Cells and Tissues

Cells and Tissues Standards SAP1. Students will analyze anatomical structures in relationship to their physiological functions. d. Relate cellular metabolism and transport to homeostasis and cellular reproduction. e. Describe how structure and function are related in terms of cell and tissue types.

Cells and Tissues Carry out all chemical activities needed to sustain life Cells are the building blocks of all living things Tissues are groups of cells that are similar in structure and function

Anatomy of the Cell Cells are not all the same All cells share general structures Cells are organized into three main regions Nucleus Cytoplasm Plasma membrane Figure 3.1a

The Nucleus Control center of the cell Contains genetic material (DNA) Three regions Nuclear membrane Nucleolus Chromatin Figure 3.1b

Nuclear Membrane Barrier of nucleus Consists of a double phospholipid membrane Contain nuclear pores that allow for exchange of material with the rest of the cell

Nucleoli Nucleus contains one or more nucleoli Sites of ribosome production Ribosomes then migrate to the cytoplasm through nuclear pores

Chromatin Composed of DNA and protein Scattered throughout the nucleus Chromatin condenses to form chromosomes when the cell divides

Plasma Membrane Barrier for cell contents Phospholipid Bi-layer Hydrophilic heads Hydrophobic tails Also contains proteins, cholesterol, glycolipids, and glycoproteins

Plasma Membrane Figure 3.2

Functions of the Membrane(s) Signaling Barrier Transport Localization of function Cell to cell communication

Signaling Membranes detect & respond to external signals Transmit them into the cell Which structure(s) in the membrane is responsible for signaling?

Barrier Membranes provide a barrier to entry of water soluble molecules. Non-polar, hydrophobic lipid tails are responsible for the barrier function.

Barrier Things that can cross: Small, non-polar molecules Gases- CO2, O2, NO, CO, others Steroids Things that can not cross: Charged particles: ions Na+, Cl-, K+, Ca2+ Large molecules- proteins, glucose

Transport Membranes are selectively permeable Some things can cross others can not Molecules that can not diffuse through the membrane must be TRANSPORTED. Transport proteins- act as carriers or channels Control movement into/out of the cell

Localization of function Compartmentalization- membranes create physical barriers to separate cell functions Allows cells to isolate chemical reactions Create concentration gradients

Cell-to-Cell Communication Membranes provide contacts between cells Mediate communication through receptors

Journal Why is the plasma membrane important for cell function and homeostasis?

Learning Goals Describe the structure of the plasma membrane. Describe the function of the plasma membrane and its parts. Understand Passive and Active Transport mechanisms. Understand why the plasma membrane is important for homeostasis.

Plasma Membrane Barrier for cell contents Double phospholipid layer Hydrophilic heads Hydrophobic tails Also contains protein, cholesterol, and glycoproteins PRESS TO PLAY MEMBRANE STRUCTURE ANIMATION

Plasma Membrane Figure 3.2

Cellular Physiology: Membrane Transport Membrane Transport – movement of substance into and out of the cell Transport is by two basic methods Passive transport No energy is required Active transport The cell must provide metabolic energy

Solutions and Transport Solution – homogeneous mixture of two or more components Solvent – dissolving medium Solutes – components in smaller quantities within a solution Intracellular fluid – nucleoplasm and cytosol Interstitial fluid – fluid on the exterior of the cell

Selective Permeability The plasma membrane allows some materials to pass while excluding others This permeability includes movement into and out of the cell

Passive Transport Processes Diffusion Particles tend to distribute themselves evenly within a solution Movement is from high concentration to low concentration, or down a concentration gradient PRESS TO PLAY DIFFUSION ANIMATION Figure 3.9

Passive Transport Processes Types of diffusion Simple diffusion Unassisted process Solutes are lipid-soluble materials or small enough to pass through membrane pores Non-polar, cholesterol, steroid hormones, small lipids

Passive Transport Processes Types of diffusion Osmosis – simple diffusion of water Highly polar water can cross the plasma membrane Facilitated diffusion Substances require a protein carrier for passive transport

Diffusion through the Plasma Membrane Figure 3.10

Passive Transport Processes Filtration Water and solutes are forced through a membrane by fluid, or hydrostatic pressure A pressure gradient must exist Solute-containing fluid is pushed from a high pressure area to a lower pressure area

Journal What is a concentration gradient? What property of the cell membrane allows cells to create gradients?

Active Transport Processes Transport substances that are unable to pass by diffusion They may be too large They may not be able to dissolve in the fat core of the membrane They may have to move against a concentration gradient Two common forms of active transport Solute pumping Bulk transport

Active Transport Processes Solute pumping Amino acids, some sugars and ions are transported by solute pumps ATP energizes protein carriers, and in most cases, moves substances against concentration gradients PRESS TO PLAY ACTIVE TRANSPORT ANIMATION

Active Transport Processes Figure 3.11

Active Transport Processes Bulk transport Exocytosis Moves materials out of the cell Material is carried in a membranous vesicle Vesicle migrates to plasma membrane Vesicle combines with plasma membrane Material is emptied to the outside

Exocytosis Figure 3.12a

Active Transport Processes Bulk transport Endocytosis Extracellular substances are engulfed by being enclosed in a membranous vesicle Types of endocytosis Phagocytosis – cell eating Pinocytosis – cell drinking

Endocytosis Figure 3.13a

Journal Explain how the cell membrane plays a role in the transportation of substances in and out of the cell.

Journal Which mechanism of membrane transport is the most important? Why?

Georgia Performance Standards SAP1. Students will analyze anatomical structures in relationship to their physiological functions. d. Relate cellular metabolism and transport to homeostasis and cellular reproduction. e. Describe how structure and function are related in terms of cell and tissue types.

Plasma Membrane Specializations Microvilli Finger-like projections that increase surface area for absorption Figure 3.3

Plasma Membrane Specializations Membrane junctions Tight junctions Desmosomes Gap junctions Figure 3.3

Cytoplasm Material outside the nucleus and inside the plasma membrane Cytosol Fluid that suspends other elements Organelles Metabolic machinery of the cell Inclusions Non-functioning units

Cytoplasmic Organelles Figure 3.4

Cytoplasmic Organelles Ribosomes Made of protein and RNA Sites of protein synthesis Found at two locations Free in the cytoplasm Attached to rough endoplasmic reticulum

Cytoplasmic Organelles Endoplasmic reticulum (ER) Fluid-filled tubules for carrying substances Two types of ER Rough Endoplasmic Reticulum Studded with ribosomes Site where building materials of cellular membrane are formed Smooth Endoplasmic Reticulum Functions in cholesterol synthesis and breakdown, fat metabolism, and detoxification of drugs

Cytoplasmic Organelles Golgi apparatus Modifies and packages proteins Produces different types of packages Secretory vesicles Cell membrane components Lysosomes

Golgi Apparatus Figure 3.6

Cytoplasmic Organelles Lysosomes Contain enzymes that digest nonusable materials within the cell Peroxisomes Membranous sacs of oxidase enzymes Detoxify harmful substances Break down free radicals (highly reactive chemicals) Replicate by pinching in half

Cytoplasmic Organelles Mitochondria “Powerhouses” of the cell Change shape continuously Carry out reactions where oxygen is used to break down food Provides ATP for cellular energy

Cytoplasmic Organelles Cytoskeleton Network of protein structures that extend throughout the cytoplasm Provides the cell with an internal framework Figure 3.7a

Cytoplasmic Organelles Cytoskeleton Three different types Microfilaments Intermediate filaments Microtubules Figure 3.7b–d

Cytoplasmic Organelles Centrioles Rod-shaped bodies made of microtubules Direct formation of mitotic spindle during cell division

Cellular Projections Not found in all cells Used for movement Cilia moves materials across the cell surface Flagellum propels the cell

Cell Diversity and Specialization Journal and EQ: How does the internal structure (amount and type of organelles) of a cell influence its function?

Georgia Performance Standards SAP1. Students will analyze anatomical structures in relationship to their physiological functions. d. Relate cellular metabolism and transport to homeostasis and cellular reproduction. e. Describe how structure and function are related in terms of cell and tissue types.

Cells that connect Fibroblast- produce protein fibers Extensive ER and Golgi body Erythrocyte No organelles, only hemoglobin to carry O2

Cells that Cover & Line Epithelial Tight sheets Abundant intermediate filaments to resist tearing

Cells that move Organs & Body Parts Skeletal muscle Elongated cells Contractile filaments Abundant mitochondria for ATP production Smooth ER to store calcium Multinucleated

Cells that Store Nutrients Adipocyte- fat cell Fat vacuole stores lipids

Cells that Fight Disease Macrophage- pseudopods extend cytoplasm, many lysosomes B-Lymphocytes- secrete huge amounts of protein antibodies

Cells that Communicate Nerve Cell- neuron Long processes to receive and send signals Extensive Rough ER to synthesize membrane proteins Extensive Golgi for secretion Cytoskeleton important for vesicle transport

Cells of Reproduction Oocyte- egg cell Many copies of organelles for rapid divisions that occur after fertilization Sperm Flagella to propel to the oocyte Mitochondria to power the flagella

Journal Why does the body need so many different types of cells?

SAP1. Students will analyze anatomical structures in relationship to their physiological functions. d. Relate cellular metabolism and transport to homeostasis and cellular reproduction. Disruptions in metabolism and transport often lead to homeostatic imbalance or in cellular reproduction.

Cell Life Cycle Cells have two major periods Interphase Cell grows Cell carries on metabolic processes Cell division Cell replicates itself Function is to produce more cells for growth and repair processes

DNA Replication Genetic material duplicated Readies cell for division into two cells Occurs toward the end of interphase DNA uncoils and each side acts as a template Figure 3.14

Events of Cell Division Mitosis Division of the nucleus Results in the formation of two daughter nuclei Cytokinesis Division of the cytoplasm Begins when mitosis is near completion Results in the formation of two daughter cells

Interphase is NOT a part of Mitosis No cell division occurs The cell carries out normal metabolic activity and growth

Stages of Mitosis Prophase First part of cell division Centromeres migrate to the poles

Stages of Mitosis Metaphase Spindle from centromeres attached to chromosomes Chromosomes aligned in the center of the cell

Stages of Mitosis Anaphase Daughter chromosomes are pulled toward the poles The cell begins to elongate

Stages of Mitosis Telophase Daughter nuclei begin forming A cleavage furrow (for cell division) begins to form

Stages of Mitosis Figure 3.15

Stages of Mitosis Figure 3.15(cont)

Journal Why is it important to understand cellular reproduction?

Protein Synthesis Gene – DNA segment that carries a blueprint for building one protein Proteins have many functions Building materials for cells Act as enzymes (biological catalysts) RNA is essential for protein synthesis

Protein Synthesis Gene – DNA segment that carries a blueprint for building one protein Proteins have many functions Building materials for cells Act as enzymes (biological catalysts) RNA is essential for protein synthesis

Role of RNA Transfer RNA (tRNA) Transfers appropriate amino acids to the ribosome for building the protein Ribosomal RNA (rRNA) Helps form the ribosomes where proteins are built Messenger RNA Carries the instructions for building a protein from the nucleus to the ribosome

Transcription and Translation Transfer of information from DNA’s base sequence to the complimentary base sequence of mRNA Translation Base sequence of nucleic acid is translated to an amino acid sequence Amino acids are the building blocks of proteins

Protein Synthesis Figure 3.16