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Chapter 3Chapter 3
Cells and Tissue
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Learning Objectives
Identify 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.
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Learning 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.
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Learning 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.
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Chapter 3Lesson 3.1
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Size and ShapeSize and Shape Human cells vary considerably in size. All are microscopic. Cells differ notably in shape. Cytoplasm contains specialized organelles
surrounded by a plasma membrane.
Cytoplasm 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.
CompositionComposition
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CompositionComposition
GeneralCharacteristicsof the cell
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Plasma membrane forms outer boundary of cell only 7 nm (3/10,000,000 of an inch) thick thin two-layered membrane of phospholipids
containing proteins form the framework of the plasma membrane
is selectively permeable
Parts of the CellParts of the Cell
Cytoplasm internal living material of cells organelles—small structures that make up most of the
cytoplasmo Ribosomes: may attach to rough endoplasmic
reticulum (ER) or lie free in cytoplasm.
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Parts of the Cell (cont’d.)Parts of the Cell (cont’d.)
Endoplasmic reticulum (ER) network of connecting sacs and canals carries substances through cytoplasm
Golgi apparatus group of flattened sacs stacked on one another near
nucleus Mitochondria
composed of inner and outer membranes each contains one DNA molecule
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Parts of the Cell (cont’d.)Parts of the Cell (cont’d.) Lysosomes
membranous-walled organelles contain digestive enzymes
Centrioles paired organelles fine tubules that lie at right angles to each other near
the nucleus
Cilia fine hairlike extensions found on free or exposed
surfaces of some cells Flagellum
single projection extending from cell surfaces much larger than cilia
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Parts of the Cell (cont’d.)Parts of the Cell (cont’d.)
Nucleus controls every organelle in the cytoplasm,
along with cell reproduction contains the genetic code component structures include nuclear
envelope, nucleoplasm, and chromatin granules
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Relationship of Cell Structure and FunctionRelationship 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.
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Movement of Substances Through Cell MembranesMovement of Substances Through Cell Membranes
Passive transport processes processes do not require added energy and
result in movement “down a concentration gradient”
types of passive transport include: diffusion
o osmosis o dialysis
filtration
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Movement of Substances Through Cell Membranes (cont’d.)Movement of Substances Through Cell Membranes (cont’d.)
Passive Transport Processes
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Movement of Substances Through Cell Membranes (cont’d.)Movement of Substances Through Cell Membranes (cont’d.)
Passive transport processes Diffusion
Substances 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.
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Movement of Substances Through Cell Membranes (cont’d.)Movement of Substances Through Cell Membranes (cont’d.)
Passive transport processes Filtration
Movement 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.
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Movement of Substances Through Cell Membranes (cont’d.)Movement of Substances Through Cell Membranes (cont’d.)
Active transport processes occurs only in living cells movement of substances is “ against/up
the concentration gradient” requires energy from adenosine
triphosphate (ATP)
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Movement of Substances Through Cell Membranes (cont’d.)Movement of Substances Through Cell Membranes (cont’d.)
Active Transport Processes
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Movement of Substances Through Cell Membranes (cont’d.)Movement of Substances Through Cell Membranes (cont’d.)
Active transport processes Ion pumps
An 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 gradients
Phagocytosis and Pinocytosis Both 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.
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Chapter 3Lesson 3.2
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Cell ReproductionCell Reproduction
Mitosis the process of cell reproduction, one cell
divides to become two cells. tied closely to the production of proteins
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Cell Reproduction (cont’d.)Cell Reproduction (cont’d.)DNA Molecule and Genetic Information Chromosomes 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 or
C-G. Called complementary base pairing.
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Genetic CodeGenetic 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 gene
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Genetic Code (cont’d.)Genetic 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: ribose phosphate nitrogen bases: cytosine, guanine, adenine,
uracil
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Genetic Code (cont’d.)Genetic Code (cont’d.)
RNA Molecules and Protein Synthesis Transcription
Double-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.
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Genetic Code (cont’d.)Genetic Code (cont’d.)
Translation Involves synthesis of proteins in cytoplasm by
ribosome Requires use of information contained in mRNA
to direct the choice and sequencing of the building blocks called amino acids
As amino acids are assembled into proper sequence, a protein strand forms.
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Genetic Code (cont’d.)Genetic Code (cont’d.)
Protein synthesis
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Cell DivisionCell Division
Reproduction of cell by division of the nucleus (mitosis) and the cytoplasm
DNA Replication Process by which each half of a DNA
molecule becomes a whole molecule identical to the original DNA molecule
Happens before mitosis
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Cell Division (cont’d.)Cell Division (cont’d.)Mitosis Process in cell division in which identical chromosomes
(DNA molecules) to each new cell are formed when the original cell divides
Enables cells to reproduce their own kind
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Stages of MitosisStages 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.
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Stages of Mitosis (cont’d.)Stages of Mitosis (cont’d.)
Metaphase—second stage Nuclear envelope and nucleolus have
disappeared. Chromosomes align across center of cell. Spindle fibers attach themselves to each
chromatid.
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Stages of Mitosis (cont’d.)Stages of Mitosis (cont’d.)
Anaphase—third phase Centromeres 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 cells
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Stages of Mitosis (cont’d.)Stages of Mitosis (cont’d.)
Telophase—fourth stage Cell division is completed. Nuclei appear in daughter cells. Nuclear envelope and nucleoli appear. Cytoplasm and organelles divide equally. Daughter cells become fully functional.
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Chapter 3Lesson 3.3
Epithelial Tissue types
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TissuesTissuesEpithelial tissue
Covers body and lines body cavities Cells packed closely together with little matrix Classified by shape and arrangement of cells
Epithelial tissue types simple squamous epithelium
single layer of very thin, irregularly shaped cells transport is function (such as absorption of oxygen
into blood) located in alveoli of lungs, lining of blood, and
lymphatic vessels stratified squamous epithelium
several layers of closely packed cells protection is primary function
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Tissues (cont’d.)Tissues (cont’d.)Epithelial tissue types
Simple columnar epithelium Single layer of tall, narrow cells Contain mucus-producing goblet cells
Stratified transitional epithelium Up to 10 layers of roughly cuboidal-shaped cells that
distort to squamous shape when stretched Functions as protection Found in body areas subject to stress and that
stretch, such as urinary bladder Pseudostratified epithelium
Single layer of tall cells that wedge together to appear as if there are two or more layers
Simple cuboidal epithelium Form tubules specialized for secretory activity Usually form clusters called glands
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Tissues (cont’d.)Tissues (cont’d.)
Classificationof epithelialtissues
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Tissues (cont’d.)Tissues (cont’d.)
Connective tissue Most abundant tissue in body Most widely distributed tissue in body Multiple types, appearances, and functions Relatively few cells in intercellular matrix Types
Areolar—glue that holds organs together Adipose (fat)—lipid storage is primary function Fibrous—consists of strong, white collagen fibers
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Tissues (cont’d.)Tissues (cont’d.)Connective tissue types
Bone—matrix is hard and calcifiedo Forms structural building blocks called osteons o Function in support and protection, stores calcium
Cartilage—chondrocyte is cell typeo Differs from bone because its matrix has the consistency of a firm plastic or gristle-like gel
Blood and Hemopoietic o Blood—matrix is fluido Hemopoietic—bloodlike connective tissue found in marrow cavities
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Tissues (cont’d.)Tissues (cont’d.)
Muscle tissue Types
Skeletal—also called striated or voluntaryo attaches to boneso control is voluntaryo striations apparent when viewed under a microscope
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Tissues (cont’d.)Tissues (cont’d.)
Muscle tissue types Cardiac—also called striated involuntary
o produces regular, involuntary contractions of cardiac muscle to produce heartbeato has faint cross striations and thicker dark bands called intercalated disks
Smooth—also called visceralo involuntary controlo appears smooth; without cross striationso has only one nucleus per fibero forms walls of blood vessels, hollow organs such as intestines and other tube-shaped structures
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Tissues (cont’d.)Tissues (cont’d.)
Nervous tissue Provides rapid communication between body
structures and control of body functions Example is spinal cord tissue Consists of two cell types: neuron and glia
Glia (neuroglia)—supportive and connecting cells
Neurons—conducting cell