Microbiology Exam 1

What are the different shapes of bacteria?

• Cocci — spherical/round

• Bacilli — rod-shaped

• Vibrio — curved or comma-shaped

• Spirilla — rigid spiral-shaped

• Spirochetes — thin, flexible corkscrew-shaped

Infectious agents only made of protein responsible for mad cow disease

prions

A diverse group that includes algae and protozoa

protists

Inhabit the gut and aid in digestion

bacteria

Small, acellular entities made of protein and nucleic acid (RNA and DNA) that cause many common diseases

viruses

Cellular organisms that are often found in extreme environments

archaea

Composed only of RNA and cause many plant diseases

viroids

It is possible to build a light microscope capable of 10,000× magnification, but the image would not be sharp because resolution is independent of magnification.

true

A 30× objective and a 20× ocular produce a total magnification of

600x

You want to look at a virus under the microscope. What kind of microscope would you use and why?

Electron microscope, because it allows for higher resolution

Gram staining divides bacterial species into two groups based on differences in cell wall structure.

true

What are the most common bacterial shapes

bacilli & cocci

The causative agent of cholera, Vibrio cholerae is what shape?

comma shaped

You will tested on Gram staining on each lab exam. On lab exams, you will be required to list the shape and arrangement of cells. Imagine that you are taking Lab Exam 1 and after staining cells, you see grape-like clusters of spherical bacteria. Which would best describe the shape and arrangement of the cells you see?

Staphylococci

Which of the following are found in the INTERIOR of a bacterial cell?

Nucleoid & Ribosome

The distance between the center of the lens and the focal point, labeled with a lower case f in this figure, is called the focal…

Length

How is lens strength related to focal length?

A lens with short focal length magnifies more than a lens with a longer focal length

What is the function of the microscope component, “Ocular”

Eyepiece used to view specimen

What is the function of the microscope component, “Objective”

Lens closest to the specimen

What is the function of the microscope component, “Condenser”

Focuses a cone of light on the slide

Which term describes the specific location where light rays meet after passing through a lens?

Focal point

Which term refers to the ability of an objective lens to separate or distinguish between small objects that are close together?

Resolution

Focal length is measured as the distance from…

The center of the lens to the focal point

In preparation for staining, the process by which internal and external structures of specimens are preserved and attached in position on a slide is called…

Fixation

The most widely used differential staining procedure in microbiology is the…

Gram stain

Bright-field microscopes typically have two focus knobs, the ___ focus adjustment knob and the ___ focus adjustment knob

Coarse; fine

Which type of staining distinguishes organisms based on their staining properties?

Differential

Light microscopes can be used to observe all of the following EXCEPT…

Most viruses

The ability to separate or distinguish between small objects using a microscope is called…

Resolution

When preparing a specimen for microscopy, which two things generally occur during the fixation step?

·Cells are attached to slide ·Cells are killed

Which genus gets its name due to the cellular arrangement of spherical cells found in clusters, like a bunch of grapes?

Staphylococcus

The ___ stain was developed by ___ in ___ simple; Frances Jalock; 1772

Gram; Christian Gram; 1884

The bacterial shape known as bacillus is different from coccus because bacillus is a…

rod shape

Since it provides a way to distinguish between Gram-negative and Gram-positive bacteria, the Gram stain is an example of…

Differential staining

Which is the cellular morphology of the bacterial cell illustrated in this image?

Fruiting body = multicellular-looking reproductive structure

Which of the following are limitations of the light microscope?

Light microscopes have a resolution limit of 0.2 micrometers … Light microscopes are not able to show detailed internal cellular structure

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

Cell wall

The two most common bacterial cell shapes are ___ and ___ both shown here

cocci; rods

Which of the following are common cellular components of bacterial cells?

Capsule; Flagella; Ribosomes; Cell wall

Which term describes the cellular arrangement of spherical cells linked in a chain?

Streptococcus

The bacterial shape known as a rod is also termed a…

Bacillus

In this image of a typical bacterial cell, the letter C points to the layer of the cell envelope closest to the cytoplasm, termed the…

plasma membrane

The cellular morphology of the bacterial cell illustrated here is…

spirochete

Which of the following cellular components is found in plant cells but not bacterial cells?

Nucleus

In this image of a typical bacterial cell, the letter A indicates the…

cytoplasm

What is the function of the common bacterial cellular component “Cell wall”

protection against osmotic stress

What is the function of the common bacterial cellular component “Cell membrane”

selectively permeable barrier

What term is used to describe the plasma membrane and all layers external to it?

Cell envelope

Which is the cellular morphology of the bacterial cell illustrated in this image?

fruiting body

Plasma membranes are organized by having…

two lipid layers

In this image of a typical bacterial cell, the letter B indicates the…

nucleoid

Elements such as carbon, oxygen, hydrogen, nitrogen, sulfur, and phosphorus are considered…

macromolecules

The ___ is defined as the plasma membrane and all surrounding layers external to it (e.g., cell wall and/or capsule)

Cell envelope

What is the relationship of the bacterial cell layer “Capsule”

well attached

What is the relationship of the bacterial cell layer “Slime layer”

easily detaches

What is the relationship of the bacterial cell layer “S-layer”

aids in cellular shape

The term cytoplasm is inclusive of…

everything within the plasma membrane

How many lipid layers are found in a bacterial plasma membrane? (Note: a lipid layer consists of a series of phospholipids arranged side to side with hydrophilic heads all facing one direction and hydrophobic tails facing the other direction.)

Two

What is the description of the cytoplasm component “Nucleoid”

composed of DNA and protein

What is the description of the cytoplasm component “Ribosome”

composed of RNA and protein

What is the description of the cytoplasm component “Plasmid”

circular DNA that is not essential

What is the description of the cytoplasm component “Cytoskeleton”

network of protein polymers

Macroelements include which of the following?

Carbon, sulfur, oxygen, nitrogen, phosphorus, and hydrogen

Which three of the following are functions of the bacterial cytoskeleton?

Participate in cell division, Determine cell shape, Localize specific proteins within the cell

What is the relationship of the extracellular layer of a bacterial cell “Capsule”

organized sugar layer

What is the relationship of the extracellular layer of a bacterial cell “Slime layer”

disorganized sugar layer

What is the relationship of the extracellular layer of a bacterial cell “S-layer”

organized protein layer

Which of the following bacterial structures is the site of protein synthesis?

Ribosome

The irregularly shaped region of a bacterial cell that contains the chromosome and numerous proteins is called the…

nucleoid

The most inclusive term to describe the contents within the plasma membrane is…

cytoplasm

Small, double-stranded, circular pieces of DNA found in addition to the bacterial chromosome are called…

plasmids

Which five of the following are found in the bacterial cell cytoplasm?

Inclusion bodies, Nucleoid, Cytoskeleton, Plasmids, Chromosome

The hundreds of thin, short hair-like projections extending from the bacterial cell are called…

pili

Bacterial cytoskeleton proteins share ancestry with which two eukaryotic proteins?

actin, tubulin

Which of the following is the typical motility structure of bacteria?

Flagella

The ___ is a structure found in all cells and is the location for protein synthesis

Ribosome

When a swimming bacterium changes direction, it will…

tumble

The bacterial nucleoid is composed of…

protein and DNA

Chemotaxis involves…

movement of bacteria away from a repellent; movement of bacteria toward an attractant

Which two of the following describes typical plasmids?

composed of DNA, double-stranded

Endospores are defined as…

dormant cells formed within a living cell

The approximate dimensions of fimbriae are…

3 to 10 nm in diameter and up to several µm long

Relative to the cell, the bacterial ___ is a long tubular structure that can spin, thereby resulting in cell motility

Flagellum

A swimming bacterium reorients during a…

Tumble

Movement of a bacterial cell toward an attractant or away from a repellent is termed

Chemotaxis

Some bacteria can make a dormant structure, called a(n) ___, which is resistant to many environmental conditions

Endospore

What is a typical size for archaeal cocci?

1–3 µm

Select all reasons that archaea are of interest to scientists

Some archaea live in extreme environments; Archaea share features with bacteria and eukaryotes; Some archaea produce methane, a greenhouse gas

The plasma membranes of bacteria and archaea differ mainly in which component?

lipids

Which four of the following characteristics are the same for bacteria and archaea?

70S ribosomes present in cytoplasm; Motility structures are present; Chromosome is double-stranded DNA; Inclusions present in the cytoplasm

Archaeal cell envelopes are different from bacterial cell envelopes in two ways, ___ and ___

the presence of unique lipids in the plasma membrane; the presence of an S-layer as the major cell wall component

Which of the following statements is false regarding environments where archaea live?

Archaea are restricted to a few extreme environments on the planet

In archaeal plasma membranes, hydrocarbons are attached to glycerol by ___ links, instead of the ester links seen in bacterial and eukaryotic lipids

ether

The archaeal cells in this image have which cellular morphology?

cocci

The surfaces of an archaeal membrane, both internal to the cell and external, are…

hydrophilic

How do the typical sizes of archaeal and bacterial cells compare?

Archaeal and bacterial cells are about the same size

Compare the two archaeal membranes illustrated here. Which of the following statements is false?

Membrane A has greater rigidity

Peptidoglycan is a major component of the cell walls of both archaea and bacteria

false

The lipids of extreme thermophiles can be expected to exhibit which chemical composition?

Tetraether monolayers

The major and sometimes only component of the archaeal cell wall is the…

s-layer