* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 3 - WordPress.com
Survey
Document related concepts
Cell growth wikipedia , lookup
Tissue engineering wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell culture wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cellular differentiation wikipedia , lookup
Signal transduction wikipedia , lookup
Cell membrane wikipedia , lookup
Cell nucleus wikipedia , lookup
Cytokinesis wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Transcript
Cells and Tissues Preview Cells: Carry out all the chemical activities needed to sustain life. Tissues: provide for a division of labor among body cells. Cells Robert Hooke, “cells” in monastery Cube- like structures observed in cork. Smallest unit, or the building block, of all living things. Contain all the parts necessary to survive in a changing world. Trillions in the body Basics of Life Primarily made of 4 Elements Carbon, Oxygen, Hydrogen, Nitrogen Trace Elements are also very important Calcium- blood clotting Iron- hemoglobin Iodine- thyroid hormone Calcium, Sodium, Potassium- electrical charge (ionic form) Sodium and Potassium- Nerve impulses Basics of Life Cells are 60% water Interstitial fluid Dilute saltwater solution All exchanges between cells and blood Cells range widely in shape and size 2 micrometers-1 meter Vast difference in function and roles Generalized Cell Anatomy Although cell types vary, all cells do have the same basic parts and certain functions common to all cells. Nucleus Cytoplasm Plasma membrane The Nucleus “headquarters” or the “control center” Gene-containing Genetic material, deoxyribonucleic acid (DNA) Instructions for building proteins Necessary for cell reproduction Nuclear Envelope (membrane) A double membrane barrier that bounds the nucleus. Between the two membranes is a fluid-filled space Two layers fuse and Nuclear Pores penetrate through Nucleoplasm Jellylike fluid inside the nuclear membrane Place where other nuclear elements are suspended Nucleoli Usually 1 or more dark round stained bodies in the nucleus Sites where ribosomes are assembled Eventually migrate into the cytoplasm and serve as actual site of protein synthesis Chromatin When the cell is not dividing, its DNA combines with protein forming a loose network of bumpy threads that are scattered throughout the nucleus. When the cell divides, the chromatin threads coil and condense to form dense, rod-like bodies chromosomes Plasma Membrane Fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment. Phospholipids Cholesterol Hydrophobic Hydrophilic Microvilli Greatly increase cell’s surface area for absorbtion Plasma Membrane Tight Junctions Impermeable junctions the bind cells together into leakproof sheets Desmosomes Anchoring junctions that prevent cells subjected to mechanical stress from being pulled apart (skin cells) Gap Junctions Allow communication, chemicals can pass directly from one cell to another ( heart and between embryonic cells) Cytoplasm Material outside the nucleus and inside the plasma membrane. Cite of most cellular activities Cytosol- semitransparent fluid that suspends the other elements Organelles Metabolic machinery of the cell Inclusions Not functioning units, chemical substances that may/may not be present depending on specific cell type. ○ Most are stored nutrients or cell products (lipid droplets) Cytoplasmic Organelles “little organs” are specialized cellular compartments, each performing their own job to maintain the life of the cell. Many bound by a membrane Allows them to maintain an internal environment apart from surrounding cytosol Mitochondria Tiny threadlike organelle, they squirm, lengthen, and change shape almost continuously Wall is a double membrane=2 plasma membranes Outer is smooth Inner protrusions called Cristae Enzymes dissolved in mitochondria membrane form cristae membranes Carry out reactions where oxygen is used to break down foods. ATP in Mitochondria When foods are broken down, energy is released- as heat and ATP molecules. Provides energy for all cellular processes to take place All living cells require a constant supply “powerhouse” The more metabolic a cell is the more mitochondria they have and more ATP they use. (liver and muscle cells) Ribosomes Bilobed, dark bodies made of proteins and ribosomal RNA. The actual site of protein synthesis Some free-float in the cytoplasm and manufacture proteins that function in cytoplasm. Others attach to membranes, combination of ribosome and membrane is the rough endoplasmic reticulum. Endoplasmic Reticulum “network within the cytoplasm” A system of fluid-filled cisterns that coil and twist through the cytoplasm Mini-circulatory system for the cell; provides a network of channels for carrying substances (primary proteins) from one part of cell to another. 2 forms, not all cells have both Rough and Smooth Endoplasmic Reticulum Rough Endoplasmic Reticulum Studded with Ribosomes All of the building materials of the cellular membranes are formed either in or on the ER. “cells membrane factory” The proteins made on the RER fold into the tubules and are dispersed to other areas of the cell in the Transport vesicles. Smooth Endoplasmic Reticulum Plays no role in protein synthesis Lipid metabolism Cholesterol Fat synthesis and breakdown Detoxification of drugs and pesticides Liver cells and body cells that produce steroid-based hormones – have a large amount of Smooth ER. Golgi Apparatus “Traffic director” for cellular proteins Stack of flattened membranous sacs usually found close to the nucleus Modify and package proteins sent to it by the Rough ER via transport vesicles. Proteins that are ready for transport accumulate, the sacs swell. Sacs pinch off and form secretory vesicles. FIGURE 3.6 PAGE 69 Lysosomes “breakdown bodies”; cells demolition site Membranous pouches containing powerful digestive enzymes. Capable of digesting worn-out or nonusable cell structures and most foreign substances that enter the cell. Enzymes they contain are formed by ribosomes in the Golgi Apparatus Very abundant in the White Blood Cells. Peroxisomes Membranous sacs containing powerful oxidase enzymes that use molecular oxygen (O2) to detox a harmful or poisonous substances. Alcohol Formaldehyde Most important role is to “disarm” Free Radicals. (numerous in Liver and Kidney) Highly reactive chemicals with unpaired electrons that can scramble the structure of proteins and nucleic acids. ○ Convert free radicals to hydrogen peroxide (H2O2) which is then turned into water Cytoskeleton Elaborate network of protein structures extends throughout the cytoplasm. Acts as the cells “bones and muscles” Made up of the following: Intermediate filaments- stable ropelike help form desmosomes and provide internal guy wires to resist pulling forces on the cell. Microfilaments- (actin and myosin) involved in cell motility and in producing changes in cell shape Microtubules- determine the overall shape of a cell and the distribution of organelles. Centrioles Lying close to the nucleus, they are rodshaped bodies that lie at right angles to each other Internally made up of fine microtubules Cila- whip-like cellular extensions that move substances along the cell surface. Ciliated cells in respiratory system Flagella- projections formed by centrioles and substantially longer (tail-like) sperm