Unit 4

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Questions and Answers

What is the primary function of enzymes in biochemical reactions?

To change the substrate into different molecules

To increase the temperature of the reaction

To provide energy for endothermic reactions

To lower the activation energy of a reaction (correct)

What happens to an enzyme when the pH level changes significantly from its optimum?

The enzyme will denature and lose its function (correct)

The enzyme will increase its activity by consuming more energy

The enzyme becomes more active and efficient

The substrate will become inactive

Which of the following correctly describes catabolic reactions?

They synthesize large molecules from smaller components.

They involve the breakdown of large molecules into smaller units. (correct)

They require energy input to proceed.

They convert smaller molecules into energy-rich forms.

What term describes proteins that have lost their functional shape due to environmental changes?

Denatured Signup and view all the answers

Which of the following best describes anabolic reactions?

They are processes that consume energy to make larger molecules. Signup and view all the answers

What is the primary function of catabolic reactions in metabolism?

Breaking down complex molecules into simpler ones Signup and view all the answers

Which of the following accurately describes autotrophs?

Organisms that utilize carbon dioxide as their sole carbon source Signup and view all the answers

Which type of organism is classified as a chemoheterotroph?

Fungi that decompose organic matter Signup and view all the answers

What distinguishes chemolithotrophs from chemoorganotrophs in terms of energy acquisition?

Chemolithotrophs use inorganic molecules, while chemoorganotrophs use organic molecules Signup and view all the answers

In what process do muscle cells primarily utilize energy produced during metabolism?

Muscle contraction for movement Signup and view all the answers

What is primarily produced during the Krebs cycle?

NADH and FADH2 Signup and view all the answers

What process directly uses the H+ ion gradient built up during the electron transport chain?

Synthesis of ATP from ADP and Pi Signup and view all the answers

Which of the following best describes the role of deamination in protein metabolism?

Removes the amine group from amino acids Signup and view all the answers

How do bacteria utilize fatty acids to produce energy?

By cycling fats into the Krebs cycle Signup and view all the answers

In which cellular structure does the electron transport chain occur in eukaryotic cells?

Mitochondria Signup and view all the answers

What is a key feature of fermentation compared to aerobic respiration?

Is an anaerobic process with low energy yield Signup and view all the answers

Which intermediate can amino acids be converted to for entry into the Krebs cycle?

Acetyl-CoA Signup and view all the answers

Which of the following correctly summarizes the function of proteases?

Break down proteins into amino acids Signup and view all the answers

Study Notes

Enzymes

Proteins that speed up chemical reactions within cells
Lower the activation energy, the energy needed to start a reaction
Act on substrates, converting them into different molecules
Work best at their optimum pH and temperature
A change in pH or temperature can denature the enzyme, altering its shape and preventing it from binding to its substrate

Factors Affecting Enzymes

pH: Enzymes have an optimum pH at which they function best. Changes in pH can denature the enzyme.
Temperature: Enzymes also have an optimum temperature range. Changes in temperature outside of this range can alter the enzyme's shape and affect its activity.

Microbial Metabolism

Anabolic Reactions: Chemical reactions that build larger molecules from smaller components. They consume energy.
Catabolic Reactions: Chemical reactions that break down large molecules into smaller components. They release energy.

Metabolism & Carbon Sources

Autotrophs: Organisms that use carbon dioxide as their sole carbon source (e.g., plants, algae, cyanobacteria).
Heterotrophs: Organisms that use organic compounds other than carbon dioxide as a carbon source (e.g., humans, fungi, animals, and most microorganisms).
Chemoheterotrophs: Heterotrophs that use nutrients obtained from living or dead organisms.

Metabolism & Energy Sources

Phototrophs: Use light as their energy source (e.g., plants). Energy is produced via photosynthesis.
Chemotrophs: Use organic or inorganic molecules as their energy source.
- Chemolithotrophs: Use inorganic molecules as their energy source.
- Chemoorganotrophs: Use organic molecules as their energy source.

Electron Transport Chain (ETC)

A series of proteins within the cell membrane (mitochondria in eukaryotes).
Proteins accept electrons from NADH and FADH2, pumping H+ ions outside the membrane.
This creates an electrochemical gradient, with H+ ions flowing back across the membrane through ATP synthase.
As H+ ions pass, ATP synthase adds Pi to ADP, producing ATP.

Protein Metabolism

Deamination: The process of removing the amine group from amino acids.
Ammonia: A byproduct of deamination, and is often excreted.
Urea: Some bacteria convert ammonia into urea and use it in the TCA cycle.
Bacteria can convert proteins into pyruvate and other intermediates like Acetyl-CoA.

Fats and Lipids Metabolism

Fats decompose into glycerol and fatty acids.
Glycerol is converted to pyruvate, which enters the TCA cycle via Acetyl-CoA.
Fatty acids are directly entered into the Krebs cycle.

Fermentation

Anaerobic metabolic process that produces low energy.
Electron acceptors and carriers are generated, enabling the organism to continue metabolic processes.

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Description

Explore the critical roles of enzymes in chemical reactions and understand how factors like pH and temperature affect their activity. This quiz also covers the basics of microbial metabolism, including anabolic and catabolic reactions, as well as the significance of autotrophs in energy processes.