Unit 3 Zoom & Lab Q Flashcards by Maajula Conteh

Why do organisms need carbon?

For macromolecules

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Why do organisms need hydrogen?

water, energy, macromolecules

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Why do organisms need oxygen?

water, macromolecules

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Why do organisms need nitrogen?

nucleic acid, proteins, NADH

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Why do organisms need phosphorus?

ATP, nucleic acids, lipids

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Why do organisms need sulfur?

proteins, cofactors

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Why do organisms need calcium?

signal transduction, transport

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Why do organisms need iron?

cofactors, DNA synthesis

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Why do organisms need magnesium?

cofactors, energy, ion regulation

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A microbe grows on the surface of skin and breaks down organic molecules in sebum (oily substance from glands in skin), using only fermentation (not aerobic respiration). What growth/nutrition terms describe this microbe?

Halophile: salt-loving (skin)
Chemoorganoheterotroph: Chemotroph: energy: chemical (organic or inorganic), Organotroph: electrons; organic, Heterotroph: carbon; organic
Aerotolerant: can survive in the presence of oxygen but does not use it for metabolism.
Mesophile; thrives in body/room temp

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Can you think of some reasons why the number of cells doesn’t increase immediately? (microbial growth curve)

Cells are adapting to the new environment.

Enzymes and proteins needed for growth are being made.

Cells might repair any damage from past conditions.

Nutrients are being absorbed by the cells.

After this, they start growing rapidly in the log phase.

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Is it possible that cell division is occurring during the lag phase?

No, cell division typically does not occur during the lag phase;

In this phase, cells are focusing on adapting to the new environment, synthesizing necessary enzymes and proteins, and preparing for growth

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What sorts of things that might cause a broth culture to move from the log phase into the stationary phase?

Nutrients run out.

Toxic waste builds up.

Oxygen gets used up (for aerobic bacteria).

Too many cells competing for space and resources.

pH changes make the environment less favorable.

Stationary phase: cells stop growing, and number of new cells = number of dying cells.

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What type of O2 requirements have the enzyme Catalase?

Obligate aerobe (21%)
Facultative anaerobe (0-21%)
some microaerophiles (2-10%)

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What type of O2 requirements have the enzyme Superoxide dismutase (SOD)?

Obligate aerobe (21%)
Facultative anaerobe (0-21%)
Microaerophiles (2-10%)
some Aerotolerant (0%)

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What type of O2 requirements have the enzyme peroxidase?

Aerotolerant (0%)
some Obligate aerobe (21%)

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What type of O2 requirements perform fermentation?

Facultative anaerobe (0-21%)
Aerotolerant (0%)
Obligate anaerobe (0%)

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What type of O2 requirements perform aerobic respiration?

Facultative anaerobe (0-21%)
Obligate aerobe (21%)
Microaerophiles (2-10%)

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What type of O2 requirements perform anaerobic respiration?

Facultative anaerobe (0-21%)
Obligate anaerobe (0%)

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Step 1 of biofilm development:

Free-swimming microbes are vulnerable to environmental stresses

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Step 2 of biofilm development:

Some microbes land on a surface, such as a tooth, and attach

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Step 3 of biofilm development:

The cells begin producing an extracellular matrix and secrete quorum-sensing molecules

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Step 4 of biofilm development:

Quorum sensing triggers cell to change their biochemistry and shape

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Step 5 of biofilm development:

New cells arrive, possible including new species, and water channels form in the biofilm

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Step 6 of biofilm development:

Some microbes escape from the biofilm to resume a free-living existence and, perhaps, to form a new biofilm on another surface

What microbes use glycolysis + fermentation?

Aerotolerant (0%) Facultative anaerobe (0-21%) Obligate anaerobe (0%)

What microbes use glycolysis + transition + Krebs + ETC?

Facultative anaerobe (0-21%) Obligate aerobe (21%) Obligate anaerobe (0%) Microaerophiles (2-10%)

Fermentation occurs **only** when oxygen is absent. True or False?

False; Fermentation can occur regardless of the presence of oxygen

How would you go about determining the consistency of an unknown?

Touch the colony with a needle

What O2 requirements (organisms) are capable of actively using oxygen in their metabolic processes (i.e., in order to generate ATP)?

Obligate aerobe (21%) Microaerophile (2-10%) Facultative anaerobe (0-21%)

What O2 requirements (organisms) would be killed if placed in an environment that totally lacks oxygen?

Obligate aerobe (21%) Microaerophile (2-10%)

What O2 requirement (organism) has the ability to perform both aerobic respiration and fermentation?

Facultative anaerobe (0-21%)

What O2 requirements (organisms) would be killed if placed in an environment that contains oxygen at atmospheric concentrations?

Microaerophile (2-10%); only a little, atmospheric is too high Obligate anaerobe (0%)

If prepared properly, a tube containing thioglycollate medium should be largely free of oxygen. What’s the name of the chemical that removes the oxygen from this medium?

Sodium thioglycollate; Sodium thioglycollate binds with free oxygen in the medium

What is the molecule that is embedded in the oxygen indicator strips of the Gas Pak called?

Reazurin

What is the catalyst that helps to **cause** the removal of oxygen in the Gas Pak called?

Palladium

Suppose that you inoculate a tube of thioglycollate medium, then incubate it at 37°C for 24 hours. After the incubation period, you notice cloudiness in the tube (the tube did not contain cloudiness before you incubated it). What caused the medium to become cloudy?

Bacterial growth; Bacteria, when grown in broth, will form turbidity or cloudiness. Thus, the cloudiness is the place where the bacteria are growing

In a Gas Pak, what is the function of the palladium pellets?

Catalyze the reaction that removes oxygen from the chamber

A tube of thioglycollate broth (inoculated with an unknown and incubated) has turbidity in the lower half of the broth. There is a thin green band at the surface of the broth. What is this unknown's oxygen requirement?

Obligate anaerobe (0%); The green band at the surface is often due to oxidation by oxygen at the top of the broth

If you were getting ready to open a Gas Pak and saw that the indicator pad was blue, what would this tell you?

That there **is** oxygen in the chamber; **Blue** indicates that there is **oxygen present** in the chamber. When **oxygen** is **removed**, the strip will be **white**

An unknown grows abundantly outside of the Gas Pak and grows sparsely within the Gas Pak. The unknown is __?

A facultative anaerobe; If the unknown grows better in the presence of oxygen, but can grow when oxygen is absent, this tells us that it uses oxygen in aerobic conditions. Thus, it is a facultative anaerobe

An exoenzyme ____

digests molecules outside the cell

Hydrolysis means ____

water is used to break apart molecules

Suppose that you had a test tube full of starch. If you poured iodine into this test tube, what color would the contents of the tube be?

Purple; Iodine reacts with starch to form a purple color

Suppose that you had a test tube that contained no starch (just water). If you poured iodine into this test tube, what color would the contents of the tube be?

Yellow-brown; Since Iodine is a yellow-brown color, this is the color of the contents of the tube

Which of these BEST describes a positive amylase result?

**Purple agar**, except for a **clear zone around the colony;** For the amylase test, one needs to add iodine to the incubated plate. The iodine will color any remaining starch purple, and an amylase positive colony will have a clear zone of hydrolysis around it.

Casein is what causes milk to look cloudy. Therefore, if bacteria are able to hydrolyze casein on a skim milk agar plate, what would you expect to see?

A clear area of medium around the colony; Caseinase is an exoenzyme, which hydrolyzes the casein outside the growth, thus producing a clear zone around the colony. Unhydrolyzed skim milk agar would look opaque

When indole, pyruvic acid and ammonia come together, they form an amino acid called?

Tryptophan;

What does Tryptophanase do?

Break down Tryptophan into indole, pyruvic acid and ammonia

What is Pyrimidine?

A type of nitrogenous base used to make nucleic acids

What is an amine?

A functional group that is part of ammonia

What two compounds in tryptophan are further catabolized by some bacteria for food?

Pyruvic acid & Ammonia

Why is the test for tryptophan hydrolysis called the indole test?

Because one of the byproducts of hydrolysis is indole

What are the hydrolysis products of tryptophan?

Ammonia Indole Pyruvic acid

Urea agar contains a pH indicator. What color does this pH indicator become in a basic environment?

Bright pink; The pH indicator is phenol red, which is bright pink in alkaline environments and yellow in acid environments

The formula for urea is CO(NH2)2 What compounds are released when urea is hydrolyzed?

**CO2 & Ammonia;** Hydrolysis is adding water to a compound to break it apart

If something is alkaline or a base, it means that...

It picks up free H+ from its surrounding environment reducing acidity

NH2 easily picks up free protons from its surrounding environment (to become NH3). Based on this information and what you know about acids and bases, you can say that, when urea is hydrolyzed, it causes the surrounding environment to become more ___

Alkaline; The amine molecule is picking up the protons from the environment to form ammonia. Thus, the surrounding environment will become more alkaline (less acidic).

If a bacterium produces catalase, then it means that the bacterium is able to live in _____ environments

aerobic

What describes a positive catalase result?

Bubbles; Catalase converts hydrogen peroxide (the reagent) to oxygen, thus producing bubbles

What best describes the function of the oxidase enzyme?

It allows oxygen to accept electrons; Oxidase is the enzyme in the electron transport chain that allows oxygen to be the final electron acceptor

Hydrolysis of starch releases __________

Glucose