Lecture 1 Human Cell Structures PDF

The structures of the cell Sheila M. Nuraddin Clinical Analysis Department College Of Pharmacy Hawler Medical University Lecture 1 part 2  History of Cell Theory mid 1600s – Anton van Leeuwenhoek – Improved microscope, observed many living...

The structures of the cell Sheila M. Nuraddin Clinical Analysis Department College Of Pharmacy Hawler Medical University Lecture 1 part 2  History of Cell Theory mid 1600s – Anton van Leeuwenhoek – Improved microscope, observed many living cells mid 1600s – Robert Hooke – Observed many cells including cork cells 1850 – Rudolf Virchow – Proposed that all cells come from existing cells  Cell Theory 1. All organisms consist of 1 or more cells. 2. Cell is the smallest unit of life. 3. All cells come from pre-existing cells.  Observing Cells Light microscope – Can observe living cells in true color – Magnification of up to ~1000x  Observing Cells Electron Microscopes – Preparation needed kills the cells – Images are black and white – may be colorized – Magnification up to ~100,000 Transmission electron microscope (TEM) – 2-D image Scanning electron microscope (SEM) – 3-D image SEM TEM Cell Size Organelle: region of cell with specialized function  Cell Structure All Cells have: (Eukaryotic and Prokaryotic) –an outermost plasma membrane –genetic material in the form of DNA –cytoplasm with ribosomes  Eukaryotic Cells Structures in all eukaryotic cells – Nucleus – Ribosomes – Endomembrane System 1.Endoplasmic reticulum – smooth and rough 2. Golgi apparatus 3. Vesicles – Mitochondria – Cytoskeleton  Nucleus Function – isolates the cell’s genetic material, DNA – DNA directs/controls the activities of the cell DNA determines which types of RNA are made The RNA leaves the nucleus and directs the synthesis of proteins in the cytoplasm.  Nucleus Nucleolus Area of condensed DNA Where ribosomal subunits are made – Subunits exit the nucleus via nuclear pores  Endomembrane System Groups of organelles responsible for: – Modifying protein chains into their final form – Synthesizing of lipids – Packaging of fully modified proteins and lipids into vesicles for export or use in the cell  Endoplasmic Reticulum (ER) – The ER is a network of sac-like structures and tubes in the cytoplasm, continuous with the outer membrane of the nuclear envelope – There are 2 types of ER: Rough ER – has ribosomes attached Smooth ER – no ribosomes attached  Endoplasmic Reticulum Rough Endoplasmic Reticulum (RER) Network of flattened membrane sacs create a “maze” – RER contains enzymes that recognize and modify proteins Ribosomes are attached to the outside of the RER and make it appear rough  Endoplasmic Reticulum Function RER Proteins are modified as they move through the RER Once modified, the proteins are packaged in transport vesicles for transport to the Golgi body  Endomembrane System Smooth ER (SER) – Tubular membrane structure – Continuous with RER – No ribosomes attached Function SER – Lipids are made inside the SER fatty acids, phospholipids, sterols.. – Lipids are packaged in transport vesicles and sent to the Golgi  Golgi Apparatus Golgi Apparatus – Stack of flattened membrane sacs Function Golgi apparatus – Completes the processing substances received from the ER – Sorts, tags and packages fully processed proteins and lipids in vesicles  Golgi Apparatus – The proteins and lipids are modified as they pass through layers of the Golgi – Molecular tags are added to the fully modified substances These tags allow the substances to be sorted and packaged appropriately. Tags also indicate where the substance is to be shipped.  Transport Vesicles Transport Vesicles – Vesicle = small membrane bound sac – Transport modified proteins and lipids from the ER to the Golgi apparatus (and from Golgi to final destination)  Endomembrane System Putting it all together – DNA directs RNA synthesis → RNA exits nucleus through a nuclear pore → ribosome → protein is made → proteins with proper code enter RER → proteins are modified in RER and lipids are made in SER → vesicles containing the proteins and lipids bud off from the ER  Endomembrane System Putting it all together →ER vesicles merge with Golgi body → proteins and lipids enter Golgi → each is fully modified as it passes through layers of Golgi → modified products are tagged, sorted and bud off in Golgi vesicles → …  Lysosomes The lysosome is an example of an organelle made at the Golgi apparatus. – Golgi packages digestive enzymes in a vesicle. The vesicle remains in the cell and: Digests unwanted or damaged cell parts Merges with food vacuoles and digest the contents  Mitochondria Function – synthesis of ATP – 3 major pathways involved in ATP production 1. Glycolysis 2. Krebs Cycle 3. Electron transport system (ETS)  Mitochondria Structure: – ~1-5 microns – Two membranes Outer membrane Inner membrane - Highly folded – Folds called cristae – Intermembrane space (or outer compartment) – Matrix DNA and ribosomes in matrix Mitochondria Review of Eukaryotic Cells Thank you