Lecture 2- Structures of prokaryote Flashcards
what are proteins made of?
polypeptides
what are polypeptides?
a long polymer of amino acids joined by peptide bonds
what are the functions of proteins?
enzymes
transport proteins
structural proteins
what is the function of enzymes?
catalyze chemical reactions
what is the function of transport proteins?
move other molecules across membranes into a cell
what is the function of structural proteins?
help determine shape of the cell
involved in cell diffusion
what is the cytoplasm of the prokaryote?
material bounded by plasma/ cytoplasmic membrane
what is the nucleoid?
region that contains the genome (DNA)
what is a typical genome?
single circular double stranded DNA, may have 1 or more plasmids
what is a plasmid?
smaller circular double stranded DNA
self replicating and carry non essential genes (selective advantage. ex. genes for antibiotic resistance)
what does DNA do?
carries genetic information of all living cells.
polymer of deoxyribonucleotides
what is the protoplast?
plasma membrane and everything within [macromolecules (amino acids, nucleotides…), soluble proteins, DNA + RNA (nucleoid)
function of ribosomes?
site of protein synthesis
what does a 70S ribosome have in it?
30S subunit
50S subunit
what is the 30S subunit? what is it made of?
small subunit
made of protein and 16S rRNA
what is the 50S subunit? what is it made of?
large subunit
made of protein and 23S rRNA and 5S rRNA
where are ribosomes in the cell?
cytoplasm (can be plasma associated ribosomes but only when they are to be exported from protein synthesis)
rough endoplasmic reticulum
what are 3 cell surface structures?
capsules and slime layers
fimbriae
pili
what are capsules and slime layers made of? what is the structure of it?
protein layers/ polysaccharides
can be thick or thin, rigid or flexible
what is the function of capsules and slime layers?
assist in attachment to surfaces, protect against phagocytosis and resist desiccation
what is fimbriae made of? what type of structures are they?
filamentous protein structures
what is the function of fimbriae?
enable organisms to stick to surfaces or form pellicles
what is longer, fimbriae or pili?
pili
what is pili made of? what type of structures are they?
filamentous protein structures
how do pili reproduce?
self replicating
what is the function of pili?
assist in surface attachment
facilitate genetic exchange between cells (conjunction)
what is type IV pili involved in?
twitching motility (how they move)
what are cell inclusion bodies?
visible aggregates in cytoplasm
what are 3 aggregates?
carbon storage polymers
inorganic inclusions
magnetosomes
what are two examples of carbon storage polymers?
poly- B- hydroxybutyrate (PHB)
glycogen granules (polymer of glucose)
what is the function of PHB?
lipid storage
what are two examples of inorganic inclusions?
polyphosphate granules (volutin)
sulfur globules
what is the function of polyphosphate granules?
storage of phosphate and energy
what is the function of sulfur globules?
storage of sulfur used in energy generation
what are magnetosomes?
magnetic inclusions
what granules do magnetosomes have inside them?
iron sulfide
what does magnetosomes having magnetic properties do?
allows it to orient itself in a magnetic field called magnetotaxis (bacteria migrate along earths magnetic field)
where are gas vesicles found?
cytoplasm of prokaryotes
how are gas vesicles shaped?
spindle- shaped hollow tubed gas filled structures made of protein
are gas vesicles permeable to water?
no, they are impermeable to water, therefore, dont allow water to pass through them
what is the function of gas vesicles?
decreasing cell density
confer buoyancy in planktonic cells
what are endospores highly differentiated?
resistant to heat, harsh chemicals and radiation
how do endospores disperse?
wind
water
animal gut
what are endospores produced from?
only by some gram positives
what are two examples of endospores?
bacillus
clostridium
both are anaerobic gram positive rods
what is a vegetative cell?
capable of normal growth (metabolically active)
what is the process of an endospore going through germination?
vegetative cell (metabolically active)
endospore develops in a vegetative mother cell (metabolically inactive)
takes 8-10 hours in there
mature spore gets released (releases due to lack of nutrients)
what are two protective features of the endospore?
layers
core
what do layers of the endospore protect against?
chemicals
enzymes
physical damage
heat
how many membranes do endospores have?
two membranes (permeability barriers against chemicals)
what does the core protect against?
heat (because they’re dehydrated)
Ca-dipicolinic acid
small acid soluble proteins
DNA damage
what are 5 things endospores can resist?
boiling for hours
UV and radiation
chemical disinfectants
desiccation
age
what is the lifecycle of a spore forming bacterium
stage 1: asymmetric cell division (DNA replicates, identical chromosomes pulled to opposite ends of the cell)
stage 2: septation (divides cell into two unequal compartments; forespore (prespore) and mother cell)
stage 3: mother cell engulfs the forespore (forespore surrounded by two membranes)
stage 4: formation of the cortex (thick layers of peptidoglycan form between the two membranes)
stage 5: coat synthesis (protein layers surround the core wall –> spore coat, exosporium) Ca+ and SASP accumulates in the core to stabilize DNA
stage 6: endospore matures (core is dehydrated to make it more heat stable)
stage 7 mother cell is lysed (mother cell disintegrates, mature spore is released)
