lecture 1 part 1 Flashcards
do all pathogenic microbes kill the host cell?
NO — some hang out in the cell and secrete viruses in the quiescent state. others do kill the cell
since the invention of ____, scientists have studied microorganisms
microscopic lenses (1600s)
the turn of the ____ century bright about the advent of antibiotics (antibacterial agents)
20th century
why did it take much longer to develop antivirals over antibiotics?
viruses infect human cells. we had to find a way to target virally infected cells ONLY and not every human cell
in the early days of the 21st century, microbiology has entered the ____ age (___&____)
GENETIC
(genomics and proteomics)
____ outbreak stimulated the development of antivirals
AIDS
is AIDS fatal nowadays?
NO — it’s a chronic disease. therefore, it’s a big money maker. HIV drugs will continue being produced
which are larger — viruses or bacteria?
bacteria
rank the classes of microorganisms based on size
smallest: viruses (0.03-0.3 micrometers)
bacteria (0.1-10 micrometers)
protozoa and fungi: 4-10 micrometers
can viruses be seen with a light microscope? what about electron?
some viruses can be seen with a light microscope. viruses can be seen with an electron microscope
what are the 2 types of viruses
naked virus and enveloped virus
are viruses cells?
NO
explain the structure of a NAKED virus
a nucleic acid enclosed in a protein coat CAPSID
explain the structure of an ENVELOPED virus
like a naked virus, it is a nucleic acid surrounded by a CAPSID (protein coat). however, an enveloped virus also has an ENVELOPE (phospholipid membrane derived from host) with VIRAL SPIKE PROTEINS stuffed around the envelope
the more faces on a geometric shape, the more ___ it is
circular
do prokaryotes have a nucleus?
no distinct nucleus. have a single circular chromosome with no membrane. called a NUCLEOID
do prokaryotes and eukaryotes have extra chromosomal DNA?
prokaryotes have extrachromosomal DNA in the form of PLASMIDS in the cytoplasm
eukaryotes have extrachromosomal DNA in organelles
do prokaryotes have organelles suspended in the cytoplasm?
no-none
differentiate between the cytoplasmic membrane of prokaryotes and eukaryotes
prokaryotes — more complex. contains the enzymes for replication, and the site of phospholipid and DNA synthesis
eukaryotes- semipermeable layer. doesn’t possess the functions of prokaryotic membrane
differentiate between the cells walls or prokaryotes and eukaryotes
prokaryotes have a rigid layer or peptidoglycan.
eukaryotic cells do not
are sterols found in prokaryotes and eukaryotes?
usually present in eukaryotes, absent in prokaryotes
differentiate between the ribosomes of prokaryotes and eukaryotes
prokaryotes —- 70s in cytoplasm
eukaryotes — 80s in cytoplasmic reticulum
what is the function of sterols in the cell
gives rigidity
are bacteria prokaryotes or eukaryotes ?
prokaryotes
all respiratory work and DNA replication is done where in bacteria?
the plasma membrane
describe the structure of a bacterium
outer to inner: capsule, cell wall, plasma membrane
capsule has fimbriae.
inside cytoplasm = ribosomes (70s), nucleoid, inclusion bodies, and chromosomes (DNA)
has flagellum for movement
a fungal cell is also known as a ___ cell
yeast
is a fungal cell prokaryotic or eukaryotic?
eukaryotic
true or false—
yeast cells and protozoan cells are unicellular, eukaryotic organisms
true
true or false
yeast cells and protozoan cells lack a proper nucleus and nucleolus
FALSE
they are eukaryotic. they have a defined nucleus and nucleolus
is food poisoning as a source of infection an example of direct or indirect
indirect
is breathing in someone else’s cough as a source of infection an example of direct or indirect contact
direct
getting bit by a mosquito as a source of infection
is this direct or indirect contact
indirect
what is HORIZONTAL vs VERTICAL transmission?
vertical - from mother to offspring
horizontal — individuals of same generation
name 5 classes of microorganisms
micro biome (normal flora)
commensal (resident, symbiotic, core microbiome)
transient colonization (transients, secondary microbiome)
opportunistic
pathogenic
name 3 benefits of commensal microorganisms
process digested food
provide essential vitamins/growth factors
protect against invasion of pathogens
true or false
the commensal population remains constant throughout life
FALSE
in a constant state of flux depending on age, diet, health
change in response to illness or treatment with antibiotics
what is the term for an imbalance in the gut microbial community due to disease ?
dysbiosis
define virulence
virulence are circumstances that allow a microorganism to achieve infection and cause disease with varying degrees of severity
true or false
both bacteria and viruses can be virulent
true (don’t be deceived by the word)
name 5 factors that affect VIRULENCE (severity of the disease)
-gaining access to the body
-avoiding multiple host defenses
-colonization of the host
-parasiting (hijacking) host resources
-inducing toxicity and damage
name 6 influences on our microbiome
-host physiology
-environment
-immune system
-host genotype
-lifestyle
-pathobiology
you listed host physiology as an influence on the microbiome.
explain what this means
the host’s
age
gender
site
you listed immune system as an influence on the microbiome
explain
previous exposure
inflammation
explain how lifestyle is an influence on the microbiome
occupation
hygiene
explain how the host genotype is an influence on the microbiome
susceptibility genes such as lack of filaggrin
filaggrin keeps the skin moist. without, it is very dry and more subject to infection
explain how pathobiology is an influence on the microbiome
underlying conditions such as diabetes
what was the human microbiome project?
an effort to sample and analyze the genome of microbes from five sites on the human body:
-skin
-nose
-oral cavity
-GI tract
-urogenital tract
true or false
we do not have microbiota in the blood and tissues
true
do bacteria have to enter the host cell to do damage?
NO.
some bacteria bind to receptors and inject cytokines that either damage the cell or kill it
can bacteria get into the bloodstream?
yes
do all viruses kill the cells they infect?
no. they can cohabitate and release more and more viruses and get more virally infected cells
are all viruses completely dependent on the host cell?
no
host proteins + they need to bring in their own proteins
but they do all some components of the host machinery
are ALL viruses intracellular pathogens?
yes
ALL viruses are __ __ based
nucleic acid
all viruses replicate by…
assembly of components
all viruses are composed of what 3 things?
the viral genome
a protective coat
associated enzymes and proteins
do all viruses contain structural proteins?
do all viruses contain enzymes and nucleic acid building proteins?
yes — all contain structural proteins
not all have enzymes and nucleic acid-building proteins
differentiate between a naked virus and an enveloped virus
naked virus = DNA or RNA, structural proteins, (only in some cases, enzymes and nucleic acid building proteins) to form a CAPSID
an enveloped virus is the CAPSID but surrounded by glycoproteins (spikes that are vitally encoded proteins) and an envelope that is usually derived from the host’s membrane
true or false
DNA and RNA viruses are vastly different in size
FALSE — they are comparable
give the size of bacteria relative to an organelle
bacteria are around half the size of a mitochondria
explain how the nucleic acid of a virus can be very variable
can be:
DNA or RNA
single or double stranded
linear or circular
continuous or segmented genome
explain how the outer layer of a virus can be very variable
capsid can take on many shapes
envelope
VAPs (viral atttachment proteins; spike proteins)
the ___ surrounds the ____
the ENVELOPE surrounds the CAPSID
name 5 shapes of a capsid
spherical
icosahedral
filamentous
brick shape
bullet shape
explain the structure of an icosahedral virus
12 sided
has vertices (endpoints) where spike proteins attach
name the 4 types of RNA viruses
+RNA
-RNA
+/- RNA (double stranded)
+RNA via DNA (RETROVIRUS)
is +RNA naked or enveloped?
can be either
is -RNA naked or enveloped?
enveloped ONLY
explain the structure of +/- RNA viruses
double capsid (double protein coat)
are retroviruses enveloped or naked?
enveloped ONLY
explain how retroviruses replicate
single strand RNA replicates via a DNA intermediate
what is the Reovirus?
+/- RNA has 10 ds (double strand) linear segments
double capsid
for the most part, viruses are (single stranded or double stranded?) (linear or circular?)
single strand linear
retroviruses are also known as…
RNA tumor viruses
