The cell Flashcards
what is spontaneous generation
the idea that life arose from non-living matter
who propose spontaneous generation
aristotle
who was the first to refute spontaneous generation
Francesco redi
what did red predict
that preventing flys from having contact with meat would prevent maggots
Who official disproved spontaneous generation
Louis pasteur
how was Pasteurs experiments different from others
the swan necks allowed outside air in but would trap any microorganisms
what are the tenants of modern cell theory
all cells only come from other cells
cells are the fundamental units of organisms
who was the first to observe nuclei
Robert brown
who was the first to describe chloroplasts and their role in starch formation
Andreas Schimper
what did kontantin mereschkowski suggest
chloroplasts may have originated from ancestral photosynthetic bacteria living symbiotically inside a eukaryotic cell, a similar hypothesis for the nucleus
what is endosymbiotic theory
the theory that mitochondria and chloroplasts arose as a result of prokaryotic cells establishing a symbiotic relationship within a eukaryotic host
what is the first event of endosymbiotic theory
ancestral eukaryote consumed aerobic bacteria that evolved into mitochondria
what is the second
early eukaryote consumed photosynthetic bacteria that evolved into chloroplasts
What is the miasma theory proposed by the greeks
disease originated from particles emanating from decomposing matter such as that in sewage or cesspits
what is germ theory of disease
diseases may result from microbial infection
who noticed mothers who gave birth to doctors and medical students had a higher death rate
Ignaz semmelweis
What did John snow track
cholera outbreaks in London to two specific water sources contaminated by sewage. the first epidemiological study
who instead on hand washing and clean areas for surgery
Joseph lister
what are Koch’s postulates based on
the idea that the cause of a specific disease could be attributed to a specific microbe “one microbe, one disease”
what does cell theory state
the cell is the fundamental unit of life
what is cytoplasm
a gel-like substance composed of water and dissolved chemicals needed for growth
where is cytoplasm found
within the plasma membrane (cell membrane)
what structures are in all cells
cytoplasm
one or more chromosomes
ribosomes
Cytosol
what are ribosomes
organelles used for the production of proteins
what characteristics of prokaryotic cells
they lack a nucleus and generally have a single circular chromosome in a nucleoid
what defines eukaryotic cells
have a nucleus surrounded by a complex nuclear membrane with multiple rod shaped chromosomes with membrane bound organelles
what is coccus
round prokaryotic cell
what is bacillus
rod shaped prokaryote
what is vibrio
curved rod
what is coccobacillus
short rod
what is spirillum
spiral
what is spirochete
long, loose, helical spiral
coccus arrangment
single coccus
diplococcus arrangement
pair of two cocci
what is a tetrad
grouping of four cells in a square
what is streptococcus
chain of cocci
what is staphylococcus
cluster of cocci
what is bacillus
single rod
what is diplobacillus
pair of rods
what is streptobacillus
chain of rods
what is palisade
v or l shaped formation of rods
what maintains morphology of prokaryotic cells
cell wall with cytoskeletal elements
what does the cell wall do
envelopes the cell membrane and protects from osmotic pressure changes
what causes osmotic pressure
differences in the concentration of solutes on opposing sides of a semipermeable membrane
what causes osmotic pressure
differences in the concentration of solutes on opposing sides of a semipermeable membrane
when does water pass a semipermeable membrane
when concentration of solutes is greater on one side of the membrane
what direction does water flow across the membrane
from the side with a lower concentration to a side with higher concentration of solutes until both sides are equal
what is an isotonic medium
when the solute concentrations inside and outside are equal
what is a hypertonic medium
when the solute concentration outside exceeds that inside the cell so water leaves the cell
what is a hypotonic medium
when the solutes on the inside of the cell are higher, so water goes in the cell.
what is tonicity
the degree to which a particular cell is able to withstand changes in osmotic pressure
what cells are better able to withstand changes in osmotic pressure
those with a cell wall
what happens to cells in a hypertonic environment without a cell wall
cells without a cell wall can become dehydrated causing crenation
what is crenation
shriveling of the cell, the plasma membrane contracts and appears scalloped or notched
what happens to cells with a cell wall in a hypertonic environment
they undergo plasmolysis
what happens in plasmolysis
plasma membrane contracts and detaches from the cell wall and there is a decrease in interior volume but the cell wall is intact
what happens to cells without a cell wall in a hypotonic environment
they are more prone to lysis
what happens to cells with a cell wall in a hypotonic environment
the cell wall helps maintain shape for a longer time before lysing
describe typical prokaryotic chromosome
circular, haploid, and not bound by a nuclear membrane
where are prokaryotic DNA
within the nuclei region of the cell
what does prokaryotic dna interact with
nucleic associated proteins that assist in the organization and packaging of the chromosome
what do NAP’s function similar to
histones in eukaryotic cells
in archaea how is the nuclei organized
by either naps or histone like DNA organizing proteins
what is extrachromosomal DNA
DNA that is not part of the chromosome
what cells contain extrachromosomal DNA
prokaryotes
where is extrachromosomal DNA found
plasmids
what are plasmids
small, circular, double stranded DNA molecules
where are plasmids more commonly found
bacteria, but can also be found in archaea and eukaryotic organisms
what kind of genes can plasmids carry
advantageous traits such as abx resistance
what are ribosomes constructed from
proteins with ribosomal RNA
where are prokaryotic ribosomes found
cytoplasm
what ribosomes are found in prokaryotes
70s ribosomes
what size ribosomes are in eukaryotic cells
80s
how are bacteria and archaean ribosomes the same
they are the same size
how are bacterial and archaean ribosomes different
they have different proteins and rRNA molecules, archaean versions are more similar to eukaryotic cells
What are inclusions
cytoplasmic structures that store excess nutrients
why are nutrients stored in a polymerized form
because it reduces the buildup of osmotic pressure that occurs as a cell accumulates solutes
what do inclusions store
glycogen and starches that contain carbon that cell can access for energy
what are volition granules
inclusions that store polymerized inorganic phosphate that can be used in metabolisms and assist in the creation of biofims
what microbes contain volutin
archaea methanosarcina, bacterium corynebacterium diphtheria and unicellular eukaryotic alga chlamydomonas
where are sulfur granules found
sulfur bacteria of genus thiobacillus to store elemental sulfur for metabolism
what is polyhydroxybutyrate
a phospholipid monolayer embedded with protein in some inclusions
what species produce PHB
bacillus and pseudomonas
how is PHB used industrially
a source of biodegradable polymers for bioplastics
example of inclusion that serve a purpose other than nutrient storage
some produce gas vacuoles, accumulations of small protein lined vesicles of gas to allow prokaryptic cells that synthesize them to alter their buoyancy to adjust their location in the water column
what are magnetosomes
inclusions of magnetic iron oxide or iron sulfide surrounded by a lipid layer
what do magnetosomes allow
cells to align along a magnetic field adding in movement
what are carboxysome inclusions
composed outer shells of thousands of protein subunits for carbon metabolism
what are carboxysomes composed of
outer shells of thousands of carboxylase and carbonic anhydrase used for carbon metabolism
what are promo-organelles
structures that compartmentalize important compounds or chemical reactions
what are endospores
structures that essentially protect the bacterial genome in a dormant stated when environmental conditions are unfavorable, they allow some bacterial cells to survive long periods without food or water and exposure to, chemical, extreme temps or radiation
vegetative cells vs endosprores in extreme temps or radiation
vegetative are sensitive, endospores are resistant
vegetative cells vs endosprores gram-staining
vegetative are gram- positive
endospores are do not absorb gram stain
vegetative cells vs endosprores water content
vegetative cells have normal water and enzymatic activity endospores are dehydrated with no metabolic activity
vegetative cells vs endosprores growth and metabolism
vegetative cells are capable of growth and metabolism endosprores are not
what is sporulation
when vegetative cells transform into endospores
when does sporulation begin
when nutrients become depleted or environmental conditions become unfavorable
What are the steps of sporulation
- DNA replicates
- membranes form around DNA
- foreshore forms additional membranes
- protective cortex forms around the spore
- protein coat forms around the cortex
- spore is released
what is a forespore
forms the core of the endospore and is a copy of the cells chromosomes and is separated from the mother cell by a second membrane
how long can endospores stay dormant
thousands of years
what happens to endospores when living conditions are favorable
they go through germination and become metabolically active again
what are some significant endospore forming gram positive bacteria
B. anthracis
c. tetani
c. difficile
c. perfringens
c. botulinum
what is the cell envelope
structures that enclose the cytoplasm and internal structures
what is the fluid mosaic model
the ability of membrane components to move fluidly within the plane of the membrane as well as the mosaic like composition of components including a diverse array of lipid and protein components
what is the plasma membrane of most bacterial and eukaryotic cell types made of
bilayer composed of phospholipids formed with ester linkages and proteins that have the ability to move laterally within the plane of membranes as well as between two phospholipid layers
how are archaean membranes different from bacteria and eukaryotic membranes
archaean membrane phospholipids are formed with ether linkages, (I dont understand this)
Rachael phospholipids have branched chains instead of straight chains
some archaean plasma membranes are lipid monolayers
what are proteins on the cell surface important for
cell to cell communication
sensing environmental conditions and pathogenic virulence factors
what do membrane proteins and phospholipids have have
carbs and glycoproteins or glycolipids
what uses simple diffusion
molecules moving from a higher concentration to a lower concentration with the concentration gradient
what is facilitated diffusion
When charged molecules, and large molecules need the help of carriers or channels in the membrane
When does active transport occur
when cells move molecules across their membrane against concentration gradients
what is a major difference between passive and active transport
active transport requires ATP or other forms of energy
what happens I group translocation
a molecule moves into a cell against its concentration gradient, it is chemicallymodified so it does not require transport against an unfavorable concentration gradient
what is an example of group translocation
bacterial phosphotransferase system, which carriers phosphorylates glucose to other sugars upon entry into cells it is an energy neutral system
what do photosynthetic prokaryotes have
an infolding of plasma membrane that encloses photosynthetic pigments and bacteriochlorophylls
what is the major component of bacterial cell walls
peptidoglycan resembles a layer of meshwork or fabric
What is peptidoglycan layers composed of
alternating molecules of NAG and NAM
how thick are gram positive cell walls
30-100nm
why is commonly embedded in a gram positive cell wall
teichoic acids, carbohydrate chains
what does teichoic acid do
stabilize the peptidoglycan by increasing rigidity and increases the ability of pathogenic positive bacteria
what is the periplasmic space
space between cell wall and plasma membrane
what does lipopolysaccharide function as
an endotoxin in infections involving gram-negative bacteria, contributing to symptoms such as fever, hemorrhaging and shock.
what are lipopolysaccharides composed of
lipid A, a core polysaccharide and an o side chain composed of sugar like molecules
how are archaean cell walls different from bacteria
they have pseudopeptidoglycan instead of peptidoglycan
they may have a layer of glycoproteins or polysaccharides instead of pseudopeptidoglycan
some lack cell walls
what are cell walls envelopes composed of
glycocalyces and s-layers
What is glycocalyx
a sugar coat important in capsules and slime layers
what is a capsule
layer outside the cell wall composed pf polysaccharides or proteins
what is a slime layer
polysaccharides, glycoproteins or glycoplipids that can be easily washed off
what does glycocalyces do
allows cells to adhere to surfaces aiding in the formation of biofilms
What is an S-layer composed of
a mixture of structural proteins and glycoproteins
where are s-layers found
in bacteria outside the cell, they are the cell wall in some archaea
What are fimbriae
short bristle like proteins projecting from the cell by the 100’s
WHAT DO FIMBRIAE DO
enable a cell to attach surfaces and other cells,
what are pili
longer less numerous protein appendages that aid in attachment to surfaces
what does an F pilus od
transfer DNA between bacterial cells
what are flagella
structures used by cells to move in an aqueous environment
what are flagella composed of
flagellin protein subunits
what is the basal body
the motor for flagella embedded in plasma membrane
what is a monotrichous flagellum
a bacterium with a singular flagellum
what is an example of a monotrichous flagellum
vibrio cholerae
what are amphitrichous flagella
flagellum or tufts of flagella at each end
what is an example of amphitrichous flagella
spirillum minor
what is lophotrichous flagella
a tuft at one end of the cell
What is peritrichous flagella
flagella on the entire surface.
