Tour of the Cell 1 2007-2008

Cells gotta work to live! What jobs do cells have to do? Build proteins proteins control every cell function Utilize energy for daily life for growth Make new cells growth repair renewal Maintain Homeostasis Digestion/Waste Removal

Building Proteins 2007-2008

Cells need workers = proteins! Building proteins read genes (DNA) instructions build proteins process proteins folding modifying removing amino acids adding other molecules e.g, making glycoproteins for cell membrane address & transport proteins

Proteins do all the work! Structural (muscle fibers, hair, skin, claws) Enzymes (speed up chemical rxns) Signals (hormones) & Receptors proteins cells DNA organism

Building Proteins Organelles involved nucleus ribosomes endoplasmic reticulum (ER) Golgi apparatus vesicles The Protein Assembly Line Golgi apparatus nucleus ribosome ER vesicles

What kind of molecules need to pass through? histone protein chromosome DNA Nucleus Function Control center of cell Contains & protects chromosomes (DNA) Instructions for building proteins Structure nuclear envelope double membrane membrane fused in spots to create pores allows large macromolecules to pass through nuclear pores pore nuclear envelope nucleolus What kind of molecules need to pass through?

production of mRNA from DNA in nucleus nuclear membrane 1 production of mRNA from DNA in nucleus small ribosomal subunit large cytoplasm mRNA nuclear pore 2 mRNA travels from nucleus to ribosome in cytoplasm through nuclear pore

Nucleolus Function ribosome production build ribosome subunits from rRNA & proteins exit through nuclear pores to cytoplasm & combine to form functional ribosomes small subunit large subunit ribosome rRNA & proteins nucleolus

“UNIVERSAL STRUCTURES” small subunit large “UNIVERSAL STRUCTURES” Ribosomes Function site of protein synthesis (translation) read instructions to build proteins from DNA Structure rRNA (ribosomal RNA) & protein 2 subunits combine 0.08mm Ribosomes Rough ER Smooth The genes for rRNA have the greatest commonality among all living things. There is very little difference in the DNA sequence of the rRNA genes in a humans vs. a bacteria. Means that this function (building of a ribosome) is so integral to life that every cell does it almost exactly the same way. Change a base and this changes the structure of the RNA which causes it to not function.

Types of Ribosomes Free ribosomes Bound ribosomes suspended in cytosol synthesize proteins that function in cytosol Bound ribosomes attached to endoplasmic reticulum synthesize proteins for export or for membranes membrane proteins

Endoplasmic Reticulum Function - many functions… processes proteins - helps complete the proteins after ribosome builds them manufactures membranes synthesis & hydrolysis of many compounds Structure membrane connected to nuclear envelope & extends throughout cell rough ER (ribosomes attached) and smooth ER accounts for 50% membranes in eukaryotic cell

Types of ER rough smooth

Smooth ER function Many metabolic processes synthesis hydrolysis synthesize lipids oils, phospholipids, steroids & sex hormones hydrolysis hydrolyze glycogen into glucose in liver detoxify drugs & poisons ex. alcohol & barbiturates most important

Which cells have lot of rough ER? Rough ER function Produce proteins for export out of cell protein secreting cells packaged into transport vesicles for export Which cells have lot of rough ER? Which cells have a lot of ER? protein production cells like pancreas = production of digestive enzymes (rough endoplasmic reticulum from a cell of exocrine pancreas (88000X))

Rough ER function - Membrane Factory Build new membrane synthesize phospholipids + membrane proteins builds membranes ER membrane expands bud off & transfer to other parts of cell that need membranes

Synthesizing proteins cytoplasm cisternal space mRNA ribosome membrane of endoplasmic reticulum polypeptide signal sequence ribosome

Which cells have lots of Golgi? Golgi Apparatus Function finishes, sorts, labels & ships cell products UPS headquarters - “shipping & receiving department” ships products in vesicles “UPS trucks” Structure Membrane sacs = “cisternae” transport vesicles secretory vesicles Cells specialized for secretion? endocrine glands: produce hormones pituitary, pancreas, adrenal, testes, ovaries exocrine glands: produce digestive enzymes & other products pancreas, mammary glands, sweat glands Which cells have lots of Golgi?

Golgi Apparatus

Vesicle transport vesicle budding from rough ER fusion of vesicle with Golgi apparatus migrating transport protein ribosome

endoplasmic reticulum nucleus protein on its way! DNA TO: RNA vesicle TO: TO: vesicle ribosomes TO: protein finished protein Golgi apparatus Making Proteins

Making proteins Putting it together… cytoplasm nucleus cell membrane transport vesicle Golgi apparatus smooth ER rough ER nuclear pore nucleus ribosome cell membrane protein secreted cytoplasm