2.6 Prokaryotic and eukaryotic cells Flashcards
Animals, plants, and fungi are all what?
complex multicellular organisms
The cells making up animals, plants, and fungi are what type
eukaryotic
There is a lot evidence that suggests that eukaryotic cells are what?
eukaryotic cells evolved from less complex prokaryotic cells
Less complex prokaryotic cells are present where?
present in great numbers and live in an incredibly diverse range of habitats
Prokaryotic cells, unicellular organisms can be classed into two what?
evolutionary domains- Archaea and Bacteria
These unicelllular organisms are classed into what two evolutionary domains?
archaea and bacteria
Where have the two evolutionary domain, archaea and bacteria evolved from?
an ancient common ancestor
What may have been among the earlliest forms of life on earth?
prokaryotic cells
When have prokaryotic cells first appeared?
around 3.5 billion years ago when the surface of the Earth was a very hostile environment
Scientists believe that prokaryotic cells were adapted to living in extremes of what??
that these early cells were adapted to living in extremes of salinity, pH and temperature
Early cells that were adapted to living in extremes of salinity, pH and temperature
that still exist today are called what?
extremophiles
Where can extremophiles be found?
in hydrothermal vents and salt lakes- similar environments to those believed to have made up the early Earth
What are extremophiles usually the domain of?
Archaea and more recently they have been found in more hospitable environments such as soil and the human digestive system
Prokarytic organisms are always what?
unicellular with a relatively simple structure
The DNA in prokaryotic organisms are not contained within what?
within a nucleus
: they have few organelles and the organelles they do have or not membrane bound
Describe the DNA in both eukaryotes and prokaryotes
the structure of the DNA contained within prokaryotes is fundamentally the same as in eukaryores but packaged differently
Describe the DNA in a prokaryote
They generally have only one molecule of DNA, a chromosome, which is supercouiled to make it more compact
What shape is the chromosome in prokayotes and why?
supercoiled to make it more compact
The genes on the supercoild chromosome of the prokaryote is often what?
often grouped into operons, meaning a number of genes are switched on or off at the same time
Which ribosomes are smaller. Prokaryotic or eukaryotic?
prokaryotic
The relative size of ribosomes in prokaryotic cells are determined by what?
the rate at which they settle, or form a sediment in solution
The larger eukaryotic ribosomes are desginated what?
80s
The smaller prokaryotic ribosomes are designated what?
70s
Both designated ribosomes are necessary for protein synthesis, although the larger 80s ribomes are involved in what?
the formation of more complex proteins
Prokaryotc cells have a cell wall made from what?
peptidoglycan, also known as murein
What is peptidoglycan, the thing cell walls are made from in prokaryotic cells/
it is a complex polymer formed from amino acids and sugars
The flagella of prokaryotes is what compared to the equivallent structure of eukaryotes and does not have the?
it is thinner and
does not have the 9+2 arrangement
In prokaryotic cells, the energy to rotate the filament that forms the flagellum is supplied from the process of what?
chemiosis, not from ATP as in eukaryotic cells
In prokaryotic cells, the flagelllum is attached to the cell membrane of a bacterium by and is rotated by what?
a basal body and rotated by a molecular motor
In prokaryotic cells, the basal-body attaches the filament comprising the flagellum to what?
the cell-surface membrane of a bacterium
In prokaryotic cells, flagellum wise, what does a molecular motor cause
causes the hook to rotate giving the filament a whip like movement, which propels the cell
The first eukaryotic cells appeared when?
about 1.5 billion years ago
Eukaryotic cells are more _____ than prokaryotic cells
complex
Where is the DNA present in eukaryotic cells and what do they exist as?
present within a nucleus and exists as multiple chromosomes
Describe the chromosomes in eukaryotic cells
DNA exists as multiple chromosomes: supercoiled
i) each one wraps around a number of proteins called histones, forming a complex for efficient packaging.
ii) this complex is called chromatin and chromatin coils and condenses to form chromosomes
Eukaryotic genes are generally what?
switched on and off individually
Eukaryotic cells have membrane bound organelles. What does this include?
mitochondria and chloroplasts
Organisms from the plant, animal, fungi, and protoctista kingdoms are all composed of what?
eukaryotic cells, many are multicellular
What is the theory of endosymbiosis
- evolution of eukaryotic cells
- mitochondria and chloroplasts, and possibly other eukaryotic organelles, were formerly free-living bacteria, that is prokaryotes
- these prokaryotes were taken inside another cell as an endosymbiont (an organism that lives within the body or cells of another organism)
Outline the difference in prokaryotes and eukaryotes with nucleus
prokaryoes- not present
eukaryotes- present
Outline the difference in prokaryotes and eukaryotes with DNA
prokaryotes- dna is naked, circular and usually no introns (not in chromosomes)
eukaryotes- DNA is bound to proteins, linear and usueally has introns
Outline the difference in prokaryotes and eukaryotes with DNA organisation
prokaryotes- fold and condense dna
eukaryotes- associate with proteins called histones
Outline the difference in prokaryotes and eukaryotes with extra chromosomal DNA
prokaryotes- circular DNA called plasmids
eukaryotes- only present in certain organelles such as chloroplasts and mitochondria
Outline the difference in prokaryotes and eukaryotes with organelles
prokaryotes- non-membrane bound
eukaryotes- membrane bound and non-membrane bound
Outline the difference in prokaryotes and eukaryotes with cell wall
prokaryotes- peptidoglycan
eukaryotes- chitin in fungi, cellulose in plants, not present in animals
Outline the difference in prokaryotes and eukaryotes with ribosomes
prokaryotes- smaller, 70s
eukaryotes- larger 80s
Outline the difference in prokaryotes and eukaryotes with cytoskeleton
prokaryotes- present
eukaryotes- present, more complex
Outline the difference in prokaryotes and eukaryotes with reproduction
prokaryotic- binary fission, does not have nucleus, asexual
eukaryotic- asexual or sexual
Outline the difference in prokaryotes and eukaryotes with cell type
prokaryotic- unicellular
eukaryotic- unicellular and multicellular
Outline the difference in prokaryotes and eukaryotes with cell-surface membrane
prokaryote- present
eukaryote- present
list three structural differences between prokaryotic cells and eukaryotic cells
- dna is free floating
- no membrane bound organelles
- prokaryotic has cell wall from peptidoglycan
- prokaryotic has no nucleus
- smaller ribosomes
- extra chromosomal DNA
Suggest why the lack of membrane-bound organelles does not stop prokaryotic cells making proteins
- Prokaryotic cells have ribosomes, which are needed for protein synthesis
- ribosomes are not membrane bound
Some antibiotics kill bacteria by disrupting the formation of peptidoglycan molecules. Explain why these antibiotics kill bacteria and why they do not have any effect on eukaryotic cells
Eukaryotic cells do not have cell walls, neither a cell wall formed of peptidolgycan molecules
-antibiotics do not damage any other cell components for example nucleus, ribosomes and mitochondria
