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 19 th 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

19

th

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

CELL WALL

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

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 ORGANISM

Cell

The basic unit of life

Tissue

Group of cells working together

Organ

Group of tissues working together

Organ System

Group of organs working together

Organism

Any living thing made of 1 or more cells

a. Nucleus

NAME THE ORGANELLE

c. Golgi body b. Chloroplast d. Mitochondria

1- Nucleus 2- Chromosomes 3- Mitochondria 4- Ribosomes 5- Chloroplasts 6- Vacuoles 7- ER 8- Cell Membrane