Notes on CellsLife is Cellular

I. History of Cell TheoryA. Microscopes

1. 1500s: merchants invented lenses to assess

cloth quality

2. Early 1600s: Hans & Zaccharias Janssen invent

the first crude microscope

3. 1665: Robert Hooke used a light microscope to look at thin slices of cork a. saw tiny compartments b. Name them “cells”

4. Late 1600s: Anton van Leeuwenhoek a. developed high quality lenses and first light microscope b. observed tiny structures in pond water [bacteria] c. “Animalcules”

1. 1830s: Matthias Schleiden & Theodor Schwann observed many organisms

a. Schleiden- plants are made of cells b. Schwann- animals are made of cells

2. Rudolph Virchow: studied cell division, bone marrow, and leukemia a. Concluded all cells come from other cells

B. Cell Theory

3. Cell Theory• All living things are composed of cells• Cells are basic units of structure and

function in living things• New cells come from existing cells

II. Cell Types

• Two categories:

–Eukaryotes- have nucleus

–Prokaryotes- do not have nucleus

A. Prokaryotes

1. No nucleus

2. No membrane-bound organelles

3. Simple, first to evolve, smaller in size

4. Examples: all bacteria

B. Eukaryotes

1. Have nucleus

2. Membrane-bound organelles [mitochondria,

chloroplasts, nucleus]

3. Complex, evolved after prokaryotes, larger in

size

4. Examples: Animals, Plants, Fungi, Protists

III. Boundaries of the Cell • Typical cells are 5-50 μmA. Plasma or Cell membrane

–thin, flexible barrier around cell

B. Cell wall

–strong layer around cell membrane (plants)

–serve to give support and structure

IV. CELL ORGANELLES

• Nucleus• Nuclear envelope = nuclear membrane• Chromatin• Chromosomes• Nucleolus• Ribosomes• Cytoplasm • Endoplasmic Reticulum

(ER)• Smooth ER• Rough ER• Golgi (Body or Apparatus)

• Vacuoles• Lysosomes • Mitochondria• Plastids • Chloroplasts • Leucoplasts • Chromoplasts • Cytoplasm • Microtubules • Microfilaments • Cilia • Flagella • Centrioles • Cytoskeleton

• Nucleus– large structure containing cell’s genetic

material and controls cell’s activities• Cytoplasm

– material inside cell

membrane but not

including the nucleus

Basic Cell Structures

Nucleolus• Small, dense region Small, dense region insideinside nucleus nucleus

– Assembles ribosomes that make proteinsAssembles ribosomes that make proteins

• Nuclear MembraneNuclear Membrane– Double-membrane layerDouble-membrane layer– Many poresMany pores

Cytoskeleton

• MicrotubulesMicrotubules– hollow tubes; “tracks” that organelles use to movehollow tubes; “tracks” that organelles use to move– Important in cell division; separate chromosomesImportant in cell division; separate chromosomes– CiliaCilia– FlagellaFlagella

• MicrofilamentsMicrofilaments– Give movement & supportGive movement & support– Tough, flexible frameworkTough, flexible framework– Motor proteins move organellesMotor proteins move organelles

Ribosomes

• Made of RNA in nucleolusMade of RNA in nucleolus

• Assemble proteinsAssemble proteins

• ““Workers”Workers”

• Endoplasmic Reticulum, “conveyor belt”Endoplasmic Reticulum, “conveyor belt”– Makes cell membrane componentsMakes cell membrane components– Modifies proteinsModifies proteins– rough and smoothrough and smooth

• Rough ERRough ER– involved in synthesis of proteinsinvolved in synthesis of proteins– Gets appearance by ribsomesGets appearance by ribsomes

• Smooth ERSmooth ER– does not have ribosomes on surfacedoes not have ribosomes on surface– Makes lipids for cell membranesMakes lipids for cell membranes

Golgi Apparatus• ““Quality control”Quality control”

• Stack of membranesStack of membranes• Proteins made by RER move hereProteins made by RER move here• Enzymes modify carbohydrates and lipids to proteinsEnzymes modify carbohydrates and lipids to proteins• Brings to the cell surface to be secreted Brings to the cell surface to be secreted

Lysosomes• ““Janitors”Janitors”

• Small, filled with enzymesSmall, filled with enzymes

• Break down lipids, carbohydrates, and proteins into particles the cell Break down lipids, carbohydrates, and proteins into particles the cell usesuses

• Break down old organellesBreak down old organelles

Vacuoles• ““Storage”Storage”

• Store HStore H22O, salts, proteins, carbsO, salts, proteins, carbs

• Support structures, like leaves and flowersSupport structures, like leaves and flowers• Plants often have a central, large vacuolePlants often have a central, large vacuole

• Smaller vacuoles called “vesicles”Smaller vacuoles called “vesicles”

Chloroplasts• ““Solar panels”Solar panels”

• Found in plantsFound in plants• photosynthesisphotosynthesis

• Two envelope Two envelope

membranesmembranes

Mitochondria• ““Power house”Power house”• Release energy from stored food Release energy from stored food • Use energy to make high-energy Use energy to make high-energy

compoundscompounds• 2 envelope membranes2 envelope membranes

• DNADNA• Inherited from mom!Inherited from mom!

• Found in all eukaryotic cellsFound in all eukaryotic cells

Cell as a factory

• Plasma membrane- “shipping/receiving department”

• Cytoskeleton- “walls, roof, and beams”• Nucleus- “the control center, CEO”• Ribosome- “workers” • Golgi Apparatus- “Quality control” • Mitochondria and chloroplasts- “power sources”• Lysosomes- “janitors”

V. Differences between Plant & Animal Cells

• Plants have/animals don’t:

B. Animals have/plants don’t:

VI. Cellular Organization

• Unicellular- “one cell”

1. more complex as one cell than a single cell of

a multicellular organism

2. performs all functions that a multicellular

organism does

B. Multicellular- “many cells” 1. Cell specialization

2. Interdependent on other cells

C. 5 Levels of Organization» Cells» Tissues» Organs» Organ systems» Organism