HW 2

HCC Learning Web When a molecule other than O, serves as the terminal electron acceptor for the electron transport chain, the organism is utilizing ———- respiration.

Anaerobic

Recall that E. coli can grow in glucose-salts medium, which contains only glucose and a few inorganic salts. This means the glucose is serving what two purposes in the cell? Check all that apply.

Starting point from which all cell components are made. Energy source.

Enzymes are usually ______. Multiple Choice proteins Correct lipids nucleic acids carbohydrates steroids

proteins Enzymes function as catalysts that speed up the rates of biological reactions. Enzymes are usually proteins.

All biochemical pathways have the same number of enzymatic reactions. True or False

False

An enzyme can only bind one substrate at a time. True or False

False

An enzyme speeds up a chemical reaction in the cell, but can only be used once. True or False

False

Glycolysis takes place in the ______. cytoplasm mitochondria cytoplasmic membrane cell wall endoplasmic reticulum

cytoplasm Glycolysis takes place in the cytoplasm.

Glycolysis is the central metabolic pathway that involves the breakdown of ______. glucose glycogen protein fatty acids starch

glucose "Glyco-" refers to sugar, and "-lysis" refers to breaking. Glycolysis is the central metabolic pathway involved in the breakdown of glucose, which is a key part of the metabolism of both aerobic and anaerobic organisms.

The Tricarboxylic Acid Cycle (TCA cycle) occurs after ______. glycolysis the electron transport chain the Calvin cycle fermentation photosynthesis

glycolysis The pyruvic acid molecules formed in glycolysis are first oxidized and then enter the cyclical pathway known as the Tricarboxylic Acid Cycle.

After glycolysis, pyruvate can be converted into ______ under anaerobic conditions. ATP lactic acid cytochrome c NADH glucose

lactic acid After glycolysis, pyruvate can be converted into lactic acid under anaerobic conditions.

Consider the biochemical pathway: A → B → C Enzyme 1 catalyzes A → B Enzyme 2 catalyzes B → C Enzyme 1 can use Multiple Choice either A or B as substrate, but not both. only B as a substrate. neither A nor B as substrate. only A as a substrate. both A and B as substrates.

only A as a substrate. Enzymes are very specific.

The terminal electron acceptor in aerobic respiration is ______. multiple choice oxygen pyruvic acid sulfate water nitrate

oxygen Oxygen is the terminal electron acceptor in aerobic respiration. In anaerobic respiration, other terminal electron acceptors such as nitrate or sulfate are used.

Which of the following binds to the active site of an enzyme? Multiple Choice ATP substrate product another enzyme water

substrate A substrate binds to the active site of an enzyme.

During glycolysis, a single 6-carbon molecule of glucose is converted to two 3-carbon pyruvate molecules. During the later steps in this process, how many molecules of ATP are generated? 1 2 12 6 4

4 In the "bottom half" of glycolysis, 4 ATP molecules are made. In the "top half", 2 ATP molecules are broken down, so the net production of ATP is 2.

The TCA (Krebs) cycle takes place in the mitochondria of eukaryote cells. Where does it take place in prokaryote cells? The cell wall The mitochondrion The cytoplasm Correct The ribosomes The nucleus

In prokaryotes, the TCA cycle takes place in the cytoplasm (cytosol).

In eukaryotic cells undergoing respiration, protons are pumped Multiple Choice -from the mitochondrial matrix to the intermembrane space. -down the electron transport chain. -across the cytoplasmic membrane. -from inside the cell to outside the cell. -from inside the mitochondria to the cytoplasm.

- from the mitochondrial matrix to the intermembrane space. In eukaryotic cells, the ETC is located in the inner membrane of mitochondria. Protons are pumped from the mitochondrial matrix to the region between the inner and outer membranes (intermembrane space).

In prokaryotic cells undergoing respiration, protons are pumped Multiple Choice -down the electron transport chain. -from outside the cell to inside the cell. -from the mitochondrial matrix to the intermembrane space. -from the periplasmic space to inside the cell. -from inside the cell to outside the cytoplasmic membrane.

-from inside the cell to outside the cytoplasmic membrane. In prokaryotic cells, the electron transport chain resides in the cytoplasmic membrane. Protons are pumped from inside the cell to the outside.

For each glucose molecule broken down by glycolysis, how many net ATP molecules are produced? 2 4 6 0 1

2 In the investment phase of glycolysis, 2 ATP molecules are used. However, in the payoff phase of glycolysis, 4 ATP molecules are made. This yields a net ATP production of 2 ATP molecules per glucose molecule.

The three central metabolic pathways—glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle (TCA cycle)—modify organic molecules to generate what three useful components for the cell? (NOTE: Please change all question marks to checkmarks for correct answers or empty boxes for incorrect answers.) NAD+ ATP Glucose Reducing power ADP Precursor metabolites Water Carbon dioxide Oxygen

ATP Reducing power Precursor metabolites The central metabolic pathways produce ATP by substrate-level phosphorylation, reducing power in the form of NADH, FADH2, and NADPH, and precursor metabolites that can be used in anabolic pathways to synthesize cellular components. Although other items are generated by these pathways—for example, carbon dioxide—these are byproducts and do not represent the purpose of the pathways.

______ refers to energy-requiring metabolic processes that result in the biosynthesis of macromolecules and cellular structures. Metabolism Anabolism Anabolism and Metabolism Catabolism Antagonism

Anabolism Anabolism refers to synthesis reactions only. Catabolism refers to energy-releasing reactions that break down molecules. Metabolism is a collective term for both anabolic and catabolic reactions.

Consider the biochemical pathway: A → B → C Enzyme 1 catalyzes A → B Enzyme 2 catalyzes B → C If enzyme 2 is inactive, which of the following compounds will accumulate? Multiple Choice C only B and C A and B B only A only

B only B will accumulate if enzyme 2 is unable to catalyze the reaction of B to C.

Glucose catabolism encompasses two key processes: (1) oxidizing glucose molecules to generate ATP, reducing power, and precursor metabolites; and (2) transferring the electrons carried by NADH and FADH, to the terminal electron acceptor. The second process, transfer of electrons, is accomplished by which of the following? Your answer is correct.

Fermentation Cellular respiration

How do chemolithotrophs acquire energy? Multiple Choice From sunlight AND decaying matter. From organic compounds From inorganic compounds From sunlight From decaying matter

From inorganic compounds Chemolithotrophs extract electrons from inorganic energy sources. These electrons then pass through an electron transport chain to generate a proton motive force to produce ATP.

The three central metabolic pathways that gradually oxidize glucose to CO, are ———-, the ———- ———- pathway, and the ———- cycle.

Glycolysis Pentose phosphate TCA (Kreb's/ Citric Acid)

A population of bacteria is breaking down some lipids to support microbial growth. Where do the products of lipid breakdown enter the central metabolic pathway? Check All That Apply Glycolysis TCA cycle Transition step Electron transport Pentose Phosphate pathway

Glycolysis TCA cycle Lipases break lipids apart into glycerol and fatty acids. The glycerol can then enter glycolysis, and the fatty acids can enter at the acetyl-CoA step.

The breakdown products of proteins can enter which of the following metabolic pathways? Check All That Apply Glycolysis Acetyl-CoA TCA cycle Electron transport chain Pentose phosphate pathway

Glycolysis TCA cycle Pentose phosphate pathway Proteins are broken down by proteases into amino acids which are then deaminated to remove the NH3 group. Depending on their structure, the remaining compounds can enter at various points in glycolysis, the pentose phosphate pathway, and the TCA cycle.

The two 3-carbon molecules glucose is split into are converted through a series of steps into pyruvate. During these steps NAD+ is converted to NADH. ATP is converted into ADP. ADP is converted to AMP. NADH is converted to NAD+. acetyl CoA is converted into oxaloacetic acid.

NAD+ is converted to NADH. During the conversion stages of 3-carbon molecules that result in forming pyruvic acid (pyruvate), NAD+ is reduced to NADH.

Which of the following is not a catabolic process? Glycolysis TCA cycle Protein synthesis Fermentation These are all catabolic processes.

Protein synthesis Protein synthesis is an anabolic process since it involves the building up of proteins from amino acids. Fermentation, glycolysis, and the TCA cycle all involve the breakdown of complex molecules and the release of energy and are considered catabolic.

The two 3-carbon molecules that glucose is split into during glycolysis are converted through a series of steps ending in what 3-carbon molecule? Citric acid Fructose-1,6-diphosphate Pyruvate Acetyl-CoA Diphosphglyceric acid

Pyruvate The two 3-carbon molecules glucose is split into during glycolysis are converted through a series of steps into pyruvate, a key metabolite.

TCA (Krebs) cycle takes place in the mitochondria of eukaryote cells. Where does it take place in prokaryote cells? The cell wall The mitochondrion The cytoplasm The ribosomes The nucleus

The cytoplasm In prokaryotes, the TCA cycle takes place in the cytoplasm (cytosol).

Which of the following correctly describe respiration? Check all that apply.

The electron transport chain uses the electrons to generate a proton motive force that can be used to generate ATP. Electrons extracted from glucose are transferred to the electron transport chain.

What is oxidation? The gain of protons by a molecule. The loss of protons from a molecule. The gain of electrons by a molecule. The loss of electrons from a molecule. The loss of electrons and protons from a molecule.

The loss of electrons from a molecule. Oxidation involves the loss of electrons by a molecule, atom or ion. Reduction, by comparison, involves the gain of electrons.

Which of the following statements accurately describe biochemical pathways? Choose all that apply. Check All That Apply They only function for a few times. They convert an initial substrate through a series of steps into an end product. They are well-organized and structured. They can be linear, branched, or cyclical. They proceed at a constant rate. They are carefully regulated. They always run at their maximum rate.

They convert an initial substrate through a series of steps into an end product. They are well-organized and structured. They can be linear, branched, or cyclical. They are carefully regulated. Metabolic pathways can be linear, branched, or cyclical. Their activity is carefully regulated, allowing increased or decreased production of products depending on the needs of the cell. Because enzymes are not used up during the reactions, a metabolic pathway can continue to function.

How many molecules of NADH are generated for each turn of the TCA cycle? Three Six Two in anaerobic cells and three in aerobic cells Two Nine

Three For one turn of the Krebs cycle, three NADH are produced.

In a biochemical pathway, the product of the first reaction becomes the substrate in the second reaction. True or False

True

For each glucose molecule that enters glycolysis, how many times does the TCA cycle "turn"? Six Four Two Three One

Two A single molecule of glucose is broken down into two pyruvate molecules during glycolysis. These are further converted into acetyl-CoA, which enters the TCA cycle. Each acetyl-CoA molecule "turns" the TCA cycle once, and each turn generates a single ATP molecule. Therefore, for each original glucose molecule, the TCA cycle "turns" twice and generates two ATP molecules.

How many ATP molecules are produced in the TCA cycle for each glucose molecule that enters glycolysis? Four Six Two Three One

Two A single molecule of glucose is broken down into two pyruvate molecules during glycolysis. These are further converted into acetyl-CoA, which enters the TCA cycle. Each acetyl-CoA molecule "turns" the TCA cycle once, and each turn generates a single ATP molecule. Therefore, for each original glucose molecule, the TCA cycle "turns" twice and generates two ATP molecules.

The energy released during the reactions of glycolysis is used to form ______. glycogen adenosine triphosphate glycerol guanine triphosphate adenosine monophosphate

adenosine triphosphate The energy released during the oxidation reactions of glycolysis is used to form adenosine triphosphate (ATP), the energy-carrying molecule for the cell.

Early in glycolysis, two phosphates are added to the glucose molecule. These phosphates come from breaking down ATP. conversion of NADH. hydrolysis of pyruvate. protein denaturation. transfer of phospholipids.

breaking down ATP. Early in glycolysis, ATP is converted into ADP and the phosphates are added to the ends of the glucose molecule.

Glycolysis makes products that feed into electron transport chain fermentation TCA cycle electron transport chain, TCA cycle AND fermentation TCA cycle AND fermentation

electron transport chain, TCA cycle AND fermentation The pyruvate made during glycolysis can be used either in the TCA cycle or fermentation, and the NADH+ is used in the electron transport chain.

Cells prefer to use carbohydrates as energy sources because they are such good donors of hydrogen and electrons the waste products of their breakdown are non-toxic they contain the greatest amount of energy per unit their internal bonds are so easy to cleave

they are such good donors of hydrogen and electrons Cells prefer to use carbohydrates such as glucose as energy sources because they are such good donors of hydrogen and electrons.

What happens to carbon dioxide after it is released during reactions of the TCA cycle? It donates electrons to the electron transport chain for ATP production. It diffuses out of the cell. It combines with H to form water. It catalyzes a glycolytic reaction. It enters a fermentation pathway to form ATP.

It diffuses out of the cell. Carbon dioxide is a byproduct of the TCA cycle reactions and when produced, it is released from the cell by diffusion.

Consider the picture representing metabolism in E. coll growing in a medium that contains only glucose and a few inorganic salts. The four outputs to the sides represent different anabollc pathways Involved in the biosynthesis of the four types of biological macromolecules. These four biological macromolecules are ————, ————, ———-, & ———-.

Lipids Carbohydrates Amino acids Nucleic acids

Cellular ——— is the process that transfers electrons extracted from glucose via the central metabolic pathways to the electron transport chain, where they are used to generate a proton motive force that can be harvested to make ATP via oxidative phosphorylation.

Respiration