Cell Structure and Function

Chapter 4

The history of cell biology

Both living and nonliving things are made of atoms, molecules and compounds.

How are living and nonliving things different?

Discovery of cells

All living things are made up of one or cells.

Cell- smallest unit that can carry on all of the processes of life.

Robert Hooke

English ScientistUsed an early light microscope to study nature in 1665.Light Microscope- uses optical lenses to magnify objects by bending light rays.He named them cells after looking at a cork and noticing that the it looked like the “cells” where monks live.

Anton van Leeuwenhoek

Dutch Trader

1st person to observe living cells

Made microscopes with a lens 10 times the magnification of Hooke’s.

Looked at Spirogyra…..called them animalcules….now called protists.

Cell Theory

The importance of these discoveries were not realized until 150 years later.

In 1838, German botanist, Matthias Schleiden concluded that all plants were composed of cells.

The next year German zoologist, Theodore Schwann concluded the same thing for animals.

German physician, Rudolf Virchow noted that all cells come from other cells.

These observations were combined to form the CELL THEORY!

The Cell Theory

All living organisms are composed of one or more cells

Cells are the basic units of structure and function in an organism

Cells come only from the reproduction of existing cells

Time Line of Cell Biology

1665- Robert Hooke observes cork cells

1827- mammalian egg discovered

1855- Virchow adds to the cell theory

1897- Golgi apparatus discovered

1996- Sheep cloned from an adult sheep cell

2004- Tissue engineering used to grow new skin and bone for transplant

Cellular basis of life

Microscopes helped biologists clarify our definition of life.

All living things share several basic characteristics of life.

Basic Characteristics

Organized parts

Obtain energy from their surroundings

Perform chemical reactions

Change with time

Respond to their environment

Reproduce

homeostasis

The ability to maintain a constant internal environment.

Cell Diversity

Cells are very diverse in shape, size, and internal organization.

Cells function influences its physical features

Cell Shape

The diversity of cell shapes reflects the different function of cells.

It can be simple or complex.

Cell size

Some cells can be seen with the naked eye.

Most cells however are only 10 to 50 micrometers in diameter. (1/500 the size of the period at the end of a sentence.)

Basic parts of a cell

Plasma Membrane- (cell membrane)- covers a cell surface and acts as a barrier between the inside and the outside of the cell.Cytoplasm- region inside the plasma membrane that includes the fluid, cytoskeleton, and all the organelles except the nucleus.Nucleus- Membrane bound organelles that contains DNA.

Types of Cells

Prokaryotes- lack membrane bound organelles, and have no nucleus. DNA gathers in a central location call the nucleoid.2 domains- Bacteria and ArcheaEukaryotes- made up of one or more cells that have a nucleus and membrane bound organelles. Organelles- well defined intracellular bodies that perform specific functions in a cell.

Cellular Organization

Over time cells begin to form groups that functioned together. Some cells retained the ability to live outside a group. Others need each other to survive.

Tissue- group of similar cells and their products that carry out a specific function

Organs- groups of tissues that perform a particular job

Organ System- group of organs that perform a specific task (circulatory system)