CHAPTER 7

A VIEW OF THE CELL

CHAPTER OBJECTIVES

• YOU WILL IDENTIFY THE PARTS OF PROKARYOTIC AND EUKARYOTIC CELLS.

• YOU WILL IDENTIFY THE STRUCTURES OF THE PLASMA MEMBRANE.

• YOU WILL RELATE THE STRUCTURE OF THE PARTS OF THE CELL TO THE PARTS OF ITS STRUCTURE.

Section 7.1

The discovery of cells

Objectives

• Relate advances of microscope technology to discoveries of cells and cell structure.

• Compare the operation of a compound light microscope with that of an electron microscope.

• Identify the main ideas of the cell theory.

Review vocabulary

• Organization: the orderly structure of cells in an organism.

New vocabulary

• Cell• Compound light microscope• Cell theory• Electron microscope• Organelle• Prokaryote• Eukaryote• Nucleus

Before microscopes….

• People believed that diseases were caused by curses and supernatural spirits.

Until the first microscope was discovered.

ANTON VAN LEEUWENHOCK1600´S

• Simple light microscope because it contained one lens and used light to view objects.

Compound light microscope

• Uses a series of lenses to magnify objects in steps.

The cell theory

Robert Hooke

• He lived at the same time than van leewenhock did.

• He used a compound light microscope to study the dead cells of oak bark.

Oak bark cells

• He named them ¨ cells¨ because they remind him of the cells where he used to live in the monastery.

Cells

• Cells are the basic unit of life.

The cell theory

1. All organisms are composed of one or more cells

2. The cell is the basic unit of structure and organization of all living organisms.

3. All cells come from pre-existing cells.

All organisms are composed of one or more cells

The cell is the basic unit of structure and organization of all living

organisms.

All cells come from pre-existing cells.

Electron microscope1930´S

• MAGNIFIED 500,000 TIMES THE ACTUAL SIZE OF THE CELL!

Electron microscope

TWO BASIC CELL TYPES

• PROKARYOTES• bacteria

• EUKARYOTES• Fungi• Humans• plants

Prokaryotes

Eukaryotes

• A single-celled or multicellular organism whose cells contain a distinct membrane-bound nucleus.

• HUMAN CELLS, PLANTS AND FUNGI CELLS

Eukaryotes

• All living organisms are composed of cells. A eukaryotic cell is a cell with a nucleus, which contains the cell's chromosomes. Plants, animals, protists, and fungi have eukaryotic cells.

Eukaryotic Membranes

• Eukaryotic cells include large amounts of membrane, which enclose the cell itself and surround each of the organelles. The membrane surrounding the cell is termed the plasma membrane. Membranes are bilayered structures, made of two layers of phospholipid.

Prokaryotes

• Comprising the bacteria and cyanobacteria, characterized by the absence of a distinct, membrane-bound nucleus or membrane-bound organelles, and by DNA that is not organized into chromosomes.

• KARYOTE= NUCLEUS• EU= TRUE• PRO= BEFORE

PROKARYOTE

Organelle

• A differentiated structure within a cell, such as a mitochondrion, vacuole, or chloroplast, that performs a specific function.

Nucleus

• A large, membrane-bound, usually spherical protoplasmic structure within a living cell, containing the cell's hereditary material and controlling its metabolism, growth, and reproduction.

Robert Brown

• Observed that eukaryotic cells contain a prominent structure.

Rudolf Virchow

• He determined that the structure that Robert Brown described was the NUCLEUS.

• Cytoplasm: plasma of the cell• Mitochondria: power house• Vacuole: post office

SECTION 7.1 QUIZ1. Describe the history of microscopes and evaluate their

impact in the study of cells.2. How does the cell theory describe the levels of

organization of living organisms?3. Compare the light microscope with the electron

microscope.4. Describe the differences between a prokaryotic and an

eukaryotic cell and identify their parts.5. Suppose you discovered a new type of plant. Applying the

cell theory, what can you say for certain about this organism?

Section 7.2

THE PLASMA MEMBRANE

OBJECTIVES

• Describe how a cell´s plasma membrane functions.

• Relate the functions of the plasma membrane to the fluid mosaic model.

Review vocabulary

• Ion: am atom or group of atoms with a positive or negative electrical charge

New vocabulary

• Plasma membrane• Selective membrane• Phospholipid• Fluid mosaic model• Transport protein

Plasma membrane

• All living cells, prokaryotic and eukaryotic, have a plasma membrane that encloses their contents and serves as a semi-porous barrier to the outside environment.

• SCHOOL´S WEB PAGE:• www.burnhamwood.schoolfusion.us

homework

• Describe what is the function of each of labeled parts of the plasma membrane.

• The plasma membrane is permeable to specific molecules, however, and allows nutrients and other essential elements to enter the cell and waste materials to leave the cell. Small molecules, such as oxygen, carbon dioxide, and water, are able to pass freely across the membrane, but the passage of larger molecules, such as amino acids and sugars, is carefully regulated.

FLUID MOSAIC MODEL

• According to the accepted current theory, known as the fluid mosaic model, the plasma membrane is composed of a double layer (bilayer) of lipids

GLYCOPROTEINS

• Plasma membranes have carbohydrates attached to their outer surfaces and are, therefore, referred to as glycoproteins

• Since the 1970s, the plasma membrane has been frequently described as a fluid mosaic, which is reflective of the discovery that oftentimes the lipid molecules in the bilayer can move about in the plane of the membrane.

Fluid mosaic model

• It is a two-dimensional fluid, or liquid crystal, in which the hydrophobic integral components such as lipids and membrane proteins are constrained within the plane of the membrane, but are free to diffuse laterally.

• http://www.youtube.com/watch?v=ULR79TiUj80

• Phospholipids are fat derivatives in which one fatty acid has been replaced by a phosphate group and one of several nitrogen-containing molecules

• http://www.youtube.com/watch?v=EwCiFZ7QBV8&feature=related

• http://www.youtube.com/watch?v=_qdJkR3Usjg&feature=related

• The hydrocarbon chains are hydrophobic (as in all fats). However, the charges on the phosphate and amino groups (in red) make that portion of the molecule hydrophilic. The result is an amphiphilic molecule.

• These molecules form a phospholipid bilayer with their hydrophilic (polar) heads facing their aqueous surroundings (e.g., the cytosol) and their hydrophobic tails facing each other.

Transport proteins

• A membrane transport protein (or simply transporter) is a protein involved in the movement of ions, small molecules, or macromolecules, such as another protein across a biological membrane.

• Transport proteins are integral membrane proteins; that is they exist within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion or active transport.

Cholesterol is Abundant in Cell Membranes

• Cholesterol is found in every cell of your body. It is especially abundant in the membranes of these cells, where it helps maintain the integrity of these membranes, and plays a role in facilitating cell signaling-- meaning the ability of your cells to communicate with each other so you function as a human, rather than a pile of cells.

• Cholesterol is an amphipathic molecule, meaning, like phospholipids, it contains a hydrophilic and a hydrophobic portion

Function of cholesterol

• Cholesterol Helps Maintain the Fluidity of Cell Membranes

• Cholesterol Helps Secure Important Proteins in the Membrane

• Cholesterol Maintains the Integrity of the Cell Membrane

Cell video

• http://www.youtube.com/watch?v=k3UXY9U0orA&feature=related

Section 7.2 homework1. Describe the plasma membrane and explain why it is called

a bilayer structure.2. Describe the structure of a phospholipid. Use the terms

polar and nonpolar in your answer.3. What are the specialized parts of the phospholipid bilayer,

and how do their structures relate to the structure of the plasma membrane?

4. Why is the structure of the plasma membrane referred to as a fluid mosaic?

5. Suggest what might happen if cells grow and reproduce in an environment where no cholesterol is avaliable?

Section 7.3

EUKARYOTIC CELL STRUCTURE

OBJECTIVES

• Identify the structure and function of the parts of a typical eukaryotic cell

• Explain the advantages of highly folded membranes in cells.

• Compare and contrast the structures of plant and animal cells.

Review vocabulary

• Enzyme: a protein that speeds up the rate of a reaction.

New vocabulary• Cell wall• Chromatin• Nucleolus• Ribosome• Cytoplasm• Endoplasmic reticulum• Golgi apparatus• Vacuole• Lysosome• Chloroplast• Plastid• Chlorophyl• Mitochondria• Cytoskeleton• Microtubule• Cillia• flagella

Cell wall

• A cell wall is a tough, flexible and sometimes fairly rigid layer surrounding a cell, located external to the cell membrane, which provides the cell with structural support, protection, and acts as a filtering mechanism.

Cell wall function

• A major function of the cell wall is to act as a pressure vessel, preventing over-expansion when water enters the cell.

Chromatin

• http://www.youtube.com/watch?v=OStI5pniHPA&feature=related

• http://www.youtube.com/watch?v=AF2wwMReTf8&feature=related

• http://www.youtube.com/watch?v=AF2wwMReTf8&feature=related

• http://www.youtube.com/watch?v=er8dAhfM9pA&feature=related

• XX= FEMALE• XY= MALE

Chromatin

• Chromatin is the complex basis of DNA and protein that makes up chromosomes.

• It is found inside the nuclei of eukaryotic cells, and within the nucleoid in prokaryotic cells

• http://www.youtube.com/watch?v=lUESmHDrN40

Nucleolus

• The nucleolus (also called nucleole) is a structure found within the nucleus in which ribosomal RNA is transcribed.

• Since it does not have a membrane, it is generally not considered an organelle.

ROUGH ENDOPLASMIC RETICULUM

What happens inside the nucleus and ER?

• http://video.google.com/videosearch?hl=es&q=cell%20video&lr=&um=1&ie=UTF-8&sa=N&tab=wv#q=protein%20synthesis&hl=es&emb=0

Ribosome

• Ribosomes (from ribonucleic acid and "Greek: soma (meaning body)") are complexes of RNA and protein that are found in all cells. Copy machine.

Cytoplasm

• The cytoplasm is the contents of a cell that is enclosed within the plasma membrane.

http://images.google.com/imgres?imgurl=http://www.biology.utah.edu/gard/Images/Actin/actin_early.jpg&imgrefurl=http://www.biology.utah.edu/gard/HTML/Cytoskeleton/Actin_body.html&h=366&w=400&sz=56&hl=es&start=10&um=1&usg=__bhi1kXoYghBHp6NZ7zxeZP35mpc=&tbnid=BjGNNtPBGeZAIM:&tbnh=113&tbnw=124&prev=/images%3Fq%3Dcytoplasm%26um%3D1%26hl%3Des%26lr%3D%26sa%3DN

Endoplasmic reticulum

Endoplasmic reticulum

• The endoplasmic reticulum (Greek endo = "within" (prefix), plásma = "formed entity", Latin reticulum = "little net"), or ER, is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae.

Rough ER function• These structures are responsible for several specialized

functions:• Store proteins• protein translation• folding and transport of proteins to be used in the

cell membrane.

Golgi apparatus• The Golgi apparatus (also called the Golgi body, Golgi

complex, or dictyosome) is an organelle found in most eukaryotic cells.

• POST OFFICE. LABELS AND PACKAGES.

STEPS OF PROTEIN SYNTHESIS

1. DNA UNFOLDS2. RIBOSOME COPIES THE DNA AND PRODUCES RNA3. THE NEW PROTEIN GOES TO THE NUCLEUS4. IF FLOWS TO THE ER BY DIFFUSION.5. THE ER TRANSLATES THE PROTEIN AND SENDS IT

TO THE GOLGI6. GOLGI PACKS IT AND SENDS IT OUTSIDE THE

CELL.

• http://video.google.com/videosearch?hl=es&q=cell%20video&lr=&um=1&ie=UTF-8&sa=N&tab=wv#q=cell%20biology&hl=es&emb=0

Vacuole• Removing unwanted structural debris • Isolating materials that might be harmful or

a threat to the cell • Containing waste products • Maintaining internal hydrostatic pressure or

turgor within the cell • Maintaining an acidic internal pH • Containing small molecules • Exporting unwanted substances from the

cell

Lysosome

• http://www.youtube.com/watch?v=BnJGDjP9iyU&feature=related

• http://www.youtube.com/watch?v=BnJGDjP9iyU&feature=related

• Lysosomes are organelles that contain digestive enzymes (acid hydrolases).

• They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.

• 4.5 pH

Chloroplast• Chloroplasts are organelles found in plant cells and

eukaryotic algae that conduct photosynthesis.

Plastid• Plastids are major organelles found in plants and algae.

Plastids often contain pigments used in photosynthesis, and the types of pigments present can change or determine the cell's color.

3 structures help in PHOTOSYNTHESIS AND PLANT

COLOR

1.CHLOROPLASTS2.PLASTIDS3.CHLOROPHYL

chlorophyll

• Chlorophyll is the molecule that absorbs sunlight and uses its energy to synthesise carbohydrates from CO2 and water

Mitochondria

• Mitochondria are the cells' power sources.

Cytoskeleton

• The cytoskeleton is made up of three kinds of protein filaments:

1.Actin filaments (also called microfilaments) 2.Intermediate filaments and 3.Microtubules

• 1665 - Robert Hooke looks at cork under a microscope. Calls the chambers he see "cells"

• 1665 - 75 Anton van Leeuwenhoek, the person incorrectly given credit for the invention of the microscope (actually, he was just damn good at making and using them, and his scopes soon became the standard, and history has just given him credit as the inventor of the microscope), studies organisms living in pond water (like you did in lab). He calls them "Animalcules."

Cillia

Cilia

• Cilia and flagella are projections from the cell. They are made up of microtubules.

• They are motile and designed either to move the cell itself or to move substances over or around the cell.

Microtubule

• Microtubules are conveyer belts inside the cells.

• They move vesicles, granules, organelles like mitochondria, and chromosomes via special attachment proteins.

flagella

flagella

• Escherichia coli cells use long, thin structures called flagella to propel themselves.

Section 7.3 quiz1. If a cell synthesize large quantities of protein molecules,

which organelles might be numerous in that cell?2. A cell´s digestive enzymes are enclosed in a membrane

bound organelle. How can these molecules function in the cell?

3. Compare and contrast the functions of a cell wall to the functions of a plasma membrane?

4. Compare the number of vacoules in plant cells and animal cells.

5. Compare the mitochondria and the chloroplasts. Why are they referred as energy trasnformers?

1. Cell2. Compound light microscope3. Cell theory4. Electron microscope5. Organelle6. Prokaryote7. Eukaryote8. Nucleus 9. Plasma membrane10. Selective membrane11. Phospholipid12. Fluid mosaic model13. Transport protein14. Cell wall15. Chromatin16. Nucleolus17. Ribosome18. Cytoplasm19. Endoplasmic reticulum20. Golgi apparatus21. Vacuole22. Lysosome23. Chloroplast24. Plastid25. Chlorophyl26. Mitochondria27. Cytoskeleton28. Microtubule29. Cillia30. flagella

Chapter highlights1. Organelle that is the boundary between the cell and the environment.2. Membrane bound organelle that transforms energy in all eukaryotic

cells.3. Highly organized structures within cells4. Organelles that are the sites of protein synthesis.5. Basic unit of organization of both unicellular and muticellular organisms.6. In what type of cell would you find chloroplast?7. An electron microscope is used when magnifing more that 10,000 X8. What is different between prokaryotes and eukaryotes?9. What strycture is not found in animal and plant cells?10. Plastids store lipids, pigment, and starch.