Structure and Function of Microbial cells Flashcards
Agar is
A media where bacteria are grown in the lab
It has moisture and nutrients
Paramecium are ( Domain and Kingdom )
Eukaryotes
Protozoa
All cells have intercellular composition ____ the outside
Different from
Metabolic properties of all cells
Cells take up nutrients, transform them, and expel waste
- Genetic ( replication, transcription, translation)
- Catalytic ( energy,biosynthesis)
What property id this?
Nutrients from the environment are converted into new cell materials to from new cell
Growth, all cells
What is the third properties of all cells ( apart from growth and metabolism )
Evaluation
Cell evolve to display new properties. Phylogenetic trees capture evolutionary relationships
All organisms evolve or they will die
Creation of the spore is an example of
Properties of some cells -> differentiation
Explain how cells interact with each other by chemical messengers
Bacteria is able to release atom reducer, as soon as concentration of this reducer is high enough , other bacteria sense it and start to act as if they are surrounded by a lot of bacteria-> formation of the biofilm
What is interesting about the property of exchanging the genetic material in bacteria
They can exchange the genetic material not only between mother-daughter cell, but also mother to mother cell
What property is this?
Some cells are capable of self-propulsion
Motility
How is the size of the cell usually described?
By surface to volume ratio
What is the problem of the surface to volume ratio for unicellular organisms and what is the result of it
It is a problem for unicellular organism, because they interact with the environment only through the surface, if they become to large , they cannot function efficiently any more, that is why there is a limit in diameter.
Limit: 0.5 micrometers- 750 micrometers in diameter
What is the typical size for animal cell and bacterial cell
Animal cell - 10000 nm
Bacterial cell- 1000 nm to 2000-3000 nm
What structures are shared by both prokaryotes and eukaryotes
Cell wall
Cytoplasmic membrane
Cytoplasm
Ribosomes
Name all the main structures present in bacteria
Cell wall Cytoplasmic membrane Nucleoid Cytoplasm Plasmid Ribosomes
What is the difference between the genetic material storage in eukaryotes and prokaryotes ?
Eukaryotes - the genetic material is bound within the nucleus
In prokaryotes the genetic material is not bound in anything -< nucleoid
Name the basic parts of the cell
Cell wall Cytoplasmic membrane Mitochondrion Nuclear membrane Nucleus Ribosomes Endoplasmic reticulum Cytoplasm Golgi complex
Why the membrane is so important ?
It keeps the inside in and outside out
What are three properties of the membrane
- Permeability barrier ( prevents leakage and functions as a gateway for transport)
- Protein anchor
- Energy conservation ( proton motive force )
What is the major source how bacteria create energy?
Proton motive force
What is the ratio of proteins/lipids
50% or less
Types of the membrane proteins by function
Sensors
Adhesins
Transporters
Enzymes
How is the model of the membrane is called
Fluid mosaic
Mosaic - because the ratio between the lipids and the proteins
Fluid- because proteins can move
What is the major phospholipid found in bacteria
Phosphatidylethanoamine
Glycerol+ 2 FA+ phosphate +ethanolamine
What linkage do archea have in the phospholipid bilayer unlike bacteria
Archea- ether C-O-C
Bacteria -ester C-O-C=O
What do archea have instead of FA in phospholipid bilayer
Phytanyl that consists of isoprene
How is the polymer of isoprene called?
Phytanyl
Why is it an advantage , creating interactions between isoprene units
They can create monolayers, it is more tough , more solid-> can survive in extreme environment
What is the name of the tails in phospholipid layer in archea?
Biphytanyl
Bacteria have FA and ___ linkages, when archea have ___ and ___linkages
Ester linkages
Phytanyl
Ether linkages
How is the lipid bilayer stabalized in eukaryotes?
sterol
what is the advantage of sterol?
Polar head
Rigid planar ring structure
Nonpolar hydrocarbon end
Types of sterol in animal cells, fungi , plant cells and protozoa
Animal-Cholesterol
Fungi-Ergosterol
Plant cells and Protozoans- stigmasterol
DO bacteria and archea have sterol
No, it is almost always absent
How do bacteria stabilize their membrane
By hopanoids
Rigid ring structure, the same function , just another molecule
How bacteria and archea store DNA?
- Circular molecule, double stranded
- Generally haploid ( one copy)
- Packaged with proteins( H-NS and other histone loke protein) aggregates to form the nucleoid)=the chromosome
- DNA in the cytoplasm , ribosomal RNA encoded on the chromosome
- May also contain plasmids
What are plasmids?
Smaller circular structures of DNA, genes for function that can be transported very easily, for example antibiotic resistance
How is the gentic material stored in Eukaryotes?
- Linear molecules, double-stranded
- Generally diploid ( two copies)
- Packaged with proteins( Histones) to form chromatin fibers=chromosome
- DNA in the nucleus
- Nucleolus:( dense DNA that codes for ribosomal RNA, ribosomal proteins , immature ribosome )
What is the difference in gene storage in bacteria and eukaryotes?
Bacteria and archea- do not have histones, their gentic material is not bounded ( as in eukaryotes- nucelus )
Eukaryotes do not have plasmids
Three major steps in production of protein from DNA
- Replication , which is mediated by DNA polymerase
- Transcription, which is mediated by RNA polymerase
- Translation, which is mediated by ribosome
Parts of ribosomes
RNA and proteins
What is the role of ribosomes
To translate mRNA into amino acids in order to form proteins
Where are ribosomes in prokaryotes and eukaryotes
Prokaryotes- free in the cytoplasm or attached to cytoplasmic membrane
Eukaryotes- free in the cytoplasm or bound to the endoplasmic reticulum
What ribsomes are in prokaryotes and eukaryotes
Prokaryotes: 70 S= 30S+50S subunits
Eukaryotes:80 S ribosomes =40S+60S
Why 60S and 80 S are important ?
their RNA are used as a genetic markers, these genes have both conserve regions and variable regions ( they are changing to mutation), so we can see how closely related two organisms are
What does S mean in ribosome subunit
Svedberg unit, describes the rate of sedimentation of the particle in the centrifuge , how far the particle will move away from the center when exposed to the centrifuge, not linear
How many proteins and what rRNA make the subinits of ribosomes
50S->23S rRNA and 5S rRNA, 31 protein
30S->16S rRNA,21 proteins
40S->30 proteins,18S RNA
60S-> 5.8S rRNA,28S rRNA,5S rRNA,40 proteins
What are organelles?
Compartments made of membranes ( phospholipid bilaeyer and proteins)
In what organism is the cell wall present and in what organisms it is absent
Plants,algae, fungi- -YES
NO- animals,protozoa
What is the cell wall
A tough , rigid barrier that helps protect the cell and give its shape
The cell wall of eukaryotes is usually composed of___
polysaccharides
Diversity of cell wall molecules( plants, algae, fungi and others)
Plants, algae and some fungi: cellulose ( polymer of glucose )
Fungi:chitin ( polymer of N-acetylglucosamine)
Also cell walls made of galactose, mannose,etc.
How the DNA is packed inside of the nucleus
DNA wraps around histones, which form loops of DNA called nucleosomes. These nucleosomes coil and stack together to form fibers called chromatin. Chromatin in turn forms larger loops and coils to form chromosomes
Two types of chromatin
Euchromatin: loosely packed, actively transcribed
Heterochromatin: densely packed, low level of transcription
Where does the translation occur if the protein is designated to the cytoplasm
Ribosome-mRNA stays free in the cytoplasm
What is the golgi body?
A set of membrane compartments involved in further processing of proteins and their distribution. Proteins are packaged in vesicles and transported to where they are required
What are lysosomes
Internal vesicles that contains hydrolytic enzymes required for degradation of materials brought in by phagocytosis and endocytosis
What is the structure of mitochondria
Porous outer membrane, inner membrane , matrix
What is the function of mitochondria?
Produce most of the ATP required by the cells
The outer membrane is made of
Many porin proteins
Very permeable for small molecules
The composition of the inner membrane
75% proteins
25% lipids
Transport proteins,enzymes,cytochromes,ATPases
What is in the matrix of mitochondria?
Enzymes ( citric acid cycle),DNA,ribosomes(70S)
Where does the proteins for the mitochondria come from?
Mitochondria are able to synthesize some of their proteins, the remaining ones are imported from the cytoplasm of the cell( they are encoded in the genome)
Structure of the chloroplast
Outer membrane->porins similar to mitochondria
Inner membrane
Stroma
Thylokoid
What is in the stroma?
Circular DNA
70S ribosomes
enzymes of the Calvin cycle
What is the thylakoid?
Closed system of interconnecting sacks and tubules
Contain enzymes and pigments that harvest light energy and the membrane-bound ATPases that use this energy to produce ATP
Where does the protein from the chloroplast come from?
Chloroplasts are able to synthesize some of their own proteins ( their own circular DNA), the remaining ones are imported from the cytoplasm of the cell
Where do photosynthetic prokaryotes have their proteins
Cytoplasmic membrane
Why chloroplast and mitochondria have two layers and 70S ribosomes
Acquisition of mitochondria and chloroplasts by eukarya cells at some point of time
What is the cytoskeleton?
A complex network of protein filaments that helps organize the cytoplasm and give the cell its shape
Microtubules consist of
alpha and beta tubulin
Actin filament consists of
Actin
Intermediate filament consist of
Keratin
Desmin
Vimentin
The role of microtubules
Serve as a highway for transporting vesicles and organelles around the cell
Move cell via flagella and cilia
Participation in cell division
The role of intermediate filaments
To anchor the nucleus
Maintain the cell shape
The role of actin filaments
To keep the shape to the cell
move cell via mucle contraction
Move organelles and cytoplasm in plants,fungi, and animals
What helps microtubules to transport the organelles around the cell
Kinesin and dynein are two proteins that attach to vesicles or organelles and walk on microtubules, transporting their cargos to where they are required
How much time does it take to transport the vesicle across the cell with microtubules?
Max 5s
What is the formula of the cilia
9 sets of doublets + 2 in the center
In what organisms flagella is covered with the plasma membrane?
Eukaryotes, but not prokaryotes
How is the movement created in the cilia?
The dynein arms slide the doublets past each other
The base of the flagellum is called
The basal body
The basal body of the gram-negative
L ring(LPS) P ring (Peptidoglycan) MS ring ( membrane superficial) C ring (cytoplasm)
The basal body of the gram-positive
P, MS and C rings
MS and C rings are covered with
Motor protein
The flagella is moved by
the proton motive force, the difference in charge creates a potential energy
Outside- positive
Inside the cytoplasmic membrane - negative
The mechanical force is created by allowing the protons to flow through the mot protein and allowing rotation in the motor protein, which will cause the turn of the central axes and the whole flagellum will rotate
What is the difference in flagellum in eukaryotes and prokaryotes
The flagellum is anchored in the cytoplasmic membrane, but not covered with it -> in bacteria
In eukaryotes the flagellum is surrounded by the cytoplasmic membrane
How the flagellum is assembled
1) MS/C ring first
2) Motor proteins are assembled around MS/C ring
3) Then P and L ring
4) Formation of the early hook ( early, because it does not have a cap yet)
The cap helps the flagellum subunits to assemble
5) Assembling flagellum subunits
How do the subunits come to the tip for the growth of the filament
Through the channel inside
The direction of the flagellum
Peritrichous ( in all direction)
Monotrichous
Lophotrichous (in one direction, but more than one)
How does the peritrichous movement work
Bundled flagella in counter clockwise direction (CCW)
Then when working in the clockwise direction , the flagella fell apart and the bacteria and reorient to start moving in the other direction,
And then CCW direction
How does polar flagella movement work
Reversible flagella In CCW rotation-> movement forward CW rotation-> reverse direction Unidirectional flagella CW direction-> forward Cell stops, reorients Moves in the other direction, only forward direction
What is the other way to move around
Gliding motility
Types of gliding motility
a) secretion of mucus behind-. movement forward
b) Type IV pilus-dependent-> retraction of the pilus->movement forward
c) glide protein -> the protein glide in one direction and the cell moves in the other
What is taxis and their types ?
Directed movement toward or away from a gradient of chemical or physical agents
Chemotaxis ( chemicals,nutrients)
Phototaxis light ( photographic)
Aerotaxis :oxygen
Osmotaxis :ionic strength ( high/low concentration)
How the bacteria move to the attractant
The bacteria will run and tumble and run when there Is no attraction
If there is an attractant, the cell is not able to sense the attractant , because it is too small to sense the difference across its length, the cell needs to compare, it starts to run more in the direction of the attractant and the tumbles will become less frequently , the bacteria needs to test out different locations, so it won’t go straight to the attractant , it will still go back and forth, but the ultimate movement will be in the right direction, just not in the most efficient manner
Two proteins required for the assembly of the fimbriae
The chaperone and the usher
How does the assembly of the fimbriae occur in gram-negative bacteria
Subunits are brought from cytoplasm to periplasm . With the help of chaperon, the proteins do not unfold or digradate and manage to make it to the usher, which is a part of the pore in the outer membrane, the usher get the proteins from the cover ( like a sausage from the package)
That assembles the proteins in the right order
Pieces are not covalently bound , they just fit into each other like puzzle pieces
Adhesion of the fimbriae to the surface is performed by
- The main subunits
- Specialized subunit at the tip ( as in the case with the P fimbriae-type 1 pillus on the tip of the fimbriae)
How does fimbriae adhesion of gram-positive occur
The adhesion to surfaces is carried out by surface adhesins, consisting of only one protein
How does fimbriae of the gram-positive bacteria occur
Subunits of the fimbriae are assembled by sortases and attached to peptidoglycan
The fimbriae of the gram-positive bacteria are anchored in ___, when in gram-negative ____
Peptidoglycan
The outer membrane
The fimbriae in gram-positive composed of ____, and in gram-negative composed of ___
Pilin proteins
How do the fimbriae subunits bound to each other
IN gram-positive -> covalently-linked
in gram-negative -> not covalently bound to one another( strand exchange)
Fimbriae assembled by
in gram-positive-> enzymatically by sortases
IN gram-negative-> by chaperon and the usher, that are coded with the fimbriae pilin genes
What is the endosperm
Highly differentiated cells that are extremely resistant to harch environment : heat,chemicals,radiation,nutrient depletion,dessication
For how long does the endosperm can remain dormant, what environment conditions are needed to “wake” it and how the endosperm is dispersed
The endosperm is dispersed by wind, water , animal digestive system
They can remain dormant for 100s of years
Need water and 37 degrees celcius are needed for germination
Another way of dormant phase and explain it
Other bacteria have found other solution:VBNC( viable , but not culturable state) that occurs when the bacteria is not dead, but not actively metabolizing, using very little energy to stay alive, but not enough to reproduce
VBNC susceptible to -> desiccation , some antibiotics require division to work, so they will not influence VNBC, VNBC heat resistant , nutrient depletion resistant, resistant to radiation
The layers of the endosperm and their characteristics
Inside out DNA inside Cortex-peptidoglycan Core wall- used to be cytoplasm. Have Calcium, dipicolinic acid (DPA)-only in spores,SASPs(small,acid soluble proteins). Have proteins for germination Spore coat - have keratin Exosporium- a layer of proteins
What does DPA, Ca and SASPs do
SASPs bind to DNA and help protect against damage (UV light)
DPA+Ca bind water and help in dehydration
How the endosperm forms
Usual vegetative cycle , when things are good
When become stressful in nutrients, the cell might decide to enter sporulation stage
The first stage of the endosperm formation: assymetric cell division and formation of the prespore , which is separated from the mother cell by septum
Then the engulfment occurs and a spore surrounded by a mother cell
The next stage is cortex formation, and there are three layers formed: cytoplasmic membrane, cell wall, cortex
Then the spore coat takes up Ca,SASPs and dipicolinic acid from the cytosol
And then the spore mature and the mother cell lysis
What are cell inclusions
In bacteria and archea, energy reserves and building blocks are sometimes stored in granules or inclusions
Storing the nutrients the time when they are going to be not so abundant
How are the cell inclusions surrounded
Can be enclosed with a single layer (phospholipid, protein, glycoprotein)
What can be a cell inclusion
Carbon
Sulfur
Polyphosphate
Magnetite (that allow to respond to magnetic field and know the direction)
How does the cell inclusion help cyano bacteria
They help the inclusions to float (buoyancy), so they can stay near the place with the sunshine
