biochemical reactions

enzymes and biochemical reactions

Human body temperature must remain within a narrow range around 37C (98.6F). At this temperature, most biochemical reactions would occur too slowly to keep us alive. Thats where enzymes come in. Enzymes are biochemical catalysts. They speed up biochemical reactions, not only in humans but in virtually all living things. Most enzymes are proteins. Two are described in Figure 9.27.

photosynthesis

Most of the energy used by living things comes either directly or indirectly from the sun. Sunlight provides the energy for photosynthesis. This is the process in which plants and certain other organisms (see Figure 9.26) synthesize glucose (C6 H12 O6 ). The process uses carbon dioxide and water and also produces oxygen. The overall chemical equation for photosynthesis is: 6CO2 + 6H2 O + Light Energy ! C6 H12 O6 + 6O2 Photosynthesis changes light energy to chemical energy. The chemical energy is stored in the bonds of glucose molecules. Glucose is used for energy by the cells of almost all living things. Plants make their own glucose. Other organisms get glucose by consuming plants (or organisms that consume plants). How do living things get energy from glucose? The answer is cellular respiration.

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cellular respiration

Cellular respiration is the process in which the cells of living things break down glucose with oxygen to produce carbon dioxide, water, and energy. The overall chemical equation for cellular respiration is: C6 H12 O6 + 6O2 ! 6CO2 + 6H2 O + Heat and Chemical Energy Cellular respiration releases some of the energy in glucose as heat. It uses the rest of the energy to form many, even smaller molecules. The smaller molecules contain just the right amount of energy to power chemical reactions inside cells. You can look at cellular respiration in more detail at this URL: MEDIA Click image to the left or use the URL below. URL:

instructional diagrams

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The diagram depicts the process of cellular respiration. There are three steps in this process. The first step is Glycolysis. In Glycolysis, glucose in the cytoplasm is broken into two molecules of pyruvic acid and two molecules of ATP by direct synthesis. Then pyruvate from Glycolysis is actively pumped into mitochondria. One carbon dioxide molecule and one hydrogen molecule are removed from the pyruvate (called oxidative decarboxylation) to produce an acetyl group, which joins to an enzyme called CoA to form acetyl CoA. This is essential for the Krebs cycle.2 Acetyl CoA gives 2 NADH molecules and acetyl-CoA enters the Citric Acid Cycle, which is also known as Kreb's cycle. This happens inside the mitochondria. The citric acid cycle is an 8-step process involving different enzymes and co-enzymes. During the cycle, acetyl-CoA (2 carbons) + oxaloacetate (4 carbons) yields citrate (6 carbons), which is rearranged to a more reactive form called isocitrate (6 carbons). Isocitrate is modified to become -ketoglutarate (5 carbons), succinyl-CoA, succinate, fumarate, malate, and, finally, oxaloacetate. The total yield from 1 glucose molecule (2 pyruvate molecules) is 6 NADH, 2 FADH2, and 2 ATP. All the hydrogen molecules which have been removed in the steps before (Krebs cycle, Link reaction) are pumped inside the mitochondria using energy that electrons release. Eventually, the electrons powering the pumping of hydrogen into the mitochondria mix with some hydrogen and oxygen to form water and the hydrogen molecules stop being pumped. Eventually, the hydrogen flows back into the cytoplasm of the mitochondria through protein channels. As the hydrogen flows, ATP is made from ADP and phosphate ions. The Electron transport Chain gives about 34 ATP by ATP synthase. The maximum energy generated per glucose molecule is 38 ATP.

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This diagram shows the biochemical reaction cycles. Since all energy source of the biological objects on the earth is the sun, the cycle starts from the sun. Sun gives light to plants. The plants produce Glucose or sugar and oxygen by the process called photosynthesis with carbon dioxide and water produced by other plants and animals. Specifically, the Chloroplasts in the plants produces the Glucose. The Glucose and the sugar and oxygen are consumed by other plants and animals by cellular respiration in mitochondria. By the cellular respiration, plants and animals produce ATP which is a source of energy. Comsuming the Glucose and oxygen, the plants and animals also produce water and carbon dioxide. The water and carbon dioxide provides the ingredient for photosynthesis of plants. With the water and carbon dioxide, the plants produces glucose and oxygen with sunlight which completes the cycle.

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The diagram depicts the Oxygen Cycle. This is the cycle that maintains the levels of oxygen in the atmosphere. Oxygen from the atmosphere is used up in two processes, namely combustion, respiration and in the formation of oxides of nitrogen. Oxygen is returned to the atmosphere in only one major process, that is, photosynthesis. Carbon dioxide and water are taken up by plants in the presence of sunlight and chlorophyll to give glucose and oxygen. This glucose and oxygen are converted into carbon dioxide and water during respiration. Respiration also gives energy for work in the form of ATP.

questions

Reactants in cellular respiration include

-->  a. oxygen.

b. water.

c. carbon dioxide.

d. two of the above

All organisms make food by photosynthesis.

a. true

-->  b. false

The synthesis of glucose requires carbon dioxide.

-->  a. true

b. false

The human enzyme named pepsin catalyzes the digestion of

a. nucleic acids.

b. fatty acids.

-->  c. proteins.

d. sugars.

Insect-catching plants such as pitcher plants obtain glucose from insects.

a. true

-->  b. false

The compound that cells break down to release energy is

a. chlorophyll.

b. carbon dioxide.

c. water.

-->  d. glucose.

Energy for photosynthesis comes from

a. water.

b. soil.

-->  c. light.

d. chemicals.

Chemical reactions provide living cells with energy.

-->  a. true

b. false

Photosynthesis is an exothermic, or energy-releasing, process.

a. true

-->  b. false

Which equation correctly represents photosynthesis?

a. C6 H12 O6 + 6O2 + energy  6CO2 + 6H2 O

b. 6CO2 + 6O2 + energy  C6 H12 O6 + 6H2 O

c. C6 H12 O6 + 6CO2 + energy  6O2 + 6H2 O

-->  d. 6CO2 + 6H2 O + energy  C6 H12 O6 + 6O2

The overall chemical reaction for photosynthesis is represented by the equation: C6 H12 O6 + 6O2 6CO2

a. true

-->  b. false

Products of cellular respiration include many small, energy-storing molecules.

-->  a. true

b. false

Cellular respiration takes place only in organisms that cannot make their own food.

a. true

-->  b. false

The process of cellular respiration requires carbon dioxide.

a. true

-->  b. false

One of the products of cellular respiration is oxygen.

a. true

-->  b. false

All living things need energy just to stay alive.

-->  a. true

b. false

Cellular respiration is an endothermic, or energy-absorbing, process.

a. true

-->  b. false

Only plants can carry out photosynthesis.

a. true

-->  b. false

Cellular respiration occurs in all living cells

-->  a. true

b. false

One of the products of cellular respiration is oxygen.

a. true

-->  b. false

process in which cells break down glucose and release energy

a. photosynthesis

b. biochemical reaction

c. oxygen

-->  d. cellular respiration

e. glucose

f. chlorophyll

g. enzyme

any chemical reaction that takes place in living things

a. photosynthesis

-->  b. biochemical reaction

c. oxygen

d. cellular respiration

e. glucose

f. chlorophyll

g. enzyme

protein that speeds up biochemical reactions

a. photosynthesis

b. biochemical reaction

c. oxygen

d. cellular respiration

e. glucose

f. chlorophyll

-->  g. enzyme

byproduct of photosynthesis

a. photosynthesis

b. biochemical reaction

-->  c. oxygen

d. cellular respiration

e. glucose

f. chlorophyll

g. enzyme

compound that cells use for energy

a. photosynthesis

b. biochemical reaction

c. oxygen

d. cellular respiration

-->  e. glucose

f. chlorophyll

g. enzyme

pigment that captures light energy

a. photosynthesis

b. biochemical reaction

c. oxygen

d. cellular respiration

e. glucose

-->  f. chlorophyll

g. enzyme

process in which certain organisms make glucose

-->  a. photosynthesis

b. biochemical reaction

c. oxygen

d. cellular respiration

e. glucose

f. chlorophyll

g. enzyme

All living things need

a. carbon dioxide.

b. sunlight.

-->  c. energy.

d. two of the above

Reactants in photosynthesis include

a. chlorophyll.

b. oxygen.

c. glucose.

-->  d. water.

Types of organisms that make their own glucose include

a. algae.

b. plants.

c. cyanobacteria.

-->  d. all of the above

All organisms that undergo photosynthesis contain

a. pepsin.

b. amylase.

-->  c. chlorophyll.

d. two of the above

Cellular respiration releases some energy in the form of

-->  a. heat.

b. light.

c. motion.

d. electricity.

Amylase catalyzes the breakdown of

a. lipids.

b. proteins.

c. nucleic acids.

-->  d. complex carbohydrates.

diagram questions

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Does cellular respiration require energy directly from the sun?

a. occasionally

b. yes

c. only when it is sunny

-->  d. no

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Identify the photosynthesis' product referred as the letter B on the diagram.

a. Water.

b. Oxygen.

-->  c. Glucose.

d. Carbon dioxide.

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What is produced from Photosynthesis?

-->  a. Heat energy

b. Sun

c. Cellular respiration

d. Air

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What occurs after photosynthesis in this diagram?

a. Sunlight

-->  b. Cellular respiration

c. Heat energy

d. ATP

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What are the byproducts of animal cellular respiration in producing ATP?

a. oxygen and glucose

b. carbon dioxide and chloroplast

c. oxygen and nitrogen

-->  d. Carbon Dioxide and water

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What is considered a by-product during photosynthesis?

a. carbon dioxide

b. glucose

-->  c. oxygen

d. water

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Which of the following does photosynthesis make?

a. carbon dioxide

b. light energy

c. water

-->  d. Glucose

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Where does light energy go to?

a. Mitochondrion

-->  b. Chloroplast

c. Energy

d. Cellular respiration

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Which element is called CO?

a. Carbon Dioxide

b. Ozone

c. Hydrogen Dioxide

-->  d. Carbon Oxide

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Carbon dioxide and water are produced by this.

a. chloroplast

-->  b. mitochondion

c. ATP

d. sun

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Which compound is C6H12O6?

-->  a. Glucose

b. Water

c. Carbon Dioxide

d. Oxygen

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How many Carbon Dioxides are sent from the Mitochondrion to the Chloroplast in this diagram?

a. 2

-->  b. 6

c. 4

d. 1

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How do living things get energy from glucose?

a. through other dead plant

b. through photosynthesis

-->  c. Through cellular respiration

d. from the sun

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What do plants let out in order for cellular respiration to occur?

-->  a. Glucose and oxygen

b. Sunlight

c. Carbon dioxide and water

d. Heat

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Which Process Produces Oxygen & Glucose?

a. Sunlight

b. Cellular Respiration

-->  c. Photosynthesis

d. Plant Cell

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How many phases are there in photosynthesis and cellular respiration?

a. 9

-->  b. 6

c. 7

d. 8

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What would happen if the rabbit expelled oxygen instead of carbon dioxide?

a. The plant will need more water to live.

b. The rabbit will be able to make its own glucose.

c. The plant will become healthier.

-->  d. The plant will not be able to synthesize glucose.

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The process of glycolysis transforms glucose into what substance?

a. NADH

b. Citric acid

-->  c. Pyruvate

d. FADH2

question_image

What would happen if there is no ADP available for the cells to uptake?

a. the cell would function normally

b. The cell would swell.

-->  c. The cell could not respire.

d. The cell would reproduce

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What are the outputs of the Citric acid cycle?

a. CO2 and 34ATP

-->  b. CO2

c. O2 and CO2

d. CO2 and 2ATP

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Which metabolic process supplies carbon precursors directly to the Electron Transport Chain?

a. Glycolysis

b. Cytoplasm

c. Mitochondria

-->  d. Citric Acid Cycle

question_image

How many times is Oxygen shown in this diagram?

a. 1

b. 4

-->  c. 2

d. 3

question_image

What cycle converts Oxygen to Carbon Dioxide in a cytoplasm with the help of Adenosine Triphosphate?

a. Through Glycogenesis.

b. Through Glyconeogenesis.

c. Through Glycolysis.

-->  d. Through the Citric Acid Cycle.

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How are electrons transferred to the cell?

-->  a. NADH

b. ATP

c. Citric Acid Cycle

d. Glycolysis

question_image

What is the process between the Electron transport chain and the Glycolysis?

a. Oxygen

b. Citric acid cycle

c. Glucose

-->  d. Electrons transferred by NADH

question_image

The Electron Transport Chain produces what products?

-->  a. Produces ATP

b. Produce pyruvate

c. Produce glucose

d. Breaks down ATP

question_image

How are the electrons carried to be used in the citric acid cycle?

a. Via oxidation

b. Via Mitochondrion

-->  c. Via NADH and FADH2

d. Via glycolysis

question_image

Which substance is produced by oxidative phosphorylation?

a. Citric acid

-->  b. ATP

c. Pyruvate

d. Glucose

question_image

At how many stages during cellular respiration ATP is produced?

a. 6

b. 2

-->  c. 3

d. 1

question_image

How many times is ATP shown in this diagram?

a. 1

b. 4

-->  c. 3

d. 2

question_image

What happens to cytosol after it goes through glycolysis?

a. evaporates

b. goes through citric acid cycle

c. nothing

-->  d. it goes through substrate level phosphorylation

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Which part of the diagram represents energy?

a. 3

b. 4

-->  c. 2

d. 1

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It is the site of the electron transport chain wherein a proton potential is created that helps power the ATP formation

a. Carbon Dioxide

b. Mitochondrion

c. Kreb's Cycle

-->  d. Inner Membrane

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What is produced in the Krebs Cycle that is needed in Electron Transport?

a. Water

b. Oxygen

-->  c. Energy

d. Carbon dioxide

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Where does the electron transport process take place?

-->  a. Inner Membrane

b. ATP

c. Glycolysis

d. Cytoplasm

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How many steps are shown within the two stages of the diagram?

a. 1

-->  b. 4

c. 2

d. 3

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Where does the energy come from during step 3?

a. ATP

-->  b. Glycolysis

c. Electron

d. Mitochondrion

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Where does the process of glycolysis take place?

-->  a. Cytoplasm

b. NADH

c. Mitochondrion outer membrane

d. Mitochondrion inner membrane

question_image

How much oxygen are in glucose?

a. 3

b. 7

-->  c. 6

d. 1

question_image

How many total ATP are shown in this diagram?

-->  a. 40

b. 30

c. 20

d. 10

question_image

What happens to glucose after Glycolysis?

a. Krebs Cycle

b. Nothing

-->  c. Is broken down by enzymes, releasing energy and pyruvic acid.

d.  the biochemical processes of respiration and energy production occur