cell structure

cell structure

1. microscopy

   • light and electron microscope ; used to see cells structure  in higher resolutions

2. functions of membranes and organelles

   • plasma membrane
     • also known as cell membrane surface. It controls what enters and leaves the cell
   • nucleus
     • it is enveloped by two nuclear membrane. Contains chromosomes 
   • nucleolus
     • new ribosomes are made there 
   • ribosomes
     • structures made of RNA and protein. found in cytoplasm & attached to RER
     • rough endoplasmic reticulum
       • Involve in protein synthesis and linking the amino acids. Moves amino acid chains from  cisternae of RER  to golgi apparatus.
       • the cisternae breaks off to form vesicles containing the amino acids
     • smooth endoplasmic reticulum
       • Involve in synthesis of steroid hormones  and breakdown of toxins
   • Golgi apparatus
     • Here the amino acids are modified, for e.g adding a carbonyl group to the them. 
     • they break off  from GA to cell membrane by exocytosis.
   • Mitochondrion
     • mitochondria in plural, here also the mitochondria has 2 envelops surrounding them.
     • they are responsible for aerobic respiration, aka ATP production. Krebs cycle occur in matrix  and oxidative phosphorylation stage occurs on membranes of the cristae. 
   • Lysosomes
     • function: digest bacteria, unwanted or damaged organelles or other cells taken by phagocytosis within the lysosome.
     • they are little membrane-bound package of hydrolytic enzymes, aka digestive.
   • centrioles
     • found in animal cells; not in plant cells
     • They are made of tiny tubules called microtubules and they form spindle fiber during cell division, in animals cells

3. prokaryotic cells

   • made up of
   • DNa lies naked in the plasma; bacteria contains small plasmids made up of Dna, never associated with histone
   • Contains only ribosomes, about 18 nm, and cell wall made up of  peptidoglycans
   • bacteria
   • archaea

4. eukaryotic cells

   • They have nucleus and nuclear envelop. They are larger than prokaryotic cells
   • animals
   • plants
     • chloroplasts
       • found only in some plants. Same nuclear envelop as mitochondria
       • stroma
         • contains many paired based membranes thylakoids
         • thylakoids
           • forms stacks called grana
           • grana
             • the grana contains chlorophyll 
             • chlorophyll
   • protista
   • fungi