All living things are made up of small individual units called cells. Cells are the smallest functioning living unit. Cells can not normally be seen with the naked eye. To usually observe a cell, you need a microscope!

Robert Hooke and Anton van Leeuwenhoek used the first 'primitive' microscopes to observe stuff in the mid 1600's! In the 400+ years since, improvements in the microscope have allowed scientists to observe cells better and to develop the cell theory.

THE CELL THEORY

1) All organisms are made up of one or more cells (unicellular or multicellular).

2) All cells carry out the 8 life functions. R + R + R + E + G + N + T + S

3) All cells come from preexisting cells. BUT...

There are a few exceptions to the cell theory...things that go against it...

A) Where did the first cells come from?
CHICKEN AND THE EGG SYNDROME

B) Viruses are NOT composed of cells. But they do contain genetic material (DNA and/or RNA). They also can reproduce in the presence of a host cell.

C) Some cell parts (mitochondria and chloroplast) contain their own genetic material (DNA and/or RNA) and can reproduce in a cell.

Remember:
3 PARTS TO THE CELL THEORY
&
3 EXCEPTIONS TO THE CELL THEORY

How life is organized...

I. Atoms and Molecules
* the building blocks of everything in the universe

II. Organelles
* small parts of cells that have specific functions
* different organelles have different jobs

III. Cells
* the building blocks of life
* all living things are made up of one (unicellular) or more (multicellular) cells
* there are many types

ex. muscle cells, neurons (brain cells),
skin cells, bone cells, blood cells

IV. Tissues
* a group of cells that perform a certain function

ex. muscles, tendons, nerves

V. Organs
* a group of tissues that perform a certain function
* like organelles, different organs carry out different functions

ex. brain, heart, skin, liver, intestines

VI. Organ Systems
* a group of organs that perform a certain function
* organ systems have specific jobs

ex. digestive system, circulatory system, nervous system, reproductive system

VII. Organism
* a thing that carries out the 8 life functions

VIII. Population
* a group of organism of the same species in a given area

IX. Community
* a group of populations in a given area

X. Ecosystem
* a community and the physical non-living environment that it exists in

XI. Biosphere
* the region of earth where life exists
* all ecosystems on the planet make up the biosphere

I. Prokaryotes
* lack any internal membranes
* only monerans are prokaryotes

II. Eukaryotes
* have many internal membrane structures:

Both prokaryotes and eukaryotes are basically alike--

* both have outer membranes
* both carry out the 8 life functions

Different Cell Parts

In cells, various specialized functions occur in specific places. These places are called organelles (small organs). Here are some of the major organelles that we will study this year.

1) Plasma Membrane (sometimes called the Cell Membrane)--
* made up of lipids (fats) and proteins

There are two layers of fats that have proteins floating inside. Kinda like 'jello with fruit in it' or like 'protein icebergs in a fatty sea'.

* regulates the transport of certain material into and out of a cell...called SELECTIVELY PERMEABLE; only some stuff can actually go through

* contain receptor molecules that aid in cell to cell communication

2) Cytoplasm--
* a watery fluid where the cell organelles are located
* many of the complex chemical reactions take place here

3) Nucleus--
* surrounded by a nuclear membrane
* only found in EUKARYOTES
* contains genetic material (DNA) in the form of chromosomes that controls the activities of the cell
* BOSS OF THE CELL! It controls all of the cell functions!

4) Nucleolus--
* found in nucleus
* involved with synthesizing ribosomes (#6 )

A) rough--the 'ER' studded with ribosomes

B) smooth--the 'ER' without any ribosomes

6) Ribosomes--
* place of protein synthesis
* can be attached to the endoplasmic reticulum OR floating around in the cytoplasm

7) Mitochondria--
* site of cellular respiration
* POWERHOUSE OF A CELL!!! Where energy is released from nutrients
* there are MANY in a single cell
* has two layers, makes up a double membrane

8) Vacuole--
" a "space" in a cell that contains water or other materials; usually for storage

A) food vacuoles--store food

B) contractile vacuoles-- squeeze out excess water

9) Lysosome--

* a vacuole that contains digestive enzymes; helps in the process of nutrition by breaking down nutrients in the cell

10) Golgi complex (or Golgi bodies)--
* packages and secretes cellular products
* a series of flattened sac

* takes products from ER and ships them to the cell membrane--POST OFFICE OF CELL

watch the following animation to see how transport happens inside the cell

Here are some organelles that are found only in specific cell types...

11) Centrioles--
* found in animal cells; rare in plants
* are cyndrical structures (like cans) found in the cytoplasm that appears to function during cell division (reproduction)

12) Chloroplasts--
* found in photosynthetic organisms
* contains chlorophyll, a pigment that makes photosynthesis possible

13) Cell Wall--
* found mostly in plant cells (some monerans, protists, and fungi too)
* a non-living structure which surrounds and supports a cell
* made of cellulose, a complex carbohydrate

14) Cilia and Flagella--
* these are hair-like organelles that extend from the surface of many different types of cells

A) cilia--are typically smaller than flagella, but they cover the outside of the organism
B) flagella--are much longer than cilia, but there usually are few on a single cell

* these structures usually aid in movement
* they can also help sweep materials along the outside of a cell

plant vs. animal cytology

There are 3 IMPORTANT differences between plant and animal cells.

A) Plant cells have a cell wall around their plasma (cell) membrane animal cell do not.

B) Plant cells have chloroplasts for photosynthesis, animal cells do not.

C) Animal cells have centrioles, which help in cell division, plant cells do not.

VIRUSES!

* are not cells!
* viruses can NOT carry out most life functions, however...they can REPRODUCE
* reproduction of viruses can only happen inside a host cell!
* viruses, along with bacteria (cells), fungi (cells), and other parasites can infect plants and animals and interfere with normal life functions!

ex. influenza, HIV, chicken pox, polio, smallpox (gone!), viral pneumonia

BIOLOGICAL INSTRUMENTATION

Continuing advances in techniques and instrumentation have enabled biologists to increase their understanding of cell structures and functions. Here is a list of some of the tools biologists use.

I. Compound Light Microscope--
* parts and function of parts will be given during lab
* can magnify thin objects up to 2000X
* can examine live organisms

II. Electron Microscope--
* can magnify images up to and beyond 250,000X
* can only show the image of dead organisms; the slides must be coated in a special fashion

III. Dissecting Microscope--
* can magnify a specimen to about 50X
* can be used to look more closely at specimens during dissection

IV. Ultracentrifuge--
* used to separate material by density
* a liquid is spun fast...about 100,000 times a minute!
* heavier material settles at the bottom, lighter material floats on top

V. Microdissection Instruments--
* used to perform 'operations' on living cells
* can transplant or remove organelles from cells