Structure and Function of Cells

Structure and Function of Cells

Learning Outcomes Explain the cell theory Explain why cell size is usually very small Describe the Fluid Mosaic Model of membranes Describe similarities and differences between prokaryotic and eukaryotic cells Explain the structure and function of the eukaryotic organelles (nucleus, rough & smooth ER, Golgi apparatus, lysosomes, mitochondria, chloroplasts) Describe the three types of cytoskeletal filaments and associated motor proteins

Antoni van Leeuwenhoek (1632-1723) improved microscope used it to look at everything

Image from a replica of a Van Leeuwenhoek Microscope Red Blood Cells

The Cell Theory All organisms are composed of cells. Cells are the fundamental units of life. All cells come from preexisting cells. Corollary 1 All cells contain genetic information. Corollary 2 -- All cells are capable of an independent existence.

1. All living things are made of cells (1824). Dutrochet stated that growth results from both an increase in the volume of cells and from the addition of new cells. Rene Dutrochet (1776-1847)

2. The cell is the basic unit of life (1839). Schleiden (1804-1881) Schwann (1810-1882)

3. All cells arise from other cells (1858). "Omnis cellula e cellula" Rudolf Virchow (1821-1902)

Cells are Very Small

Cells are Very Small 1 10 nm 100 nm 1 2 µm 10 100 µm

Cells are Very Small

Cells are Very Small Cells depend on diffusion for obtaining nutrients and getting rid of waste products Diffusion is the NET movement of atoms or molecules from areas of high concentration to areas of low concentration. The driving force for diffusion is the random movement of molecules as a result of thermal energy.

Scientists use Microscopes to Study Cells Light Microscopes

Transmission Electron Microscope

The Cell A Minimalist View What are the basic components of a cell? 1) Plasma Membrane boundary 2) Genetic Material blueprint DNA 3) Protein Machinery translates info in DNA into physical parts of the cell (proteins)

Biological Membranes are Lipid Bilayers

Biological Membranes are Lipid Bilayers

Fluid Mosaic Model of Membrane Structure Fluid lipid and protein components are free to diffuse in the plane of the membrane Mosaic membrane contains two different types of macromolecules lipids and proteins

Prokaryotic and Eukaryotic Cells Prokaryotic and eukaryotic cells differ in their organization at the subcellular level.

Prokaryotic Cells cytoplasm, with ribosomes DNA in nucleoid plasma membrane cell wall capsule pilus bacterial flagellum

Ribosomes: Protein Synthesis Machinery

Eukaryotic Cells Contain Many Organelles central vacuole rough ER smooth ER Golgi body vesicle

Nucleus Nuclear envelope nuclear pore nucleolus nucleoplasm DNA

The Endomembrane System Nucleus Synthesis Sorting Delivery Smooth ER Rough ER Transport vesicle Lysosome Nuclear envelope Transport vesicle Golgi apparatus Plasma membrane Proteins needed in the ER, Golgi, lysosomes, or PM, and secreted proteins are synthesized on the RER and then transported through the endomembrane system to their final destination.

Endoplasmic Reticulum Rough and Smooth ER are both networks of membranes but they have VERY DIFFERENT FUNCTIONS RER SER

Synthesis of proteins destined for the plasma membrane, secretion, or lysosomes. Rough ER

Smooth ER Synthesis of lipids, phospholipids, steroids Detoxification of many drugs

Golgi Apparatus Proteins enter from the RER Proteins are sorted to their final destination

Golgi Apparatus modifies proteins adds sugars sorts proteins to final destination lysosomes plasma membrane secretory vesicles

Lysosomes Digestion of macromolecules

The Endomembrane System Nucleus Smooth ER Rough ER Nuclear envelope Golgi apparatus Transport vesicle Plasma membrane Lysosome Transport vesicle

Vacuoles plant central vacuole central vacuole

Vacuoles contractile vacuoles https://youtu.be/9ynm5zow59q

Energy Transducers Mitochondria and Chloroplasts Transduction - transforming energy from one form to another Examples -- One chemical form to another (e.g., glucose ATP) Electrical to chemical Light to chemical

Mitochondria outer membrane inner membrane outer compartment inner compartment Site of cellular respiration

Chloroplasts Site of photosynthesis

The Cytoskeleton Three filament systems Microfilaments Intermediate Filaments Microtubules actin various IF proteins tubulin Increasing diameter

Intermediate Filaments Structural components of cells

Hair is made of keratin, an intermediate filament protein

Microfilaments & Microtubules In addition to having roles in maintaining cell structure, these cytoskeletal components also play roles in generating motility. cytoskel motor motile process (examples) actin myosin muscle contraction phagocytosis tubulin dynein kinesin cilia and flagella mitosis

Microfilaments Involved in support and movement https://youtu.be/0wcwgmqouai

Microtubules Involved in support and movement of components within cells

https://youtu.be/iujv-ypilwu

Most cells have arrays of actin (blue), microtubules (green), and IFs (red).