Introduction to Cells Ch. 7 Ch. 7 Compound Light Microscope: allows light to pass through a specimen and magnifies the image with lenses Compound Light Microscope: allows light to pass through a specimen and magnifies the image with lenses

Electron microscopes – use beams of electrons to produce images. Electron microscopes – use beams of electrons to produce images. Three-dimensional images! Three-dimensional images! 1-4

The Discovery of the Cell Robert Hooke – first to see and identify cork “cells.” Robert Hooke – first to see and identify cork “cells.” 7-1

The Cell Theory Cell Theory: Cell Theory: 1. All living things are composed of cells 2. Cells are the basic living units of all organisms 3. New cells are produced from existing cells -a cell divides to form two identical cells Virchow 7-1

Other Inventors of Cell Theory Theodore Schwann - all animals are made up of cells Theodore Schwann - all animals are made up of cells Matthais Schleiden - all plants are made up of cells Matthais Schleiden - all plants are made up of cells Schwann Schleiden

Cells are the basic unit of life Cells are the basic unit of life Unicellular Organisms: Bacteria Unicellular Organisms: Bacteria Multicellular Oganisms: Animal & Plant Cells Multicellular Oganisms: Animal & Plant Cells Pancreatic cell Blood cell Muscle cell

All Cells have 3 characteristics: 1. surrounded by a barrier called a cell membrane 2. have biological information (DNA) 3. have cytoplasm

Two Main Groups of Cells Prokaryotes Prokaryotes NO membrane bound organelles NO membrane bound organelles has circular DNA, no nucleus has circular DNA, no nucleus cell functions carried out in cytoplasm cell functions carried out in cytoplasm unicellular unicellular Example: Bacteria Example: Bacteria

Eukaryotes: Eukaryotes: membrane bound organelles membrane bound organelles DNA is in the nucleus DNA is in the nucleus cell functions carried out by organelles cell functions carried out by organelles Most multicellular Most multicellular Example: Animal & Plant Cells Example: Animal & Plant Cells

Eukaryotic Cell Structure Nucleus – contains DNA that codes for proteins Nucleus – contains DNA that codes for proteins Cytoplasm – the portion of the cell outside the nucleus; “jelly-like” fluid Cytoplasm – the portion of the cell outside the nucleus; “jelly-like” fluid 7-2

Nuclear Membrane – surrounds the nucleus. Nuclear Membrane – surrounds the nucleus. Chromosomes – folded and twisted strands of DNA in the nucleus. Chromosomes – folded and twisted strands of DNA in the nucleus. Nucleolus – makes ribosomes. Nucleolus – makes ribosomes Inside the Nucleus

Nuclear Envelope Nucleolus 7-2

Ribosomes – site where cell makes enzymes and other Proteins! Ribosomes – site where cell makes enzymes and other Proteins! 7-2

Ribosomes Ribosome 7-2

Endoplasmic reticulum (ER)flattened, double-layered membranes Endoplasmic reticulum (ER)– flattened, double-layered membranes site of chemical reactions site of chemical reactions Rough ER – has ribosomes Rough ER – has ribosomes Smooth ER – no ribosomes Smooth ER – no ribosomes 7-2

Endoplasmic Reticulum (ER) Rough ER Smooth ER 7-2

Golgi Apparatus –sorts and packages proteins. 7-2

Golgi Apparatus 7-2

Lysosomes – contain digestive enzymes. Lysosomes – contain digestive enzymes. Digest food, old organelles, viruses/bacteria. Digest food, old organelles, viruses/bacteria. 7-2

Vacuoles – temporary storage Vacuoles – temporary storage 7-2

Vacuoles Vacuoles 7-2

Mitochondria – produces energy for the cell Mitochondria – produces energy for the cell “Powerhouse of the Cell!” “Powerhouse of the Cell!” 7-2

Mitochondria Mitochondria 7-2

Chloroplasts – converts light energy of the sun into sugars (Photosynthesis) Chloroplasts – converts light energy of the sun into sugars (Photosynthesis) Found only in plants. Found only in plants

Chloroplasts Chloroplast 7-2

Centrioles – separates chromatids (DNA) during cell division Centrioles – separates chromatids (DNA) during cell division Found only in animals. Found only in animals.

Cytoskeleton – provides structure for the cell 7-2

Cell Boundaries Plasma membrane – thin, flexible membrane that surrounds the cell. Plasma membrane – thin, flexible membrane that surrounds the cell

Cell Boundaries Cell walls – firm wall around the cell membrane found only in bacteria and plants. Cell walls – firm wall around the cell membrane found only in bacteria and plants. Protects & gives shape to cells Protects & gives shape to cells

A D G C B F E

Plasma Membrane and Homeostasis 7-3

Homeostasis – Maintaining a Balance Plasma membrane - Plasma membrane - Semi-permeable, allows only certain materials to move in and out of the cell 7-3

Cell Membrane Structure Lipid Bilayer – two sheets of lipids (phospholipids) Lipid Bilayer – two sheets of lipids (phospholipids) 7-3

Protein channels – help move material across the cell membrane Protein channels – help move material across the cell membrane 7-3 Cell Membrane Structure

Fluid Mosaic Model Fluid Mosaic Model 7-3

Cellular Transport movement of material in and out of cells movement of material in and out of cells 7-4

Solution Concentration : # of molecules per volume of container * * * * * * * * * * * * * * * * * * * * * High Conc. Low Conc.

Diffusion Diffusion – the movement of molecules from an area of HIGH concentration to an area of LOW concentration until EVENLY SPREAD Diffusion – the movement of molecules from an area of HIGH concentration to an area of LOW concentration until EVENLY SPREAD Diffusion 7-3

Diffusion of Gases Diffusion of Gases

Osmosis Special type of diffusion Special type of diffusion The movement of WATER from where it is in high concentration to where it is in low concentration across a selectively permeable membrane (cell membrane) The movement of WATER from where it is in high concentration to where it is in low concentration across a selectively permeable membrane (cell membrane)

Osmosis in cells 1% salt solution + H20 10% salt solution 10% salt solution -H20 -H20 H20 Water flows from High to Low Concentration

Osmosis Practice Cell 90% H2O 10% NaCl 90% H2O 10% NaCl Concentrations are equal, so no net movement of water! 7-3

Osmosis Practice Cell 90% H2O 10% NaCl 80% H2O 20% NaCl Concentration of water is greater in the cell than out, so water will move out! 7-3

Osmosis Practice Cell 80% H2O 20% NaCl 90% H2O 10% NaCl Concentration of water is greater outside the cell than in, so water will move out! 7-3

Plasmolysis Cell membranes shrink or expand Cell membranes shrink or expand Dependent on salt concen- trations Dependent on salt concen- trations

Facilitated Diffusion Facilitated Diffusion Facilitated diffusion – when the plasma membrane “helps” particles pass through protein channels. Facilitated diffusion – when the plasma membrane “helps” particles pass through protein channels. No energy used. No energy used.

Active Transport Active Transport Active transport – when the plasma membrane uses energy to move particles against a concentration gradient. Active transport – when the plasma membrane uses energy to move particles against a concentration gradient. Uses Transport Proteins Uses Transport Proteins 7-3

Endocytosis Endocytosis – process by which a cell takes material into the cell by infolding of the cell membrane phagocytosis phagocytosis & pinocytosis Exocytosis Exocytosis – process by which a cell releases large amounts of material BOTH REQUIRE ATP ENERGY!!! Moving large particles Moving large particles

Active or Passive Transport ? Which requires ATP energy? Which requires ATP energy? Which goes with the concentration gradient? Which goes with the concentration gradient? Which goes against the gradient? Which goes against the gradient?

Concentration Gradient * * *

Passive Transport Diffusion or Osmosis Diffusion or Osmosis Going with the gradient Going with the gradient No ATP energy required No ATP energy required * * * * * High Conc. To Low Conc.

Active Transport Against the gradient Against the gradient Requires ATP Requires ATP Low to High Concentrations Low to High Concentrations * * * * * * * * * * *

Facilitated Diffusion and Active Transport 7-3

Organization in Multicellular Organsisms Tissues Organs Organ System Organism Cells 7-4

Plasmolysis in Elodea Cells Elodea in tap water Elodea in 10% NaCl