Peroxisomes. Endomembrane System. Vacuoles 9/25/15

Transcription

1 Contains enzymes in a membranous sac that produce H 2 O 2 Help survive environmental toxins including alcohol Help the cell use oxygen to break down fatty acids Peroxisomes Endo System Components of the endo system: Nuclear envelope Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Plasma These components are either continuous or connected via transfer by vesicles Vacuoles Plants, can be a large lysosome store water, chemicals, pigments, poisons or waste product Animals contractile vacuole to maintain water balance Nucleus Chloroplast Nucleus Central vacuole Contractile vacuoles 1

2 Mitochondria Mitochondria Energy converting organelle Cellular Respiration Converting energy in food to ATP Double two compartments (outer and inner s) 1. Inter space - between the s where H+ build up occurs 2. Cristae - increase surface area for ATP production - ATP Synthase is embedded here 3. Mitochondrial matrix - The Citric Acid Cycle is located here This transmission electron micrograph shows a mitochondrion as viewed with an electron microscope. Notice the inner and outer s, the cristae, and the mitochondrial matrix. (credit: modification of work by Matthew Britton; scale-bar data from Matt Russell) Chloroplasts Sites of photosynthesis Double like mitochondria Internal space like mitochondria Contain stacks of thylakoids (not like mito) This simplified diagram of a chloroplast shows the outer, inner, thylakoids, grana, and stroma. The Cytoskeleton (a) Microfilaments Internal Scaffolding (b) Intermediate filaments (c) Microtubules web of protein strands Microfilaments Intermediate 7 nm Main function: changes in cell shape filaments 10 nm 25 nm Main function: maintenance of cell shape Main functions: maintenance of cell shape, movement of organelles, cell mobility (cilia and flagella) Microtubules Provides structure Facilitates the movement of materials inside the cell Facilitates cell movement 2

3 Extracellular Matrix Animal Cell Surfaces Animal and other eukaryotes are organized into single functional organisms These are held together with cell surfaces Extracellular Matrix Helps hold cells together, affects cell behavior by contacting proteins in plasma and cytoskeleton within the cell Glycoprotein complex with long polysaccharide Collagen fiber Connecting glycoprotein Integrin Plasma Microfilaments EXTRACELLULAR FLUID CYTOPLASM Gives the plant structural strength Cell Wall helps regulate the intake and retention of water Cell-to-Cell Communication Plasmodesmata Channels always open Connects cytoplasm of plant cells Gap junctions Channels protein assemblages open only as necessary Allow movement of small molecules/electrical signals between cells Plant tissues Animal tissues plasma (a) Plasmodesmata In plants, a series of tiny pores cell walls between plant cells, the plasmodesmata, allow for the movement of materials among cells. cytoplasm Thanks to the plasmodesmata channels, the cytoplasm of one cell plasmodesmata is continuous with the cytoplasm of the next; the plant as a whole can be thought of as having a single complement of continuous gap junction cytoplasm. (b) Gap junctions In animals, protein assemblies plasma come into alignment with one s another, forming communication cytoplasm channels between cells. A cluster of many such assemblies perhaps several hundred is called a gap junction. 3

4 Binding Cells Together Tight Junctions leak proof sheet digestive or nervous system Anchoring Junctions rivets with cytoskeleton Gap junctions also connect cells Tight junctions Anchoring junction Gap junctions Plasma s of adjacent cells Extracellular matrix Plasma Membrane (cell ) = a phospholipid bilayer with proteins, other lipids and carbohydrates Fluid mosaic Membrane Proteins Anchoring proteins CAMs = cell adhesion molecules Recogni7on proteins e.g. self vs. foreign or non- self Enzymes Receptor proteins Carrier proteins Channel proteins 4

5 Permeability refers to the ease with which substances can cross the plasma (cell) plasma (cell) s are selec&vely permeable (some7mes called semipermeable ) Permeability is affected by the: Par7cle solubility in lipid Par7cle size vs. protein channel (pore) size Par7cle electric charge vs. local charge and/or channel charge Presence of specific protein carriers (transporters) for the par7cle Temperature Transport Membrane Transport Processes Passive processes: do not use ATP energy Energy for transport provided by constant random molecular mo7on (due to heat energy present) Par7cles move from higher to lower concentra7on (down their concentra-on gradient) un7l equilibrium (no net movement of par7cles) is reached Simple diffusion Facilitated diffusion Osmosis Ac&ve processes: ATP energy required Substance can be moved in or out of cell regardless of concentra7on gradient Ac9ve transport Endocytosis Exocytosis Simple diffusion Concentra7on difference Small, lipid- soluble molecules Pass directly through O 2, CO 2, fany acids, steroids, alcohol, lipid- soluble vitamins (A, D, E, K) 5

6 Facilitated diffusion Pass through protein channels (pores) (not shown) polar molecules e.g. H 2 0 charged par7cles ions, e.g. Na +, Cl -, etc. Larger polar molecules can pass through protein carriers (shown) e.g. glucose, amino acids Diffusion of water through a selec7vely permeable Solu7on types From low solute concentra7on to high solute concentra7on hypertonic isotonic hypotonic refer to the solu7on that a cell is in Cells will behave differently in solu7ons of various tonici7es Osmosis Active transport molecules are pumped against their concentra7on gradient [low] [high] Carrier protein and energy (ATP) required e.g. the Na + /K + exchange pump (not shown here) 6

7 Bulk Movement of Material Material e.g. bacteria, proteins, etc. moves into or out of cells in membranous vesicles (sacs) ATP needed to manipulate and move vesicles and cell Types (see next 3 slides for figures): Endocytosis Phagocytosis ( cell ea7ng ) Pinocytosis ( cell drinking ) Exocytosis Endocytosis Endocytosis cell takes in macromolecules by forming vesicles from the plasma reversal of exocytosis, involving different proteins Three types of endocytosis: 1. Phagocytosis ( cellular ea7ng ) 2. Pinocytosis ( cellular drinking ) 3. Receptor- mediated endocytosis Pinocytosis and Receptor Mediated Endocytosis RECEPTOR-MEDIATED ENDOCYTOSIS Receptor Coat protein Coated vesicle Coated pit Ligand Fig. 7-20b Coat protein A coated pit and a coated vesicle formed during receptor- mediated endocytosis (TEMs) PINOCYTOSIS Plasma Plasma 0.5 µm 0.25 µm Vesicle Pinocytosis vesicles forming (arrows) in a cell lining a small blood vessel (TEM) 7

8 Exocytosis 8