Microbiology Ch 4

How are Gram-positive and Gram-negative flagella different?

A Gram-positive flagellum has only two rings in its basal body; Gram-negatives each have four.

Efflux pumps can be used to pump antibiotics out of a cell once they enter to protect the cell. This will be done against the concentration gradient of the antibiotic. Which of the active transports would most likely be used?

A Uniport would pump the antibiotic out without needing to bring additional molecules into the cell, and would not allow the antibiotic to diffuse back in.

Which of the following scenarios is an example of bacterial motility?

A bacterium moving towards a food source

Sodium and potassium ions need to be pumped simultaneously against their concentration gradients. Which one of the transport proteins would be most effective at this?

Antiport

How does water enter and exit a cell?

By simple diffusion or by use of an integral transport protein

What structural part of a bacterial flagellum is composed of flagellin?

Filament

Which of the following statements about bacterial flagella is true?

Flagella can rotate 360 degrees.

Porins are present in ______________bacteria because, in these organisms, molecules entering the cell must pass through an extra layer of ___________.

Gram-negative; membrane

Which of the following molecules would be blocked by a cell membrane?

Ions

What is the advantage to spirochetes of the corkscrew movement provided by axial filaments?

It allows the cells to move more easily through viscous human tissues and fluids, such as mucus.

What is a hallmark of passive transport across cell membranes?

It occurs along an electrochemical gradient, and may involve the use of transport proteins.

Which of the following statements regarding active transport is false?

It powers the diffusion of water across the cell membrane.

Which of the following types of bacterial cells would have flagella located at only one end of the cell?

Lophotrichous and monotrichous

Which of the following types of bacterial cells would have only a single flagellum?

Monotrichous

Which of the following molecules is shared by both Gram-positive and Gram-negative organisms?

N-acetylmuramic acid

Which of the following terms refers to a bacterium moving towards a light source?

Positive phototaxis

Which of the following would not move freely across the cytoplasmic membrane?

Positively charged hydrogen ions

The basal body is comprised of which structural component(s) of flagella?

Rod and Rings

How is simple diffusion different from other types of passive transport?

Simple diffusion does not require a permease.

What type of transport uses two transport proteins?

Symport

Which of the active transport types employs diffusion?

Symport

How do axial filaments differ from regular bacterial flagella?

The axial filament is located between the cell membrane and the outer membrane.

What will happen to a cell that is placed in a solution containing a high concentration of sugar, a molecule that cannot pass across the cell membrane?

The cell will lose its interior water, causing it to shrivel up and possibly die.

Why is no energy required in passive transport?

The concentration gradient drives the movement.

Why are receptors on the cell surface necessary for bacterial movement?

The receptors sense the stimulus and send signals to the flagella.

What makes phospholipid membranes good at keeping some molecules out, and allowing others to freely pass?

They have both hydrophilic and hydrophobic regions.

Why are ATPases associated with active transport proteins?

They provide transport proteins with the energy needed to pump molecules against their concentration gradients.

How is osmosis different from simple diffusion?

Water movement is driven by the concentration of solutes rather than its own concentration.

Nonspecific permeases

allow a variety of molecules to cross the cytoplasmic membrane.

The rings

anchor the flagellum to the cell membrane.

Amoxicillin is an antibiotic that inhibits the formation of peptide cross-links. Amoxicillin, therefore, would most likely inhibit the growth of __________.

both Gram-positive and Gram-negative organisms

Pathogenic bacteria

can be identified and classified by differences in their flagellar proteins.

Axial filaments are composed of

endoflagella.

A glycoprotein

is a type of peripheral protein above that can be used as a receptor or in enzymatic functions.

Once equilibrium is reached,

molecules move, but there is no net movement in a particular direction.

Taxis is

movement towards or away from a stimulus.

As a bacterium approaches a food source, one would expect

runs to become more frequent.

Axial filaments are found on

spirochetes.

Tumbles occur when

the flagella rotate clockwise.

Peritrichous bacteria make a run when

the flagella turn counterclockwise and become bundled.

Hydrophobic molecules would enter a cell

through integral transport proteins.

Integral proteins are mostly involved in

transport function.

A positively charged sodium ion

would require the use of integral protein channels to pass through a cell membrane.