T1.2 Ultrastructure of Cells Flashcards
Bacteria
Have an external cell wall, plasma membrane, circular DNA within the cytoplasm and ribosomes. Some bacteria are encapsulated (polysaccharide capsule outside cell wall)
Capsule
Polysaccardie layer, protects against viruses an losing water, not all have them, but IB assumes they do
Cell wall
protective layer that maintains the shape of the cell, composed of peptidoglycan (carbohydrate protein complex)
Plasma Membrane
Regulates passage of materials in and out of cell
Pili
Hair like extensions that are used for attachment during conjugation
Conjugation
Transferring DNA being prokaryotes type of sexual reproduction
Flagellum
Whip-like structure used for movement, molecular motor inside cell membrane
Ribosome (prokaryotes)
Free floating, 70s size, synthesizes proteins using an mRNA template
Nucleoid
Irregular shaped, free-floating region that contains all or most of the DNA, no true nucleus
Plasmid
Autonomously replicating small circle of DNA, usually contains antibiotic resistance, used in biotechnology to shuttle genes around
Compartmentalization
seen in eukaryotes; consequence of organelles being membrane-bound.
4 reasons for compartmentalization
enzymes and substrates can be more concentrated in a particular area
Substances that could cause damage to the cell can be kept inside the membrane of an organelle
pH can be maintained at ideal level for a particular process
organelles with their contents can be moved around within the cell
Single Membrane bound organelles
rough er, smooth er, golgi apparatus, lysosome, vesicle, vacuoles
Double membrane bound organelles
nucleus, mitochondria, chloroplast
Binary fission
Organism duplicates it genetic material, grows larger, then segregates the DNA, and then splits the cell
