1.2: Ultrastructure of Cells Flashcards
Prokaryotes
Are unicellular organisms
Prokaryotes
Are unicellular organisms
Cell Structure of Prokaryotes
Prokaryotes have two specific domains:
- Eubacteria= peptidoglycan in cell walls
cannot survive in extreme environments
-Archaebacteria= no peptidoglycan in cell walls
live in extreme environments
They both have no nuclei
Are unicellular
Have ribosomes
And have no membrane organelles
Ultrastructure of Prokaryotes
1.
Cell Wall:
Encloses the cell and helps it maintain its shape
- prevents it from bursting into hypotonic media
Plasma membrane
Surrounds the cell
Controls the movement of substances in and out the cell
Cytoplasm
Is the site of all metabolic reactions
Fills the cell
Pili
Protein filament that helps with adhesion and the transfer of DNA between two cells
70S ribosome
the site of protein synthesis
Nucleoid
Includes naked DNA
Controls all the activities of the cell
Plasmid
Small circular DNA carrying a small number of genes, which give the cell antibiotic resistance and are used in creating genetically modified bacteria.
Flagella
responsible for the locomotion of the cell. whip-like structure
Binary fission
The mode of reproduction of bacteria
Means of asexual reproduction of prokaryotes
Steps involved:
-the chromosome replicated semi-conservatively, beginning at the point of origin
-the 2 copies of DNA move to the opposite ends of the cell
-the cell wall elongates
-the plasma membrane grows inward and pinches off to form two separate, genetically identical cells
Eukaryotes
are organisms:
whose cell has a nucleus
with complex cells; the genetic material is isolated from the cytoplasm by the nucleus
Cell Structure of Eukaryotes
Divided into 4 main kingdoms:
- Protista= multicellular organisms without specialised tissue
-Fungi=have a cell wall made of chitin
obtain nutrition via heterotrophic absorption
-Plantae= have a cell wall made of cellulose and obtain nutrition from photosynthesis
-Animalia= no cell wall and obtain nutrition from via heterotrophic ingestion
Ultrastructure of Eukaryotes
1. Mitochandrion(dria)
The site of cellular respiration and where ATP is generated.