Organelles of the Cell & How They Work Together. Packet #7

Transcription

1 Organelles of the Cell & How They Work Together Packet #7

2 Introduction

3 Introduction Organization of cells is basically similar in all cells. Additionally, most cells are tiny Ranging from cubic micrometers in volume. Cells are typically small because of the relationship between surface area and volume. The multiple small cells must be able to support an entire living {large} organism.

4 Organelles of the Cell Nucleus

5 Nucleus Large structure surrounded by double membrane. Contains nucleous and chromosomes. Processes occurring within the nucleus Cell Cycle Meiosis DNA Replication Transcription

6 Nucleus Nucleous Granular body within nucleus RNA and proteins are found within the nucleous Processes occurring within the nucleous: - rrna production Ribosome assembly.

7 Nucleus Chromosomes Composed of complex DNA and protein known as chromatin. Contain genes that govern structure and activity of cell. More to come later.

8 Nucleus Nuclear Envelope Controls traffic between the nucleus and the cytoplasm. Pores in the nuclear membrane allow materials to pass in and out of the nucleus.

9 Organelles of the Cytoplasm

10 Plasma Membrane Encloses cell content Regulates movement of materials in and out of cell Helps maintain cell shape Allows communication with other cells.

11 Endoplasmic Reticulum Major manufacturing center. Network of internal membranes extending through cytoplasm. Synthesizes lipids and proteins Origin of intracellular transport vesicles that carry proteins.

12 Smooth Endoplasmic Reticulum Lacks ribosomes on outer surface. Lipids are produced at the smooth endoplasmic reticulum. Involved in drug detox SER produces detoxifying chemicals.

13 Rough Endoplasmic Reticulum Ribosomes are found on the surface The ribosomes, found on the rough ER, are manufacturing proteins destined for secretion or for incorporation into membranes. Translation

14 Ribosomes Granules composed of RNA and protein Some may attach to ER {forming the RER} while others float free in the cytosol Used in synthesis of polypeptides (proteins) once attached to ER.

15 Golgi Apparatus Stacks of flattened membrane sacs. Processes, sorts and modifies proteins. Packages secreted proteins arriving from rough endoplasmic reticulum. Processed product is passed to other organelles or to the plasma membrane. The Golgi complex also manufactures lysosomes.

16 Working Together

17 Lysosomes Compartments, in the form of membranous sacs, that are used for digestion. Contain enzymes to break down ingested materials, secretions and wastes. Involved in apoptosis Programmed cell death. Inappropriate apoptosis may be involved in cancer, AIDS and Alzheimer s disease. Mutated genes allow for deformed lysosomes. Involved in the metamorphosis of amphibians and some human diseases Rheumatoid arthritis and Tay-Sachs disease.

18 Large fluid-filled membranous sacs that are mostly found in plant cells, cells of fungi and algae. Plant vacuoles allow cells to increase in size. Protist vacuoles are involved in digestion and excretion. Store materials, wastes, water and maintain hydrostatic pressure. Vacuoles

19 Peroxisomes Membranous sacs containing a variety of enzymes Site of many diverse metabolic chemical reactions Perform redox reactions That involve the making or splitting of hydrogen peroxide by the addition or removal of a hydrogen ion.

20 Transform energy originating from glucose, lipids or proteins into ATP. Mitochondria are double membrane bound. Involved in apoptosis by activating capsules. Mitochondria contain their own DNA and mutations in mitochondrial DNA have been linked to several genetic diseases. Mitochondria

21 Plastids {Chloroplasts} ATP and other energy-rich compounds are formed and then used to convert CO 2 to carbohydrate. Double membrane structure that encloses internal thykaloid membranes. Site of photosynthesis. Chlorophyll captures light energy. Chromoplasts contain pigments and are common in petals and ripe fruit.

22 Cytoplasm/Cytoskeleton

23 The cytoskeleton provides for cell shape and allows movement. Introduction

24 Microtubules Hollow tubes composed of subunits of tubulin protein. Provide structural support Play role in movement of cell and organelles. Play role in cell division.

25 Microfilaments Solid, rod like structures composed of actin protein. Provide structural support. Actin and myosin are the contractile units of muscle cells. Play role in cell and organelle movement and cell division.

26 Intermediate Filaments Tough fibers composed of proteins. Help strengthen cytoskeleton. Stabilizes cell shape.

27 Pair of hollow cylinders located near the nucleus Each centriole consists of nine microtubule triplets. (9 * 3 structure) Mitotic spindle {spindle apparatus} forms between centrioles during animal cell division. May anchor and organize microtubule formation in animal cells. Absent in most plant cells. Centrioles

28 Cilia Short projections extending from surface of cell covered by plasma membrane composed of microtubules. Used for movement in some unicellular organisms. Used to move materials on surface of some tissues.

29 Flagella Long projections made of peripheral microtubules. Extend from surface of cell covered by plasma membrane. Cell locomotion by sperm cells and some unicellular organisms.

30 Extracellular Matrix

31 Introduction Surround most cells. Most eukaryotic cells have a cell coat formed by molecules associated with the plasma membrane.

32 ECM & Animal Cells Animal cells have extracellular proteins. Collagen The main protein Fibronectin Organizes the ECM Integrins Membrane protein receptors

33 ECM, Plant Cells, Fungal Cells and Bacterial Cells All may have cellulosecontaining cell walls. Primary cell wall Expands as the cell grows. Secondary cell wall Formed between the primary cell wall and the cell membrane. Middle Lamella Glues adjacent plant cells together.

34 Review