Bioenergetics and Energy Sources

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following statements about heterotrophs is true?

Heterotrophs obtain energy by consuming other organisms. (correct)

Heterotrophs can synthesize energy from inorganic substances.

Heterotrophs only include carnivores and herbivores.

Heterotrophs can produce their own food through photosynthesis.

What is the primary difference between photosynthesis and chemosynthesis?

Photosynthesis occurs in plants, while chemosynthesis occurs in animals.

Photosynthesis requires sunlight, while chemosynthesis occurs without sunlight. (correct)

Photosynthesis uses inorganic materials, while chemosynthesis uses sunlight.

Photosynthesis produces energy; chemosynthesis does not.

Which of the following best describes the classification of carnivores, herbivores, and omnivores?

They are groups based on the type of food they consume. (correct)

They are all omnivores that consume decaying matter.

They can all produce energy through photosynthesis.

They are types of saprotrophs.

In redox reactions, what happens to the atom that loses electrons?

It is called the reducing agent. Signup and view all the answers

What is true about saprotrophic fungi?

They obtain energy from decaying organic matter. Signup and view all the answers

Which type of organism relies solely on consuming plants for energy?

Herbivores Signup and view all the answers

What characterizes the process of chemosynthesis?

It can occur in extreme environments. Signup and view all the answers

Which of the following statements about redox reactions is accurate?

They always happen together and involve electron transfer. Signup and view all the answers

What is the primary purpose of fermentation in cells?

To generate ATP in the absence of oxygen Signup and view all the answers

Which of the following processes occurs during alcoholic fermentation?

Pyruvate is converted to acetaldehyde Signup and view all the answers

What is the net gain of ATP from glycolysis before fermentation occurs?

2 ATP Signup and view all the answers

Which product is formed as a result of lactic acid fermentation?

Lactic acid Signup and view all the answers

How much ATP is theoretically produced from glucose during aerobic respiration?

36-38 ATP Signup and view all the answers

What happens to NADH during fermentation?

NADH donates electrons to pyruvate Signup and view all the answers

Which organisms are known to undergo lactic acid fermentation?

Bacteria and Human muscle cells Signup and view all the answers

In the absence of oxygen, which compound does pyruvate produce in lactic acid fermentation?

Lactic acid Signup and view all the answers

What is the modern definition of oxidation?

Loss of electrons Signup and view all the answers

Which process do photosynthetic autotrophs use to produce food?

Light energy Signup and view all the answers

What does ATP hydrolysis produce?

ADP and phosphate Signup and view all the answers

What is the function of ATP in cells?

Instant energy source Signup and view all the answers

Which combination of molecules makes up ATP?

Adenine, ribose, three phosphate groups Signup and view all the answers

In the ATP cycle, what happens during phosphorylation?

ADP gains a phosphate group Signup and view all the answers

What type of energy do chemosynthetic autotrophs utilize?

Chemical energy from inorganic substances Signup and view all the answers

What is the significant result of the ATP-ADP cycle?

Continuous energy supply for cellular functions Signup and view all the answers

What is a key characteristic of enzymes in the context of biological reactions?

They serve as biological catalysts. Signup and view all the answers

What happens to enzymes when the temperature is too low?

They will not work and get deactivated. Signup and view all the answers

Which of the following is NOT a property of VIPs (Very Important Proteins)?

They can absorb light. Signup and view all the answers

What role do accessory pigments play in photosynthesis?

They absorb additional wavelengths of light not absorbed by chlorophyll a. Signup and view all the answers

Which enzyme is known to be slow and has two substrates?

RuBisCO Signup and view all the answers

Where are enzymes located in eukaryotic cells involved in photosynthesis?

In the thylakoid membrane of chloroplasts Signup and view all the answers

Which statement about the denaturation of enzymes is true?

Denaturation can happen due to excessive high temperatures. Signup and view all the answers

What are light harvesting complex pigments also referred to as?

Signup and view all the answers

What is the first step of pyruvate oxidation?

Addition of a water molecule to form citric acid Signup and view all the answers

During which process does pyruvate lose carbon dioxide and hydrogen ions?

Transition step Signup and view all the answers

What molecule is formed when pyruvate combines with coenzyme A?

Acetyl-CoA Signup and view all the answers

Which molecule carries electrons and hydrogen ions away after the oxidative decarboxylation of isocitrate?

NADH Signup and view all the answers

What is the result of the conversion of isocitrate to alpha-ketoglutaric acid?

Release of carbon atoms as CO2 Signup and view all the answers

What directly enters the Krebs cycle after the transition step?

Acetyl-CoA Signup and view all the answers

Which compound is not directly usable by the cell for work?

NADH Signup and view all the answers

What step generates a small amount of ATP during the Krebs cycle?

Conversion of succinyl-CoA to succinate Signup and view all the answers

What is the primary function of succinyl CoA in the Krebs cycle?

It is converted into succinic acid. Signup and view all the answers

What role does NADH play during cellular respiration?

It carries electrons to the electron transport chain. Signup and view all the answers

What is produced when fumaric acid reacts with water?

Malic acid Signup and view all the answers

How does the electron transport chain contribute to ATP production?

By pumping protons across a membrane to create a gradient. Signup and view all the answers

What ensures the continuous operation of the Krebs cycle?

The regeneration of oxaloacetic acid. Signup and view all the answers

Which of the following is a product of the oxidation of succinic acid?

FADH2 Signup and view all the answers

What type of energy-carrying molecules are produced in the Krebs cycle?

Both ATP and GTP Signup and view all the answers

Which molecules are organized into the electron transport chain complexes?

Flavoproteins, quinones, iron-sulfur proteins, and cytochromes Signup and view all the answers

Study Notes

Bioenergetics

Branch of biology studying how living things obtain and use energy.

Heterotrophs

Cannot make their own food
Obtain energy and nutrients by consuming other organisms

Animals

Carnivores: Eat animals
Herbivores: Eat plants
Omnivores: Eat both plants and animals

Fungi

Do not consume food by eating
Absorb nutrients from their environment
Eat decaying organic matter

Autotrophs

Produce their own food using simple substances.
Photosynthetic: Use light energy (plants, algae, some bacteria), CO2, H2O to make glucose, O2
Chemosynthetic: Use chemical energy

Photosynthesis

6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O
Makes glucose, oxygen, and water
Two stages: Light Reactions, Calvin Cycle
Requires reactants (CO2 and H2O), energy (visible light), and photosynthetic pigments (chlorophyll).

Redox Reactions

Oxidation-Reduction: Always happen together.
Oxidation: Loss of electrons (or addition of oxygen)
Reduction: Gain of electrons (or removal of oxygen)
Important in energy transfer reactions

ATP (Adenosine Triphosphate)

Immediate source of energy for cells
Unstable molecule due to negatively charged phosphate groups
Broken down (hydrolyzed) to release energy

ATP-ADP Cycle

ATP → ADP + Pi + Energy (Hydrolysis)
ADP + Pi + Energy → ATP (Phosphorylation)

History

Adenosine from Adenine, Ribose (5-carbon sugar) and Triphosphate

Triphosphate

Alpha Phosphate Group: Attached to ribose
Beta Phosphate Group: Connected by a high-energy phosphoanhydride bond
Gamma Phosphate Group: Joined to Beta by a high-energy phosphoanhydride bond

Phosphoanhydride Bond

High-energy bond, stores energy
Unstable because of negatively charged phosphate groups

Photosynthetic Pigments

Chlorophyll a: Primary pigment in photosynthesis, absorbs red and blue light, reflects green light
Chlorophyll b: Accessory pigment, absorbs light that chlorophyll a cannot
Carotenoids: Accessory pigments, absorb blue and green light, reflect yellow, orange, and red light(beta carotene)

Photosystem

Contains chlorophyll a molecules and accessory pigments
Light-harvesting complex: Collects light energy
Reaction center: Chlorophyll a to initiate electron transfer.

Enzymes

Biological catalysts, speed up reactions
Sensitive to temperature and pH
RuBisCO: Enzyme for carbon fixation in the Calvin Cycle (slow enzyme with two substrates
ATP Synthase: Enzyme that produces ATP (through chemiosmosis)
Ferredoxin-NADP reductase: Enzyme to reduce NADP to NADPH

Factors Affecting Photosynthesis

Light intensity
Temperature
CO2 concentration
Water availability
Nutrient availability

Light Reactions

Occur in the thylakoid membrane.
Reactants: H2O, ADP, NADP+
Products: O2, ATP, NADPH

Optimal Temperature Range

Varies depending on the species
High temperatures can denature enzymes

Photophosphorylation

The process of making ATP using light energy. (This typically refers to the process in Photosynthesis)

Calvin Cycle

Occurs in the stroma of the chloroplast.
Uses ATP and NADPH from the light reactions
Converts CO2 into glucose
RuBisCO: Enz. that catalyzes rx. between CO2 and RuBP

Cellular Respiration

Aerobic Respiration: Involves glycolysis, Krebs (Citric Acid) Cycle, Electron Transport Chain
Anaerobic: Fermentation (Ethanol, Lactic Acid)
Breakdown of glucose to produce ATP

Glycolysis

Occurs in the cytoplasm (cytosol)
Glucose broken down into two pyruvate molecules
Two stages: Energy investment, Energy harvest
Net gain: 2 ATP, 2 NADH

Pyruvate Oxidation (Transition Step)

Pyruvate converts to Acetyl-CoA
CO2 is released
NAD+ is reduced to NADH

Krebs Cycle (Citric Acid Cycle)

Occurs in the mitochondrial matrix
Acetyl-CoA reacts with oxaloacetate to form citrate (6 carbon molecule)
Series of redox reactions
Produces ATP, NADH, FADH2, and CO2

Electron Transport Chain (ETC)

Located in the inner mitochondrial membrane
Electrons from NADH and FADH2 pass through complexes, releasing energy
Pumps H+ across the inner mitochondrial membrane
H+ gradient used by ATP synthase to produce ATP through chemiosmosis.

Fermentation

Anaerobic process when oxygen is unavailable
Regenerates NAD+ so glycolysis can continue
Ethanol and lactic acid fermentation.

Energy Yield

Theoretical yield: 36-38 ATP per glucose
Actual yield: Around 30 ATP per glucose.
Varies by species and specific conditions.

Anaerobic Respiration

Alternative respiration where electron acceptor is something other than oxygen (e.g., sulfate, nitrate)
Results in lower ATP yield than aerobic respiration

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the various ways living organisms obtain and utilize energy, focusing on processes such as photosynthesis and the roles of different types of organisms like autotrophs and heterotrophs. Test your knowledge on the intricacies of bioenergetics and energy transformations within biological systems.