Prokaryotic & Eukaryotic Cells Flashcards
What is a prokaryotic cell ?
A unicellular organism that lacks membrane-bound nucleus or any membrane bound organelles
What is the range size of prokaryotic cells ?
Between 0.1mµ to 10mµ
What are the 3 basic shapes of prokaryotic cells ?
Spherical (cocci)
Rod-like (bacilli)
Helically coiled (spirilla)
What are the 7 membrane bound organelles ?
Nucleus, Endoplasmic reticulum, Golgi apparatus, Vacuoles, Lysosomes, Mitochondria, Chloroplast (in plants)
What are the 2 types of prokarytic cells ?
Archaea
Bacteria
What is a plasma membrane ?
- Membrane that separates the cell from the external environment
- selectively permanent barrier: nutrient & waste transport, location of many metabolic processes (respiration, photosynthesis), detection of environmental cues for chemotaxis
What does the plasma membrane in prokaryotic cells contain ?
Lipid bilayer containing proteins
What is cytosol ?
The aqueous component of the cytoplasm of a cell, within which various organelles and particles suspend.
What is in the nucleotide in prokaryotic cells?
- Single circular DNA
- Free in cytoplasm
- Not associated with proteins
Wha is a nucleotide in prokaryotic cells?
A region within the cell of a prokaryote that contains the genetic material
what are the characterises of bacterial cell walls?
- Rigid
- 3-25nm thick
- Composed of PEPTIDOGLYCAN (oliogosaccharides + proteins)
outer membrane is very permiable as it contains porin proteins which form pores in the lipid bilayer.
What is plasmid ?
A small circular DNA molecule within a cell
What are the chracterists of a plasmid?
- Replicate idependently
- Plasmid often carry genes that may benefit the survival of the organism
- Contributes to antibiotic resistance
How do prokaryotic cells reproduce?
Binary Fission
What is the process of binary fission?
1- The single, circular DNA molecule undergoes DNA replication
2- Any plasmids present undergo replication
3- The parent cell divides into 2 cells, with cytoplasm roughly halved between the 2 daughter cells
4- The 2 daughter cells each contain a single copy of the circular DNA molecule and a variable number of plasmids
*** if a daughter cell does not receive the single circular DNA molecule or at least one copy of a plasmid they die
Gas vacuole (bacterial and archaeal structures and their functions)
Buoyancy for floating aquatic environments
Ribosomes (bacterial and archaeal structures and their functions)
- Protein synthesis
- 70S / 16 in small subunit
- 23S and 5S in large unit
Inclusions (bacterial and archaeal structures and their functions)
Storage of carbon, phosphate and other substances
Periplasmic space (bacterial and archaeal structures and their functions)
- In Gram negative bacteria contains hydrolytic enzymes and binding proteins for nutrient uptake
- In Gram positive bacteria and archaea cells, may be smaller or absent
Cell wall (bacterial and archaeal structures and their functions)
provides shape and protection from osmotic stress
Capsules and smile layers (bacterial and archaeal structures and their functions)
Resistance to phagocytosis, adherence to surfaces; rare in archaea
Fimbriae and pilli (bacterial and archaeal structures and their functions)
Attachment to surfaces, bacterial conjugation & transformation, twitching & gliding motility
Flagella (bacterial and archaeal structures and their functions)
Swimming motility
Endospore (bacterial and archaeal structures and their functions)
Survival under harsh environmental conditions; only observed in bacteria
Cytoplasmic membrane
- Thin structure that surrounds the cell
- 6 to 8 nm
- Vital barrier that separates cytoplasm from environment
- Highly selective permeable barrier; enables concentration of specific metabolites and excretion of waste products
Archaea membranes
- ETHER linkages in phospholipids in Archaea nut Bacteria and Eukarya have ESTER linkages
- Archaeal lipids lack fatty acids; have isoprenes instead
- Major lipids are glycerol dieters and tetraethers
- Can exist as lipid monolayers, bilayers or mixture (superior thermostability)