Microbiology HW #2 Flashcards (Ch 4-6)
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Questions and Answers

How many molecules of NADH are generated for each turn of the TCA cycle?

3

How many ATP molecules are produced in the TCA cycle for each glucose molecule that enters glycolysis?

2

For each glucose molecule that enters glycolysis, how many times does the TCA cycle 'turn'?

2

The main purpose of cellular respiration is to

<p>Produce energy</p> Signup and view all the answers

Where do NADH and FADH2 go after being produced in the TCA cycle?

<p>Electron transport chain</p> Signup and view all the answers

In prokaryotes and eukaryotes, the TCA cycle takes place in the mitochondria.

<p>False</p> Signup and view all the answers

Where does the TCA cycle take place in bacteria?

<p>Cytoplasm</p> Signup and view all the answers

Hydrogen is transported from other reactions to the electron transport chain by ______.

<p>NADH and FADH2</p> Signup and view all the answers

Hydrogen consists of

<p>One proton and one electron</p> Signup and view all the answers

During the electron transport chain, ATP will be made from

<p>ADP + Pi</p> Signup and view all the answers

Which of the following contain a metal ion that can accept and donate electrons?

<p>Cytochromes</p> Signup and view all the answers

The coenzyme NADH is generated by

<p>Oxidation reactions in glycolysis and the Krebs cycle</p> Signup and view all the answers

The electron carrier proteins in the electron transport chain shuttle electrons to

<p>A terminal electron acceptor</p> Signup and view all the answers

During the electron transport chain in bacteria, protons are

<p>Shuttled to the outside of the cell membrane</p> Signup and view all the answers

In anaerobic respiration, the terminal electron acceptor would also be oxygen.

<p>False</p> Signup and view all the answers

The enzyme ATP synthase uses energy from ______ to make ATP.

<p>Protons re-entering the cell</p> Signup and view all the answers

In bacteria, the electron transport chain is located in

<p>The cytoplasmic membrane</p> Signup and view all the answers

In aerobic respiration, the last carrier protein in the electron transport chain transfers

<p>Two electrons to oxygen</p> Signup and view all the answers

The electron transport chain is part of ______.

<p>Respiration</p> Signup and view all the answers

A culture of bacteria is breaking down sugars to yield energy. This is best described as ______.

<p>Catabolism</p> Signup and view all the answers

Some enzymes require a cofactor or a coenzyme in order to be active. What is the difference between cofactors and coenzymes?

<p>Cofactors are non-protein components that assist enzymes and are typically trace elements; coenzymes are organic cofactors that loosely carry molecules or electrons.</p> Signup and view all the answers

In prokaryotic cells, the electron transport chain (ETC) is located in the ______, whereas in eukaryotic cells, the ETC is located in the ______.

<p>Cytoplasmic membrane; inner membrane of mitochondria</p> Signup and view all the answers

In eukaryotic cells undergoing respiration, protons are pumped

<p>From the mitochondrial matrix to the intermembrane space</p> Signup and view all the answers

When polysaccharides are broken down, their breakdown products can be oxidized for energy by entering which of the following metabolic pathways?

<p>Glycolysis</p> Signup and view all the answers

Most bacteria reproduce by ______.

<p>binary fission</p> Signup and view all the answers

Starting from a single bacterium, after six generations of binary fission, how many bacterial cells will be present?

<p>64</p> Signup and view all the answers

Which of the following environmental factors is the most important in influencing the growth rate of bacteria?

<p>Temperature</p> Signup and view all the answers

What happens to bacterial cells when their maximum growth temperature is exceeded?

<p>Cells begin to die when their maximum growth temperature is exceeded.</p> Signup and view all the answers

According to the graph, what is the impact of cold temperatures on E. coli?

<p>As temperatures decrease, the growth rate decreases.</p> Signup and view all the answers

According to the figure, food stored for one to two hours at a temperature of 32 degrees Celsius would be safe to eat.

<p>False</p> Signup and view all the answers

If conditions are favorable, the generation time of bacteria

<p>can be as short as 30 minutes.</p> Signup and view all the answers

The environmental factor that influences bacterial growth the most is

<p>temperature</p> Signup and view all the answers

The safe temperature ranges for the storage of foods are determined by

<p>the low temperature at which microbes stop multiplying and the high temperature at which they die.</p> Signup and view all the answers

Which is the best definition of generation time?

<p>The time it takes for the number of cells in a population to double.</p> Signup and view all the answers

Both human cells and bacterial cells divide by mitosis.

<p>False</p> Signup and view all the answers

Cells must ______ their DNA prior to cell division.

<p>replicate</p> Signup and view all the answers

Environmental factors control microbial growth through their effect on enzyme activity.

<p>True</p> Signup and view all the answers

Most cultured bacteria tend to multiply by _____.

<p>binary fission</p> Signup and view all the answers

Cell division is triggered exclusively when cells attain a threshold mass.

<p>False</p> Signup and view all the answers

DNA helicase is responsible for adding nucleotides to the growing end of the DNA.

<p>False</p> Signup and view all the answers

The structure that divides the bacterial cell in two is called the?

<p>cross septum</p> Signup and view all the answers

The most common organisms causing food spoilage are

<p>bacteria, yeasts, and molds</p> Signup and view all the answers

By keeping food cold, the growth rate of food spoilage microorganisms is?

<p>decreased</p> Signup and view all the answers

Which of the following are examples of biofilms?

<p>Furry grayish-white growth on old bread or fruit</p> Signup and view all the answers

When studying microbes, why is it important to separate mixed communities into individual pure cultures of the different species?

<p>So we can understand the biochemical characteristics of one species without confusing it with another species.</p> Signup and view all the answers

From which of the following would you be most likely to obtain a pure culture?

<p>A single colony on a streak plate</p> Signup and view all the answers

During which stage of growth does cell division equal the rate of cell death?

<p>Stationary phase</p> Signup and view all the answers

You have a culture of bacteria in which cells are actively expressing genes and synthesizing enzymes, but cells are not dividing. This culture is most likely in ______ phase.

<p>lag</p> Signup and view all the answers

Which of the following are considered the major elements that primarily make up components of cells in microorganisms and all living things?

<p>Molybdenum</p> Signup and view all the answers

Microbes will only grow until the least represented (limiting) nutrient is used up.

<p>True</p> Signup and view all the answers

Microbes that grow readily on the bench top or in a temperature-controlled incubator that is not sealed from the atmosphere in the room are ______.

<p>aerobes</p> Signup and view all the answers

Which of the following is a method of choice for achieving a sufficient level of microbial control in routine day-to-day situations?

<p>Washing and scrubbing with soaps and detergents</p> Signup and view all the answers

Destruction of all microbial life

<p>sterilization</p> Signup and view all the answers

Reduction of most microbial life on inanimate surfaces

<p>disinfection</p> Signup and view all the answers

Mechanical removal of most microbes from living or inanimate surfaces

<p>decontamination</p> Signup and view all the answers

Slows microbial growth but does not reduce the number of existing microbes.

<p>preservation</p> Signup and view all the answers

Which of the following destroys acellular infectious agents?

<p>virucides</p> Signup and view all the answers

Handwashing with regular soap removes all normal microbiota from the skin.

<p>False</p> Signup and view all the answers

Choose which of the following best describes the difference between a disinfectant and an antiseptic.

<p>Disinfectants are antimicrobial chemicals used on inanimate surfaces or objects to remove most of the pathogenic microorganisms. Antiseptics are antimicrobial chemicals that can be used on skin or tissues to achieve the same result.</p> Signup and view all the answers

The more bacteria present on or in something, the longer it takes to kill them all.

<p>True</p> Signup and view all the answers

Moist heat primarily destroys microbes by?

<p>Denaturing their proteins</p> Signup and view all the answers

Boiling is not a reliable method for sterilization because

<p>True</p> Signup and view all the answers

Regarding the use of heat to control microbial growth, dry heat at lower temperatures is as effective as moist heat at the same temperature.

<p>False</p> Signup and view all the answers

Select the reasons sugar or salt can be used for food preservation.

<p>They may cause plasmolysis</p> Signup and view all the answers

Enzymes are usually ______.

<p>proteins</p> Signup and view all the answers

Which of the following binds to the active site of an enzyme?

<p>substrate</p> Signup and view all the answers

An enzyme speeds up a chemical reaction in the cell, but can only be used once.

<p>False</p> Signup and view all the answers

Consider the biochemical pathway: A → B → C. Enzyme 1 catalyzes A → B. Enzyme 2 catalyzes B → C. Enzyme 1 can use

<p>both A and B as substrates.</p> Signup and view all the answers

Consider the biochemical pathway: A → B → C. Enzyme 1 catalyzes A → B. Enzyme 2 catalyzes B → C. If enzyme 2 is inactive, which of the following compounds will accumulate?

<p>B only</p> Signup and view all the answers

All biochemical pathways have the same number of enzymatic reactions.

<p>False</p> Signup and view all the answers

In a biochemical pathway, the product of the first reaction becomes the substrate in the second reaction.

<p>True</p> Signup and view all the answers

Cells obtain energy by ______ food molecules such as glucose.

<p>oxidizing</p> Signup and view all the answers

A hydrogen atom consists of?

<p>a proton and an electron.</p> Signup and view all the answers

Whenever a molecule is oxidized, another molecule must be reduced.

<p>True</p> Signup and view all the answers

What happens to the protons received from NADH in bacteria?

<p>They are transported across the cytoplasmic membrane, setting up a proton motive force.</p> Signup and view all the answers

In aerobic respiration, oxygen acts as

<p>the terminal electron acceptor.</p> Signup and view all the answers

In the electron transport chain, protons are pumped across the cell membrane. This results in

<p>the formation of a proton motive force.</p> Signup and view all the answers

The energy captured in the phosphorylation of ADP to ATP comes from the proton motive force created in respiration.

<p>True</p> Signup and view all the answers

In bacteria, proton pumps are protein complexes that

<p>move protons from the interior of the cell to the exterior.</p> Signup and view all the answers

The synthesis of ATP via ATP synthase, driven by a proton motive force, is called ______.

<p>chemiosmosis</p> Signup and view all the answers

Protons used to set up the proton motive force are generated as macromolecules like glucose are oxidized in the cell.

<p>True</p> Signup and view all the answers

The cytoplasmic membrane is permeable to protons.

<p>False</p> Signup and view all the answers

The terminal electron acceptor in aerobic respiration is ______.

<p>oxygen</p> Signup and view all the answers

Glycolysis is the central metabolic pathway that involves the breakdown of ______.

<p>glucose</p> Signup and view all the answers

The energy released during the reactions of glycolysis is used to form ______.

<p>adenosine triphosphate</p> Signup and view all the answers

Cells prefer to use carbohydrates as energy sources because

<p>they are such good donors of hydrogen and electrons</p> Signup and view all the answers

What is oxidation?

<p>The loss of electrons from a molecule.</p> Signup and view all the answers

Early in glycolysis, two phosphates are added to the glucose molecule. These phosphates come from

<p>breaking down ATP.</p> Signup and view all the answers

During glycolysis, a single 6-carbon molecule of glucose is converted to two 3-carbon pyruvate molecules. During the later steps in this process, how many molecules of ATP are generated?

<p>4</p> Signup and view all the answers

The two 3-carbon molecules glucose is split into are converted through a series of steps into pyruvate. During these steps

<p>NAD+ is converted to NADH.</p> Signup and view all the answers

After glycolysis, pyruvate can be converted into ______ under anaerobic conditions.

<p>lactic acid</p> Signup and view all the answers

Glycolysis makes products that feed into

<p>electron transport chain, TCA cycle AND fermentation</p> Signup and view all the answers

The two 3-carbon molecules that glucose is split into during glycolysis are converted through a series of steps ending in what 3-carbon molecule?

<p>Pyruvate</p> Signup and view all the answers

For each glucose molecule broken down by glycolysis, how many net ATP molecules are produced?

<p>2</p> Signup and view all the answers

______ refers to energy-requiring metabolic processes that result in the biosynthesis of macromolecules and cellular structures.

<p>Anabolism</p> Signup and view all the answers

Which of the following is not a catabolic process?

<p>Protein synthesis</p> Signup and view all the answers

The Tricarboxylic Acid Cycle (TCA cycle) occurs after ______.

<p>glycolysis</p> Signup and view all the answers

Glycolysis takes place in the ______.

<p>cytoplasm</p> Signup and view all the answers

The TCA (Krebs) cycle takes place in the mitochondria of eukaryote cells. Where does it take place in prokaryote cells?

<p>The cytoplasm</p> Signup and view all the answers

What happens to carbon dioxide after it is released during reactions of the TCA cycle?

<p>It diffuses out of the cell.</p> Signup and view all the answers

Study Notes

Bacterial Reproduction and Growth

  • Most bacteria reproduce by binary fission, a process where one cell divides into two.
  • Starting with one bacterium, six generations of binary fission results in 64 bacterial cells.
  • The most crucial environmental factor affecting bacterial growth is temperature.
  • When bacterial cells exceed their maximum growth temperature, cell death occurs.

Temperature Effects on Bacteria

  • Cold temperatures decrease the growth rate of E. coli, and exposure below 6 degrees Celsius can lead to cell death.
  • Food stored at 32 degrees Celsius for 1-2 hours is not safe to eat.
  • Favorable conditions can lead to a bacterial generation time of as short as 30 minutes.

Nutrient Influences and Growth Phases

  • The major environmental factor influencing bacterial growth is temperature.
  • The safe storage temperature range for foods relies on the temperature at which microbes stop multiplying and when they die.
  • Generation time is defined as the time taken for the number of cells in a population to double.

Cell Division and Molecular Biology

  • Human cells divide by mitosis, while bacterial cells primarily divide by binary fission.
  • Cells must replicate their DNA before division.
  • Environmental conditions impact microbial growth through effects on enzyme activity.

Culturing Microorganisms

  • Most cultured bacteria grow through binary fission.
  • Cell division is triggered when cells reach a threshold mass.
  • In the laboratory, pure cultures are obtained from individual colonies on agar plates, which aids in biochemical characterization.

Growth Phases in Cultures

  • In the stationary phase, cell division rate equals cell death rate.
  • Cultures where cells are expressing genes but not dividing are in the lag phase.
  • Key elements in cell composition include nitrogen, carbon, oxygen, sulfur, and phosphorus.

Microbial Control and Food Preservation

  • Microbes grow until the least available nutrient is exhausted.
  • Common practices for microbial control include washing and scrubbing surfaces with soap.
  • Methods like disinfection and decontamination reduce microbial presence on surfaces.

Enzyme Function and Biochemistry

  • Enzymes are typically composed of proteins and bind substrates at their active sites.
  • Enzymatic pathways involve obtaining energy by oxidizing food molecules, such as glucose.
  • Oxidation is defined as the loss of electrons from a molecule.

Glycolysis and Energy Production

  • Glycolysis occurs primarily in the cytoplasm and converts glucose to pyruvate.
  • For each glucose molecule, the TCA cycle produces two ATP molecules.
  • The TCA cycle generates three NADH molecules per turn, and NADH and FADH2 are crucial for the electron transport chain.

Cellular Respiration in Prokaryotes and Eukaryotes

  • In prokaryotes, the TCA cycle occurs in the cytoplasm; it takes place in mitochondria in eukaryotes.
  • The terminal electron acceptor in aerobic respiration is oxygen.
  • Energy from food completes through cellular respiration, mainly generating ATP.

Proton Motive Force

  • Protons are pumped across membranes during the electron transport chain, creating a proton motive force that drives ATP synthesis.
  • The process of synthesizing ATP via ATP synthase is known as chemiosmosis.
  • The oxidation of macromolecules like glucose generates protons that establish this force.

Conclusion on Energy and Metabolism

  • Cell metabolism consists of anabolic (biosynthetic) and catabolic (breakdown) processes.
  • Cells preferentially use carbohydrates as energy sources due to their ability to donate hydrogen and electrons effectively.
  • The relationship between oxidation and reduction is critical, as the oxidation of one molecule necessitates the reduction of another.### Cytochromes and Electron Transport
  • Cytochromes are key components in the electron transport chain, facilitating electron transfer.
  • The terminal electron acceptor in this chain is not oxygen during anaerobic respiration; instead, it can be nitrates or sulfates.
  • Electron transport in bacteria occurs across the cytoplasmic membrane, actively pumping protons to create an electrochemical gradient.

NADH and Energy Production

  • NADH is produced through oxidation reactions during glycolysis and the Krebs cycle, playing a critical role in cellular respiration.
  • ATP synthase, an enzyme crucial for ATP production, utilizes the energy from protons re-entering the cell via chemiosmosis during the electron transport chain.

Electron Carrier Proteins

  • Electron carrier proteins shuttle electrons directly to a terminal electron acceptor, which is essential for continuing the flow of electrons in respiration.
  • In aerobic respiration, two electrons from the last carrier protein are transferred directly to oxygen, facilitating water formation.

Metabolism and Energy Yielding

  • The process of breaking down sugars by bacteria for energy classification is called catabolism.
  • Enzymes often require cofactors or coenzymes to function; cofactors are non-protein elements, whereas coenzymes are organic molecules that transport electrons or functional groups.

Location of Electron Transport Chain

  • In prokaryotic cells, the electron transport chain is located in the cytoplasmic membrane; in eukaryotic cells, it resides in the inner membrane of mitochondria.
  • During aerobic respiration, protons are pumped from the mitochondrial matrix into the intermembrane space, creating a proton gradient essential for ATP synthesis.

Utilization of Breakdown Products

  • Breakdown products of polysaccharides can enter the metabolic pathways of glycolysis, the transition step via acetyl-CoA, the TCA cycle, or directly into the electron transport chain, where they can be oxidized for energy.

Summary of Key Definitions and Concepts

  • Cofactors vs. Coenzymes: Cofactors are trace elements assisting enzymes, while coenzymes are organic molecules that loosely carry electrons or molecules.
  • Respiration Types: Anaerobic respiration does not utilize oxygen as a terminal electron acceptor, which is a crucial distinction in cellular respiration processes.

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Test your knowledge on key concepts from Microbiology chapters 4 to 6 with these flashcards. The quiz covers important topics such as bacterial reproduction and the factors influencing bacterial growth. Perfect for students preparing for exams and wanting to reinforce their understanding of microbiological principles.

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