Cell structure Biology AS level

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the nucleus

  • this is the biggest organelle in a cell and this is the part of the cell that contains the DNA and co ordinates the cells functions
  • it has a double membrane
  • it has the nucleous inside of it ( it looks like a nucleus in a nucleus) which makes rRNA which will go on to form ribosomes when combined with proteins
  • it has pores( gaps) in its membrane and this is to allow for the movement of RNA and necleotides to go and make DNA in the ribosomes
  • it has necleoplasm in the cell which holds the chromatin which is DNA and histones a protein combined
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the mitchondria

  • this is the place of respiration in a cell and it produces ATP which is the energy currency of a cell the fulid called matrix in them has enzymes which allow them to do this 
  • it has a double membrane
  • self replicating as they have their own DNA inside of them 
  • the inner mebrance is folded to make crista to increase the surface area of the inside of the cell to speed up respiration
  • they make ATP ( adeosine triphosphate) which is the energy currency of cells , this is a nucleotide 
  • they contain ribosomes
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endoplasmic reticulum

there are 2 types which has the same structure which is parrllel double sacs forming flattened shapes called cisternae, ER acts as roads in a cell as it transports what it produces to other parts of a cell to be used 

rough ER 

  • this has ribosomes on the outside of it and is involved in the formation of proteins and them being transported

Smooth ER 

  • has no ribsomes and deals with the transport and making of lipids in a cell also steriods

when they release what they have produced they will go onto help form the golgi body when the membranes of the vesicles formed fuse with the rest of the golgi body

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Golgi body and lysosomes

is often linked to the ER as this is where the proteins that are made by the rough ER is processed it might have other things added to it like prosthetic groups and then it will be packaged in golgi body membrane and sent to where it needs to be used in the cell or it will be sent out of the cell to be used for example hormones  it is sent off in the form of vesicles it also forms lysosomes which contain digestive enzymes to destroy worn out organelles autolysis and can go into a vacuole and digest the contents this is phagocytosis

like ER it is made up of flattened sacs which are built up when the proteins are produced by the rough ER and added to the the golgi membrane

this organelle is different sizes in each cell depending on what it has to make and how much it has to make

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chloroplasts

  • have a double membrane
  • take part in photosynthesis
  • has fluid inside which is called stroma which contains the enzymes needed for photosynthesis
  • there is network of sacs in the chloroplasts which are called thylakoids
  • and Grana are formed when you stack thylakoids up the connections in-between the granua are called inter-granal lamella or inter - granelal thylakoids  they have a high surface area to absorb light ( they key function of the=is organelle-) and are very compact too
  • they contain  dna so are self replicating
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centrioles

are part of cell division they are made of microtubeles and when 2 of them join they join at right angles , they are found in  a clear part of the cytoplasm called the centrosome

when the cell divides they will split up and replicate , then they will go to the opposite ends of the nucleus and form spindles which allows them to split up the replicated chromosomes to form 2 daughter cells 

mitosis (http://www.cellsalive.com/cells/cellpix/spindle.gif)

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ribosomes

  • are made of rRNA ( ribosomal RNA ) and proteins
  • they are where proteins are made so a key part of protein sythesis
  • they can be spread out in the cytoplasm or attached to the RER
  • these are the smallest organelles
  • they are made up of one small sub unit and one large sub unit
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Comments

Chloe Thorn

i have other biology resources up too :)

ELectrica!

gr8 effort made...you have covered the main things ...(comparing to my notes)

thanks

Chloe Thorn

glad it helped :)

Chloe Thorn

glad it helped :)

Shaaref

this is absolutely great, Thankyou so much. I'm starting college this year and i'm preparing for colleg before hand , do u know anything that can help me be fully prepared for college, i'm studying 3 sciences and maths

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