microbio ch 3 smartwork

Order the following events as they occur from beginning to end during DNA replication in a dividing cell.

- DNA at origin unzips, and two replication forks form - replisomes synthesize daughter chromosomes bidirectionally - terminator site is replicated - septum forms - daughter cells separate

Regarding the enzyme in Part 2, _________________ of these would be required if a new round of DNA replication began before the first one terminated.

12

Vinegar has preservative and antimicrobial properties due to the ability of the active ingredient to cross the membrane as ______________. Once in the cytoplasm, it becomes _______________, thereby, disturbing normal pH. Choose one: A. CH3COOH, deprotonated B. CH3COO-, deprotonated C. CH3COOH, protonated D. CH3COO-, protonated

A. CH3COOH, deprotonated

Phospholipids with an ether link between glycerol and the fatty acids are found in Choose one: A. archaea. B. bacteria. C. plants. D. fungi.

A. archaea.

In bacterial cells, Choose one: A. transcription, translation, and DNA replication can all occur at the same time in the same cell compartment. B. transcription, translation, and DNA replication are all spatially separate. C. transcription and translation occur together but not while DNA replication is occurring. D. transcription and DNA replication can occur together, but translation is spatially separate from transcription and replication.

A. transcription, translation, and DNA replication can all occur at the same time in the same cell compartment.

Which of the following statements regarding the bacterial sacculus are true? Choose one or more: A.It provides protection from osmotic rupture. B.It is also known as the cell wall. C.It is impervious to polar or charged molecules. D.It is composed of peptidoglycan. E.The crucial cross-linking reactions occur inside the cell (i.e., in the cytoplasm).

A.It provides protection from osmotic rupture. B.It is also known as the cell wall. D.It is composed of peptidoglycan.

Why do bacteria usually contain an even number of replisomes? Choose one: A. DNA is double-stranded and each single strand requires its own replisome. B. Because replication is bidirectional, there are two replication forks emanating from the origin of replication. C. Bacteria need only one replisome; the other serves as a backup copy. D. There are two copies of the gene that codes for DNA polymerase, an important enzymatic protein component of replisomes.

B. Because replication is bidirectional, there are two replication forks emanating from the origin of replication.

Which of the following cellular components is considered an endotoxin that is harmless as long as the pathogen remains intact but when released by a lysed cell overstimulates host defenses, which may result in a lethal endotoxic shock? Choose one: A. The cell wall B. Lipopolysaccharides C. Inner membrane phospholipids D. Periplasmic proteins

B. Lipopolysaccharides

Which of the following is NOT a function of the cell membrane? Choose one: A. Detection of environmental signals B. Production of proteins C. Transport of molecules into and out of the cell D. Separation of charge across the membrane

B. Production of proteins

You have isolated a microorganism from seawater that contains thylakoid membranes, gas vacuoles, and carboxysomes. It is most likely Choose one: A. an ameba. B. a cyanobacterium. C. Caulobacter. D. algae. E. E. coli.

B. a cyanobacterium.

Which portion of LPS is most responsible for its toxic effects? Choose one: A. disaccharide diphosphate B. lipid A C. core polysaccharide D. O-antigen polysaccharide E. fatty acids

B. lipid A

The lipopolysaccharides are found in the Choose one: A. periplasm. B. outer membrane. C. inner membrane. D. cytoplasm.

B. outer membrane.

Active transport is required for bacterial cells to Choose one: A. exchange oxygen and carbon dioxide with the environment. B. transport solutes against their concentration gradient. C. bring any charged molecule into the cell. D. move large polar solutes along their concentration gradient. E. move to environments with a higher nutrient concentration.

B. transport solutes against their concentration gradient.

The most abundant molecule in the cell is Choose one: A. lipids. B. water. C. proteins. D. DNA.

B. water.

Which key enzyme directly involved in the above process is not explicitly shown in the illustration? Choose one: A. DNA polymerase B. ATP synthase C. RNA polymerase D. transpeptidase E. sortase

C. RNA polymerase

In the image below of a dividing bacterium, what structure is indicated by the arrows? Choose one: A. The origin of replication B. The flagellum C. The septum D. The replisome

C. The septum

Penicillin's mode of action is to inhibit Choose one: A. DNA replication by allosterically binding to DNA polymerase. B. translation by binding to the 30S ribosomal subunit. C. cell wall cross-link formation. D. translation by binding to the 50S ribosomal subunit.

C. cell wall cross-link formation.

The cell envelopes of mycobacteria contain large amounts of these molecules, which make them "acid-fast." Choose one: A. fibronectin-binding proteins B. peptidoglycans C. mycolic acids D. arabinogalactans E. teichoic acids

C. mycolic acids

Which class of molecules can directly cross the cell membrane without the aid of transport proteins? Choose one: A. Ions B. Sugars C. Amino acids D. Uncharged gasses

D. Uncharged gasses

A Gram-negative cell envelope contains Choose one: A. a cell membrane covered by a thick layer of peptidoglycan. B. a double membrane, but no peptidoglycan cell wall. C. a thick layer of peptidoglycan only. D. an inner cell membrane, thin peptidoglycan layer, and outer membrane. E. a thin layer of peptidoglycan surrounded by a cell membrane.

D. an inner cell membrane, thin peptidoglycan layer, and outer membrane.

Movement of molecular oxygen (O2) and carbon dioxide (CO2) across the cell membrane Choose one: A. occurs only unidirectionally, such that oxygen is allowed to enter and carbon dioxide (waste) is able to leave. B. requires energy in the form of ATP or the proton motive force. C. occurs passively, but membrane transporters are required to facilitate their movement. D. occurs by passive diffusion. E. only occurs when the O and C atoms are part of some other molecule (e.g., a sugar or amino acid).

D. occurs by passive diffusion.

Antibiotics that weaken the peptidoglycan cell wall make a bacterium more prone to Choose one: A. detaching from surfaces. B. shrinkage in hypertonic solutions. C. starvation. D. osmotic lysis. E. phagocytosis by macrophages.

D. osmotic lysis.

An actively dividing bacterial cell (such as E. coli) typically contains two molecules of __________ and only one molecule of ________________ , each of which constitutes approximately 1% of total cell weight.

DNA , peptidoglycan

Which of the following is true of the newly synthesized daughter chromosomes? Choose one: A. Each strand on each chromosome contains interspersed segments of new and parental DNA. B. One consists of a double helix of two new DNA strands, whereas the other is entirely parental. C. They remain single-stranded until after septation. D. They are both double-stranded, but nonidentical, because of crossing over. E. Each chromosome contains one parental and one newly synthesized DNA strand.

E. Each chromosome contains one parental and one newly synthesized DNA strand.

Cells of a normally rod-shaped bacterium (e.g., Bacillus subtilis) that have completely lost the ability to produce the MreB protein would mostly likely be Choose one: A. filamentous in form. B. nonflagellated. C. unable to divide symmetrically. D. stalked (like Caulobacter). E. coccoid-shaped.

E. coccoid-shaped.

Reports of disease caused by enteropathogenic E. coli and its relative, Salmonella, usually include a description of the responsible serotype. For example, in 1993, hundreds of infections from Shiga-toxin-producing E. coli resulted from undercooked hamburgers sold by Jack-in-the-Box restaurants. The outbreak was caused by the now-infamous E. coli strain O157:H7. The "O" in this designation refers to an antigen on which of the following molecules? Choose one: A. outer membrane porins B. capsular oligosaccharide C. outer membrane lipoprotein D. osmoregulatory proteins E. lipopolysaccharide

E. lipopolysaccharide

What type of enzyme in the replisome catalyzes addition of nucleotides to the growing DNA strands? Choose one: A. transcriptase B. gyrase C. recombinase D. helicase E. polymerase

E. polymerase

Many bacteria adapt to adverse environmental conditions by modifying the composition of their cell membranes. For example, the membranes of bacteria subjected to heat stress often contain high levels of which of these compounds? Choose one: A. cholesterol B. polyunsaturated fatty acids C. unsaturated fatty acids D. ether-linked terpenoids E. saturated fatty acids

E. saturated fatty acids

The diameter of bacterial cells is controlled by the ____________ protein.

FtsZ

Which of the cell components listed below are characteristic of all bacteria, and which are specialized structures found in only some bacteria?

all: phospholipids, DNA, ribosomes some: stalks, flagella, carboxysomes, gas vesicles, pili

Water molecules are sufficiently small that they do not require specific transporters to cross biological membranes. But because they are polar, diffusion of these molecules across the phospholipid bilayer is slow. Peter Agre won the 2003 Nobel Prize in Chemistry for his discovery that the rapid movement of water into and out of cells occurs via ___________

aquaporins

The FtzZ protein, found in both coccoid and rod-shaped bacteria, is important for maintaining the cell's _____________-

diameter

Which of the following features related to chromosomes and gene expression are characteristic of eukaryotes and/or prokaryotes? (Rare exceptions may occur.)

eukaryotes: nucleus with nuclear membrane, diploid, dna replication and gene expression are separated prokaryotes: haploid, nucleoid, dna replication and gene expression can occur simultaneously both: dna is genetic material, ribosomes translate mRNA into protein

Certain aquatic bacteria use magnetosomes to direct them to environments with optimal levels of______________

oxygen

All cells are made up of water and essential ions as well as small and large organic molecules. Order the following components in E. coli during balanced exponential growth from greatest to least in terms of percentage of total cellular weight.

water, protein, nucleic acid, lipids, inorganic ions