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CELL STRUCTURE AND FUNCTION PART 2: Cytoplasm and Organelles.

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Presentation on theme: "CELL STRUCTURE AND FUNCTION PART 2: Cytoplasm and Organelles."— Presentation transcript:

1 CELL STRUCTURE AND FUNCTION PART 2: Cytoplasm and Organelles

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3 Cytoplasm: internal contents of cell Cytoplasm = cytosol + organelles + inclusions --Masses/aggregations of molecules not surrounded by membranes -- specialized structures w/ specific functions -- Division of labor and compartmentalization Where most cellular activity occurs -- Liquidy/syrupy-like -- H 2 O + dissolved molecules & ions

4 Organelles: Non-membrane Bound ribosomes Centrioles/centrosomes Cytoskeleton proteosomes Cilia—discussed later Microvilli—discussed later Membrane Bound nucleus Endoplasmic Reticulum Golgi Apparatus vessicles lysosomes peroxisomes mitochondria There are two categories of organelles:

5 Organelle membranes Membrane = phospholipid bilayer + embedded proteins Selectively permeable membrane Separates/isolates the contents or processes of the organelle from the general cytoplasm. Allows interactions and regulation due to membrane receptors, enzymes, anchors, and transporters

6 Organelles the build/synthesize Free Ribosomes sER rER w/ fixed ribosomes mitochondria Golgi apparatus Proteins for use in cytosol (cytoplasm) Proteins for use in a membrane or release from cell Creates peroxisomes Lipids, e.g. phospholipids (and possibly carbs) Alters/modifies products of ER Makes lysosomes ATP & CO2

7 Organelles the break things down lysosomes Peroxisomes Proteosomes mitochondria Waste, ingested macromolecules, & pathogens many proteins, polysaccharides, lipids, nucleic acids 30+ enzymes lipids & toxins/harmful substances Different enzymes than lysosomes Proteins Nutrients & O2

8 Organelles the support/connect and transport Vesicles Cytoskeleton (microtubules, microfilaments, intermediate filaments) Cell shape Cell movement Attachement point for organelles Transport routes Transport within cell. Transport to and from the PM “Delivery packages”

9 Cytoskeleton = microtubules, microfilaments + intermediate filaments Proteins based Gives cell shape Provides support/strength Cell movement (or shape change) Holds internal structures in place “railway” for internal transport

10 Ribosomes: Make/produce/synthesize proteins Free –Floating in cytosol –Make proteins for cell’s own use Fixed –Bound to the endoplasmic reticulum –Make proteins for release or incorporation into a membrane Ribosome (The non-purple parts are the protein being made from an RNA molecule). ribosome + RNA + amino acids  proteins

11 proteosomes Breaks down certain types of proteins (w/ enzymes) –Not the only structure that breaks down proteins Proteins in  protein fragments out

12 vessicles Transport materials within cell and transport materials to and from the PM

13 Endoplasmic reticulum (ER) rER = ER with ribosomes attached –Produces proteins for release from –Produce proteins that are part of membrane and/or lysosomes sER –create lipids (e.g, phospholipids, cholesterol, & steroid-based hormones) –storing certain types of lipids –in liver and kidney cells detoxification or inactivation of drugs or foreign molecules (in liver and kidney) –creating and storing glycogen (e.g., liver and skeletal muscle cells)

14 Golgi apparatus (body) Modify proteins & glycoproteins sort proteins and glycoproteins Send vesicles to the plasma membrane More membrane & adding membrane proteins/altering membrane protein composistion. From ER

15 lysosomes Created by golgi Destroy/breakdown molecules, foreign matter (pathogens), and organelles purposeful self-destruction of cells,

16 mitochondria Produce ATP through breakdown of O2 and nutrients Nutrients (e.g., glucose) + O 2  CO 2 + H ATP + heat Two membranes (double membrane) Own DNA Semi-autonomous nutrients O2O2 ATP CO 2

17 peroxisomes Breakdown of wastes and other accumulating materials –Especially fatty acids & hydrogen peroxide (H2O2 ) NOT created by golgi

18 Nucleus Contains and protects DNA Ribosome parts are created here RNA created here Surrounded by nuclear membrane (envelope) Two membranes (double membrane) Nuclear pores regulate permeability (transport into/out of) DNA

19 19 Protein Flow through the Golgi Apparatus

20 20 Protein Flow through the Golgi Apparatus 1.Proteins synthesized in RER get packaged into transport vesicles 2.Transport vesicles pinch off from RER and fuse with the receiving cis-face of the Golgi apparatus 3.The proteins move between the cisternae of the Golgi apparatus and become modified in the cisternae 4.Modified proteins are then packaged in secretory vesicles 5.Secretory vesicles will either participate in exocytosis or become lysosomes within the cell

21 Endomembrane System and Membrane Flow: Proteins and membranes move or “flow” from one organelle to another and too and/or from the PM. This is called membrane flow. Any membrane that is involved with this process is part of the endomembrane system.

22 Endomembrane System and Membrane Flow: Organelles and internalized vessicles

23 Cell Differentiation Our description of cells was/has been of a ‘generic’ cell. Most cells have most of the components discussed Specialized cells have a combination of cell features unique to their function. The specialized (differentiated) cells of our body are different in their: 1.The DNA they use and proteins they make (and/or use) 2.Shape 3.Organelle composition

24 Differentiated Cells: Note the shape differences between these cells: Long thin neurons Flat sheet of epithelial cells Tightly packed muscle cells

25 More detailed descriptions of organelles For your reference out of class Also see the summary/description posted on the website

26 Organelle Based Disorders: i.e., organelles matter Leber's hereditary optic neuropathy –blindness due to mutation in and dysfunction of mitochondria (leads to death of ganglion cells of retina and/or optic nerve).Leber's hereditary optic neuropathy Mitochondrial Myopathy: malfunctioning muscle tissue (skeletal or cardiac) causing, pain, weakness and disfunction of affected organ. Mitochondrial Neuropathies affect nervous system. Tay-Sachs Disease (Lysosomes)—build up of glycoproteins cause congnative/mental decline or lack of development and progress loss of motor function Pompe’s Disease/Glycogen storage disorders (lysosomes) can’t break down glycogen progressive muscle weakness at glycogen builds up— deadly when involved heart. Lipid storage disorders (lysosome)—can’t break down various lipids causes progressive disfunction of Brain, PNS, liver, spleen, and bone marrow Peroxisomes: X-linked adrenoleukodystrophy (ALD) Peroxisimes: Zellweger syndrome enlarged liver, iron and copper levels are high, jaundice, vision problems including glaucoma, muscle weaknessZellweger syndrome


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