Biology Chapter 8: Metabolism and Enzymes

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Questions and Answers

What is the primary function of anabolic metabolism?

Building complex macromolecules from simpler ones (correct)

Generating ATP through oxidative phosphorylation

Converting glucose into pyruvic acid

Breaking down macromolecules for energy

Which statement about enzymes is correct?

Enzymes are consumed during the reactions they catalyze.

Enzymes increase the activation energy required for reactions.

Enzymes act as biological catalysts and are not altered in the process. (correct)

Enzymes alter the chemical structure of substrates.

What occurs during the process of enzyme denaturation?

The enzyme produces more active sites for binding

The enzyme becomes more stable at high temperatures.

The enzyme increases its catalytic activity.

The enzyme's shape is distorted, preventing substrate binding. (correct)

Which of the following processes is NOT a pathway of primary catabolism?

Citric Acid Cycle Signup and view all the answers

How do constitutive enzymes differ from regulated enzymes?

Constitutive enzymes are present in a constant amount regardless of substrate levels. Signup and view all the answers

Which process involves breaking down glucose without the requirement of oxygen?

Fermentation Signup and view all the answers

What is the role of coenzymes in enzyme activity?

They assist enzymes in catalyzing reactions. Signup and view all the answers

What is primarily stored as energy in biological systems?

ATP Signup and view all the answers

What is the definition of the minimum temperature for microbial growth?

The lowest temperature that allows continuous growth and metabolism. Signup and view all the answers

Which group of microorganisms thrives at temperatures below 15°C?

Psychrophiles Signup and view all the answers

Which type of anaerobic organism can survive in the presence of oxygen but does not utilize it?

Aerotolerant anaerobes Signup and view all the answers

What is the characteristic of mesophiles regarding their optimal temperature?

Their optimal temperature lies between 20°C and 40°C. Signup and view all the answers

What phase of the growth curve represents a period of adjustment for newly inoculated cells?

Lag phase Signup and view all the answers

What distinguishes obligate aerobes from facultative anaerobes?

Obligate aerobes cannot grow without oxygen, while facultative anaerobes can use it if available. Signup and view all the answers

Which type of microorganisms require high salt concentrations for optimal growth?

Halophiles Signup and view all the answers

The time required for a full cycle of binary fission is referred to as what?

Generation time Signup and view all the answers

What is the primary function of catabolic processes in cells?

To provide energy for complex building reactions Signup and view all the answers

Which type of microbe is classified as a heterotroph?

A microbe that absorbs nutrients from its environment Signup and view all the answers

Which nutrient plays a crucial role in stabilizing cell walls and endospores in bacteria?

Calcium $(Ca)$ Signup and view all the answers

What direction does water move in a hypertonic solution?

Out of the cell, causing it to shrink Signup and view all the answers

What is the definition of sterilization?

The complete destruction or removal of all viable microorganisms Signup and view all the answers

What is the role of lipases in the cell?

To break down fatty acids Signup and view all the answers

Which of the following statements about disinfectants is incorrect?

They are effective against bacterial endospores. Signup and view all the answers

Which method allows for the differentiation between live and dead cells?

Flow cytometer Signup and view all the answers

Which of the following is a micronutrient involved in enzyme function?

Iron $(Fe)$ Signup and view all the answers

What term describes the temporary prevention of microbial multiplication without killing them?

Microbistasis Signup and view all the answers

During beta oxidation, what is produced from fatty acids?

Acetyl CoA Signup and view all the answers

Which of the following describes the primary action of surfactants as microbicidal agents?

They lower the surface tension of cell membranes. Signup and view all the answers

What type of microbe is classified as a phototroph?

Microbe that utilizes sunlight for energy Signup and view all the answers

What is the effect of elevating temperature on microbial death rate?

Allows for shorter exposure times to achieve microbial death Signup and view all the answers

Which group of microbes has the highest resistance to antimicrobial agents?

Bacterial endospores Signup and view all the answers

Which methods are classified as physical agents for decontamination?

Moist heat and radiation Signup and view all the answers

What is the primary function of the reverse transcriptase (RT) enzyme in HIV?

To reversion of RNA to DNA Signup and view all the answers

What is the consequence of drug resistance in microorganisms?

Microorganisms tolerate previously inhibitory amounts of drugs Signup and view all the answers

What percentage of infections involve biofilms?

60% Signup and view all the answers

Which technique provides data on antimicrobial susceptibility?

Kirby-Bauer technique Signup and view all the answers

What is the minimum inhibitory concentration (MIC)?

The smallest concentration of drug that visibly inhibits growth Signup and view all the answers

Which is NOT one of the major side effects of drugs?

Enhanced immune response Signup and view all the answers

What type of infections can lead to superinfection?

Infections from resistant microorganisms during antimicrobial therapy Signup and view all the answers

What is a characteristic of MDR pumps in bacteria?

They can be encoded by plasmids or chromosomes Signup and view all the answers

What does thermal death time refer to?

The shortest time required to kill all test microbes at a specified temperature. Signup and view all the answers

Which process aims to kill potential infection agents while retaining flavor and nutritional value?

Pasteurization Signup and view all the answers

How does ultraviolet radiation primarily function?

Mainly aimed at disinfection. Signup and view all the answers

What is a key characteristic of ethylene oxide (ETO)?

It reacts vigorously with functional groups of DNA. Signup and view all the answers

Which of the following best describes the activity of quaternary ammonium compounds?

Their effectiveness is diminished in the presence of organic matter. Signup and view all the answers

What kind of radiation is termed nonionizing radiation?

Ultraviolet radiation that does not ionize atoms. Signup and view all the answers

Which germicide is considered a rapid and broad-spectrum sterilant?

Glutaraldehyde Signup and view all the answers

What is the principal mechanism by which alcohol inactivates enveloped viruses?

Due to its surfactant effect on the viral envelope. Signup and view all the answers

Study Notes

Chapter 8 Notes

Metabolism is the sum of all chemical reactions in the body to maintain homeostasis.
Two types of metabolism:
- Anabolism: building up macromolecules for structure and function.
- Catabolism: breaking down macromolecules for energy.
Enzymes are biological catalysts that speed up reactions by lowering activation energy.
- Enzymes don't become part of the products.
- Enzymes aren't consumed or altered during the process.
- Cofactors support enzymes, including coenzymes, some derived from vitamins.
Denaturation occurs when weak bonds holding an enzyme's shape are broken, disrupting its active site.
Constitutive enzymes are present in constant amounts, unaffected by substrate levels.
Regulated enzymes' quantities change based on substrate levels.
Enzyme synthesis can be controlled through induction or repression.
Energy is primarily stored as ATP.
Oxidation-reduction (redox) reactions involve electron transfer for energy release and storage.

Chapter 7 Notes

Bioelements are essential to all living things, required in large or small amounts for cell structure and function.
Macronutrients are involved in cell structure and metabolism, including carbon, hydrogen, and oxygen.
Micronutrients, or trace elements, are essential at lower concentrations for enzyme function.
Examples of essential elements: potassium (K), sodium (NA), calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn).
Macronutrients make up complex molecules like carbohydrates, proteins, and lipids.
Microbes need an energy source and a carbon source.
- Phototrophs use light energy
- Chemotrophs use chemical energy
Microbes need a suitable temperature for growth and metabolism
Three pathways of metabolism are glycolysis, the Krebs cycle, and the respiratory chain.
Bacteria can use respiration and fermentation.
- Respiration requires oxygen to produce ATP
- Fermentation is an alternative energy production pathway that does not use oxygen.

Chapter 7 Notes (continued)

Different microbes thrive in diverse temperatures.
- Psychrophiles are cold-loving (optimal growth below 15°C).
- Psychrotrophs can grow above 0°C.
- Mesophiles thrive in moderate temperatures between 20 and 40°C (pathogens often grow in this range).
- Thermophiles thrive in high temperatures.
- Organisms have different requirements for oxygen levels:
  - Obligate aerobes require oxygen
  - Microaerophiles require low oxygen
  - Facultative anaerobes use oxygen when available
  - Aerotolerant anaerobes tolerate oxygen but do not use it
  - Obligate anaerobes cannot tolerate oxygen.
Microbial growth follows a predictable pattern called a growth curve.
- Lag phase: initial adjustment period.
- Log phase: exponential growth.
- Stationary phase: growth rate declines, new cells equal cells dying.
- Death phase: number of viable cells progressively declines.
Measurements of microbial growth include direct cell counts, Coulter counters, and flow cytometers.

Chapter 11 Notes

Contaminants are unwanted microbes.
Decontamination methods use physical agents (heat, radiation) or chemical agents (sterilants, disinfectants, antiseptics) to eliminate or reduce microbes.
Microbes are categorized by resistance to treatments.
Sterilization eliminates all microbes, including spores.
Disinfection kills most vegetative pathogens but not spores.
Antiseptics are used on living tissues.
Sanitization reduces microbes to safe levels.
Factors affecting microbial control include concentration, duration, presence of organic matter.
Physical methods include heat, radiation, and filtration.

Chapter 11 Notes (continued)

Chemical methods of microbial control include:
- Halogens: disinfectants and antiseptics
- Alcohols: disinfectants and antiseptics
- Hydrogen peroxide: oxidizing agent that destroys microbes.
- Glutaraldehyde: sterilizing agent.
- Ethylene oxide: sterilizing agent for heat sensitive items
- Quaternary ammonium compounds (quats): disinfectants, used against bacteria, fungi, enveloped viruses.

Chapter 12 Notes

Antimicrobial chemotherapy aims to destroy microbes without harming host tissue.
Antibiotics target specific microbial processes (e.g., cell wall synthesis, protein synthesis).
Resistance mechanisms in microbes, including the development of drug efflux pumps or target modification, limit effectiveness of antibiotics.
Drugs have varying mechanisms of action, including those that prevent cell wall synthesis, protein synthesis, nucleic acid synthesis, or metabolic pathways.
Antimicrobial drug resistance involves microbial adaptation to withstand treatment.

Chapter 12 Notes (continued)

Various side-effects of antimicrobial therapy are direct toxicity, allergic reactions, and disruption of normal microbiota.
Superinfections can result from the disruption of normal flora.
Kirby-Bauer technique and tube dilution tests evaluate susceptibility of microbes to specific drugs.
Minimum inhibitory concentration (MIC) is the lowest drug concentration that inhibits microbial growth.

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Explore the key concepts of metabolism and enzymes in this quiz based on Chapter 8. Learn about the two types of metabolism, the role of enzymes as catalysts, and factors affecting enzyme activity. Test your understanding of how these processes maintain homeostasis in the body.