Chapter 5 (Bio 5)

carbon fixation

Using energy from ATP, and electrons and hydrogen ions from NADPH, CO2 from the atmosphere is converted into sugar.

Catabolism

a pathway releasing energy by breaking apart larger compounds

Anabolism

a pathway that creates compounds out of smaller molecules

Glycolysis

glucose is split and converted to pyruvate, releasing some ATP

During cellular respiration, ________ is the step that produces the greatest number of ATP molecules.

oxidative phosphorylation Over 80 percent of the ATP produced during cellular respiration is the result of oxidative phosphorylation.

Chlorophyll

pigment specialized for absorbing light energy - Needed for photosynthesis

Oxidative phosphorylation

the high energy from electrons is transferred to lots of ATP

Active site

the place where the enzyme and substrate bind The shape of the active site determines its specificity The shape is effected by temperature, pH, and salt concentration

The molecule ________ is produced to carry energy and is broken down during cellular processes to use that energy.

ATP ATP fuels metabolic reactions. Energy is released when it is broken down to ADP and a free phosphate.

During which cellular process is ATP NOT released?

Calvin cycle While the majority of ATP produced during cellular respiration is generated from the process of oxidative phosphorylation, some ATP is released during the Krebs cycle as well as in the process of glycolysis. The electron transport chain of photosynthesis produces ATP, but the Calvin cycle does not.

Which of the following statements about energy metabolism is FALSE?

Plants provide the H2O and CO2 that animals need to carry out respiration. Cellular respiration does not use H2O or CO2 as reactants; these are actually two of the products of respiration. Plants provide the glucose and O2 that make respiration possible.

Metabolism

all the chemical reactions that occur inside cells

Anabolism usually ________ energy to produce polymers, whereas catabolism ________ energy to produce monomers.

requires; releases Anabolic reactions require energy, while catabolic reactions release energy.

Light-independent reactions, or Calvin cycle

- Do not require solar energy - Require energy from energy carriers and ATP - Carbon dioxide + energy carriers + ATP = sugar • Carbon fixation: turns carbon into sugar

Light reactions

- Require solar energy - Sunlight + water = energy carriers + ATP + oxygen

ATP adenosine triphosphate

- Usable energy in ATP is held in the energy-rich phosphate bonds. - Energy is released when a molecule of ATP loses its terminal phosphate group, resulting in: • A molecule of ADP (adenosine diphosphate) • A free phosphate - Converting ADP and phosphate back into ATP takes metabolic energy.

Which of the following statements about enzymes is FALSE?

A specific enzyme can catalyze a variety of chemical reactions. Enzymes are highly specific and generally only catalyze a single type of chemical reaction. The other statements are part of the definition used to categorize a catalyst as an enzyme.

What kind of reaction is shown here?

Catabolism Catabolic reactions break larger molecules into smaller ones. This complex polymer is being broken down into monomers.

fermentation

Glycolysis may be followed by a fermentation process that allows its continuation without ever needing oxygen (human cells do not perform fermentation)

Which of the following represents the correct order of events, from first to last, that occur during the catabolism of glucose in the presence of O2?

Glycolysis; Krebs cycle; oxidative phosphorylation Glycolysis occurs with or without oxygen. In the presence of oxygen, the cell can complete cellular respiration by continuing with the Krebs cycle and then oxidative phosphorylation.

Which of the following is used in photosynthesis and released during cellular respiration?

H2O Both H2O and CO2 are used during photosynthesis to help make glucose and are produced during the breakdown of glucose that occurs during cellular respiration. While sunlight is used in photosynthesis, it is not involved in cellular respiration.

The protons moved by the proton pump during the light reactions of photosynthesis come from

H2O. The splitting of H2O molecules in the light reactions produces the protons that are moved across the thylakoid membrane by the proton pump.

Which of the following statements is true about the reaction shown?

It is driven by enzymes. The Calvin cycle is driven by enzymes that convert carbon dioxide into sugars. Rubisco is the enzyme crucial in catalyzing the first step in this process. This process takes place in the stroma of the chloroplast and occurs independently of light input.

Which of the following is closely associated with mitochondria?

Krebs cycle Chloroplasts (not mitochondria) contain thylakoids. The Calvin cycle occurs in the chloroplast while the Krebs cycle occurs in the mitochondria. Glycolysis occurs in the cytoplasm.

Which of the following ultimately provides the O2 used during the process of oxidative phosphorylation?

Light reactions of photosynthesis Oxygen is made when H2O molecules are split to generate electrons during the light reactions of photosynthesis.

The electrons that are released by the splitting of H2O molecules during photosynthesis ultimately end up in

NADPH. Splitting H2O molecules provides electrons to the photosystems used during the light reactions. These photosystems need new electrons because some of them are used to generate NADPH from NADP+.

If you consider the combined processes of photosynthesis and cellular respiration, the electrons found in H2O at the beginning of the light reactions end up attaching to ________ during respiration.

O2 to make new H2O It is interesting that electrons both begin their journey through metabolism in H2O and end that journey in the H2O that is made when O2 serves as the final electron acceptor in oxidative phosphorylation, combining with protons to form new "metabolic" water.

Which of the following statements regarding photosynthesis and cellular respiration is FALSE?

The process of photosynthesis does not require the input of energy. Recall that the process of photosynthesis is driven by the energy of sunlight. This energy is used to assist in the process of fixing CO2 to produce glucose.

Which of the following is NOT directly used in the Calvin Cycle?

Water While water is used in the light reactions of photosynthesis, it is not used in the Calvin cycle. In the Calvin cycle ATP helps to fuel the fixation of carbon from carbon dioxide into glucose, and this reaction is catalyzed by the enzyme rubisco.

In a multistep metabolic pathway, the products of the first enzyme-catalyzed reaction typically

are the substrates for the next reaction in the pathway. Multistep metabolic pathways usually take place within a single cell and the enzymes that catalyze each step are physically close together inside the cell. The products of one reaction serve as the substrate for the next step, until the final product is made. The product of the first reaction would certainly not be the final product of the multistep pathway, and so would not exit the cell immediately.

When yeast cells are deprived of oxygen, they

can produce a small amount of ATP along with ethanol as a byproduct. Yeast cells undergo fermentation in the absence of oxygen, which allows them to produce ATP through glycolysis alone, with ethanol and carbon dioxide as a byproduct. Lactic acid is produced by muscle cells undergoing fermentation.

Metabolic reactions that break down complex molecules into smaller compounds, thereby releasing usable energy for the cell, are best described as

catabolic This is the definition of catabolic reactions. Photosynthesis is anabolic.

Metabolic pathways

chains of linked chemical reactions - Produce key biological molecules in a cell • Example: amino acids, nucleotides, fatty acids - Break down key biological molecules in a cell • Example: carbohydrates and lipids

Chloroplasts

contain an extensive network of membranous structures called thylakoids

Thylakoids

contain enzymes needed for photosynthesis and a green pigment called chlorophyll

Glycolysis takes place in the ________ and produces ________, which in the presence of O2 then enters the ________.

cytoplasm; pyruvate; mitochondrion to complete cellular respiration Glycolysis is the only portion of cellular respiration that occurs outside the mitochondria. If oxygen is present, pyruvate can enter the mitochondrion to complete cellular respiration.

Energy carriers

deliver usable "on demand" energy. - Every living cell uses ATP (adenosine triphosphate). • ATP powers almost all activities in the cell. • If a cell exhausts its ATP supply, it will die. - NADPH, NADH, and FADH2 are also energy carriers. • Each one is a specialist in terms of the amount of energy it carries and the types of chemical reactions to which it supplies energy and from which it receives energy.

Fermentation

enables cells to generate ATP through glycolysis alone. - Occurs in the cytoplasm of the cell - An anaerobic process (does not require oxygen) - Pyruvate is processed to either 1. Alcohol and CO2 2. Lactic acid - Both processes result in production of the NADH energy carrier to support glycolysis.

One strategy that makes metabolic pathways more efficient is that Correct!

enzymes for a given pathway are located in the same place within the cell. Concentrating both substrates and enzymes in the same cellular location is one way to make metabolic pathways more efficient, as the products of one enzyme-catalyzed reaction become the reactants for the next reaction. Other ways include attaching enzymes to membranes or combining them into free-floating multienzyme complexes.

The Krebs cycle takes place in the

matrix of the mitochondrion. The cytoplasm is the site of glycolysis, the Krebs cycle occurs in the mitochondrial matrix, and oxidative phosphorylation takes place in and around the inner mitochondrial membrane.

The ultimate source of energy for most living systems is

sunlight. Although glucose is used by cells to produce ATP, the glucose must first be made through photosynthesis. Sunlight provides the energy needed to make glucose through the process of photosynthesis. Organisms that perform photosynthesis, like plants, some bacteria, and some protozoans, can use this glucose directly, while organisms that eat photosynthesizers or other consumers get this glucose indirectly.

Glycolysis

the first stage of cellular respiration - Occurs in the cytoplasm of the cell - An anaerobic process (does not require oxygen) - Sugars are split to make a three-carbon compound called pyruvate - For each glucose molecule that is split, the results are: • Two useful molecules of ATP • Two molecules of NADH

Oxidative phosphorylation is to respiration as ________ is to photosynthesis.

the light-dependent reaction Both processes use an electron transport chain that ultimately generates ATP.

Cellular respiration

the process of breaking down sugars into energy for cellular use

Photosynthesis

the process of gathering energy from the sun to create carbohydrates the way our planet stores energy from the sun and produces oxygen for animals to breathe. - Occurs in cells of some bacteria, all algae, and all plants - Takes place inside chloroplast organelles

The Krebs cycle

the second stage of cellular respiration Occurs in the mitochondria of the cell An aerobic process (but does not directly require oxygen) Is a sequence of enzyme-driven reactions The carbon backbone of the pyruvate molecule is broken apart, releasing CO2 This produces the energy carriers ATP, NADH, and FADH2, which are sent to oxidative phosphorylation.

Oxidative phosphorylation

the third stage of cellular respiration - Occurs in the mitochondria of the cell - An aerobic process (requires oxygen) - An electron transport chain passes the electrons and hydrogen atoms removed from NADH and FADH2 to molecular O2, creating water (H2O) - ATP synthase generates ATP

Kreb's cycle

with oxygen, energy from pyruvate is converted to ATP, and high-energy electrons are generated