lecture exam 2 Flashcards
- obligate intracellular parasite
- nonliving and is not made of cells
virus
only purpose of a virus is to _____
replicate
where can viruses only function?
inside a living cell
- not cellular
- can only replicate inside of a host cell
- no ATP generating system
- no ribosomes
- contain only one nucleic acid
- no metabolism
why are viruses not living?
A virus that infects bacteria
Bacteriophage
viruses are diverse in ___ and ___
size / morphology
does size correlate to severity of a virus?
no
what are viruses made of?
- protein coat (capsid)
- nucleic acid
- made of capsomeres
- protects the nucleic acid
- responsible for the shape
capsid protein coat
all viruses have ____ ___ and one ___ ___
some viruses have an ____
protein coats / nucleic acid;
envelope
viruses whose capsids are not covered by an envelope
nonenveloped viruses
virus that contains additional layers around the nucleocapsid
enveloped virus
- Animal Viruses
- Plant Viruses
- Bacterial Viruses (Bacteriophages or Phages)
Virus Specificity
the formation of biological viruses during the infection process in the target host cells
Viral Replication
with a virus, the ____ ____ ____ causes damage and symptoms not the virus
immune system’s response
1) ATTACHMENT
2) PENETRATION
3) UNCOATING
4) BIOSYNTHESIS
5) late translation
6) MATURATION
7) RELEASE
steps of viral replication
in an enveloped virus, the envelope fuses with ___ ___ of the cell membrane of the host cell
lipid bilayer
what is the purpose of a virus?
to replicate more viruses
viruses release from the host cells by ____
budding
T4 bacteriophage is a very ____ virus and only infects ____
complex / E. coli B
- animal cell has entire nucleic acid and coat in cell / bacteriophage only has a nucleic acid injected into a host cell
- animal cell lysis may survive or die / bacteriophage always lyse and die
what are the 2 differences in bacteriophage viruses and animal cell viruses?
a state in which phage DNA is incorporated into the host cell without lysis
Lysogeny
the lytic cycle is ___
the lysogenic cycle is ___
common / rare
process in which a virus enters a cell, makes a copy of itself, and causes the cell to burst
lytic cycle
a viral reproductive cycle in which the viral DNA is added to the host cell’s DNA and is copied along with the host cell’s DNA
lysogenic cycle
when a bacterium acquires a new trait from its temperate phage
lysogenic conversion
bacteria that release _____, _____, and ____ must be lysogenized in order to be able to produce the toxins
botulinum toxin / scarlet fever toxin / diphtheria toxin
in general, viruses do not produce _____
toxins
what is an oncogenic virus?
cancer-causing virus in animals
how do we control viral infections?
- vaccines
- antivirals
- masks
small circular RNA molecules that infect plants and disrupt their growth
naked RNA
Viroids
potato spindle tuber disease
disease caused by viroids
infectious proteins
Prions
What does prion stand for?
proteinaceous infectious particle
how are prion diseases usually contracted?
eating prions in your diet
there are no treatment or cures for _____ diseases
prion
scrapie
Kuru
Chronic Wasting Disease
Mad Cow Disease
Creutzfeldt-Jakob disease
prion diseases
prion disease in sheep
Scrapie
Prion disease that infects humans (cannibalism - common in Papa New Guinea)
Kuru
prion disease in elk and deer
Chronic Wasting Disease
prion diseases in cattle
- cow brain (feeding cows w/ scrapie)
mad cow disease (bovine spongiform encephalopathy)
prion disease in humans (human variant of mad cow disease)
Creutzfeldt-Jakob disease
prions cause proteins to _____
misfold into infectious forms
Catalysts for chemical reactions in living things
Enzymes
all enzymes are ____ but not all ____ are enzymes
proteins
enzymes catalyze ____ reactions ONLY
sponataneous
A reaction that will proceed without any outside energy (proceed on its own)
spontaneous reaction
the region of an enzyme that attaches to a substrate
Active site of an enzyme
A temporary complex formed when an enzyme binds to its substrate molecule(s).
enzyme-substrate complex
nonprotein enzyme helpers required by some enzymes for activity
Cofactors
organic cofactor
- ex: vitamin B
coenzyme
the enzymatic activity increases with ____ temperature until the enzyme is ___ by heat and inactivated
increasing / denatured
optimal pH for enzymes
pH between 6 and 8
with increasing substrate concentration, the rate of the reaction ___ until the active sites on all enzymes are filled
increases
after an enzyme is denatured, can it become active again?
no
energy currency of the cell
ATP
PEP (phosphoenolpyruvate) has ____ the amount of energy of ATP
twice
why is PEP (molecule in gylcolisis) not the energy currency of ATP?
it costs too much energy to make
- carbon source (amino acids, CO2)
- nitrogen source (amino acids, NH4, N2)
- certain inorganic ions (MG2+, PO4 -3)
- essential metabolites (vitamins)
- water
nutrients that is required by the cell to produce
what bacteria can make every vitamin and nutrients that it needs to function?
E. coli
why is oxygen not a nutrient?
it is not broken down for energy or used in biosynthesis
what is the only reason our body needs oxygen?
as a final electron acceptor in metabolism
converting atmospheric molecular nitrogen into organic nitrogen compounds which can be used by many organisms
nitrogen fixation
is a protein a nutrient for a cell?
no they are too big to get into cells
proteins get nutrients from their breakdown products called
amino acids
how do we measure growth of microorganisms?
measure increase in numbers (exponential growth)
bacteria reproduces by ___ ___
binary fission
- temperature
- pH
- oxygen
conditions for growth
when bacteria are in low temperatures, they grow ____
slowly or not at all
when bacteria are in high temperatures, proteins _____
denature
Aerobic
requires oxygen
Anaerobic
requires lack of oxygen
grow in the presence or absence of oxygen
facultative anaerobes
in the presence of oxygen, all organisms produce ____ which is deadly
superoxide
aerobe organisms produce ___ ___ to get rid of superoxide (O2-)
superoxide dismutase
Counting the number of cells while looking through a microscope
direct microscopic count
what is a disadvantage to using direct microscopic count?
you count all cells including dead ones