Prokaryotic and Eukaryotic Cell Systems Flashcards
What are the 2 major prokaryotes?
- bacteria (e.g. E. coli)
- archaea (single called organism)
What are the 4 main structures share by all prokaryotes, bacteria and archaea
- The plasma membrane
- Cytoplasm
- Ribosomes
- Genetic material (DNA and RNA)
What extra cellular features doe prokaryotes have (that eukaryotes do not)?
- a cell wall
- pili
- flagella
What are the functions of a plasma membrane?
- contain the cell (physical limits)
- control of what comes in and out of the cell
- communicate with the surrounding environments
Describe the prokaryotic cytoplasm
The cytoplasm in prokaryotic cells is a gel-like fluid (called Jello)
-contains: gDNA, plasmid DNA, ribosomes and proteins
Describe a prokaryotic ribosome
They are smaller, slightly different shape and conposition than eukaryotic ribosomes
They have about half the ribosomal RNA (rRNA) and 1/3 fewer proteins than eukaryotic ribosomes
Describe prokaryotic genetic material
- contains large quantities of genetic material in the form of RNA and DNA
- the DNA looks like a sting in the middle of the cell
- there is no nucleus
- has minimal genomes(prokaryotic genomes are much smaller that eukaryotic genomes)
What is the typical prokaryotic gene structure?
- absence of introns (non-coding sequence
- polycistronic, presence of operons (several genes expressed under the same promotor in the mRNA
What does the cell wall (prokaryotes) provide?
Strength and rigidity
What is the cell wall (prokaryotes) composed of?
- a peptidoglycan (sugar and peptide molecule
- proteins
- polysaccharides
- lipids
Describe a Gram+ cell wall
- relatively thick and featureless under an electron microscope
- peptidoglycan is major component (~50%)
- no lipid and often no protein
- polymers (teichoic acid and/or teichuronic acid) covalently bonded to peptidoglycan
Describe a Gram- cell wall
- the cell envelope consists of 2 membranes-the cytoplasmic and the outer membrane with a thin layer of peptidoglycan in between
- the outer membrane contains lipopolysaccharides (LPS), lipids and proteins- LPS is located exclusively in the outer membrane with lipid embedded in the membrane and polysaccharide protruding from it
What are the 4 main characteristics of eukaryotic cells?
- eukaryotes have DNA organised in chromosomes complexed with histones (within a double membrane)
- its cytoplasm is defined and supported by a complex cytoskeleton system controlling organelle movement
- have an external glycocalyx (animals) or cell wall (plants, algae, fungi)
- complex internal membrane system in which membrane is cycled via a cellular packaging and dispatch centre (the Golgi body)
What are ‘histones’?
Any of a group of 5 small basic proteins, occurring in the nucleus of eukaryotic cells, that organise DNA into strands into nucleosomes by forming molecular complexes are which the DNA winds
What are the 5 main structures shared by all eukaryotes?
- Plasma membrane
- Cytoplasm
- Ribosomes
- Genetic material (DNA/RNA)
- Organelles
Describe the plasma membrane of a eukaryote
There plasma membrane is similar to that of a prokaryote, but larger
Eukaryotic cells contain internal membranes that delimit the different organelles
Describe the membrane of a vacuole
Surrounded by a single membrane, similar to the plasma membrane
Called the tonoplast
Describe the membrane of the Golgi apparatus and endoplasmic reticulum
Bound by a single membrane
Describe the membrane of the mitochondria
It is surrounded by an outer membrane and an inner membrane to create a matrix (2 membranes)
Describe the membrane of the chloroplast
Surrounded by 2 membranes containing a membrane network called thylakoids (envelope)
Describe the membrane of the nucleus
2 membranes to create an envelope
Describe the eukaryotic cytoplasm
It is more complex than that of prokaryotes as it contains proteins and metabolites
What qualities does the eukaryotic cytoplasm give the cell?
- structure
- cellular movements
- cell signalling
Describe a eukaryotic ribosome
Eukaryotic ribosomes are larger with a different shape and composition- also have more RNA and proteins than prokaryotes
Describe eukaryotic genetic material
The DNA is organised in chromosomes with complex histones
Contained in a double membrane bound nucleus
Eukaryotes have more DNA than prokaryotes, also have a higher genetic complexity
Describe the eukaryotic gene structure
- presence of introns in genes (one gene encodes on protein)
- genes are monocistronic = they function as single units and are expressed individually under the control of individual promoters
Name the organelles that all eukaryotic cells have
- a nucleus
- mitochondria
- Golgi and ER
Name the additional organelles that plants and algae have
- large vacuoles
- plastids (chloroplasts and amyloplasts-responsible for the synthesis and storage of starch granules through the polymerisation of glucose
Describe the eukaryotic cell wall
Eukaryotes either have an external glycocalyx or a cell wall
Plants, algae and fungi have a cell wall made out of cellulose
Animal cells have a glycocalyx, a fuzz-like coat made of glycoproteins and polysaccharides
What is the size of the cell in prokaryotes and eukaryotes?
Prokaryotes:
Typically 0.2-2.0μm (diameter)
Eukaryotes:
Typically 10-100μm (diameter)
Are there membrane-enclosed organelles in prokaryotes and eukaryotes?
Prokaryotes:
Absent
Eukaryotes:
Present (lysosomes, Golgi, ER, mitochondria, chloroplasts, nucleus etc)
What is the flagella like in prokaryotes and eukaryotes?
Prokaryotes:
Consists of 2 protein building blocks
Eukaryotes:
Complex-consists if multiple microtubules
Describe the glycocalyx in prokaryotes and eukaryotes
Prokaryotes:
Present as a capsule or slime layer
Eukaryotes:
Present in some cells that lack cell wall
Describe the cell wall in prokaryotes and eukaryotes
Prokaryotes:
Usually present, chemically complex
Eukaryotes:
When present chemically simple
Describe the plasma membrane in prokaryotes and eukaryotes
Prokaryotes:
No carbohydrates and generally lack sterols
Eukaryotes:
Sterols and carbohydrates that serve as receptors present
Describe the cytoplasm in prokaryotes and eukaryotes
Prokaryotes:
No cytoskeleton or cytoplasmic streaming
Eukaryotes:
Cytoplasmic streaming and cytoskeleton
Describe the ribosomes in prokaryotes and eukaryotes
Prokaryotes:
Smaller (70S)
Eukaryotes:
Larger (80S)
Describe the chromosomal arrangement in prokaryotes and eukaryotes
Prokaryotes:
Single circular chromosomes - lack histones
Eukaryotes:
Multiple linear chromosomes with histones
How do prokaryotes and eukaryotes divide?
Prokaryotes:
Binary fission, conjugation, budding, fragmentation
Eukaryotes:
Mitosis, meiosis
Describe sexual reproduction in prokaryotes and eukaryotes
Prokaryotes:
No meiosis -transfer of DNA fragments only (conjugation)
Eukaryotes:
Involves meiosis
