Chapter 7 Cell Structure and Function

Anton van Leeuwenhoek Father of the microscope ’s used lens technology fabric quality telescope same time 1st to see life in a drop of water (“animalcules”)

Robert Hooke st to examine plant tissue Resembled monastery’s tiny rooms “Cells”

Contributing Scientists Matthias Schleiden: all plants are made of cells Theodor Schwann: All animals are made of cells Rudolf Virchow: Cells come from other preexisting cells

The Cell Theory All living things are composed of cells Cells are the basic units of structure and function in living things New cells are produced from existing cells

What do all cells have in common? Cell membrane thin, flexible barrier surrounding the cell (protection) Cytoplasm fluid within the cell Genetic Material (DNA/RNA)

Major Groups of Organisms 1.Bacteria 2.Protists (amoeba, algae, seaweed) 3.Fungi 4.Plants 5.Animals

Basic Cell Types Prokaryotic Cells cell membrane cytoplasm genetic material (lack a nucleus) bacteria Cell membrane cytoplasm Genetic Material

Eukaryotic Cells Cell membrane Cytoplasm Nucleus Membrane- bound organelles animals, plants, fungi and protists

Prokaryotic Cell Cell membrane Cytoplasm Nucleus Organelles Eukaryotic Cell Section 7-1 Go to Section:

7-2 A Closer Look at the Cell Your objective is to… Describe the main functions of each cell structure

Cell Wall Plants, bacteria (prokaryotes), fungi, algae (protists) Provides structure and protection Gas and water exchange Plants - made of polysaccharide cellulose

Nucleus Controls cell processes Contains DNA deoxyribose nucleic acid codes for protein and other molecules

Chromatin DNA bound to protein Chromosomes chromatin condenses during cell division Nucleolus make ribosomes Nuclear Envelope 2 layers with pores that allow for the passage of material

Nucleus The Nucleus Nucleolus Nuclear envelope Nuclear pores Chromatin

Cytoskeleton Network of protein filaments (microtubules and microfilaments) Maintains cell shape Cell Movement Intracellular Movement moves organelles important during cell division

Microtubules: hollow structures made of protein called tubulin. Important in maintaining cell shape play important role in cell division Help build cilia and flagella Tubulin: used to form a pair of structured called Centrioles, which are critical in cell division, in animal cells

Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion Figure 7-7 Cytoskeleton

Tracks for organelle movement

Structures for Movement: Flagella-tail-like structures to propel cell in whipping motion Cilia- hair-like projections that beat together to move the cell

Transportation

The Organelles Specialized structures within the cytoplasm of the cell that perform specific jobs

Ribosomes One of the most important organelles Use genetic information found in the nucleus to make protein Found free in cytoplasm or on RER

Endoplasmic Reticulum 2 types Rough and Smooth Cell membrane assembly (i.e.. lipid components are assembled) Rough contain ribosomes certain proteins are modified chemically here Smooth No ribosomes Contain enzymes that have specialized tasks Syntheis of membrane lipids Detoxification of drugs

Endoplasmic Reticulum Ribosomes Endoplasmic Reticulum

Golgi Apparatus Receive proteins from RER Modifies, sorts and packages those proteins Use enzymes to attach carbohydrates and lipids to proteins Sent to final destination or keeps for storage in cell

Lysosomes Filled with enzymes that breakdown large molecules into smaller molecules Lipids, carbohydrates and proteins Recycle old organelles and debris that no longer function to avoid “clutter”

Vacuoles Storage units for water, salts, proteins and carbohydrates Provide support for plants “water” from their heavy structures Contractile vacuole helps maintain homeostasis in single celled organisms Pumps water in and out

Vacuole

Mitochondria Convert food into high- energy compounds (ATP) that the cell uses to power growth, development and movement ATP = Energy 2 membranes Contains DNA Comes from the cytoplasm from our mothers egg Mitochondrion

Chloroplasts Found in plants and algae photosynthesis 2 membranes Contains DNA

Organelle DNA Organelle’s do not contain DNA EXCEPT chloroplasts and mitochondrion Small DNA molecules Lynn Margulis: descendants of ancient prokaryotes

Animal vs. Plant Cells Plant Cells have the following (Animal Cells do not): Cell Wall Chloroplasts Central Water Vacuole

Plant Cell Nucleolus Nucleus Smooth endoplasmic reticulum Rough endoplasmic reticulum Cell wall Cell membrane Chloroplast Nuclear envelope Ribosome (free) Ribosome (attached) Golgi apparatus Mitochondrion Vacuole

Animal Cell Smooth endoplasmic Nucleolus Nucleus Nuclear envelope Rough endoplasmic reticulum Centrioles Mitochondrion reticulum Ribosome (free) Cell membrane Ribosome (attached) Golgi apparatus

7-3 The Cell Membrane

Cell membrane Basics Regulates what enters and leaves the cell Provides support and protection Made of double layered sheet called a lipid bilayer.

Lipid Bilayer Proteins and Carbohydrates embedded in bilayer Proteins form channels and pump Carbohydrates are attached to the proteins Act like ID cards that allow cells to identify one another

Hydrophobic Lipid Tails Nonpolar Hydrophilic Lipid Heads Polar

Cell Walls Provide support and protection for the cell Lie outside of cell membrane Plants, algae, fungi, many prokaryotes Carbohydrate and protein produced within cell then released to surface Cellulose in plant cells Wood and paper

Cytoplasm Fluid within a cell Extremely important to regulate the movement of this fluid Movement of dissolved molecules in the fluid from side of membrane to fluid on other side. Solution of many different substances in water The concentration of a solution is the mass of solute in a given volume, or mass/volume

Fluids ICF = Intracellular Fluid (inside cell/cytoplasm) ECF = Extracellular Fluid (outside cell) Always dissolved particles in both of these fluids Dissolved particles = solutes Concentration of solutes can vary High = more solute Low = less solute

Figure 7-15 The Structure of the Cell Membrane Outside of cell Carbohydrate Proteins ell embrane Inside of cell Protein (cytoplasm) channel chains Lipid bilayer

Diffusion Movement of materials from a high concentration to a lower concentration until equilibrium is reached requires no energy = passive transport If low to high= active transport

Permeability Ability of membrane to allow substances to diffuse through Levels of permeability: Permeable- any solutes can pass through Semi-permeable/Selectively Permeable- certain solutes are selected to pass through Impermeable- nothing is able to pass through All cell membranes are selective = picky/choosy Impermeability is not an option  cell would die! Why???

Osmosis A type of diffusion Diffusion of water (solvent) across a selectively permeable membrane Types of Solutions hypertonic - higher concentration of dissolved particles (solute) hypotonic - lower concentration of dissolved particles (solute) isotonic - identical concentration In a cell membrane, osmosis exerts pressure on the hypertonic side

Osmosis occurs b/c the solute is unable to pass through the membrane. Water can always pass through the membrane.

Continues until the concentrations are equal

Solutions outside of the cell…..

Problems in Organisms (Maintaining Homeostasis) Plants turgor pressure rigid vs. wilting Antibiotic effects on bacteria Single Celled Organisms contractile vacuole homeostasis Animals cells bathed in isotonic fluids “blood”

Facilitated Diffusion Specific protein channels for specific substances that cannot diffuse on their own glucose channel to help transport glucose

Glucose molecules Facilitated Diffusion Protein channel

Active Transport movement of materials from lower concentration to higher concentration requires energy = ATP

Molecule to be carried Active Transport

Figure 7-19 Active Transport-going against concentration gradient Molecule to be carried Energy Molecule being carried (low to high). Natural is from high to low (diffusion and facilitated diffusion).

Endocytosis & Exocytosis Process of taking material into the cell by means of infoldings or pockets, of the cell membrane called Endocytosis 2 types Phagocytosis Pinocytosis Process of releasing large amounts of material from the cell is called Exocytosis

Phagocytosis Large particles taken into cell Extension of cytoplasm engulfs large particles outside cell Pocket folds into cell with contents and breaks loose from cell membrane then forms a vacuole inside cell (in cytoplasm).

Pinocytosis Liquid being taken into a cell through pockets that form along the cell membrane Exocytosis Cells release large amounts of material from the cell. Cell membrane forces contents out of cell

Unicellular Organisms A single cell is the entire organism Include prokaryotes and eukaryotes Examples include: algae, yeasts, fungi, bacteria

Multicellular Organisms Cells are interdependent (like a team) Cell specialization- separate roles for each type of cell (ex. Blood cell, nerve cell, muscle cell) Cells are specialized to perform particular functions within organism

Levels of Organization 4 levels of organization Cells Tissue- group of similar cells that perform particular function Most animals have 4 types of tissue Muscle, epithelial, nervous, connective Organ- groups of tissues working together Organ Systems- group of organs working together to perform specific function (11 major systems in human body)

Example of levels of Organization Each muscle in your body is an individual organ Within each muscle is more than one type of tissue (Example: nervous tissue and connective tissue) Each tissue performs a specialized task to help this particular organ (muscle) function. Muscle CellSmooth muscle tissue Stomach Digestive system