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Cells 

 

 

This is the one I'll use on the exam!

I'll also use this on the exam.  Know which type of junction is found in which tissue/organ.

Where do you find adherins junctions?

Where do you find gap junctions?

Where do you find Desmosomes?

 

 

You don't need to know all of this stuff, but it's here if you're interested

Cell Theory

•      The cell is the basic structural and functional unit of life

•      Organismal activity depends on individual and collective activity of cells

•      Biochemical activities of cells are dictated by subcellular structure

•      Continuity of life has a cellular basis

Structure of a Generalized Cell

Plasma Membrane

•      Separates intracellular fluids from extracellular fluids

•      Plays a dynamic role in cellular activity

•      Glycocalyx is a glycoprotein area abutting the cell that provides highly specific biological markers by which cells recognize one another

Fluid Mosaic Model

•      Double bilayer of lipids with imbedded, dispersed proteins

•      Bilayer consists of phospholipids, cholesterol, and glycolipids

•    Glycolipids are lipids with bound carbohydrate

•    Phospholipids have hydrophobic and hydrophilic bipoles

Functions of Membrane Proteins

•      Transport

•      Enzymatic activity

•      Receptors for signal transduction

•      Intercellular adhesion

•      Cell-cell recognition

•      Attachment to cytoskeleton and extracellular matrix

Membrane Junctions

•      Tight junction – impermeable junction that encircles the cell

•      Desmosome – anchoring junction scattered along the sides of cells

•      Gap junction – a nexus that allows chemical substances to pass between cells

    Adhesion junctions – similar to desmosomes

Passive Membrane Transport: Diffusion

•      Simple diffusion – nonpolar and lipid-soluble substances

•    Diffuse directly through the lipid bilayer

•    Diffuse through channel proteins

•      Facilitated diffusion – large, polar molecules such as simple sugars

•    Combine with protein carriers

Passive Membrane Transport: Osmosis

•      Occurs when the concentration of a solvent is different on opposite sides of a membrane

•      Diffusion of water across a semipermeable membrane

•      Osmolarity – total concentration of solute particles in a solution

Passive Membrane Transport: Filtration

•      The passage of water and solutes through a membrane by hydrostatic pressure

•      Pressure gradient pushes solute-containing fluid from a higher-pressure area to a lower-pressure area

Tonicity

•      Isotonic – solutions with the same solute concentration as that of the cytosol

•      Hypertonic – solutions having greater solute concentration than that of the cytosol

•      Hypotonic – solutions having lesser solute concentration than that of the cytosol

Sodium-Potassium Pump

Active Transport

•      Uses ATP to move solutes across a membrane

•      Requires carrier proteins

Vesicular Transport

•      Transport of large particles and macromolecules across plasma membranes

•    Exocytosis – moves substance from the cell interior to the extracellular space

•    Endocytosis – enables large particles and macromolecules to enter the cell

•    Phagocytosis – pseudopods engulf solids and bring them into the cell’s interior

3

Roles of Membrane Receptors

•      Contact signaling – important in normal development and immunity

•      Electrical signaling – voltage-regulated “ion gates” in nerve and muscle tissue

•      Chemical signaling – neurotransmitters bind to chemically gated channel-linked receptors in nerve and muscle tissue

Cytoplasm

•      Cytoplasm – material between plasma membrane and the nucleus

•      Cytosol – largely water with dissolved protein, salts, sugars, and other solutes

•      Cytoplasmic organelles – metabolic machinery of the cell

•      Inclusions – chemical substances such as glycosomes, glycogen granules, and pigment

Cytoplasmic Organelles

•      Specialized cellular compartments

•      Membranous

•    Mitochondria, peroxisomes, lysosomes, endoplasmic reticulum, and Golgi apparatus

•      Nonmembranous

•    Cytoskeleton, centrioles, and ribosomes

Mitochondria

•      Double membrane structure with shelflike cristae

•      Provide most of the cell’s ATP via aerobic cellular respiration

•      Contain their own DNA and RNA

Ribosomes

•      Granules containing protein and rRNA

•      Site of protein synthesis

•      Free ribosomes synthesize soluble proteins

•      Membrane-bound ribosomes synthesize proteins to be incorporated into membranes

Endoplasmic Reticulum (ER)

•      Interconnected tubes and parallel membranes enclosing cisternae

•      Continuous with the nuclear membrane

•      Two varieties – rough ER and smooth ER

Endoplasmic Reticulum (ER)

Rough ER

•      External surface studded with ribosomes

•      Manufactures all secreted proteins

•      Responsible for the synthesis of integral membrane proteins and phospholipids for cell membranes

Smooth ER

•      Tubules arranged in a looping network

•      Catalyzes the following reactions in various organs of the body

•    In the liver – lipid and cholesterol metabolism, breakdown of glycogen and, along with the kidneys, detoxification of drugs

•    In the testes – synthesis of steroid-based hormones

•    In the intestinal cells – absorption, synthesis, and transport of fats

•    In skeletal and cardiac muscle – storage and release of calcium

Golgi Apparatus

•      Stacked and flattened membranous sacs

•      Functions in modification, concentration, and packaging of proteins

•      Transport vessels from the ER fuse with the cis face of the Golgi apparatus

•      Proteins then pass through the Golgi apparatus to the trans face

•      Secretory vesicles leave the trans face of the Golgi stack and move to designated parts of the cell

Lysosomes

•      Spherical membranous bags containing digestive enzymes

•      Digest ingested bacteria, viruses, and toxins

•      Degrade nonfunctional organelles

•      Breakdown glycogen and release thyroid hormone

•      Breakdown nonuseful tissue

•       Breakdown bone to release Ca2+

Peroxisomes

•      Membranous sacs containing oxidases and catalases

•      Detoxify harmful or toxic substances

•      Neutralize dangerous free radicals

•    Free radicals – highly reactive chemicals with unpaired electrons (i.e., O2–)

Cytoskeleton

•      The “skeleton” on the cell

•      Dynamic, elaborate series of rods running through the cytosol

•      Consists of microtubules, microfilaments, and intermediate filaments

Cytoskeleton

Microtubules

•      Dynamic, hollow tubes made of the spherical protein tubulin

•      Determine the overall shape of the cell and distribution of organelles

Microfilaments

•      Dynamic strands of the protein actin

•      Attached to the cytoplasmic side of the plasma membrane

•      Braces and strengthens the cell surface

•      Attach to CAMs and function in endocytosis and exocytosis

Intermediate Filaments

•      Tough, insoluble protein fibers with high tensile strength

•      Resist pulling forces on the cell and help form desmosomes

Centrioles

•      Small barrel-shaped organelles located in the centrosome near the nucleus

•      Pinwheel array of nine triplets of microtubules

•      Organize mitotic spindle during mitosis

•      Form the bases of cilia and flagella

Cilia

•      Whiplike, motile cellular extensions on exposed surfaces of certain cells

•      Move substances in one direction across cell surfaces

Nucleus

•      Nuclear envelope, nucleoli, and chromatin

•      Gene-containing control center of the cell

•      Contains the genetic library with blueprints for nearly all cellular proteins

•      Dictates the kinds and amounts of proteins to be synthesized

Nuclear Envelope

•      Selectively permeable double membrane barrier containing pores

•      Encloses jellylike nucleoplasm, which contains essential solutes

•      Outer membrane is continuous with the rough ER and is studded with ribosomes

•      Inner membrane is lined with the nuclear lamina, which maintains the shape of the nucleus

•      Pore complex regulates transport of large molecules into and out of the nucleus

Nucleoli

•      Dark-staining spherical bodies within the nucleus

•      Site of ribosome production

Chromatin

•      Threadlike strands of DNA and histones

•      Arranged in fundamental units called nucleosomes

•      Form condensed, barlike bodies of chromosomes when the nucleus starts to divide

 

 

THE CELL

Study guide for the lecture is the powerpoint, Lab is either a picture or a model of the cell

What you need to know:

  1. All of the facts in the powerpoint

  2. Be able to identify all organelles

Here's a video I made to help you with exactly what I want you to know about everything but the organelles which is on the following video

17:49

 

Overview of Organelles and cell function.  This includes prokaryotes and plants cells as well but just think, you have more bacterial cells on and in your body than body cells!   14:17

The Plasma Membrane - a short overview  of transport mechanisms 2:02

Endocytosis and Exocytosis  1:40

So where would you think you would find cells that perform endo and exocytosis?  (besides WBCs)

Membrane Transport  8:04

Osmosis and diffusion, passive transport.  Active transport requires energy.  Hypotonicity, hypertonicity and isotonicity.  Know what they are!

 

Fluid Mosaic Model  1:27

The Inner Life of a Cell.  The most powerful animation to show what happens in a cell.  Don't worry that you don't understand what he's talking about.

You may download this doc