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MCAT Biology Review 3
Microbiology
47
Biology
Not Applicable
07/19/2011

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Term
Capsid
Definition

The protein coat of a virus that contains several hundred genes in the form of DNA or RNA.

Contains the nucleic acid.

Term
receptor
Definition
A specific glycoprotein on the host cell membrane that a virus adsorbs to begin infection.
Term
Lytic infection
Definition

The virus commandeers the cell's reproductive amchinery and begins reproducing new viruses.

 

The cell may fill with viruses until it lyses or bursts, or it can release the virus one at a time through reverse endocytotic processes.

 

A virus that follows this is a virulent virus.

Term
Latent Period
Definition
The period from the infection to the lysis.
Term
Lysogenic infection
Definition

The viral DNA is incorporated into the host genome, or if it is an RNA virus and possesses reverse transcriptase, DNA is actually reverse-transcribed from RNA and then incorporated into the host cell genome.

These are temperate viruses.

Term
Provirus
Definition
A virus that maitains its DNA incorporated into the DNA of a host cell.
Term
Plus-strand RNA
Definition

The protein can be directly translated from the RNA.

Include retroviruses that carries reverse transcriptase to create DNA from RNA.

 

The DNA is incorporated into the genome of the host cell.

Term
Minus-strand RNA
Definition
These viruses are the compliment to mRNA and must be transcribed to plus-RNA before being translated.
Term
Prokaryotes
Definition

Do not have membrane bound organelles/nucleus.

Split into Archaea and Bacteria.

Term
Archaea
Definition
Prokaryotes that have as much in common with bacteria as they do with eukaryotes.
Term
Autotrophs
Definition
Capable of using CO2 as their sole source of carbon. Create their own food.
Term
Heterotrophs
Definition
Use preformed, organic molecules as their source for carbon.
Term
Phototrophs
Definition
Use light as their energy source
Term
Chemotrophs
Definition
Use the oxidation of organic or inorganic matter as their energy source.
Term
Cocci bacteria
Definition
Round
Term
Bacilli
Definition
Rod Shaped
Term
Spirilla Bacteria
Definition
Rigidly shaped helical bacteria
Term
Spirochetes
Definition
Term
Spirilla
Definition
Non-rigid helical bateria.
Term
Phospholipid
Definition

Composed of a phosphate group, two fatty acid chains, and a glycerol backbone.

 

Phosphate is polar, fatty acids are nonpolar.

Term
Integral Proteins (Intrinsic Proteins)
Definition
Amphipathic proteins that traverse the membrane from the inside of a cell to the outside.
Term
Peripheral (Extrinsic) Proteins
Definition
Situated entired on the surfaces of the membrane. The are ionically bonded to integral proteins or the polar group of a lipid.
Term
Chemical Concentration Gradient
Definition
A gradual change in concentration of a compound over a distance.
Term
Factors that affect semipermeability
Definition
Size and polarity.
Term
Passive Diffusion
Definition
The diffusion where molecules move through leakage channels across the membrane due to random motion.
Term
Transport/Carrier Proteins
Definition
Designed to facilitate the diffusion of specific molecules across a membrane.
Term
Faciliated Diffusion
Definition

Diffusion that occurs down the electro-chemical gradient of all species involved.

 

Ex: glucose supply in human cells.

 

Makes membranes selectively permeable: can select between molecules of similar size and charge.

Term
Active transport
Definition

Moving compounds against the electro-chemical gradient.

Requires the expenditure of energy.

Term

Bacteria are (hypertonic/hypotonic) to their environment?

 

Definition

Hypertonic.

There are more particles in their cytosol than in the aqueous solution surrounding them.

Term
Hypertonic
Definition
More particles in the cytosol of the cell than in the aqueous solution surrounding it.
Term
Isotonic
Definition

Equal particles in the cytosol of the cell compared to the aqueous solution surrounding it.

Term
Hypotonic
Definition

Less particles in the cytosol of the cell than in the aqueous solution surrounding it.

Term
Peptidoglycan
Definition

A series of disaccharide polymer chains with amino acids, three of which are not found in proteins.

 

Makes up the cell wall.

 

Porous, so it allows large molecules to pass through.

Term
Gram staining
Definition

Used to prepare bacteria for viewing under a microscope.

 

Stains gram positive (purple) and negative (pink) differently.

 

Term
Gram-positive Bacteria
Definition
Thick peptidoglycan wall that prevents stain from leaking out so it appears purple.
Term
Gram-negative Bacteria
Definition

Have a thing peptidoglycan wall that allows most stain to be washed off and appear pink.

Has a second plasma membrane outside the peptidoglycan wall composed of lipopolysaccharides.

Term
Bacterial Flagella
Definition

Long, hollow, rigid, helical cylinders made from globular protein called flagellin.

 

Not the same as eukaryotic flagella which are composed of microtubules.

Term
Modes of bacteria genetic recombination
Definition
Transduction, Transformation and Conjugation
Term
Binary Fission
Definition

A form of asexual reproduction that occurs in bacteria.

 

Term
Conjugation
Definition

Requires one bacteria to have a plasmid with the gene that codes for a sex pilus (conjugative plasmid).

 

Term
Plasmid
Definition
Small circles of DNA that exist and replicated independantly of the bacterial chromosome.
Term
F plasmid
Definition

fertility factor.

 

With the factor is F+

Without is F-

Term
Transformation 
Definition

The process by which bacteria may incorporate DNA from their external environment into their genome.

 

DNA aquired directly from the medium.

Term
Transduction
Definition

When the capsid of bacteriophage mistakenly encapsulate a DNA frag of a host cell and then these virions infect the new bacterium injecting harmless bacterial DNA frags in stead of virulent viral DNA fragments.

 

Transfer of DNA via a virus.

Term
Saprophytic
Definition
Can live off dead organic matter
Term
Septa
Definition
Cell wall of a fungi composed of the polysaccharide chitin
Term
Fungi
Definition

Eukaryotic heterotrophs that spend most of their livess in the haploid state.

 

They can reproduce sexually and asexually.

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