Chapter 10 Cells and Tissue Form PDF

Morris Hartl Knoll Lue Michael Heitz Hens Lozovsky Merrill Phillis Pires Liu Biology: How Life Works Active Lecture Slides Chapter 10 Cell and Tissue Form Copyright © Macmillan Learning Loyola University Maryland Internal...

Morris Hartl Knoll Lue Michael Heitz Hens Lozovsky Merrill Phillis Pires Liu Biology: How Life Works Active Lecture Slides Chapter 10 Cell and Tissue Form Copyright © Macmillan Learning Loyola University Maryland Internal Use Only  Chapter 10 Cell and Tissue Form Loyola University Maryland Internal Use Only  In multicellular organisms... Cells come together in COMMUNITIES! Community members… – Each have special roles – Communicate with one another for optimum efficiency – Come together as a whole This chapter begins that exploration of cells coming together! …and of course, cellular structure plays an important role in… Loyola University Maryland Internal Use Only Cells come together to form tissues A tissue is a collection of cells that have structure that allows them to work together to perform a specific function The shape of cells and organs reflects their function Loyola University Maryland Internal Use Only How cells are organized into tissues Cells are organized internally by the cytoskeleton. The cytoskeleton can also connect cells to external structures Cells are connected and communicate through cell junctions The extracellular matrix between cells provides structural support and helps with communication The ECM may include the basal lamina, a structure that lies below and provides structure for layers of cells (epithelial tissues have this) Loyola University Maryland Internal Use Only Tissues come together to form organs Two or more tissues combine and function together to make up an organ Organs perform a major function (ie: respiratory organ system) Loyola University Maryland Internal Use Only  The cytoskeleton, cell junctions, and the extracellular matrix all contribute to… the shape of cells the integrity* of tissues and organs the function of tissues and organs * Refers to the intact condition of the tissue or organ Loyola University Maryland Internal Use Only CYTOSKELETON Loyola University Maryland Internal Use Only  Cytoskeleton Structure: Formed from long chains of protein subunits joined together (they are polymers!) General Function: Provides internal structural support and enables movement of substances within the cell Loyola University Maryland Internal Use Only  Cytoskeleton consists of 3 types of cytoskeletal elements Intermediate Microfilaments filaments Microtubules Loyola University Maryland Internal Use Only  Microfilaments Structure: Actin monomers Short, thin double helix Extensively branched just beneath cell membrane Loyola University Maryland Internal Use Only  Microfilaments Functions (is involved in): Supports cell shape Transport of materials inside cells (transport of vesicles) Contraction of muscle cells Cell division Cell movement (crawling) Loyola University Maryland Internal Use Only Microfilaments shown in the cytoplasm and nucleus involved in cell shape and structure Loyola University Maryland Internal Use Only Microfilaments supporting the cell shape of microvilli in the human small intestine Loyola University Maryland Internal Use Only Microfilaments involved in the transport of vesicles (with “cargo”) in the cell Vesicle with “cargo” Figure not in text Microfilament Loyola University Maryland Internal Use Only  Microfilaments involved in the contraction of muscle cells in humans Figures not in text Loyola University Maryland Internal Use Only Microfilaments involved in cell division in humans and many other organisms Figure not in text Loyola University Maryland Internal Use Only  Microfilaments involved in crawling movement in some organisms (amoeba) Cortex (outer cytoplasm): gel with actin network 100 μm Inner cytoplasm (more fluid) Extending pseudopodium (b) Amoeboid movement Figure not in text Loyola University Maryland Internal Use Only  Intermediate Filaments Structure: Made up of different proteins depending on the cell type Function (involved in): Provide mechanical strength to the cell, therefore… Cell (and tissue) shape and support Loyola University Maryland Internal Use Only Example: Intermediate filaments linking cells together in human skin (providing cell and tissue shape and support) Loyola University Maryland Internal Use Only  Genetic defects in genes to make those intermediate filaments can cause disease Fragile skin that easily blisters Loyola University Maryland Internal Use Only Microtubules Structure: Hollow tube of tubulin dimers Loyola University Maryland Internal Use Only Microtubules Functions (involved in): Cell shape and support Hold cell’s organelles in place Transport of materials inside cells (transport of vesicles) Cell movement (cilia and flagella) Movement of chromosomes during cell division Loyola University Maryland Internal Use Only  Microtubules shown in the cytoplasm and nucleus involved in cell shape and structure Figure not in text Cells are stained for microtubules Loyola University Maryland Internal Use Only  Microtubules involved in holding organelles in place Figure not in text Cells are stained for microtubules Loyola University Maryland Internal Use Only Microtubules involved in the transport of vesicles (with “cargo”) in the cell Vesicle with “cargo” Figure not in text Microtubule Loyola University Maryland Internal Use Only  Microtubules involved in cell or fluid movement using cilia or flagella in eukaryotic cells Loyola University Maryland Internal Use Only  Microtubules involved in the movement of chromosomes in cell division of eukaryotic cells Figure in CH11 (Cell is dividing) Chromosomes are BLUE Microtubules are GREEN Loyola University Maryland Internal Use Only  Microtubules and Microfilaments are dynamic structures Undergo polymerization (adding subunits) and depolymerization (losing subunits) Ex. In cell division go through rapid cycles of shortening followed by slower growth (dynamic instability) Loyola University Maryland Internal Use Only Dynamic Instability of Microtubules Loyola University Maryland Internal Use Only Motor proteins contribute to movement within the cell Motor proteins use microtubules and microfilaments as tracks to transport materials (ex. Vesicles carrying “cargo”) within a cell Ex. Kinesin and dynein move materials to and from regions in the cell Loyola University Maryland Internal Use Only  Motor proteins contribute to movement within the cell Ex. A different motor protein, myosin is used in muscle contraction Loyola University Maryland Internal Use Only  Nice summary of cytoskeletal elements (next slide) Need to know… What they are What protein subunits they consist of What their major functions are Loyola University Maryland Internal Use Only Loyola University Maryland Internal Use Only CELL ADHESION MOLECULES AND CELL JUNCTIONS Loyola University Maryland Internal Use Only  Cell adhesion molecules allow cells to attach to other cells and to the extracellular matrix (ECM is the next topic) Cadherins (cell adhesion molecule) binds adjacent cells Used in 2 of the types of the types of cell junctions Loyola University Maryland Internal Use Only  Cell adhesion molecules allow cells to attach to other cells and to the extracellular matrix (ECM is the next topic) Integrins provide a way for cells to attach to the extracellular matrix in 1 of the types of cell junctions The association is important for tissues under physical stress (such as skin) Loyola University Maryland Internal Use Only  Examples of cell adhesion molecules at work: 2 Sponges Loyola University Maryland Internal Use Only  Examples of cell adhesion molecules at work: 2 regions of an amphibian embryo Loyola University Maryland Internal Use Only  Cell Junctions Cell junctions connect cells to other cells or tissues and are reinforced by the cytoskeleton Loyola University Maryland Internal Use Only Types and Roles of Cell Junctions Anchoring Adherens junction Desmosome Hemidesmosome Barrier Tight junction Communicating Gap junction (animals) Plasmodesmata (plants) Loyola University Maryland Internal Use Only  Anchoring Cell Junctions Adherens junction Desmosome Hemidesmosome Allow for the attachment of cells to cells and to the ECM Loyola University Maryland Internal Use Only Adherens Junctions Location of cadherin cell adhesion molecules Attach cell to cell Loyola University Maryland Internal Use Only Desmosomes Location of “button-like” grouping of cadherin cell adhesion molecules Attach cell to cell Loyola University Maryland Internal Use Only Hemidesmosomes Location of “button-like” grouping of integrin cell adhesion molecules Attach skin cells to a “base layer” Loyola University Maryland Internal Use Only  Barrier Cell Junctions Tight junction Creates a seal/barrier between cells Prevents substances from moving in between cells Loyola University Maryland Internal Use Only  Tight Junctions Have special proteins that create a seal between cells Loyola University Maryland Internal Use Only Communicating Cell Junctions Gap junction (animals) Plasmodesmata (plants) Allow for… (You probably guessed it!) Loyola University Maryland Internal Use Only  Gap Junctions and Plasmodesmata Gap junctions allow two cells to communicate through joined rings of proteins Plasmodesmata connect two plant cells via Plasmodesmata—Plant Cell channels that can cross Plasmodesmata are connections the cell wall. Thus, cell between two membranes and plant cells that cross the cell cytoplasm of 2 cells wall and membrane continuous Loyola University Maryland Internal Use Only  Nice summary of cell junctions (next slide) Need to know… What they are What cytoskeletal structure they interact with What their general and primary functions Loyola University Maryland Internal Use Only Loyola University Maryland Internal Use Only EXTRACELLULAR MATRIX Loyola University Maryland Internal Use Only  Extracellular Matrix (ECM) Outside of the cellular membrane Structure and function depends on the organism ECM Inside of the cell Figure not in text Loyola University Maryland Internal Use Only Plant Extracellular Matrix (ECM) Cell Wall Outside of the cellular membrane Mostly cellulose Structure of the cell Support of the organism Barrier to infection Other roles too! Loyola University Maryland Internal Use Only  Animal Extracellular Matrix (ECM) Insoluble meshwork composed of proteins and polysaccharides that provides structural support and informational cues for cells ECM Inside of the cell Figure not in text Loyola University Maryland Internal Use Only  Animal Extracellular Matrix (ECM) Abundant in animal connective tissue Lots of collagen (protein) Collagen makes up >25% of the protein in the human body Loyola University Maryland Internal Use Only  Collagen is a great example of structure and function Twisted coils of protein like a braided rope used in rock climbing Much stronger than a solid coil! Loyola University Maryland Internal Use Only Basal lamina is a specialized layer of ECM underneath epithelial tissue Collagen in the basal lamina provides flexible support Loyola University Maryland Internal Use Only The Extracellular Matrix and Cancer Cancer is metastatic when tumor cells escape the tumor and move to another spot on the body This involves crossing the extracellular matrix and basal lamina Loyola University Maryland Internal Use Only The Extracellular Matrix and Cancer Cell adhesion molecules (integrins) help the cancer cells cross the basal lamina Drugs targeting the integrins are in clinical trials Loyola University Maryland Internal Use Only  The Extracellular Matrix’s Influence on Cell Shape The surface where cells grow and attach to has a significant effect on cell shape Cells grown on glass Cells grown in liquid Loyola University Maryland Internal Use Only