Biology: Metabolism and Enzymes

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Questions and Answers

What term describes the conditions beyond an organism's tolerable limits for its normal metabolic rate?

Metabolic adaptation

Physiological stress

Adverse conditions (correct)

Thermal regulation

What is the primary characteristic of predictive dormancy?

Occurs before adverse conditions begin (correct)

Requires a higher metabolic rate

Is triggered by environmental change

Happens during food shortages

Which of the following is a primary function of hibernation?

To conserve energy during cold temperatures (correct)

To survive hot temperatures

To enhance metabolic activity

To increase the heart rate

What occurs to an organism’s metabolic rate during dormancy?

Decreases markedly Signup and view all the answers

What is the function of aestivation?

To survive hot conditions or drought Signup and view all the answers

What defines daily torpor?

A period of metabolic reduction occurring daily Signup and view all the answers

Why do organisms migrate?

To avoid periods of metabolic adversity Signup and view all the answers

Which type of behavior is considered inherited and inflexible?

Innate behavior Signup and view all the answers

What is the role of a receptor in the body?

To detect changes in conditions Signup and view all the answers

Which part of the brain detects changes in body temperature?

Hypothalamus Signup and view all the answers

What mechanism does the body use to cool down when experiencing high temperatures?

Increased sweat production Signup and view all the answers

How do skin arterioles respond to high body temperatures?

They widen, allowing more blood flow to the surface Signup and view all the answers

What effect does cold temperature have on hair erector muscles?

They contract to trap insulating air Signup and view all the answers

Why is it essential for organisms to maintain stable body temperatures?

To ensure enzymes function optimally Signup and view all the answers

What happens to the metabolic rate when body temperature is high?

It decreases Signup and view all the answers

How do nerve impulses contribute to thermoregulation?

They transmit messages from receptors to effectors Signup and view all the answers

What is meant by a viable cell count?

Number of cells that are alive and capable of reproduction Signup and view all the answers

During which phase does secondary metabolism occur?

Stationary phase Signup and view all the answers

What is the purpose of mutagenesis?

To increase the rate of mutations Signup and view all the answers

What do restriction endonucleases do?

They cut DNA into fragments at specific sequences Signup and view all the answers

What is one of the problems associated with strains improved through mutagenesis?

They are often genetically unstable Signup and view all the answers

What is recombinant DNA technology primarily used for?

Transferring genetic material from one organism to another Signup and view all the answers

What characterizes complementary sticky ends in DNA?

They overlap and match together Signup and view all the answers

What is the role of DNA ligase?

To seal DNA fragments together Signup and view all the answers

What is produced during the energy payoff phase of glycolysis?

4 ATP Signup and view all the answers

What is the role of NADH in the final stage of aerobic respiration?

To deliver electrons and hydrogen ions Signup and view all the answers

What occurs to the acetyl group in the second stage of aerobic respiration?

It combines with coenzyme A Signup and view all the answers

What is a key reason for using microorganisms in industry?

They produce many useful products Signup and view all the answers

Where does the second stage of aerobic respiration take place?

Matrix of the mitochondria Signup and view all the answers

What is the final electron acceptor in the electron transport chain?

Oxygen Signup and view all the answers

Which of the following is NOT a component found in a growth medium?

Heavy metals Signup and view all the answers

What is the main function of ATP synthase during the final stage of aerobic respiration?

To produce ATP from ADP + Pi Signup and view all the answers

What type of growth media can be classified as solid?

Agar Signup and view all the answers

Which of the following is a vital reason for maintaining sterile conditions in culturing microorganisms?

To avoid contamination by other microorganisms Signup and view all the answers

During the second stage of aerobic respiration, how many times does the cycle occur per glucose molecule?

Twice Signup and view all the answers

What is referred to as 'generation time' in microbial growth?

The time needed for cells to double in number Signup and view all the answers

What is generated as a byproduct during the reactions of the citric acid cycle?

Carbon dioxide Signup and view all the answers

During which phase of microbial growth do cells primarily adjust to a new environment?

Lag phase Signup and view all the answers

What occurs during the stationary phase of microbial growth?

Nutrient depletion and accumulation of waste Signup and view all the answers

What is a consequence of the death phase in microbial growth?

Toxic metabolites build up, causing cell death Signup and view all the answers

What is the main purpose of end-product inhibition in cellular metabolism?

To prevent wasteful breakdown of intermediates Signup and view all the answers

What is the summary equation for aerobic respiration?

Glucose + oxygen -> carbon dioxide + water + 38 ATP Signup and view all the answers

In which cellular location does glycolysis occur?

Cytoplasm Signup and view all the answers

What is produced as a result of anaerobic fermentation in animals?

Lactate Signup and view all the answers

What happens to ATP when it is broken down?

Energy is released Signup and view all the answers

How is ATP generated from ADP in the cell?

By adding a phosphate group with energy input Signup and view all the answers

What defines fermentation in plants and yeast?

Glucose is converted into carbon dioxide and ethanol Signup and view all the answers

What role does phosphorylation play in cellular processes?

It transfers energy to make molecules more reactive Signup and view all the answers

Study Notes

Metabolism

Metabolism is all enzyme-controlled chemical reactions within cells.
Anabolic pathways build large molecules from smaller ones, requiring energy.
Catabolic pathways break down large molecules into smaller ones, releasing energy.
Amino acids form proteins; glucose forms carbon dioxide and water (in presence of oxygen).

Metabolic Pathways

Irreversible steps maintain stable substance concentrations within cells.
Reversible steps allow pathways to continue or reverse.
Alternative routes allow reactions to proceed if necessary enzymes or substrates are unavailable.

Membranes

Membranes are made of phospholipids and proteins.
Protein roles include pumps, pores, and enzymes.

Genes & Enzymes

Gene expression controls metabolic pathways by controlling enzyme production (enzymes are proteins).
Enzymes are biological catalysts speeding up reactions by lowering activation energy.
Properties of catalysts: speed up reactions, remain unchanged during reactions.
Properties of enzymes: work with specific substrates, have active sites with complementary shapes for substrates. Active sites work via induced fit model, making them dynamic and flexible.
Activation energy is the energy needed for a reaction to start.
Induced fit describes the shape change of the enzyme's active site to fit the substrate.
Affinity means chemical attraction between molecules (used in substrate/enzyme relationships).
Enzymes are specific because they only work with substrates that have a high affinity for their active sites, which need to be complementary.

Enzyme Activity Factors

Factors that affect enzyme activity include: temperature, pH levels, substrate concentration, and inhibitor presence.

Inhibitors

Inhibitors decrease the rate of enzyme controlled reactions.
Competitive inhibitors have a similar shape to substrates and bind to the active site.
Overcoming competitive inhibition is done by increasing substrate concentration.
Non-competitive inhibitors bind to sites outside the active site, changing the active site's shape.

Enzyme Activation

Activator binding allows enzymes to have active shapes.
End-product (feedback) inhibition stops a pathway as the product builds up

Cellular Respiration

 - Cellular respiration is a series of enzyme-controlled reactions to release energy from food and generate ATP.
 - Aerobic respiration occurs when oxygen is present.
 - Fermentation occurs without oxygen.

Aerobic Respiration Summary Equation

Glucose + oxygen produces carbon dioxide + water + 38 ATP.

Fermentation Summary Equation (Animals)

Glucose -> Pyruvate -> Lactate

Fermentation Summary Equation (Plants & Yeast)

Glucose -> Pyruvate -> Carbon dioxide + Ethanol.

ATP & ADP

ATP is a high energy chemical compound containing three phosphates.
ADP is a low energy chemical compound with two phosphates.
ATP is constantly generated from ADP and Pi

Phosphorylation

Phosphorylation is the addition of a phosphate to a molecule.

Glycolysis

Glycolysis is the first stage of respiration.
Glycolysis occurs in the cytoplasm.
The stages result in Glucose -> 2 Pyruvate; NAD -> NADH; 2 ATP used in energy investment phase (2ATP net gain)

Citric Acid Cycle (Krebs Cycle)

The citric acid cycle is the second stage of aerobic respiration.
It occurs in the matrix of mitochondria.
It includes reactions producing 2 ATP, NADH, and FADH2.
Pyruvate -> Acetyl Coenzyme A + CO2

Electron Transport Chain (ETC)

ETC is the final stage of aerobic respiration that occurs in the inner membrane of mitochondria.
NADH and FADH2 deliver electrons/hydrogen ions.
Hydrogen ions flow back into mitochondria producing ATP.
Oxygen is the final electron acceptor creating water.

Metabolic Rate

Metabolic rate is the amount of energy used per unit time.

Measuring Metabolic Rate

Oxygen uptake, heat production, or carbon dioxide production can measure metabolic rate.

Circulatory Systems

Fish have a single circulatory system.
Amphibians and reptiles have an incomplete double circulatory system.
Mammals and birds have a complete double circulatory system.
Incomplete double circulatory can't fully oxygenate blood as oxygenated and deoxygenated blood mix.

Conformers & Regulators

Conformers have internal environments reliant on external conditions; have a lower metabolic cost.
Regulators maintain internal environments; have a higher metabolic cost.

Thermoregulation

The hypothalamus detects changes and sends nerve impulses to effectors.
Effectors include sweat glands, arterioles, hair erector muscles, and skeletal muscles.
In high temps sweat glands are activated causing evaporation of water and cooling.

Dormancy, Hibernation, and Aestivation

Dormancy is a reduced metabolic rate.
Hibernation is predictive dormancy for cold temperatures.
Aestivation is consequential dormancy for hot temperatures.
Daily torpor refers to cyclical reduced metabolic states in animals like small mammals and birds.

Migration

Migration is the movement by a species from one location to another.
Reasons include avoiding conditions such as low food supply or severe weather
Migration strategies are often tracked via ringing/banding, electronic tagging, colour marking, and GPS signals.

Inherited & Learned Behaviour

Innate behaviour is inherited; inflexible; automatic.
Learned behaviour is gained through experience; adaptable.

Microorganisms in Industries

Microorganisms are important in industries due to their rapid growth and reproduction, high productivity of useful products and their highly adaptable metabolism for a variety of substrates.

Growth Medium

Growth medium is a mix of chemicals for microorganisms.
Components of growth medium includes energy sources, raw materials for molecule building
Growth media can be liquid (broth) or solid (agar).
Maintaining sterility ensures growth is only from the desired organism.

Aseptic Techniques

Aseptic techniques are sterile procedures that keep cultures from unwanted contamination.
Important to control environmental variables like temperature, pH, and oxygen concentration.

Microorganism Growth Phases

Four phases are lag, exponential, stationary, and death.
During the lag phase there is very little cell growth as cells adapt to new growth mediums.
The exponential phase has rapid growth due to optimal conditions and sufficient nutrients
During the stationary phase the birth rate equals the death rate, meaning no net cell gain or loss.
In the death phase there is a loss of cells due to insufficient nutrients

Cell Counts

Viable cell count: only counts active/living cells.
Total cell count: living and dead cells.

Secondary Metabolism

Secondary metabolism involves producing chemicals not essential for growth, and provides advantage to the organism e.g. antibiotics.
Most involved during the stationary phase.

Improving Microorganisms

Approaches include mutagenesis (introducing mutations to improve specific characteristics) and genetic engineering (recombinant DNA) to enhance characteristics like growth rates and production quantities.

Mutagenesis/Recombinant DNA

Mutagenesis increases mutation rates through a mutagenic agent, used to improve traits of the organism.
Recombinant DNA transfers genetic materials (e.g. DNA transfer between species).
Restriction endonucleases cut DNA into fragments at specific sites for insertion into a plasmid (vector) via complementary sticky ends.
DNA ligase seals fragments back together. Vectors must have their origin of replication and other features for insertion and growth in a new organism

Vectors

A vector is a carrier (e.g., plasmid) for transferring DNA.
Important characteristics include a selectable marker (gene resistance) to identify cells with the new DNA, an origin of replication, restriction sites, and the ability to self-replicate.
Limitations of using prokaryotes for eukaryotic gene expression is the folding proteins/polypeptides.

Overcoming Prokaryotic Limitations

Use eukaryotes, such as yeast, who correctly fold proteins/polypeptides .

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Description

Test your knowledge on metabolism, metabolic pathways, and the role of enzymes in biological processes. This quiz covers key concepts including anabolic and catabolic pathways, membrane structure, and the influence of genes on enzyme production. Challenge yourself and deepen your understanding of these essential biochemical processes.