Test 3 Study Guide

Question 1

Metabolism

Answer 1

All chemical and physical workings of a cell

Two types of chemical reactions, catabolic and anabolic.

Question 2

Anabolic vs Catabolic

Answer 2

Catabolism - degradative; breaks the bonds of larger molecules forming smaller molecules; releases energy.

Anabolism – biosynthesis; process that forms larger macromolecules from smaller molecules; requires energy input.

Question 3

Condensation vs Hydrolysis

Answer 3

Condensation involves the formation of a new chemical bond while hydrolysis involves the breakdown of a chemical bond.

Question 4

Enzymes

Answer 4

Biological catalysts that increase the rate of a chemical reaction by lowering the energy of activation (the resistance to a reaction)

Question 5

Types of enzymes

Answer 5

Simple enzymes – consist of protein alone

Conjugated enzymes or holoenzymes – contain protein and nonprotein molecules

Apoenzyme – protein portion. Exhibit primary, secondary, tertiary protein organization
     Larger enzymes show quaternary structure
     Active site (catalytic site): Site for specific substrate binding

Cofactors – nonprotein portion
Inorganic elements.
Metallic Cofactors (metal ions)
Activate enzymes
Help bring the active site and substrate close together
Participate directly in chemical reactions with the enzyme-substrate complex

  Coenzymes (organic factors)
       Serve as temporary carrier for some substrates
       Vitamins as the most common

Question 6

Aerobic cellular respiration

Answer 6

Series or enzyme-catalyzed reactions in which electrons are
transferred from fuel molecules to oxygen as a final electron
acceptor

• Glycolysis – glucose (6C) is oxidized and split into 2
molecules of pyruvic acid (3C), NADH is generated

• Pyruvate Oxidation

• TCA – processes pyruvic acid and generates 3 CO2
molecules , NADH and FADH2 are generated

• Electron transport chain – accepts electrons from NADH
and FADH; generates energy through sequential redox
reactions called oxidative phosphorylation

Question 7

Anaerobic respiration

Answer 7

Functions like aerobic respiration except it utilizes oxygen
containing ions, rather than free oxygen, as the final electron
acceptor: NO nitrite and NO Nitrate

Most obligate anaerobes use the H+ generated during
glycolysis and the Kreb’s cycle to reduce some compound
other than O2

glycolysis, the Kreb’s cycle, respiratory chain; molecular oxygen is not the final electron acceptor

Question 8

Fermentation

Answer 8

Incomplete oxidation of glucose or other carbohydrates in the
absence of oxygen

Uses organic compounds as terminal electron acceptors

Yields a small amount of ATP

Production of ethyl alcohol by yeasts acting on glucose

Formation of acid, gas, and other products by the action of
various bacteria on pyruvic acid

Question 9

Stages of cellular respiration and reduction

Answer 9

The stages of cellular respiration include glycolysis, pyruvate oxidation, the citric acid or Krebs cycle, and oxidative phosphorylation.

Question 10

Oxidation vs Reduction

Answer 10

Oxidation is the gain of oxygen, loss of hydrogen. Reduction is the loss of oxygen, gain of hydrogen.

Oxidation occurs when a reactant loses electrons during the reaction. Reduction occurs when a reactant gains electrons during the reaction.

Question 11

DNA vs RNA

Answer 11

(a) RNA contains the sugar ribose, while DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom), and (b) RNA has the nucleobase uracil while DNA contains thymine.

Question 12

Transcription vs translation

Answer 12

Transcription is the synthesis of RNA from a DNA template where the code in the DNA is converted into a complementary RNA code. Translation is the synthesis of a protein from an mRNA template where the code in the mRNA is converted into an amino acid sequence in a protein.

Question 13

The genetic code and interpretation

Answer 13

Represented by mRNA codons and their specific amino acids

Code is universal among organisms and redundant

Transcription produces mRNA complementary to the DNA gene

During translation, tRNAs use their anticodon to interpret the mRNA codons and bring in the specific amino acids

Question 14

Chromosome vs gene mutation

Answer 14

Unlike a gene mutation which alters a single gene or larger segment of DNA on a chromosome, chromosome mutations change and impact the entire chromosome.

Question 15

Examples of genetic recombination events

Answer 15

Genetic recombination – occurs when an organism
acquires and expresses genes that originated in another
organism

3 means for genetic recombination in bacteria:
• Conjugation
• Transformation
• Transduction

Question 16

Cellular respiration vs Photosynthesis

Answer 16

Photosynthesis converts carbon dioxide and water into oxygen and glucose. Glucose is used as food by the plant and oxygen is a by-product.

Cellular respiration converts oxygen and glucose into water and carbon dioxide.

Question 17

Stages of photosynthesis

Answer 17

Light-dependent reaction– photons are absorbed by chlorophyll, carotenoid, and phycobilin pigments

Water split by photolysis, releasing O2 gas and provides electrons to drive photophosphorylation

Released light energy used to synthesize ATP and NADPH

Light-independent reaction – dark reactions – Calvin cycle – uses ATP to fix CO2 to ribulose-1,5-bisphosphate and convert it to glucose

Question 18

ATP Yield for Aerobic Respiration

Answer 18

Glycolysis: 2ATP, 2NADH, 2 Pyruvate

Transition: 2NADH, 2CO2

Krebs Cycle: 4CO2, 6NADH, 2ATP, 2FADH

Electron Transport: 34ATP, 6H20

Question 19

DNA replication

Answer 19

Making an exact duplicate of the DNA involves 30 different enzymes:

Helicase unwinds and unzips the DNA double helix

An RNA primer is synthesized at the origin of replication by a primase

DNA polymerase III then adds nucleotides in a 5′ to 3′ direction
Leading strand – synthesized continuously in 5′ to 3′ direction
Lagging strand – synthesized 5′ to 3′ in short segments; overall direction is 3′ to 5′; okazaki fragments

DNA polymerase I removes the RNA primers and replaces them with DNA

Question 20

Glycolysis

Answer 20

Glycolysis is the process of breaking down glucose.

Glycolysis can take place with or without oxygen.

Glycolysis produces two molecules of pyruvate, two molecules of ATP, two molecules of NADH, and two molecules of water.

Glycolysis takes place in the cytoplasm.

Question 21

Pyruvate Oxidation

Answer 21

Converts pyruvate to Acetyl Coenzyme A and CO2

Makes 2 NADH per cycle in prokaryotes.

Makes 2 FADH2 per cycle in eukaryotes.

Occurs in the cytoplasm in prokaryotes.

Occurs in the mitochondrial matrix in eukaryotes.

Question 22

Citric Acid Cycle (Krebs Cycle)

Answer 22

Acetyl CoA reacts with oxaloacetate to form citric acids.

Citric acid is oxidized to form oxaloacetate.

Produces 1 ATP per cycle, 2 CO2 per cycle, 3 NADH per cycle, 1 FADH2 per cycle.

ATP synthesis is by substrate level phosphorylation.

Occurs in the cytoplasm of prokaryotes. Occurs in the mitochondrial matrix of eukaryotes.

Question 23

Electron Transport Chain

Answer 23

Occurs on the plasma membrane of prokaryotes.

Occurs on the inner mitochondrial membrane of eukaryotes.

3 ATP from each NADH, 2 ATP from each FADH2

ATP synthesis occurs by oxidative phosphorylation.

Oxygen is the final electron acceptor in eukaryotes.