Cells: The Units of Life

The Cell Theory

Some Random Cell Facts

The average human being is composed of around 100 Trillion individual cells!!!

It would take as many as 50 cells to cover the area of a dot on the letter “i”

Discovery of Cells

1665- English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork.

He described the cells as tiny boxes or a honeycomb

He thought that cells only existed in plants and fungi

Anton van Leuwenhoek

1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms

He called them “animalcules”

He also observed blood cells from fish, birds, frogs, dogs, and humans

Therefore, it was known that cells are found in animals as well as plants

150-200 Year Gap???

Between the Hooke/Leuwenhoek discoveries and the mid 19th century, very little cell advancements were made.

This is probably due to the widely accepted, traditional belief in Spontaneous Generation.

Examples:

-Mice from dirty clothes/corn husks

-Maggots from rotting meat

19th Century Advancement

Much doubt existed around Spontaneous Generation Conclusively disproved by Louis Pasteur

Pasteur: Ummm, I don’t think so!!!

+

=?

Development of Cell Theory

1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells

1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.

Development of Cell Theory

1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells.

The Cell Theory Complete

The 3 Basic Components of the Cell Theory were now complete:

1. All organisms are composed of one or more cells. (Schleiden & Schwann)(1838-39)

2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)(1838-39)

3. All cells are produced by the division of preexisting cells. (Virchow)(1858)

Modern Cell Theory

Modern Cell Theory contains 4 statements, in addition to the original Cell Theory:

The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division.

All cells are basically the same in chemical composition and metabolic activities.

All basic chemical & physiological functions are carried out inside the cells.(movement, digestion,etc)

Cell activity depends on the activities of sub-cellular structures within the cell(organelles, nucleus, plasma membrane)

How Has The Cell Theory Been Used?

The basic discovered truths about cells, listed in the Cell Theory, are the basis for things such as:– Disease/Health/Medical Research and Cures(AIDS,

Cancer, Vaccines, Cloning, Stem Cell Research, etc.)

Parts of the Cell: Organelles

COMMON CELL TRAITS

A cell is the smallest unit that is capable of performing life functions.

2 Types of Cells

COMPARING CELLS

The size & shape of a cell relates to its function. (job it does)

Prokaryotic Cells(proh KAYR ee yah tihk)

cells without membrane-bound structures

EX: bacteria

pond scum

Eukaryotic Cells(yew KAYR ee yah tihk)

cells with membrane-bound structures

EX: animals, plants, fungi and protists

protects the cell gives shape is made of cellulose A cell wall is found in plants, algae, fungi, & most

bacteria.

CELL WALL

CELL MEMBRANE

Outer covering, protective layer around ALL cells

For cells with cell walls,the cell membrane is inside the cell wall

Allows food, oxygen, & water into the cell & waste products out of the cell.

CYTOPLASM

gelatin-like inside cell membrane constantly flows aka protoplasm

CYTOSKELETON

scaffolding-like structure in cytoplasm

helps the cell maintain or change its shape

made of protein

NUCLEUS

Directs all cell activities Contains instructions

for everything the cell does

These instructions are found on a hereditary material called DNA

Usually the largest organelle

NUCLEAR MEMBRANE

separates nucleus from cytoplasm

controls movement of materials in & out of nucleus

NUCLEOLUS

Aka “little nucleus” Found in the nucleus

CHROMATIN

contains genetic code that controls cell made of DNA & proteins

CHLOROPLASTS

Green organelles that make food

found only in plant cells

CHLOROPHYLL

A green pigment that gives leaves & stems their color

Captures sunlight energy that is used to produce food called glucose

Glucose is a type of sugar

MITOCHONDRIA

Organelles that release energy from food

This energy is released by breaking down food into carbon dioxide

AKA the powerhouse b/c they release energy from food

Some muscle cells have 20,000 mitochondria

RIBOSOMES

Make proteins Float freely or attached to

the endoplasmic reticulum (ER)

Ribosomes are made in the nucleolus

ENDOPLASMIC RETICULUM

A series of folded membranes that move materials (proteins) around in a cell

like a conveyor belt Smooth ER – ribosomes not

attached to ER Rough ER – ribosomes

attached to ER

GOLGI BODIES (GAWL jee)

Stacked flattened membranes

Sort and package proteins

VACUOLES

Temporary storage spaces

Store food, water, waste

LYSOSOMES (LI suh sohmz)

The word "lysosome" is Latin for "kill body." The purpose of the lysosome is to digest things.

They might be used to digest food or break down the cell when it dies.

Break down food molecules, cell wastes & worn out cell parts

FROM CELL TO ORGANISMCell

The basic unit of life

TissueGroup of cells working together

OrganGroup of tissues working together

OrganismAny living thing made of 1 or more cells

Organ SystemGroup of organs working together

NAME THE ORGANELLE

d. Mitochondriab. Chloroplast

c. Golgi body a. Nucleus

1- Nucleus

2- Chromosomes

3- Mitochondria

4- Ribosomes

5- Chloroplasts

6- Vacuoles

7- ER

8- Cell Membrane