Tour of the Cell and the Central Dogma

Prokaryote bacteria cells Types of cells Eukaryote animal cells - no organelles - organelles Eukaryote plant cells

Why organelles?  Specialized structures  specialized functions  cilia or flagella for locomotion  Containers  partition cell into compartments  create different local environments  separate pH, or concentration of materials  distinct & incompatible functions  lysosome & its digestive enzymes  Membranes as sites for chemical reactions  unique combinations of lipids & proteins  embedded enzymes & reaction centers  chloroplasts & mitochondria mitochondria chloroplast Golgi ER

Cells gotta work to live!  What jobs do cells have to do?  make proteins  proteins control every cell function  make energy  for daily life  for growth  make more cells  growth  repair  renewal

Building Proteins

Proteins do all the work! cells DNA proteins organism

Cells functions  Building proteins  read DNA instructions  build proteins  process proteins  folding  modifying  removing amino acids  adding other molecules e.g, making glycoproteins for cell membrane  address & transport proteins

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

nuclear pores nuclear pore nuclear envelope nucleolus histone protein chromosome DNA  Function  protects DNA  Structure  nuclear envelope  double membrane  membrane fused in spots to create pores  allows large macromolecules to pass through Nucleus

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

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

small subunit large subunit Ribosomes  Function  protein production  Structure  rRNA & protein  2 subunits combine 0.08  m Ribosomes Rough ER Smooth ER

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

Endoplasmic Reticulum  Function  processes proteins  manufactures membranes  synthesis & hydrolysis of many compounds  Structure  membrane connected to nuclear envelope & extends throughout cell

Types of ER roughsmooth

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

Membrane Factory  Build new membrane  synthesize phospholipids  builds membranes  ER membrane expands  bud off & transfer to other parts of cell that need membranes

Rough ER function  Produce proteins for export out of cell  protein secreting cells  packaged into transport vesicles for export

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

Golgi Apparatus Which cells have lots of Golgi? transport vesicles secretory vesicles  Function  finishes, sorts, tags & ships cell products  like “UPS shipping department”  ships products in vesicles  membrane sacs  “UPS trucks”

Golgi Apparatus

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

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

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

28 Vacuoles  Storage of water or ions, pigments, hold food, pump out water.  Are larger than vesicles formed from golgi/E.R.  In plants is enclosed by Tonoplast (membrane) and provides cell with hydrostatic pressure

29 Peroxisomes  Contain enzymes (catalase) that break down H 2 O 2 formed during metabolism of alcohols, F.A.’s.  Specialized forms [glyoxysome] found in seeds and function during germination.

30 Cytoskeleton  Protein fibers that support and give shape to a cell, involved in organelle movement throughout cell, chromosome movement during cell division and large cell movements (cell motility and cytokinesis)  3 Groups of Fibers classified according to size:  Mircrotubules (thickest)  Intermediated filaments (middle sized)  Microfilaments (thinnest)

31 Components of the Cytoskeleton  Microtubules  hollow tube.  Provide framework for cell, organized by centrosome from which they usually originate.  “Rail” system for organelle transport.  Component of Centriole.  Replicated prior to mitosis.  Form Cilia and Flagella.  arrangement (eukaryotic characteristic)

6/28/ Components of the Cytoskeleton  Microfilaments (aka actin filaments)  Solid “rope”of two actin proteins  Thinner and more flexible than microtubules  Principle component of muscle fibers.  Provide mechanism to support cell shape. Found just inside the c. mem.  Enable cell movement, phagocytosis and cytokinesis.

33 Cell-to Cell Junctions  Plants  Plasmodesmata  Perforations in cell wall that allow passage for water/solutes to adjacent cells.  Animals  Tight Junctions. Prevent leakage between cells (ie. Stomach)  Desmosomes. Mechanically attach cells to each other. Serve as anchoring sites for inter. filaments in cell.  Gap Junctions. Analogous to plasmodesma. Fxn as comm. Pathway between cells. Cardiac muscle, nerves.

6/28/ Intracellular Junctions

35 Plant Cell Walls  Protect plants, allow for shape and prevent excess H 2 O uptake.  Composed of cellulose  Plasmodesmata connect neighboring cells.

6/28/ Extracellular matrix (ECM)  Intricate network of proteins and polysaccharides that are organized into a meshwork on the outside of cells.  Large polysaccharides and proteoglygans form a “gel-like” material that resist compression.  Proteins like collagen (most abundant protein in animals as part of bone and skin) and elastin (stretch and recoil) provide structure and strength.  Adhesive-like proteins (fibronectins and laminin) help cells attach to the appropriate part of the ECM.

6/28/ Extracellular matrix (ECM)

Any Questions!!