Microbiology Test #1

What is the basic unit of structure and function in living organisms?

The cell

What was Robert Hooke’s contribution to the study of cells?

He observed cork (part of tree bark) under a microscope and introduced the term “cells” in 1665.

How do microscopic and macroscopic differ?

Microscopic: requires a microscope to see clearly. Macroscopic: visible with the unaided eye.

Why is the nucleus described as the cell’s “brain”?

It houses DNA containing instructions that help direct the cell’s activities.

What does the nuclear membrane surround?

The nucleus within the cell.

What does the cell membrane enclose?

The cell’s contents.

What is protoplasm?

The water-based, jellylike living material of a cell.

Where is cytoplasm located in a cell that has a nucleus?

Inside the cell membrane, but outside the nucleus

What is the material inside the nucleus called? (Two possible answers)

Nucleoplasm, also called karyoplasm.

What is the nucleoid?

The region of a prokaryotic cell containing its main DNA, without a surrounding nuclear membrane.

In a cell with a nucleus, what two parts make up the protoplasm?

Cytoplasm and nucleoplasm

What does it mean for a cell to be eukaryotic?

A true nucleus enclosed by a nuclear membrane.

What does “pre-nucleated” mean in the description of prokaryotes?

Their cells lack a membrane-enclosed nucleus.

How many main chromosomes do most bacteria have?

One chromosome.

What material fills a bacterial cell around its nucleoid?

Cytoplasm

How many main chromosomes do most bacteria have?

One chromosome.

Is the bacterial cell membrane flexible or rigid? What about the cell wall?

The cell membrane is flexible; the cell wall is rigid.

Where is a bacterial cell wall located relative to the cell membrane?

Outside the cell membrane.

Eubacteria and archaebacteria have what type of cell?

Prokaryotic—they lack a membrane-enclosed nucleus.

What are the modern names for eubacteria and archaebacteria?

Eubacteria: Bacteria. Archaebacteria: Archaea.

Which group of prokaryotes is sometimes described as “primitive”?

Archaebacteria (Archaea).

Archae- means “ancient,” but these organisms have continued evolving.

1) What does cellular reproduction produce?

2) What does cellular reproduction produce for unicellular organisms?

1) New cells.

2) For a unicellular organism, this produces new organisms.

How is microbial death defined in terms of reproductive ability?

Permanent loss of the ability to reproduce under suitable conditions.

What are two major roles of nutrients in cells?

1) They provide materials to synthesize (build) cell components

2) They serve as sources of energy.

What role does ATP play in cellular activities?

It supplies usable energy to power cellular work.

What is excretion?

The release of waste products from the cell.

What does it mean that cells respond to their environment?

They change their activity or behavior when their surroundings change.

What is a mutation?

A change in the DNA sequence.

How can a mutation affect a cell’s ability to reproduce?

Depending on the change, reproduction may be:

1) impaired

2) improved

3) unaffected

What is taxonomy?

The identification, classification, and naming of organisms.

Who introduced the binomial naming system?

Carl Linnaeus.

What classification system did Whittaker propose, and what helped him group organisms?

The five-kingdom system. He grouped organisms partly by how they get nutrients—through absorption, ingestion, or photosynthesis.

1) What two parts make up an organism’s binomial scientific name?

2) Together what do they identify?

The genus name (first word) and the specific epithet (second word). Together, they identify the species.

How should a binomial scientific name be formatted when typed?

Capitalize the genus, lowercase the specific epithet, and italicize both words. Example: Staphylococcus epidermidis.

What are the five kingdoms in Whittaker’s classification system?

1) Monera

2) Protista

3) Fungi

4) Animalia

5) Plantae

Which organisms belong to Monera in the five-kingdom system, and how do they obtain nutrients?

Bacteria. Most absorb nutrients; some perform photosynthesis.

In the five-kingdom model used in class, which kingdom contains protozoa, and how do they get food?

Protista. Protozoa are described as animal-like and obtain food by ingestion.

In the five-kingdom model used in class, which kingdom includes algae, and how do they make food?

Protista; photosynthesis.

In the five-kingdom model used in class, which kingdom includes “lower fungi” and how do they obtain nutrients?

Protista; absorption.

How do organisms in kingdom Fungi obtain nutrients, and what are examples of this kingdom?

By absorption.

Examples include: molds, mildew, smuts, puffballs, and mushrooms.

How do animals (Animalia) and most plants (Plantae) get food?

Animals take in food by ingestion; most plants make food through photosynthesis.

What is absorption as a method of obtaining nutrients?

Taking up nutrients that are dissolved in water.

What is photosynthesis, and what role does chlorophyll play?

Photosynthesis uses light energy to make food. Chlorophyll is a pigment that absorbs light energy for the process.

What is ingestion?

Taking in food particles or other small pieces of material, called “particulate matter.”

What is the difference between bacterial morphology and bacterial arrangement?

Morphology describes an individual cell’s shape; arrangement describes how cells are grouped together.

What bacterial shape does coccus describe, and what is its plural?

Round or spherical (“berry-shaped”); the plural is cocci.

What bacterial shape does bacillus describe, and what is its plural?

Rod-shaped; the plural is bacilli.

What bacterial shape does spirillum describe, and what is its plural?

Spiral-shaped; the plural is spirilla.

What bacterial arrangement does staph- describe?

Clusters, like a bunch of grapes.

What bacterial arrangement does strep- describe?

Chains

What is a bacterial tetrad?

Four cocci arranged in a square

What does sarcinae describe in bacterial arrangements?

Packets of eight cocci arranged in a cube.

What bacterial arrangement does diplo- describe?

Pairs of cells.

What shape are Staphylococcus epidermidis cells, and how are they grouped?

Round cells (cocci) in clusters

What shape are Streptococcus pyogenes cells, and how are they grouped?

Round cells (cocci) in chains.

What cell shape does Bacillus subtilis have?

Rod-shaped cells

What does rRNA stand for, and what does it help form?

Ribosomal RNA. It combines with proteins to form ribosomes.

What is the main job of a ribosome?

To make proteins.

Why are rRNA sequences compared when classifying organisms?

Their similarities and differences help reveal evolutionary relationships and distinguish major groups, including domains.

What are the three domains of cellular life?

Bacteria (eubacteria)

Archaea (archaebacteria)

Eukarya (eukaryotes).

Which classification category is broader: a domain or a kingdom?

A domain is broader than a kingdom

What does endosymbiotic theory explain about mitochondria and chloroplasts?

They originated from independently living bacteria that lived inside ancestral host cells and eventually became permanent parts of those cells

How do protozoa and algae compare in cell type and number of cells?

Protozoa are animal-like, unicellular eukaryotes.

Algae are plant-like eukaryotes that can be unicellular or multicellular

How do active protozoa and typical algae differ in: chlorophyll and rigid cell walls?

Active protozoa generally lack both chlorophyll and a rigid cell wall.

Typical algae have both

Where are protozoa and algae commonly found?

Protozoa: water and moist soil.

Algae: mainly water-based environments.

What does it mean that most protozoa are motile?

They can move themselves

How does Paramecium use its cilia?

For movement and feeding: the cilia help move the cell and sweep food toward its feeding opening.

What are pseudopods, and how does an amoeba use them?

Temporary extensions of cytoplasm, also called false feet.

An amoeba uses them to creep along surfaces and surround food for ingestion

What is cytoplasmic streaming in an amoeba and what does it help do?

The flow of cytoplasm inside the cell, helping extend pseudopods and move the cell.

What is endocytosis?

The cell membrane surrounds material and brings it into the cell.

What is a protozoan cyst, and why is it useful?

A protective, less active stage enclosed by a resistant wall. It helps the organism survive unfavorable conditions and transfer to another environment or host.

What does it mean that many protozoa have complex life cycles?

The same organism passes through several different stages or forms, which may include an active form and a protective cyst form.

What does the term sporozoan refer to?

A member of a group of parasitic protozoa.

Are algae always microscopic?

No. Algae include microscopic forms and macroscopic forms that are visible without a microscope.

How are substances from algae used in foods such as ice cream and custards?

As thickeners and emulsifiers: making mixtures thicker and helping ingredients such as fat and water stay mixed.

What is a polysaccharide?

A carbohydrate made of many sugar units linked together.

What is agar, and where does it come from?

A gel-forming material made of polysaccharides, obtained from certain algae.

Why are some algae-derived compounds studied for possible use in anti-inflammatory medicines?

Some compounds, including certain polysaccharides, have shown inflammation-reducing effects in laboratory studies.

What are culture media, and what kind of medium is nutrient broth?

Culture media are nutrient-containing materials used to grow microorganisms in a laboratory. Nutrient broth is a liquid culture medium.

Why add agar to a culture medium if microbes can already grow in nutrient broth?

Agar makes a firm gel on which colonies—visible groups of microbes—can grow separately, making them easier to examine and isolate.

What can cloudiness, or turbidity, in nutrient broth suggest?

Microbial growth, such as bacterial multiplication. Many cells suspended in the broth can make it look cloudy.

What fluid is collected during a spinal tap, and what does it normally look like?

Cerebrospinal fluid (CSF), which surrounds the brain and spinal cord. It is normally clear.

What can cloudy cerebrospinal fluid suggest, and does clear fluid rule out meningitis?

Cloudiness can suggest infection or inflammation, including bacterial meningitis, often because of increased white blood cells. Appearance alone cannot confirm or rule out meningitis.

What is a nutrient agar slant?

Solid nutrient agar that hardens at an angle in a test tube, creating a slanted surface for bacterial growth.

What is a nutrient agar deep, and what can the location of bacterial growth show?

Agar that hardens upright in a test tube. Growth location can show oxygen preference because oxygen is highest at the top and decreases deeper down.

What are the main characteristics of fungi?

They are eukaryotic, lack chlorophyll, have a rigid cell wall, and obtain nutrients by absorption

How can fungi vary in number of cells and size?

They can be unicellular or multicellular and microscopic or macroscopic.

How does mold grow?

As microscopic, thread-like filaments.

What is one microscopic mold filament called?

hypha

What is the macroscopic mass formed by many hyphae called?

mycelium.

How does the color of mold change as it ages?

Young mold is white; as it ages, it develops its characteristic color.

What are three commercial uses of fungi listed in the notes?

Cheese, soy sauce, and penicillin

What fungus is associated with penicillin?

Penicillium notatum

What are fungal infections called, and what is noted about their treatment?

Mycoses; treatment is longer.

What yeast is listed as normal flora?

Candida albicans

Where is Candida albicans normally found?

On mucous membranes.

What is the difference between microbiota and microbiome?

Microbiota are the microorganisms living in an area

Microbiome is the broader microbial community and its genetic material.

What type of cells are yeast?

Unicellular eukaryotic cells

How does yeast multiply?

Through budding.

What type of infection can Candida albicans cause?

An opportunistic infection