Biology 180 Exam 3

Which of the following filaments is made from adding smaller protein subunits together?

Actin filaments Microtubule filaments Intermediate filaments All of the above

viral envelope

A membrane, derived from membranes of the host cell, that cloaks the capsid, which in turn encloses a viral genome.

Which of the following will most likely increase the virulence of a bacterium?

A plasmid containing an antibiotic resistance gene A capsule Endotoxins All of the above

Which of the following best describes a virus?

A protein coat surrounding nucleic acid.

This bacterium derives nutrition by digesting human intestinal contents (in other words, food) away from any air. Thus, this bacterium should be an:

Anaerobic chemoheterotroph

Which of the following best describes the DNA in prokaryotic cells?

Circular

In which of the following relationships does one species benefit and the other is neither harmed nor helped?

Commensalism

Bacteria carry small, extra chromosomal segments of DNA called...

Plasmid

Which of the following is found in plant cells but not in animal cells?

Plasmodesmata

Which statement about the genomes of prokaryotes is correct?

Prokaryotic genomes are composed of circular DNA.

What is the difference between gram negative and gram positive bacteria?

Different cell walls and cell membranes

Which of the following locations would you find a intermediate filament?

Fingernail

What is the enzyme that moves phospholipids from one phospholipid leaflet to the other?

Flippase

What do we call the life cycle of the virus that results in the death of the host cell?

Lytic Cycle

Which of the following is NOT an advantage of internal membranes?

Greater control of mobility

A temperate phage goes dormant between which stages of the lytic cycle?

Entry and Synthesis

Which cytoskeletal structure is most closely associated with the centrosome?

Microtubule

Which of the cytoskeletal proteins is most closely associated with the spindle apparatus that separate the chromosomes during mitosis?

Microtubules

Actin is a critical component of the "thin filament" found in all contractile muscle tissue. Which of the following motor proteins binds to actin to cause muscle contraction?

Myosin

Protein synthesis is the primary role of which of the following organelles?

Ribosomes and rough ER

Which organelle receives, processes, and ships proteins?

Rough Er and Golgi

Rotational movement of phospholipids in the membrane is most commonly described as:

Spinning around a vertical axis of rotation in the same monolayer.

Which of the following is the most probable fate of a newly emerging virus that causes rapid and high mortality in its host?

The newly emerging virus will die out rather quickly or will mutate to be far less lethal.

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

The plants would develop the typical symptoms of TMV infection.

Which of the following analogies best describes the process of transformation?

Walking down the street, seeing a piece of used gum, and plopping it into your mouth.

When viruses replicate, where do they get the proteins needed to form the capsule?

They use the host's protein synthesizing machinery and the viral nucleic acid to make new proteins.

viral nucleic acid

copied from viral nucleic acids

One way to increase the fluidity of a membrane would be to:

ncrease the number of unsaturated fatty acids in the membrane.

The predatory bacterium, Bdellovibrio bacteriophorus, drills into a prey bacterium and, once inside, digests it. In an attack upon a gram-negative bacterium that has a slimy cell covering. What is the correct sequence of structures penetrated by B. bacteriophorus on its way to the prey's cytoplasm? 1. Membrane composed mostly of lipopolysaccharide 2. Plasma membrane 3. Peptidoglycan 4. Capsule

4, 1, 3, 2

Which of the following is characteristic of the lytic cycle?

A large number of phages are released at a time.

The genome of a bacterial cell is sequenced and several remnants of phage DNA are uncovered. The most likely explanation is:

A transduction has occurred.

A prerequisite for undergoing conjugation is:

An F factor

Of the two types of prokaryotes, which is more closely related to eukaryotes?

Archaea

Which of the following types of organism would you most likely find living in the hot pools of Yellowstone?

Archaea

An organism that needs only CO2 from the air as a carbon source is called a/an

Autotroph

Which of the following is true regarding BOTH mitochondria and chloroplasts?

Both organelles contain their own ribosomes.

In general, what is the primary ecological role of prokaryotes?

Breaking down organic matter.

Which of the following process requires a pilus?

Conjugation

Which of the following best describes a plasmid?

Contains non-essential genes.

Which term best describes the jelly-like substance found outside the organelles, but inside the plasma membrane?

Cytosol

Bacteria perform each of the following ecological roles. Which role typically does not involve a symbiosis (i.e., a physical association between two species)?

Decomposer

A yeast cell that uses oxygen when it is available but can also survive in the absence of oxygen would be considered a/an:

Facultative anaerobe

All viruses contain DNA.

False

The two monolayers of a biological membrane have the same phospholipid composition.

False

Which of the following is true regarding centrosomes?

Function as microtubule organizing centers.

Carl Woese and collaborators identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains?

Genetic characteristics such as ribosomal RNA sequences

Which statement about the domain archaea is TRUE?

Genetic prospecting has recently revealed the existence of many previously unknown archaean species.

Which of the following can be effective in preventing the onset of viral infection in humans?

Getting Vaccinated

In order to study the different components of a cell, scientists will use a blender to lyse (this means "break open") a collection of cells and then centrifuge the cell lysate. Membrane fragments end up in a pellet at the bottom of the centrifuge tube. Membrane proteins were originally classified based upon how easy it was to separate them from this pellet. The mildest treatment involves addition of a concentrated salt solution that competes with ionic and hydrogen bonds. A more aggressive treatment involves the addition of a detergent solution that interrupts Van der Waal bonds. Based on what you know about membrane proteins and the weak bonds that associated them with the membrane which of the following statements do you think is most correct? (P.S. - this is a thinking/application question)

High salt releases peripheral membrane proteins and detergent releases integral membrane proteins.

Which of the following pairs of membrane protein descriptions is mutually exclusive (meaning that if you are one, you can't be the other)?

Integral membrane protein and peripheral membrane protein

When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are:

Integral proteins

Which of the following activities can a temperate phage carry out that a virulent phage cannot?

Integration: viral DNA is spliced into host genome.

Which of the three cytoskeletal components is the most stable?

Intermediate filaments

Some viruses contain a membrane envelope in addition to the protein capsule. Where do they get the envelope?

It is derived from the host cell's plasma membrane.

Which of the following methods does not create an integral membrane protein?

Lipid Anchor

Which statement best describes the lysosomes?

Low Ph of 5

Capsomers and Viral Accessory proteins

Made by host Ribosomes

What is the most common source of genetic diversity in prokaryotes?

Mutation

In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf's non-living, waxy covering while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, however, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? Check those that apply.

Nutrient recycler, Mutualist, Parasite

Which of the following organelles is NOT a member of the endomembrane system?

Peroxisomes

Which organelle is most closely associated with oxidation reactions?

Peroxisomes

The defining characteristic of a glycoprotein is:

Presence of one or more oligosaccharide attachments.

The best represented (most common) viral genome type is:

Single stranded- RNA

What kinds of molecules pass through a cell membrane most easily?

Small and hydrophobic

Site of lipid synthesis

Smooth ER

Which of these analogies best explains the difference between the cytosol and the cytoplasm?

The cytoplasm is like the Atlantic Ocean and the cytosol is like the sea water in it.

The host range of a virus is determined by:

The proteins on its surface The proteins on the surface of the host cell

Though plants, fungi, and prokaryotes all have cell walls, we place them in different taxa. Which of these observations comes closest to explaining the basis for placing these organisms in different taxa, well before relevant data from molecular systematics became available?

Their cell walls are composed of very different biochemicals.

Which of the following terms is associated with a chloroplast?

Thylakoids

A membrane protein has an alpha helix that crosses the bilayer and on the extracellular surface has several glycoproteins attached. Which is the best descriptor of this protein?

Transmembrane Protein

Which of the following span the phospholipids bilayer, usually a number of times?

Transmembrane Proteins

Which of the following movements occurs but is rare for a phospholipid in a biological membrane? (Do not select choices that do not occur). Mark all that apply.

Transversal movement

The outer monolayer of the plasma membrane is called the extracellular leaflet.

True

An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?

cell-cell recognition

Powerhouse of the cell.

mitochondria

These organelles are physically connected to each other.

rough and smooth ER