Lecture Exam #2 - Microbiology

Chapter 7, 8, 9 & 13

Methanogens are a type of archaea found in various habitats on the planet, including deep-sea vents in the deepest parts of the ocean. They produce methane gas by reducing carbon dioxide, using hydrogen gas under anaerobic conditions. Given these characteristics, methanogens are a type of __________.

chemoautotroph

Which of the following elements are NOT one of the six elements found in lipids, nucleic acids, and proteins?

\
* carbon
* oxygen
* potassium
* phosphorus
* calcium
* iron
* nitrogen
* hydrogen
* sulfur

* potassium
* calcium
* iron

Osmosis is best defined as the movement of

water molecules across a membrane from an area of high water concentration to an area of lower concentration.

Which of the following will pass through a cell membrane most easily?

\
* large nonpolar molecules
* large neutral molecules
* small polar molecules
* small nonpolar molecules
* large polar molecules

* small nonpolar molecules

Bacteria found in the stomach of cud-chewing mammals, such as cows, are essential in the breakdown of cellulose. This relationship is an example of __________.

endosymbiosis

The *general* term used to denote a situation in which two organisms live together in a close partnership required by one or both members is __________.

symbiosis

What type(s) of organisms were found growing in the Berkeley Pit?

 

* bacteria
* single-celled eukaryotes
* fungi
* All of these choices are correct.

* All of these choices are correct.

Approximately how many different species of prokaryotes and eukaryotes were found living in the Berkeley Pit?

100

An acidophile lives in what pH environment?

pH 0–6

True or false: Extremophiles only include the bacteria and the archeons.

False

Extremophiles are able to live in toxic environments due to

evolution of genetic traits

What evolutionary changes did the organisms make to survive in the toxic environment of the Berkeley Pit?

 

* modified cell membranes
* modified enzymes
* produced protective biofilms
* All of these choices are correct.

* All of these choices are correct.

The cell wall of a bacterial cell

prevents lysis of the cell in hypotonic conditions

Nutrient molecules that contain the basic framework of carbon and hydrogen are called __________ nutrients.

organic

The use of concentrated salt or sugar solutions as food preservatives creates a __________ environment, which inhibits bacterial growth.

hypertonic

The FtsZ protein is needed to form the __________.

septum

The energy source for contraction of the FtsZ ring during cell division comes from __________.

the hydrolysis of GTP

Which enzyme is *NOT* involved in DNA replication?

 

* DNA polymerase
* gyrase
* RNA polymerase
* helicase \n

* RNA polymerase

Cells cannot begin a new round of replication until they have completely finished dividing.

False

Most cultured bacteria tend to multiply by

binary fission

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

False

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

False

Differences in the bacteria found in the GI tract of humans compared to those found in the GI tract of primates is most likely an example of __________.

coevolution

Please label the image to test your understanding of bacterial growth curves.

carbon

product of respiration and used in photosynthesis

oxygen

necessary for the metabolism of nutrients by aerobes; significant element in organic compounds and inorganic compounds

potassium

plays a role in protein synthesis and membrane transport

phosphorus

key component of genetic material in cells

calcium

stabilizes cell walls, and adds resistance to bacterial endospores

iron

essential element for the structure of new respiratory proteins

chemoautotroph

4H2 + CO2 -> CH4 + 2H2O

photoautotroph

CO2 + H2O -> (CH2O)n + O2

chemoheterotroph

C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP

Rank the following components from least to most abundant.

lipids

nucleic acids

proteins

water

An enzyme promotes a reaction by serving as a physical site upon which the reactant molecules, called __________, can be positioned for various interactions.

substrates

__________ inhibition occurs when the inhibitor molecule is contending with the substrate for the binding site.

Competitive

Which of the following are correct descriptions of biological oxidation-reduction reactions?

* The compound that loses electrons is oxidized.
* The compound that loses electrons is reduced.
* The compound that gains electrons is oxidized.
* The compound that gains electrons is reduced.

* The compound that loses electrons is oxidized.
* The compound that gains electrons is reduced.

Please select all of the structural components of ATP.

\
* 5-carbon ribose sugar
* chain of two phosphate groups
* chain of three phosphate groups
* adenine
* guanine

* 5-carbon ribose sugar
* chain of three phosphate groups
* adenine

_____________ refers only to energy-requiring processes that result in synthesis of cell molecules and structures.

Anabolism

Which of the following is *NOT* a catabolic process?

 

* hydrolysis of ATP
* photosynthesis
* fermentation
* glycolysis \n

* photosynthesis

The Krebs cycle occurs after _________.

glycolysis

The NADH involved in the electron transport chain is made

by oxidation reactions in glycolysis and the Krebs cycle

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

a terminal acceptor

During the electron transport chain in bacteria, protons are

shuttled to the outside of the cell membrane

Coenzyme Q

transfers protons from inside the membrane to outside the membrane

In this reaction, ATP synthase uses energy from ______ to make ATP.

protons re-entering the cell

In bacteria, the electron transport chain is located

in the plasma membrane

The last carrier protein in the electron transport chain transfers

two electrons to oxygen

The electron transport chain is part of ______.

* aerobic respiration

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

\
True or False

False

Consider the biochemical pathway:

A – E1 –> B – E2 –> C

\n Enzyme 1 can utilize

only A as substrate.

In feedback inhibition, the inhibitor of the biochemical pathway is typically

the final product of the biochemical pathway.

The electron transport chain consists of a series of membrane-bound carriers that shuttle protons and electrons to NADH.

\
True or False

False

The electrons excited by sunlight are replaced by electrons from __________ in photosystem I, and by electrons from __________ in photosystem II.

photosystem II; water

The Calvin cycle begins by the attachment of CO2 to which of the following?

\
* RuBP
* glucose
* 3-phosphoglycerate
* glyceraldehyde 3-phosphate

RuBP

Aerobic respiration and fermentation are similar in that they both begin with the process of __________ and they both produce ATP and __________. 

glycolysis; CO2

Pictured here is the coenzyme NAD+. This molecule serves as an electron carrier in many biological reactions. Conversion of NAD+ to NADH is a ____________,__ which is accompanied by the __________ of two electrons.

reduction; gain

photophosphorylation

uses light-driven electron transport to generate ATP

substrate-level phosphorylation

transfer of phosphate from high-energy compound to ADP to directly generate ATP

oxidative phosphorylation

uses electron transport and an enzyme to generate ATP

Phycobilin

red and blue-green

Carotenoid

yellow, orange, red

Chlorophyll

green

Reactions that release energy as they proceed are called _________,__ while reactions that require energy to complete are called ___________.

exergonic; endergonic

After DNA replication two identical DNA molecules are formed.

\
True or False

True

In a repressible operon, excess product acts as a corepressor to increase transcription of the operon.

\
True or False

False

DNA replication begins at multiple sites on the bacterial chromosome.'

\
True or False

False

A structural gene encodes the information for a specific protein.

\
True or False

True

Which of the following is not true about transposons?

\
* They are capable of shifting from one cell to another.
* They can move into the host genome.
* They replicate themselves before moving.
* They are able to leave the host genome via a vector.
* They can move from one site in the host genome to another site.

* They are able to leave the host genome via a vector.

Where does *Acinetobacter baumannii* typically live?

soil and water

Infections caused by *A. baumannii* have most frequently been seen in which group of people?

 

* soldiers returning from current battlefields
* cystic fibrosis patients on ventilators
* HIV/AIDS patients
* premature newborns

* soldiers returning from current battlefields

A “healthcare-associated” infection is an infection acquired through which means?

 

* water
* indirect fecal-oral transmission
* admission to a hospital for other reasons
* food contaminated with endospores \n

* admission to a hospital for other reasons

What was the most probable source of *A. baumannii* in this woman’s infection?

\
* urinary catheter
* ventilator tube
* colistin treatment
* hospital visitors

* ventilator tube

The strain of *A.* *baumanni* cultured late in this woman’s infection was most likely a(n) ______ strain.

XDR

HIV is an example of a _________,__ which uses __________ to synthesize DNA from an RNA genome template.

retrovirus; reverse transcriptase

One reason mutations are so problematic is that bacterial cells have no ability to repair a mutation once it has occurred. 

\
T/F

False

Group the following structures into the appropriate category.

The __________ subunit of the ribosome is the site of peptide bond formation.

large

In the presence of tryptophan, transcription of the trp operon is on.

\
T/F

False

Translation is characterized by

the blueprint of the RNA molecule used to bind amino acids together to form proteins.

Riboswitches are a type of __________ RNA in bacteria that can start or stop a step in gene expression.

noncoding

During DNA replication, the lagging strand is synthesized continuously, while the leading strand is synthesized discontinuously.

\
T/F

False

The __________ is the sum total of genetic material in a cell.

genome

In bacteria, mRNA transcripts are first recognized by the __________ subunit of the ribosome. 

small

DNA is the blueprint that indicates which kinds of proteins to make and how to make them.

\
T/F

True

DNA polymerase

can only add nucleotides in a certain direction.

On one of the strands of bacterial DNA, the new complementary strand is synthesized discontinuously into small pieces of DNA called

Okazaki fragments.

One bacterial chromosome replicates to become two chromosomes with

each made of one strand of DNA from the original chromosome and one newly synthesized strand

Which of the following occurs as the ribosome shifts down the mRNA by a distance of one codon?

\
* The tRNA that was in the P site picks up another amino acid.
* The tRNA that was in the P site moves into the A site.
* The tRNA that was in the A site moves into the P site.
* The tRNA that was in the A site releases the growing polypeptide chain.
* The tRNA that was in the A site picks up another amino acid.

* The tRNA that was in the A site moves into the P site.

Which of the following is correct regarding sigma factor?

\
* It forms mRNA.
* It is involved in the termination of replication.
* It recognizes the promoter region.
* It forms an open complex.

* It recognizes the promoter region

Please place the steps in the correct order to assess your knowledge of Koch’s postulates.

The minimum number of organisms necessary to enter through the portal of entry and establish infection is the __________.

infectious dose

What allows *Salmonella* to enter the intestinal cell?

protein secretion system

What cell component helps pull the *Salmonella* cells into the cell?

actin filaments

A second protein secretion system results in

a protective coating surrounding the infective bacterial cell.

How does the protective coating help *Salmonella* evade destruction?

Lysosomes cannot fuse with the infectious cells.

What occurs within the protective coating?

 

* The bacteria secrete exotoxins.
* The bacteria enter the bloodstream.
* Lysosomes fuse with the coating to prevent bacterial destruction.
* The bacteria divide rapidly.

* The bacteria divide rapidly.

Dengue fever is transmitted by the bite of a mosquito that has been infected with the virus after it has bitten a person who has dengue fever. In this scenario, the portal of exit would be the __________.

blood

Please select the body sites that serve as portals of entry for microbes.

\
* vagina


* nose
* mouth
* endocrine gland
* brain
* liver
* urethra
* skin

* vagina


* nose
* mouth
* urethra
* skin

Please move the correct terms and/or concepts into their corresponding empty boxes within the figure to complete the concept map.