prokaryotes and eukaryotes Flashcards
what are the 4 key processes that are common between prokaryote and eukaryote
- Growth
- Reproduction
- Responsiveness
- Metabolism
what is growth in the process of life
-increase in size
what is reproduction in the process of life
-an increase in number
•this may be accomplished sexually (using gametes, or sex cells)
•asexually (alone)
what is responsiveness in the process of life
-the change of internal or external properties in response to changing environmental conditions
•The ability to move may not be common across all types
what is metabolism in the process of life
-the ability to take in nutrients and utilise controlled chemical reactions to generate energy
•This energy is used to fuel the other three processes
what do viruses do and not do
- Don’t grow
- Only reproduce in a host cell
- Only some are responsive to the host cell
- Uses the host cells metabolism
what is the major difference between prokaryote and eukaryote
One of the major differences between the prokaryotes and eukaryotes is size
•Prokaryotes are typically 1μm in diameter
•Small size for control of metabolism in cytoplasm?•Eukaryotes can be 10-100μm
•1μm = 1 millionth of a meter, so very small.
name and describe an exception of the difference in size between prokaryote and eukaryote
- In 1985, Epulopiscium fisheloni was discovered in sturgeon intestine
- Hair like structures originally thought to be cilia (eukaryotic), turned out to be bacterial flagella (prokaryotic)
- Cells are 600μm, so visible without a microscope
difference and similarity of prokaryotes and eukaryotes
- Both eukaryotes and prokaryotes have a membrane bound structure capsule capable of the four processes
- However, there are differences between the organelles present
- Also differences in which organelles are present
describe the cell structure in prokaryotic nucleus
- The word prokaryote comes from the Greek for before nucleus
- Prokaryotes do not have a nucleus, Eukaryotes do. •Genetic material is not surrounded by a membrane
- Bacteria may also carry additional genetic material on circular DNA molecules called plasmids
- Easily transferred between bacteria- antibiotic resistance
describe the cell structure in eukaryotic nucleus
-DNA (negatively charged) wound around histones (positively charged)
•Tight packing into nucleosomes
•Chromosomes form from the nucleosomes
•In large eukaryotes, nucleus visible using light microscope (1-2um)
is the central dogma of molecular biology the same for both eukaryotes and prokaryotes
yes it is same for both (picture)
what is difference in ribosomes for prokaryote and eukaryote
•Assemble proteins from amino acids based on mRNA •Contain significant amounts of RNA •prokaryote ribosome has 70s -eukaryote ribosome has 80s (picture)
what did carl woese do
- He compared the gene sequences which coded for the small sub-units of RNA from:
- Methanogens
- Bacteria
- Eukaryotes
- He then looked at the association coefficients between the sequences
the genetic material in prokaryotes and eukaryotes
There are differences between the genetic material and how it is stored within the Prokaryotic and Eukaryotic cell
what are archaea
The Archaea are fancy Prokaryotes that are different from the Bacteria.
where can bacteria carry genetic information that eukaryotes cannot
Bacteria can carry genetic information on plasmids, which eukaryotes cannot
describe the cell wall in prokaryotes
Prokaryotic cells are surrounded by a cell wall.
•Provides structure, shape and some functions
•Protection from osmotic forces
•Cell adhesion (sticking together, or sticking to something else)
•Antimicrobial resistance (penicillin attacks cell walls, mammals do not have!)
•The Archaea have a cell wall, but it is different from the Bacteria
what is the bacteria cell wall called
peptidoglycan
describe the bacteria cell wall- peptidoglycan
-The bacterial cell wall is made from peptidoglycan
•Repeating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
•NAG and NAM are covalently linked – “Glycan”
•The chains of Glycan are linked with a four amino acid cross-bridge – tetrapeptide “peptido”
what did Hans Christian Gram come up with in 1884
he came up with that there are two types of common cell wall structures in a bacteria cell wall by doing the Gram Stain
describe the gram stain and what it does (4)
- Crystal Violet – Stains Peptidoglycan Purple
- Iodine – ‘Fixes’ any bound crystal violet
- Ethanol – washes away any unbound crystal violet
- Carbol fuschin/safranin- Stains the cell wall
what is Gram- Positive
- Thick peptidoglycan (as much as 90%)
- Teichoic acids
- Retains crystal violet
what is Gram Negative
- Thin peptidoglycan
- No teichoic acids
- Outer membrane
in the outer membrane what can lipid A do and when is it released
Lipid A is released on cell death, can trigger a number of responses in mammals, e.g. fever
what is the capsule attached to in bacteria
Firmly attached to the cell wall in a tight matrix
how are slime layers bound
loosely bound
describe the capsule and slime layer in bacteria
- Polysaccharide based
- Play a role in adhesion to surfaces – environmental and pathogenic purposes
- Biofilms
- Resistance to phagocytosis
- Resistance to desiccation
what is the fimbriae
protein filaments that allow sticking to surfaces for biofilms
describe fimbriae
- bristle-like
- present in multiple numbers
- adhere to host tissues
what is the pili
they are similar to fimbriae but longer.
•Facilitate genetic exchange between prokaryotic cells.
•Colonisation of surfaces
•Motility
describe pili
- bristle- like
- longer than fimbriae
- present singly or in pairs
what are bacteria that lack cell wall referred to as
protoplasts
give an example of a protoplast and describe it
an example of protoplast is Mycoplasma pneumonia
•Membranes are ‘tougher’ to resist osmotic change
•Pathogen, can bind to cilia in the respiratory tract, killing the cell and preventing mucus removal.
describe archaeal cell walls
Not peptidoglycan based
•Classification as different from bacteria
•Reflect extreme environments (Term 2 lectures)•For instance, halophiles have SO4- incorporated to bind Na+
what are archaeal cell walls based on
- Based on:
- Pseudomurein
- Polysaccharides
- Glycoproteins
what do eukaryotes cell wall do
Some Eukarya have cell walls
•Fungi, algae, plants and some protozoa
•Provides shape and protection from the external environment (e.g. osmotic pressure)
what are eukaryotes cell wall made up of
- Made of various polysaccharides
- Plants – cellulose
- Fungi – cellulose, chitin and/or glucomannan
- Algae – various, cellulose, protein, agar, carrageenan, silicates, algin, calcium carbonate
some organisms don’t have a cell wall
- which organisms?
- what do they have instead
- Animal and most protozoan cells lack a cell wall
- Instead they have carbohydrate glycocalyces attached to the plasma membrane
- Helps anchor cells together
- Protection from dehydration
- Recognition and communication
- Similar to the Slime layer and capsule of prokaryotes, which are also generally referred to as glycocalyces
what are the other names called to cell membrane
- plasma membrane
- cytoplasmic membrane
what are cytoplasmic membranes composed off
- Composed of a phospholipid bilayer
- In bacteria, hydrocarbons are linked to glycerol by ester linkages
- In archaea, there are no phosphate groups and have ether linkages.
describe the function of the membrane
- Separates the cell contents from the external environment
- Controls the contents of the cell and substances that move through it
- Bilayer is impermeable to most substances
- Proteins allow transport across the cell
- Can be either passive or active.
- Active requires energy.
what are the four types of passive processes in a cytoplasmic membrane
- diffusion
- facilitated diffusion
- osmosis
- other channels called permeases
what is diffusion
Diffusion – moves across the cell membrane from high concentration to low concentration. Only occurs for small (e.g. oxygen) or lipid soluble molecules (e.g. alcohols)
-goes through the phospholipid bilayer
what is facilitated diffusion
Facilitated diffusion - bilayer blocks the movement of large or electrically charged molecules. Proteins act as channels that are non specific
-goes through non-specific channel proteins
describe facilitated diffusion through permeases
Other channels, called permeases are specific to certain substrates and has a binding site for that substrate
-facilitated diffusion through a permease specific for one chemical; binding of substrate causes shape change in channel protein
osmosis in cytoplasmic membranes
Osmosis – diffusion is based around the movement of solutes (things dissolved in water). Should there be no transporter for a solute, then water will move instead to balance the concentration
e.g. If there is a high concentration of an impermeable substance outside the cell, water will move out of the cell to lower the concentration.
describe hypotonic solution
animals- water goes inside the cell and the cell becomes lysed
plants- water goes inside the cell and the cell becomes turgid (which can be normal)
describe isotonic solution
animals- water goes in and out it is equilibrium so it is normal
plants- water goes in and out of the cell; it is flaccid
describe hypertonic solutions
animals- water goes out of the cell so the cell has shrivelled
plants- water goes out of the cell, it is plasmolysed
name cells without a cell wall
e.g. mycoplasmas, animal cells
name cells with a cell wall
Cells with a wall: plants, fungi and bacteria
what is active transport and what may it involve
- Active transport- Similar to facilitated diffusion, only the permease requires the use of energy to transport.
- May involve the transport of one substance (uniport)
- Two may move in the same direction (symport)
- May involve a one in, one out (antiport)
what are the 3 ways in which u can transport with active transport
- May involve the transport of one substance (uniport)
- Two may move in the same direction (symport)
- May involve a one in, one out (antiport)
where does group translocation only occur
-only occurs in some prokaryotes
what is group translocation
biological process where a molecule crossing the cell membrane not only gets transported but also gets transformed in itself. Traps the altered substance in the cell (stops it moving back)
give an example of group translocation
Example- accumulation of glucose, glucose is phosphorylated as it is transported to Glucose-6-phosphate. •This cannot be transported back across even if glucose concentration falls outside the cell as a result
describe the cytoplasmic structure of a eukaryote
- Similar fluid mosaic structure of the cell membrane. •Contain sterols (such as cholesterol), which most bacteria lack
- Sterols help maintain membrane fluidity
- No group translocation
what is the cytosol
- Liquid component of the cytoplasm in which everything is dissolved
- Ions, carbohydrates, proteins (enzymes), lipids and waste
what does the cytosol contain
-Contains the cell DNA in the nucleoid region (remember, no nucleus!)
•Some chemical reactions occur
•May also have deposits, called inclusions. This is where reserves of components are stored
•Lipids, starch, N, P or S containing substances
what can the cytosol store
Can store carbon as glycogen, or a polymer of poly-β-hydroxybutyric acid (PHB)
•Chemically modified PHB can be used for producing biodegradable plastic
what is locomotion
movement
what is the locomotion for prokaryotes
-flagella
what is the locomotion for eukaryotes
- flagella
- cilia
- pseudopodia
where is the flagella
-outside cell wall
what is flagella made up off
Made of chains of flagellin
what is the flagella attached too
- Attached to a protein hook
- Anchored to the wall and membrane by the basal body
- Propeller motion
what is an axial filament
a central often contractile filament of a flagellum : axoneme.
what are axial filaments made up off
Endoflagella
another name for axial filaments
spirochetes are distinguished from other bacterial phyla by the location of their flagella, called endoflagella
where is axial filament and what does it do
Anchored at one end of a cell
•Rotation causes cell to move
what is the motion on a eukaryotic flagellum
Rather than a propeller like motion in prokaryotes, it is a whip like motion
what is a amoeba
type of cell or unicellular organism which has the ability to alter its shape, primarily by extending and retracting pseudopods.
what does amoeba do
Movement or surrounding of a cell for endocytosis
•Phagocytosis- if food is solid
•Pinocytosis- if food is liquid
what is the cilia
internal hair-like structures
•Shorter and more numerous than flagella
what does the cilia do and how does it work
Beat rhythmically
•Propulsion in single cells
•Movement of mucus through respiratory tract
what can eukaryotes use for movement and so can prokaryotes
- Both can produce flagella but the structure and movement are different
- Eukaryotes may also use cilia or pseudopodia (amoeba)
- For both, its okay to be non-motile
what is reproduction
•Microbial growth not only refers to increase in size, but also population size
how do prokaryotes reproduce
Prokaryotes reproduce by binary fission (asexual)
•Binary, since two cells arise from the original cell.
describe the genetic exchange in prokaryotes e.g. bacteria
•Possible for genetic exchange to occur between bacteria
•In transformation (a), when a cell lyses the DNA easily breaks down into smaller fragments
•These fragments can be taken in and incorporated into the chromosome of the recipient cell
•In transduction (b) a bacterial cell is infected with a virus, or phage
•When repackaging new viral particles, the host DNA can be packaged instead of the viral DNA
•When the phage is released and infects a new cell, the original host DNA is placed inside the new host instead of viral DNA
-In conjugation (c) a donor cell attaches to the recipient via a pilus
•This pulls the recipient to the donor
•Transfer of plasmid or chromosomal DNA can then take place.
(look at picture)
reproduction in eukaryotes
- Eukaryotes can reproduce asexually
- Binary fission
- Budding
- Fragmentation
- Spore formation
- Schizogeny (associated with plasmodium)
what is sexual reproduction
•Many eukaryotes reproduce sexually
•Involves the formation of gametes
•Fusion of two gametes forms a zygote
•Some algae fungi and protozoa can do both
-it is through meiosis (generation of haploid cells)
