General Biology II Test #1

Plant viruses spread disease by two major routes:

1. Horizontal transmission, entering through damaged cell walls 2. Vertical transmission, inheriting the virus from a parent

Three processes contribute to the emergence of new viral illnesses

1. RNA viruses have an unusually high rate of mutation 2. The disease can be disseminated from a small, isolated human population and can eventually spread around the world 3. About three-quarters of new human diseases originate by spreading to humans from animals

What three factors contribute to this genetic variation?

1. Rapid reproduction 2. Mutation 3. Genetic recombination

_______________________ kill sensitive bacteria, but not bacteria with specific R plasmids

Antibiotics

________________ require Co2 or related compounds as a carbon source

Autotrophs

_______________________________, also called phages, are viruses that infect bacteria. They have an elongated capsid head that _______ their DNA.

Bacteriophages, encloses

_______________________ obtain energy from chemicals

Chemotrophs

__________________________ is the process where genetic material is transferred between prokaryotic cells.

Conjugation

Viral genomes may consist of either double- or single-stranded _________ or __________.

DNA or RNA

Viruses are classified as _______ viruses or ________ viruses.

DNA or RNA

Cells without the F factor function as ___________ ________________ during conjugation

DNA recipients

There are two key variables used to classify viruses that infect animals An __________ or __________ genome, either single-stranded or double stranded The presence or absence of a ___________________ envelope,

DNA, RNA, membranous

The __________ virus is one of several emerging viruses that cause hemorrhagic fever, and often fatal illnesses.

Ebola

A piece of DNA called the _ ______________________ is required for the production of pili

F factor

Cells containing the _ ______________ function as DNA donors during conjugation

F plasmid

________________________ ___________________ can use O2 if it is present or carry out fermentation or anaerobic respiration if it is not

Facultative anaerobes

_________________ may be scattered about the surface or concentrated at one or both ends of the cell.

Flagella

______________________ are the most common structures used by prokaryotes for movement.

Flagella

Scientists use the _________________ __________________ to classify bacteria by cell wall composition.

Gram Stain

_________________________________ bacteria have less peptidoglycan and an outer membrane that contains lipopolysaccharides

Gram-negative (pink)

__________________________________________ bacteria have simpler walls with a large amount of peptidoglycan.

Gram-positive (purple)

Draw and label a Bacteriophage

Head, DNA, Tail sheath, and tail fiber

__________________ require an organic nutrient to make organic compounds

Heterotrophs

________________________ is essential for the production of amino acids and nucleic acids in all organisms

Nitrogen

___________________ ___________________ require O2 for cellular respiration

Obligate aerobes

____________ are the best understood of all viruses.

Phages

____________ obtain energy from light

Phototrophs

_____________(or sex pill) are longer than fimbriae and allow prokaryotes to exchange DNA.

Pili

______________ are infectious proteins that appear to cause degenerative brain diseases in animals.

Prions

____________________ have considerable genetic variation

Prokaryotes

________________________ were the first organisms to inhibit the earth

Prokaryotes

What type of cells have a variety of shapes.

Prokaryotic

_____ ________________ carry genes for antibiotic reasons

R plasmids

________________________ ______________________ _____________________ stunts growth of tobacco plants and gives their leaves a mosaic coloration. In the late 1800's researchers hypnotized that unusually small bacteria might be responsible.

Tobacco Mosaic Disease

_______________________________ is the movement of genes between bacteria by phages (from "bacteriophages," viruses that infect bacteria)

Transduction

In 1935, ____________ _______________ confirmed that later hypothesis by crystalizing the infectious particle, now known as tobacco mosaic virus.

Wendall Stanley

Other examples include the Chikungunya virus and the recently emerging ________ virus.

Zika

Provided some of the F plasmid's DNA is transferred, the recipient cell becomes _ _______________ ____________________.

a recombinant cell

Obligate anaerobes are poisoned by O2 and live by fermentation or use substances other than O2 for __________________ _________________.

anaerobic respiration

Viral infections cannot be treated by __________________.

antibiotics

Emerging viruses are those that suddenly become ______________.

apparent

Viruses _______ ______ cells

are not

Prokaryotes reproduce _________________________; offspring cells are generally identical. *For example, Escherichia coli cells reproduce using _______________ __________________.

asexually, binary fission

A ___________ is the protein shell than encloses the viral genome.

capsid

A sticky outer layer of polysaccharides or protein called a _________________ is present in some prokaryotes.

capsule

The ________________ allows adherence to the substrate, or other individuals, and can shield pathogenic bacteria from the host immune system

capsule

The cell wall maintains ________________ _______________, protects the cell, and prevents it from bursting in a hypotonic environment

cell shape

Eukaryote cell walls are made of cellulose or ___________.

chitin

The viral DNA molecule is incorporated into the host cell's ______________________.

chromosome

Most of the genome consits of a _____________ chromosome

circular

The F factor is transferable during _______________________.

conjugation

Every time the host divides, it ____________ ____________ ______________ DNA and passes the copies to daughter cells.

copies the phage

Later work suggested that the infectious agent _________ _____________ ___________ ____________ with bacteria

did not share features

The flagella pr prokaryotes and eukaryotes ______________ in structure, mechanism of propulsion, and molecular composition

differ

Some viruses cause infected cells to produce toxins that lead to ____________ systems.

disease

Many prokaryotes form metabolically inactive ________________________ which can remain viable in harsh conditions for centuries

endospores

Prokaryotes can be categorized by how they obtain ______________ and _____________.

energy, carbon

Where as few bacteriophages have an ________________ or an __________________ genome, many animals viruses have both,

envelope, RNA

Some prokaryotes have hairlike appendages called _________________ that allow them to stick to their substrate or other individuals in a colony

fimbriae

Rapid reproduction, mutation, and genetic recombination promote ______________ ________________ in prokaryotes.

genetic diversity

Viruses may damage or kill cells by causing the release of ____________ enzymes from ________________.

hydrolytic, lysosomes

Prions are _______________________ ____________________ _____________________, can be transmitted in food, act slowly, and are virtually indestructible.

incorrectly folded proteins

Prokaryotic cells usually ______________ complex compartmentalization

lack

The Prokaryotic genome has ______ ________ than the eukaryotic genome

less DNA

The genome is either a single ____________ or circular ____________ molecule of the nucleic acid

linear, circular

The _______________ _______________ replicates the phage genome without destroying the host.

lysogenic cycle

The __________ __________ is a phage replicative cycle that culminated the death of the host cell.

lytic cycle

Phages have two alternative reproductive mechanisms: the ___________ __________ and the ____________ ____________.

lytic cycle and the lysogenic cycle

An environmental signal can trigger the virus genome to exit the bacterial chromosome and switch to the __________ __________.

lytic mode

Scrapie in sheep, __________ ___________ _________, and Creutzfeldt-Jakob disease in humans are all caused by prions.

mad cow disease

Prokaryotic _________________ varies with respect to O2

metabolism

Through ________________ ________________ the fraction of bacteria with genes for resistance increases in a population exposed to antibiotic.

natural selection

Prokaryotes can metabolize ________________ in a variety of ways

nitrogen

For example, some prokaryotes convert atmospheric nitrogen (N2) to amonia (NH3) in a process called _______________ ________________.

nitrogen fixation

A virus is a very small infectious particle consisting of ___________ __________ enclosed in a protein coat and, in some cases, a membranous envelope.

nucleic acid

The chromosome is not contained in a nucleus; it is located in the ___________ region with no surrounding membrane.

nucleoid

In bacteria, the DNA transfer is always ___________ way

one

Archaea contain polysaccharides and proteins but lack ____________________.

peptidoglycan

Most bacterial cell walls contain __________________________(a network of sugar polymers cross-linked by polypeptides)

peptidoglycan

Many antibiotics target _______________________ and damage bacterial _____ ______. Gram-positive bacteria are particularly susceptible to this kind of antibiotic.

peptidoglycan, cell walls

A donor cell attaches to a recipient by a __________, pulls it closer, and transfers DNA through a structure called the "mating bridge"

pilus

Typical prokaryotes also have smaller rings of independently replicating DNA called ______________.

plasmids

The lytic cycle produces new phages and lyses (break open) the hosts cells wall, releasing the ____________ viruses.

progeny

The integrated viral DNA is known as _____________________.

prophage

A __________________ __________________ piece attaches the phage to the host and injects the phage DNA inside.

protein tail

Mutation rates are low, but mutations accumulate __________________ because generation times are short and populations are large

rapidly

Viruses cannot ________________________ or carry out metabolism outside of a host cell.

reproduce

Viruses are much ____________________ in structure than even prokaryotic cells

simpler

What are the three most common types of Prokaryotic cells?

spheres (cocci), rods (bacilli), and spirals

About half of all prokaryotes exhibit ___________, the ability to move toward or away from a stimulus *for example, __________________ is the movement toward or away from a chemical stimulus

taxis, Chemotaxis

Phages that use both the lytic and lysogenic cycles are called ______________ _________________.

temperature phages

What is Genetic recombination?

the combining of DNA from two sources, contributes to diversity

Others have molecular components such as envelope proteins that are ___________.

toxic

A prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment in a process called ___________________________.

transformation

Prokaryotic DNA from different individuals can be brought together by __________________________, _________________________, and ______________________.

transformation, transduction, conjugation

Most Prokaryotes are _______________________, although some species are from colonies

unicellular

A ______________ is a harmless derivatives of pathogenic microbes that stimulate the immune system to mount defense against the harmful pathogen.

vaccine

Vaccines can prevent certain _____________ illnesses.

viral

A phage that reproduces only by the lytic cycle is called a _____________ ___________.

virulent phage

A ______________________ is an infectious particle consisting of genes packaged in a protein coat.

virus