated net) - Two pairs of electrons passed to both NAD+, reducing both of them to NADH - No free oxygen is consumed

Question 46

Krebs Cycle: Simplified Reactioin

Answer 46

Pyruvate + 4 NAD+ + 1 FAD+ ----> 3 CO2 + 4 NADH + 1 FADH2 + 1 ATP

Question 47

Summary of Krebs Cycle

Answer 47

- For each glucose molecule, 2 pyruvate enter the pathway - The 3-carbon pyruvate molecule is broken down one carbon at a time over a series of 9 reactions, producing CO2 as a product - Everything except the first step is cyclic: pyruvic acid + NAD+ ----> Acetyl CoA (2C) + CO2 + NADH - Acetyl CoA will then combine with a 4-carbon oxaloacetic acid molecule forming a 6-carbon citric acid molecule; two additional carbons removed one at a time - The energy released from the reactions are lost as heat and stored in the electron carriers using redox reactions - Produces 1 ATP, 4 NADH, 1 FADH2

Question 48

Electron Transport Chain

Answer 48

NADH and FADH2 are oxidized into NAD+ and FAD+; the electrons are transferred to a series of five to seven electron acceptors (proteins) found within a membrane; these electrons have energy that will construct ATP molecules for the cell

Question 49

ATP Synthase

Answer 49

An enzyme used to make ATP; found in the cell membranes of prokaryotic organisms and in the inner mitochondrial membrane of eukaryotic organisms

Question 50

Terminal Electron Acceptor (TEA)

Answer 50

The last molecule to accept the electrons found in the NADH and FADH2 molecules; oxygen in aerobic respiration and oxygen containing salts in anaerobic respiration

Question 51

Aerobic Respiration

Answer 51

Krebs + ETC using oxygen; oxygen is reduced to water

Question 52

Anaerobic Respiration

Answer 52

Krebs + ETC using inorganic molecules

Question 53

Fermentation

Answer 53

Pyruvate is further oxidized without free oxygen; unless glycolysis is included in the calculations, these additional pathways do not produce usable energy (ATP); main purpose is to convert NADH into NAD+ to be used in glycolysis

Question 54

Two Main Types of Fermentation

Answer 54

- Alcohol (yeast, some bacteria) | - Acidic (humans, some bacteria

Question 55

Propionibacterium

Answer 55

Conduct acidic fermentation that gives Swiss cheese its characteristic flavor; the holes represent the CO2 escaping the cheese

Question 56

Mixed Acid Fermentation

Answer 56

Type of Fermentation in which some bacteria produce a mixture of acetic, lactic, succinic, and formic acids (super fermenters: lower the pH of medium below 4.0)

Question 57

Drawbacks to Fermentation

Answer 57

- Wastes large amounts of energy found in glucose; only net of 2 ATP produced from a single glucose molecule; chemical reactions are only 2% efficient - The waste products produced can impede or stop cell function

Question 58

Other Carbohydrates (besides glucose) Used to Produce ATP

Answer 58

- Other sugars (fructose, sucrose, lactose, etc.) will first meed to be converted into glucose and then proceed into glycolysis - Polysaccharides are broken down into multiple glucose (1000+) and then each is placed into glycolysis

Question 59

Triglycerides Used to Produce ATP

Answer 59

- Must first be broken down to its component molecules: 3 fatty acids and a glycerol molecule - Fatty acids are converted into numerous Acetyl CoA by beta-oxidation - Acetyl CoA are inserted into the Krebs Cycle, bypassing the transition step - Glycerol is converted into pyruvate which is inserted into the Krebs cycle - Approximately 458 ATP can be generated from a single one of these molecules

Question 60

Proteins Used to Produce ATP

Answer 60

- Can be used if the cell does not have enough carbohydrates or triglycerides available to use as energy for ATP production - First, broken down into individual amino acids - NH2 must be removed from each amino acid (deamination) and converted to urea - The remaining portions of the amino acids are converted into one of the substrates of the Krebs Cycle - Each amino acid is reduced into NADH and FADH2 in the Krebs Cycle and used later to generate ATP in the ETC (12-16 ATP are generated per amino acid)