A Tour of the Cell An inside look at the structure and function

of cells

Zacharias Janssen ◦ A Dutch lens grinder invented the first compound

microscope by placing two lenses together in a tube.

◦ Lead to the discovery of cells and smaller organisms

◦ Major technological breakthrough for biologists.

History of the Microscope

Anton van Leeuwenhoek◦ Known as the father of modern microscopy.◦ Discovered single-celled animal-like organisms that

are now called protozoan's.

Robert Hook◦ Took the first look through a microscope at cork

cells.◦ He noticed many different chambers and called

them cells.◦ First one to draw pictures of organisms under a

microscope.

First Microscope Users

Dissecting◦ Used to view live specimen while dissecting

Compound Light◦ Can be used to view living or dead organisms with

increased magnification. SEM or TEM

◦ Allows you to see 3-D images of specimens. ◦ Can only view specimens that are dead!

Types of Microscopes

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Matthais Schleiden- Studied plants and found out that they were made of individual cells.

Theodor Schwann- Looked at animal tissues and realized that they were made of indivual cells.

Rudolph Virchow- Proposed that all cells are produced from the division of exisiting cells.

These three ideas are the basis of Modern CELL THEORY!!!

Important People

All living things are composed of one or more cells.

Cells are the basic unit of structure and function for all organisms.

Cells only come from previously existing cells.

Cell Theory

Cells are the basic building blocks of organisms

Most cells can only be observed under a microscope

The basic types of cells can include

Plant Animal Bacteria

Introduction to Cells

Basic Structure of a Cell

Prokaryotic- lack a nucleus and membrane bound organelles called organelles. ◦ Mostly bacteria cells

Eukaryotic – have a nucleus and membrane bound organelles. (protista, plant, animals, and fungi)

Cell Types

• Cell membrane & cell wall

• Nucleoid region contains the DNA

• Contain ribosomes (no membrane) to make proteins in their cytoplasm

Prokaryotes

Contain 3 basic cell structures:

Nucleus Cell Membrane Cytoplasm with

organelles

Eukaryotes

Plant Cell Animal Cell

Main Types of Eukaryotic Cells

Are membrane bound structures inside the cell that are used to complete daily processes.

They act like organs in our bodies and create, breakdown and expel materials necessary for life.

Organelles

Controls the movement of materials into and out of the cell

Selectively permeable Lies immediately against the cell

wall in plant cells Made of protein and phospholipids Fluid Mosaic

Cell Membrane or (Plasma Membrane)

Cell Membrane

Jelly-like substance (cytosol) enclosed by the cell membrane

-Provides a medium for chemical reactions to take place

- Contains organelles to carry out specific jobs

Cytoplasm

- Powerhouse of the cell- Rod shape- Site of cellular

respiration which uses organic compounds to produce ATP

- Number of mitochondria in a cell depends on the work that type of cell does (liver cells=2,500)

- Cristae folded membranes inside the organelle

Mitochondria

Most numerous No membrane Made of proteins and

RNA MAKE PROTEINS Can be free in the

cytoplasm or attached to ER

Ribosomes

Smooth ER lacks ribosomes & makes enzymes and steroids USED In the cell

Rough ER has ribosomes on its surface & makes proteins to EXPORT

Closely associated with the nucleus

Smooth and Rough Endoplasmic Reticulum

Stacks of flattened sacs

Have a shipping side & a receiving side (like a post office)

Receive & modify proteins made by ER

Transport vesicles with modified proteins pinch off the ends

Golgi Bodies or Apparatus

Contain digestive enzymes Break down food and worn out cell parts for

cells

Lysosome

Site of water and waste storage.

Animal cells have small ones throughout the cell.

Plants have a large central vacuole.

Vacuoles

Controls the normal activities of the cell◦Bounded by a

nuclear membrane (envelope)

◦Contains chromosomes (DNA)

◦Nucleolus Inside nucleus Makes ribosomes

Nucleus

Hair-like structures that are used for movement.

Cilia- are short and there are thousands of them.

Flagella- long whip-like structure.

Cilia and Flagella

Cell Wall◦Dead layer

(cellulose fibers)◦Freely permeable◦Gives shape to

the cell

Central Vacuole ◦ Store waste and

enzymes

Plant Cell Structures

◦Contain the green pigment chlorophyll

◦Traps sunlight to make sugars (food) photosynthesis

Chloroplasts (plastids)

Centriole◦ Near the nucleus◦ Paired structures◦ Help cell divide

Animal Cell Organelles

-structure to maintain cell shape and size-protein strands- include spindle fibers used in cell division

Cytoskeleton

The shape of a cell is the result of its function.

Cell Shape

Different Kinds of Animal Cells

white blood cell

red blood cell

cheek cells

sperm

nerve cell

muscle cell

Amoeba

Paramecium

Plant Cell vs. Animal Cell

Animal cells Irregular shape No cell wall Relatively smaller in

size Vacuole small or

absent Nucleus at the center Glycogen as food

storage

Plant cells Regular shape Cell wall present Relatively larger in

size Large central

vacuole

Nucleus near cell wall

Starch as food storage