Cell ultra-structure assessment statements

Eukaryotic cells vs Prokaryotic cells  

• Found in animals and plants/ Found in Bacteria  
• Flagellum made of tubulin/ Flagellum made of flagellin  
• Ribosomes are 80s/ Ribsomes are 70s 
• Membrane bound organelles/ No membrane bound organelles  
• Cellulose cell wall/ Peptidoglycan cell wall  
• Linear DNA/ Circular DNA 
• Reproduction by mitosis and meiosis/ Reproduction by binary fusion 

Prokaryotic cells may also contain: 

• Mesosome which is a folded part of the cell membrane used respiration 
• Slime capsual which goes all around the cell to prolong its life 
• Plasmid which is a small loop of DNA which can be swapped for adaptations

• Nucleus: Used for transcription containing chromatin. It has a nuclear pore, envolope and plama. It has a double membrane 
• Nucleolus: Used for ribosoem synthesis contains RNA nucleotides. It is a dense part in a cell
• Mitochondria: Used for aerobic respiration. It has a double membrane with a matrix and cristae
• Golgi apparatus: This is used for modification of proteins. Made up squashed vesicels and cisternae 
• Rough endoplasmic rediculum: It makes proteins which are used outside the cell. Is lined with ribosomes 
• Smooth endoplasmic rediculum: It is used for making lipids 
• Ribosomes: This is where translation takes place. They contain a large and a samll subunit 
• Cytoskeloton: This maintains the cell structure and is used for cell transport
• Centrioles: This are used in Mitosis and Meiosis to pull chromatids to the polls of the cell. They create spindle fibres. They are made of microtubials arranged at right angles
• Lysosome: They are vesicles with hydrolytic enzymes inside of them. They are important for programmed cell death

Specialization in Eukaryotes: 

• A cell becomes specalized when certain genes become active and inactive due to transribtion factors.
• The active genes produce mRNA and this mRNA is then made in to proteins 
• These proteins then take over the cell and cause it to be specialised 

Specialization in prokayotes: 

• This comes about due to repressor proteins E.G. The Lac Operon
• The Lac Operon deals with lactose and only needs to be created when it is present. 
• So a repressor protein binds to the strand of DNA that isn't needed and stops it from being transcribed and translated
• When lactose is present the repressor protein is still created but it interacts with the lactose and is taken away allowing genes to be transcribed and translated

Once a protein has be translated it moves in to the rough endoplasmic resiculum where it is fully created.

It then goes in to a transport vesicle where it makes it's way to the Golgi apparatus where it is modified and specialsed. 

It is then packaged in to a secretory vesicle where is moves to the edge of the cell and is exocytsed out. 

Some proteins may not go to the Golgi becuase they do not need to be modifed 

Tissue: A collection of the same cells that work together for a function 

Organ: A collection of different cells tha work together for a function 

System: A group of organs that work together to perform a function