PROKARYOTIC CELLS Flashcards
What are prokaryotic cells ?
Cells such as bacteria cells which contain no nucleus or membrane bound organelles. Contain DNA which freely moves in the cytoplasm and is non - linear . Genes only contain exons. Prokaryotic cells consist of :
. flagella
. cell wall made of murein
. capsule surrounding the cell
. single circular DNA molecule
. plasmids
what are the ribosomes like in prokaryotic cells ?
they are smaller than the ones in eukaryotic cells and are 70 s.
what is the cell wall made of in prokaryotic cells?
Murein
what do prokaryotic cells consist of instead of a nucleus?
contain a single circular DNA molecule which moves freely in the cytoplasm and it is not protein bound.
what are plasmids ?
small loops pf additional DNA which carry a few genes, eg: antibiotic resistance
what does the capsule do ?
its a slimy layer of protein which prevents bacteria from desiccating (drying out) and protects bacteria against the host cells immune system.
what does the flagella do ?
it rotates to enable the bacteria to move and it is used for locomotion. It consists of a membrane infold called mesosome which increases SA for respiration.
binary fission of prokaryotic cells ?
prokaryotic cells divide by binary fission. Binary fission is much smaller than mitosis and it does not consist of a nucleus , chromosomes. spindle fibres or membrane bound organelles. It is different than mitosis as no nuclear envelope is to be broken down & no spindle fibres present.
1) the single circular DNA molecule undergoes DNA replication
2) any plasmids present undergo DNA replication.
3) parent cell divides into two cells , the two daughter cells halve by the cytoplasm.
4) you are left with two daughter cells where each consist of a single circular DNA molecule and varaible number of plasmids.
( if daughter cells do not consist of this then they will die)
