DiffDiffBiologyBiologyCh. 7Ch. 7

DiffDiffBiologyBiologyCh. 7Ch. 7

A View of the Cell

A View of the Cell

CH. 7 A View of the Cell

CH. 7 A View of the Cell

A.A. HistoryHistory- before 1600’s - fiber/tissue

thought to be the basic unit of life

- spontaneous generation

1. Robert Hooke (1665)- observed cork cells

I. The Cell Theory:

I.The Cell Theory:

Robert Hooke (1665)- Coined term ‘Cell’

Robert Hooke (1665)- Coined term ‘Cell’

2. Van Leeuwenhoek

(1683) 2. Van Leeuwenhoek

(1683) - first to

see living cells

Von Leeuwenhoek (1683)- first to see living cells

Von Leeuwenhoek (1683)- first to see living cells

3.Mathias Schleiden (1838)

3.Mathias Schleiden (1838)- plants made

up of cells

4.4.Theodor SchwannTheodor Schwann (1838)

4.4.Theodor SchwannTheodor Schwann (1838)- animals made

up of cells

5.5.Rudolph VirchowRudolph Virchow (1855)

5.5.Rudolph VirchowRudolph Virchow (1855)

- cells come from other cells

B.The Cell Theory(3 parts):

B.The Cell Theory(3 parts):1.All living things are made

of cells.2.All cells come from

preexisting cells.3.Cells are the basic units

of structure and function.

- developed over several hundred years involving many scientists

- followed the development of the microscope

Research Method: Light Microscopy

Research Method: Light Microscopy

TECHNIQUE RESULTS

Brightfield (unstained specimen). Passes light directly through specimen. Unless cell is naturally pigmented or artificially stained, image has little contrast. [Parts (a)–(d) show a human cheek epithelial cell.]

(a)

Brightfield (stained specimen). Staining with various dyes enhances contrast, but most staining procedures require that cells be fixed (preserved).

(b)

Phase-contrast. Enhances contrast in unstained cells by amplifying variations in density within specimen; especially useful for examining living, unpigmented cells.

(c)

50 µm

Differential-interference-contrast (Nomarski). Like phase-contrast microscopy, it uses optical modifications to exaggerate differences indensity, making the image appear almost 3D.

Fluorescence. Shows the locations of specific molecules in the cell by tagging the molecules with fluorescent dyes or antibodies. These fluorescent substances absorb ultraviolet radiation and emit visible light, as shown here in a cell from an artery.

Confocal. Uses lasers and special optics for “optical sectioning” of fluorescently-stained specimens. Only a single plane of focus is illuminated; out-of-focus fluorescence above and below the plane is subtracted by a computer. A sharp image results, as seen in stained nervous tissue (top), where nerve cells are green, support cells are red, and regions of overlap are yellow. A standard fluorescence micrograph (bottom) of this relatively thick tissue is blurry.

50 µm

50 µm

(d)

(e)

(f)

Micrograph of a neuron

and dendrites using

antibodies, fluorescent

proteins, and confocal

microscope

Micrograph of a neuron

and dendrites using

antibodies, fluorescent

proteins, and confocal

microscope

Research Method: Electron Microscopy

Research Method: Electron Microscopy

TECHNIQUE RESULTS

Scanning electron micro-scopy (SEM). Micrographs takenwith a scanning electron micro-scope show a 3D image of the surface of a specimen. This SEM shows the surface of a cell from a rabbit trachea (windpipe) covered with motile organelles called cilia. Beating of the cilia helps moveinhaled debris upward toward the throat.

(a)

Transmission electron micro-scopy (TEM). A transmission electron microscope profiles a thin section of a specimen. Here we see a section through a tracheal cell, revealing its ultrastructure. In preparing the TEM, some cilia were cut along their lengths, creating longitudinal sections, while other cilia were cut straight across, creating cross sections.

(b)

Cilia 1 µm

Longitudinalsection ofcilium

Cross sectionof cilium

1 µm

Light Microscopes vs. Electron MicroscopeLight Microscopes vs. Electron Microscope

Light Microscope Electron Microscope

Weak Magnification—up to 1000x

Strong Magnification—500,000x

Cheap Expensive

Can look at living organism Can only look at dead organism

Everything that lives is made of cells.

Everything that lives is made of cells.

C.Two Basic Cell Types:

C.Two Basic Cell Types:1.1. Prokaryotes:Prokaryotes:

- no nucleus nor organelles- simple internal structure- very small, primitive,

unicellular- bacteria

ProkaryoProkaryoteteProkaryoProkaryotete

Bacteria Cell

2.Eukaryotes:2.Eukaryotes:- have a nucleus and

membrane-bound organelles- complex internal structure- animals, plants, fungi,

protists

EukaryotEukaryotee

EukaryotEukaryotee

Animal Cell

EukaryotEukaryotee

EukaryotEukaryotee

Plant Cell

Prokaryotes vs EukaryotesProkaryotes vs EukaryotesProkaryotes Eukaryotes

Plasma membrane Plasma membrane

Cytoplasm Cytoplasm

Ribosomes (makes proteins) Ribosomes(makes proteins)

DNA DNA

Prokaryotes Eukaryotes

No nucleus nucleus

No membrane bound organelles

Membrane bound organelles

DNA is not associated with proteins

DNA is associated with protiens (histones)

DNA not in nucleus DNA is in nucleus

3. Cytoplasm

II. Cell StructureII. Cell Structure- 3 main parts of cells:1. Plasma membrane

2. Nucleus

1.Composition- bilayer of phospholipids embedded with proteins- “fluid mosaic” theory

A.Plasma membrane: A.Plasma membrane:

Plasma membranePlasma membrane

lipid bilayerprotein

s

Plasma membranePlasma membrane

Glycoprotein

Carbohydrate

Microfilamentsof cytoskeletonCholesterol Peripheral

proteinIntegralprotein

CYTOPLASMIC SIDEOF MEMBRANE

EXTRACELLULARSIDE OF MEMBRANE

Glycolipid

Fibers of extracellularmatrix (ECM)

- holds cell together- regulates movement of

molecules into or out of the cell

2.Function:2.Function:

3.Cell Wall3.Cell Wall- Prokaryotes (bacteria), fungi

and plants have a cell wall- Animal cells do NOT have a cell wall.- rigid, layered structure on the

outside of cells that protects and supports cell

- found on cells of plants, fungi, and bacteria

- plant cell walls made of cellulose

Cell Wall Cell Wall

Membrane ProteinsMembrane Proteins

Look at the oligosaccharideHelps with cell to cell recognition

Peripheral proteinsPeripheral proteinsAdhere

temporarily to the plasma membrane

Regulate cell signaling

GlycoproteinGlycoproteinCell ReceptorStructureHormonesCell attachmentEnzyme

CholesterolCholesterolMaintains fluidity

-In the heat keeps phospholipids together

- In the cold prevents phospholipids from being to close to each other. **prevents rigidity.

GlycolipidGlycolipidProvides energyServe as markers

for cell to cell recognition

Nucleus

B.Nucleus:

B.Nucleus:- control center of the cell- contains chromatin (DNA

“blueprint” for cell’s proteins)

End of 7.1 and 7.2 Notes

End of 7.1 and 7.2 Notes

Stop studying here.

1. Nucleolus:1. Nucleolus:- makes ribosomes

2.2. Chromatin:Chromatin:- active form of chromosomes- long threads of DNA and protein

Cytoplasm

- liquid interior of the cell- mostly water with dissolved

substances (O2,CO2, sugar, etc.)

C. CytoplasmC. Cytoplasm

OrganellesCytoplasm

- contains Organelles:tiny structures that carry out specialized functions

C. CytoplasmC. Cytoplasm

D. Assembly, Storage,and Transport

D. Assembly, Storage,and Transport

1. Ribosomes:1. Ribosomes:- where proteins are made in a

cell- found in both prokaryotes and

eukaryotes

2. Endoplasmic Reticulum:

2. Endoplasmic Reticulum:

- produces and transports molecules

3. Golgi Body:3. Golgi Body:- store, modify, and package

proteins, hormones, etc.

- stores food, waste, sugar, water, etc.

4.Vacuole:4.Vacuole:

Vacuole

Stored food or waste

5. Lysosome:5. Lysosome:- digest food molecules or

worn-out cells

6. Leucoplasts:6. Leucoplasts: - store starch (plants only)

7.7. Chromoplasts:Chromoplasts:- contain colorful

pigments (plants only)

E.E. Energy Energy TransformationsTransformations

- "power house" of cells1.Mitochondrion:1.Mitochondrion:1.Mitochondrion:1.Mitochondrion:

- site of cellular respiration

Glucose + Oxygen Energy + CO2 +

H2O

C6H12O6 + O2

1.Mitochondrion:1.Mitochondrion:1.Mitochondrion:1.Mitochondrion:

- site of photosynthesis in plant cells

2.2. Chloroplasts:Chloroplasts:2.2. Chloroplasts:Chloroplasts:

Sunlight + H2O + CO2 C6H12O6 +

O2

2.2.Chloroplasts:Chloroplasts:2.2.Chloroplasts:Chloroplasts:

F. Support and Locomotion

F. Support and Locomotion

1.Cytoskeleton- internal framework of cell

a. Microtubulesb. Microfilaments

- contractile proteins- enable cells to move

2. Centrioles2. Centrioles- aid in the division of animal

cells

3. Cell Locomotion3. Cell Locomotiona.Cilia:

- short fibers, usually in large number

b.Flagella:- long fibers, usually single or pairs

III. Cellular TransportIII. Cellular Transport- molecules constantly

enter and leave the cell

A. DiffusionA. Diffusion- movement of molecules from

high concentration to low conc.

- until dynamic equilibrium reached

- requires no cell energy (passive)

B.B. Osmosis:Osmosis:B.B. Osmosis:Osmosis:- diffusion of water through a

selectively permeable membrane

C. Effects of OsmosisC. Effects of Osmosis1.1. Isotonic SolutionIsotonic Solution

- concentration of solutes the same on inside and

outside of cell

2. Hypotonic Solution2. Hypotonic Solution- solution outside of cell

contains a lower conc. of solutes than the cell (more water)

a)a) Turgor pressure:Turgor pressure:a)a) Turgor pressure:Turgor pressure:- pressure inside plant cells

Leaves and Onion Epidermis

Leaves and Onion Epidermis

a)a) Turgor pressure:Turgor pressure:a)a) Turgor pressure:Turgor pressure:

Plant Movements from Osmosis

Plant Movements from Osmosis

a)a) Turgor pressure:Turgor pressure:a)a) Turgor pressure:Turgor pressure:

b) Cytolysis:b) Cytolysis:b) Cytolysis:b) Cytolysis:- bursting of cells due to

increased osmotic pressure

c) Contractile Vacuoles:

c) Contractile Vacuoles:

- “pump” water out of cells of paramecium, ameba, etc. living in a hypotonic

solution

ParameciumParamecium

3.Hypertonic Solution

3.Hypertonic Solution- solution outside of cell

contains a higher conc. of solutes than the cell (less water)

a) Plasmolysis:a) Plasmolysis:a) Plasmolysis:a) Plasmolysis:- loss of cytoplasm

(shrinking of the cell)

b) Wilting:b) Wilting:b) Wilting:b) Wilting:- loss of turgor in plant cells

D.Passive vs. Active Transport

D.Passive vs. Active Transport

1.Passive Transport:- requires no energya) Diffusion and Osmosis

b) Facilitated b) Facilitated Diffusion:Diffusion:

b) Facilitated b) Facilitated Diffusion:Diffusion:- transport proteins in

membrane move sugar, amino acids, etc.

- follows concentration gradient

b) Facilitated b) Facilitated Diffusion:Diffusion:

b) Facilitated b) Facilitated Diffusion:Diffusion:

2.2.Active Transport:Active Transport:2.2.Active Transport:Active Transport:- requires cell energy

a)a)Carrier proteinsCarrier proteins transport molecules from low. conc. to high conc. using cell energy

Active Active Transport:Transport:

Active Active Transport:Transport:

b)b) Endocytosis:Endocytosis:b)b) Endocytosis:Endocytosis:

b)b) Endocytosis:Endocytosis:b)b) Endocytosis:Endocytosis:- movement of large amounts of

material into a cell by engulfing and enclosing within a membrane

- forms a vacuole within cell

b)b)Endocytosis:Endocytosis:b)b)Endocytosis:Endocytosis:

AmebaAmeba

c)c) Exocytosis:Exocytosis:c)c) Exocytosis:Exocytosis:

c)c) Exocytosis:Exocytosis:c)c) Exocytosis:Exocytosis:- expelling large amounts of

material from the cell

c)c) Exocytosis:Exocytosis:c)c) Exocytosis:Exocytosis:

Paramecium

Paramecium

The

End

The

End

Elodea Leaf CellsElodea Leaf Cells

Tomato CellsTomato Cells

Potato CellsPotato Cells

Human Epithelial Cells

Human Epithelial Cells

Onion Cells- Unstained (40x)

Onion Cells- Unstained (40x)

Onion Cells- Stained (40x)Onion Cells- Stained (40x)

Bacteria CellsBacteria Cells

CoccuCoccuss

BacilluBacilluss

SpirilluSpirillumm

Von Leeuwenhoek (1675)- first to see live cells

Von Leeuwenhoek (1675)- first to see live cells