2Learning ObjectivesIdentify and discuss the basic structure and function of the three major components of a cell.List and briefly discuss the functions of the primary cellular organelles.Compare the major passive and active transport processes that act to move substances through cell membranes.
3Learning Objectives (cont’d.) Compare and discuss DNA and RNA and their function in protein synthesis.Discuss the stages of mitosis and explain the importance of cellular reproduction.
4Learning Objectives (cont’d.) Explain how epithelial tissue is grouped according to shape and arrangement of cells.List and briefly discuss the major types of connective and muscle tissue.List the three structural components of a neuron.
6Size and Shape Composition Human cells vary considerably in size. All are microscopic.Cells differ notably in shape.Cytoplasm contains specialized organelles surrounded by a plasma membrane.CompositionCytoplasm contains specialized organelles.Plasma membrane surrounds each cell.Organization of cytoplasmic substances is important for life.The small, circular body called the nucleus is inside the cell.An ovum has a diameter of 150 micrometers.A red blood cell has a diameter of 7.5 micrometer.What are some of the shapes of different cell types?
7Composition General Characteristics of the cell Ask students to cite the functions of specific cell parts.What are the three parts of a cell?
8Parts of the Cell Plasma membrane forms outer boundary of cell only 7 nm (3/10,000,000 of an inch) thickthin two-layered membrane of phospholipids containing proteins form the framework of the plasma membraneis selectively permeableCytoplasminternal living material of cellsorganelles—small structures that make up most of the cytoplasmRibosomes: may attach to rough endoplasmic reticulum (ER) or lie free in cytoplasm.What is cholesterol, and what is its function?What are some of the other functions of the plasma membrane?
9Parts of the Cell (cont’d.) Endoplasmic reticulum (ER)network of connecting sacs and canalscarries substances through cytoplasmGolgi apparatusgroup of flattened sacs stacked on one another near nucleusMitochondriacomposed of inner and outer membraneseach contains one DNA moleculeWhat are the two types of ER? How do they function?
10Parts of the Cell (cont’d.) Lysosomesmembranous-walled organellescontain digestive enzymesCentriolespaired organellesfine tubules that lie at right angles to each other near the nucleusCiliafine hairlike extensions found on free or exposed surfaces of some cellsFlagellumsingle projection extending from cell surfacesmuch larger than ciliaDescribe the protective function of lysosomes.What is the role that centrioles play during cell division?
11Parts of the Cell (cont’d.) Nucleuscontrols every organelle in the cytoplasm, along with cell reproductioncontains the genetic codecomponent structures include nuclear envelope, nucleoplasm, and chromatin granulesWhat is the genetic code?
12Relationship of Cell Structure and Function Regulation of life processes.Survival of species through reproduction of the individual.Relationship of structure to function is apparent in number and type of organelles seen in different cells.What are some examples of specialized organelles?
13Movement of Substances Through Cell Membranes Passive transport processesprocesses do not require added energy and result in movement “down a concentration gradient”types of passive transport include:diffusionosmosisdialysisfiltrationWhat are the two transport processes for moving substances into and out of cells? How are they different?
14Movement of Substances Through Cell Membranes (cont’d.) Passive Transport ProcessesTo form urine in the kidney, wastes are filtered out of the blood into the kidney tubules because of differences in hydrostatic pressure.
15Movement of Substances Through Cell Membranes (cont’d.) Passive transport processesDiffusionSubstances scatter themselves evenly throughout an available space.It is unnecessary to add energy to the system.Movement is from high to low concentration.Osmosis and dialysis are specialized examples of diffusion.What are osmosis and dialysis?What are solutes?
16Movement of Substances Through Cell Membranes (cont’d.) Passive transport processesFiltrationMovement of water and solutes through a membrane because of a greater pushing force on one side of the membrane than on the other.This force is called hydrostatic pressure.Responsible for urine formation.Give some additional examples of filtration.
17Movement of Substances Through Cell Membranes (cont’d.) Active transport processesoccurs only in living cellsmovement of substances is “ against/up the concentration gradient”requires energy from adenosine triphosphate (ATP)What is adenosine triphosphate (ATP)?
18Movement of Substances Through Cell Membranes (cont’d.) Active Transport Processes
19Movement of Substances Through Cell Membranes (cont’d.) Active transport processesIon pumpsAn ion pump is protein complex in cell membrane called a carrier.Ion pumps use energy from ATP to move substances across cell membranes against their concentration gradientsPhagocytosis and PinocytosisBoth are active transport mechanisms because they require cell energy.Phagocytosis is a protective mechanism often used to destroy bacteria.Pinocytosis is used to incorporate fluids or dissolved substances into cells.
21Cell Reproduction Mitosis the process of cell reproduction, one cell divides to become two cells.tied closely to the production of proteinsWhat molecules play a crucial role in protein synthesis and mitosis? (DNA and RNA)
22Cell Reproduction (cont’d.) DNA Molecule and Genetic InformationChromosomes are composed largely of DNA.DNA shaped like a long, narrow spiral staircase.Each step in the DNA ladder consists of pair of bases.Only two combinations of bases will occur A-T orC-G.Called complementary base pairing.What are the components of DNA? (Sugar, phosphate, nitrogen bases)What are the base pairs? (adenine–thymine and guanine-cytosine)
23Genetic Code DNA Molecule and Genetic Information Genes dictate formation of enzymes and other proteins by ribosomes.Although the types of base pairs in all chromosomes are the same, the sequence varies.Each gene directs the synthesis of a specific protein.Genetic code—the storage of information in each geneHow many chromosomes are in human body cells? (46)
24Genetic Code (cont’d.) RNA Molecules and Protein Synthesis Ribonucleic acid (RNA) transfers genetic information from the nucleus to the cytoplasm.RNA is made up of:sugar: ribosephosphatenitrogen bases: cytosine, guanine, adenine, uracilWhere does protein synthesis occur?
25Genetic Code (cont’d.) RNA Molecules and Protein Synthesis TranscriptionDouble-stranded DNA separates to form messenger RNA (mRNA).Each strand of mRNA duplicates a particular gene (base-pair sequence) from a segment of DNA.mRNA molecules pass from the nucleus to the cytoplasm where they direct protein synthesis in ribosomes and ER.
26Genetic Code (cont’d.) Translation Involves synthesis of proteins in cytoplasm by ribosomeRequires use of information contained in mRNA to direct the choice and sequencing of the building blocks called amino acidsAs amino acids are assembled into proper sequence, a protein strand forms.What happens after the protein strand is formed?
27Genetic Code (cont’d.) Protein synthesis Go through the steps of transcription and translation as shown in the figure.
28Cell DivisionReproduction of cell by division of the nucleus (mitosis) and the cytoplasmDNA ReplicationProcess by which each half of a DNA molecule becomes a whole molecule identical to the original DNA moleculeHappens before mitosisWhat is interphase?
29Cell Division (cont’d.) MitosisProcess in cell division in which identical chromosomes (DNA molecules) to each new cell are formed when the original cell dividesEnables cells to reproduce their own kindName the four stages of mitosis. (prophase, metaphase, anaphase, telophase)
30Stages of Mitosis Prophase—first stage Chromatin granules become organized.Chromosomes (pairs of linked chromatids) appear.Chromatids are held together by beadlike structure called centromere.Centrioles move away from each other.Spindle fibers form between centrioles.Nuclear envelope disappears, freeing genetic material.
31Stages of Mitosis (cont’d.) Metaphase—second stageNuclear envelope and nucleolus have disappeared.Chromosomes align across center of cell.Spindle fibers attach themselves to each chromatid.What do spindle fibers resemble?
32Stages of Mitosis (cont’d.) Anaphase—third phaseCentromeres break apart.Separated chromatids are now called chromosomes once again.Chromosomes are pulled to opposite ends of cell.Cleavage furrow develops at end of anaphase.Beginning to divide cell into two daughter cellsDaughter cells have identical genetic characteristics. Each may later undergo mitosis.
33Stages of Mitosis (cont’d.) Telophase—fourth stageCell division is completed.Nuclei appear in daughter cells.Nuclear envelope and nucleoli appear.Cytoplasm and organelles divide equally.Daughter cells become fully functional.What are the results of cell division?Discuss neoplasm
35Tissues Epithelial tissue Covers body and lines body cavities Cells packed closely together with little matrixClassified by shape and arrangement of cellsEpithelial tissue typessimple squamous epitheliumsingle layer of very thin, irregularly shaped cellstransport is function (such as absorption of oxygen into blood)located in alveoli of lungs, lining of blood, and lymphatic vesselsstratified squamous epitheliumseveral layers of closely packed cellsprotection is primary functionWhat are the four shapes of epithelial cells?In what ways can they be arranged?
36Tissues (cont’d.) Epithelial tissue types Simple columnar epithelium Single layer of tall, narrow cellsContain mucus-producing goblet cellsStratified transitional epitheliumUp to 10 layers of roughly cuboidal-shaped cells that distort to squamous shape when stretchedFunctions as protectionFound in body areas subject to stress and that stretch, such as urinary bladderPseudostratified epitheliumSingle layer of tall cells that wedge together to appear as if there are two or more layersSimple cuboidal epitheliumForm tubules specialized for secretory activityUsually form clusters called glandsWhat is the special function of simple columnar epithelium?Where can these cells be found?
38Tissues (cont’d.) Connective tissue Most abundant tissue in body Most widely distributed tissue in bodyMultiple types, appearances, and functionsRelatively few cells in intercellular matrixTypesAreolar—glue that holds organs togetherAdipose (fat)—lipid storage is primary functionFibrous—consists of strong, white collagen fibersWhere is connective tissue found?
39Tissues (cont’d.) Connective tissue types Bone—matrix is hard and calcifiedForms structural building blocks called osteonsFunction in support and protection, stores calciumCartilage—chondrocyte is cell typeDiffers from bone because its matrix has the consistency of a firm plastic or gristle-like gelBlood and HemopoieticBlood—matrix is fluidHemopoietic—bloodlike connective tissue found in marrow cavitiesOsteons are also called Haversian systems.What is the function of hemopoietic tissue?
40Tissues (cont’d.) Muscle tissue Types Skeletal—also called striated or voluntaryattaches to bonescontrol is voluntarystriations apparent when viewed under a microscopeDescribe the structure and distinctive traits of skeletal muscle cells.
41Tissues (cont’d.) Muscle tissue types Cardiac—also called striated involuntaryproduces regular, involuntary contractions of cardiac muscle to produce heartbeathas faint cross striations and thicker dark bands called intercalated disksSmooth—also called visceralinvoluntary controlappears smooth; without cross striationshas only one nucleus per fiberforms walls of blood vessels, hollow organs such as intestines and other tube-shaped structuresGive some examples of smooth muscles. (digestive tract, respiratory tubes)
42Tissues (cont’d.) Nervous tissue Provides rapid communication between body structures and control of body functionsExample is spinal cord tissueConsists of two cell types: neuron and gliaGlia (neuroglia)—supportive and connecting cellsNeurons—conducting cellGive a general description of a neuron.What does an axon do?What does a dendrite do?