Prokaryotic Cells and Viruses Flashcards
Cell Wall
made of glycoprotein murein
supports cell and prevents changing shape
Capsule (SOME PROKARYOTES)
made up of secreted slime
helps protect bacteria from attack by cells from immune system
Plasmids
small loops of DNA NOT part of circular DNA molecule
contain genes for such like antibiotic resistance
can be passed between prokaryotes
not always present
some prokaryotic cells have several
DNA
NO nucleus
DNA floats free in cytoplasm as a circular loop
NOT attached to any histone proteins
Flagellum (SOME PROKARYOTES)
long hair like structure
rotates to allow movement
some have more than one
Cytoplasm
contains no membrane bound organelles
ribosomes are present but are smaller than eukaryotic cell ribosomes
Plasma membrane
mainly lipids and proteins
controls passage of substances in and out of the cell
Viruses
Acellular - not technically alive
smaller than bacteria
ALL must invade and reproduce inside cells of host organisms in order to survive
Virus structure
genetic material core (RNA/DNA)
protein coat around core (capsid)
attachment proteins stick out from edge of capsid - allows virus to cling to suitable host cell
Binary Fission
circular DNA and plasmids replicate
loop only once, plasmids many times
cell gets bigger and loops move to opposite poles of cell
cytoplasm begins to divide and new cell walls begin to form
cytoplasm divides and results in two daughter cell with one cop of circular DNA but variable no. copies of plasmids
Virus replication
use attachment proteins to bind to complementary receptor proteins on host cell surface
receptor proteins are cell specific so some viruses can only infect one type of cell (others can infect many types)
Viruses inject their D/RNA into host cell
hijacked cell uses its own organelles to replicate viral particles
