Microbiology Exam 3
What are biofims?
A biofilm is an aggregate of microorganisms in which cells adhere to each other on a surface. Encased community of bacteria
What does DNA stand for?
deoxyribonucleic acid
What are prions?
misfolded versions of normal protein (infectious protein) that can cause disease ex. mad cow disease
What do viroids infect?
plants only
What type of virus is the HIV virus?
retrovirus
Define transformation
competent bacterial cells can bind and import DNA from their surroundings ex. streptococcus, bacillus
Define retrovirus
viruses that have RNA instead of DNA
Viral genomes: list the types
1. DNA to RNA 2. RNA to RNA 3. RNA to DNA 4. RNA to DNA to RNA
What are the steps of pathogenesis?
1. entry (via portal) 2. tissue attachment and colonization 3. immune avoidance 4. host damage 5. pathogen exit (via portal)
What is a pathogenicity island?
A genomic island that contains virulence factors
What is a bacteriophage?
A virus that infects bacteria
How do bacteria stick to surfaces?
Adhesin (any microbial factor that promotes attachment) Types of adhesins: pili and nonpilus adhesins
What type(s) of nucleic acids can virsues have?
All viruses either contain DNA or RNA but not both.
What does the field of bioinformatics study?
Allow scientists to make predictions about function for a set of genes and then test those predictions experimentally
What computer programs have been used to study genomes?
BLAST (Basic Local Alignment Search Tool) and National Microbial Pathogen Data Resource
What is the hygiene hypothesis?
Childhood exposure to germs and certain infections helps the immune system develop
How do natural selection evolve?
Chooses which mutation will become established in a genome. Selective pressure (survival of the fittest)
Why are new vaccines made for influenza each year?
Continually generate new strains requiring repeated immunizations
What is the central dogma (information flow)?
DNA--> RNA--> Protein
What are genes?
Genes are sections of DNA that control a single genetic trait.
Name some non-enveloped virsues that are human pathogens
HPV, common cold, polio
What are viral envelops made up of?
Host cell membranes (phospholipids and proteins) but some include glycoproteins
Name and draw 3 virus structures (they are determined by the capsid structure)
Icosahedral, filamentous, complex tailed or amorphous.... INCLUDE PICTURES
Name some enveloped viruses that are human pathogens
Influenza virus, Hepatitis C and HIV
Define conjugation
Involves cell to cell contact. DNA donor cells produce a protein tube called a conjugation (sex) pilus.
Can prokaryotes perfrom meiosis?
No
What is an obligate intracellular parasite?
Parasites that cannot reproduce outside their host cell, so they can require host cells to reproduce and complete their life cycles. -Chlamydia, Rickettsia, viruses
What are probiotics?
Probiotics are live bacteria. These are 'good bacteria' and are similar to those in the gut. Probiotics are added to foods such a yogurt. It's thought they may help keep your digestive system healthier by replacing gut bacteria that are lost during antibiotic treatment.
How do mutations evolve?
Random changes in the nucelotide sequence of a gene. Outside influence.
What are plasmids?
Small, circular, extrachromosomal DNA molecules found in bacteria
Name all possible componets of a virus (4)
Small, infectious particles Nonliving Transmissible Destroy cells
RNA viruses - their replication is more complicated because the host cells don't have the enzymes needed to use their genome.
Statement
What is HIV targets cell?
T cells
The host range of viruses is narrow- what does this mean? Why are they so specific?
The group of cells that a virus can infect is slim
What is taxonomy?
The scientific study of how living things are classified
Define genome
The whole of the genetic information of an organism
How do viruses replicate?
They use a host cell (lytic and lysogenic cycles)
What are ways in which pili are used?
Type I: static, hairlike appendages used only for attachment (velcro for attachment) Type II: dynamic, thin, and flexible for "twitching motility" (like a grappling hook)
Define transduction
Virus mediated DNA transfer
How does virus size compare to bacterial size?
Viruses are smaller than bacterial size.
Can viruses infect cells of all kingdoms?
Yes
Define recombination
a combination of genes different from either parent.
Define nucelotide
a compound consisting of a nucleoside linked to a phosphate group
What are viroids?
small rings of naked RNA without capsid, that only infect plants
What is a provirus?
viral DNA that is integrated into the host cell's chromosome
What is an enveloped virus?
virus that contains additional layers around the nucleocapsid
What is a naked virus?
virus without an envelope
How are animal viruses grown in the lab?
•Immortalized cell •Ex. Cancer cells •HeLa (Henrietta Lacks) •Inoculated with virus suspension •Viruses adhere to cells. •Culture fluid is removed. •Fluid is replaced by a gelatin medium that retards the dispersal of viruses from infected cells. •When host cells die, plaques are observed.
