BIOL 201, Lecture 3BIO-SCEINCE – FCCU

Dr Saba Butt

Use of lenses for magnifying was an old story.

Sometime about the year 1590, two Dutch spectacle makers, Janssen and his father Hans started experimenting with the lenses.

They put several lenses in a tube and the object near the end of the tube appeared to be greatly enlarged.

They had just invented the compound microscope (which is a microscope that uses two or more lenses).

Galileo heard of their experiments and started experimenting on his own. He described the principles of lenses and light rays and improved both the microscope and telescope.

Anthony Leeuwenhoek of Holland became very interested in lenses while working with magnifying glasses in a dry goods store.

He used the magnifying glass to count threads in woven cloth.

He improved the lenses to produce greater magnification, and his microscopes were able to magnify up to 270X!

Anthony Leeuwenhoek saw bacteria, yeast, blood cells and many tiny animals swimming about in a drop of water. From his great contributions, many discoveries and research papers, Anthony Leeuwenhoek (1632-1723) has since been called the "Father of Microscopy".

Robert Hooke, an Englishman (who is sometimes called the “English Father of Microscopy”), also spent much of his life working with microscopes and improved their design and capabilities.

Robert Hooke (1635-1703) observed the “cells” for the first time.

In 1660, he used a microscope to look at tree barks and found tiny compartments – the

cells.

Antonie Philips van Leeuwenhoek (1632-1723) observed small organisms under the microscope and named them “animalcules”; We call them “microorganisms” now.

He also improved the design of microscope.

Microscope by Hooke and image taken through this

Leeuwenhoek also described muscle fibers, blood capillaries, bacteria and spermatozoa.

Single celled organisms, bacteria

Fossil records indicate that mounds of bacteria once covered young Earth

Some started photosynthesis to produce enough oxygen to give rise to the aerobic organisms

With a population of increasingly diverse bacterial life, the stage was set for some amazing things to happen

There is compelling evidence that mitochondria and chloroplasts were once primitive bacterial cells

Symbiosis occurs when two different species benefit from living and working together. When one organism actually lives inside the other it's called endosymbiosis

Over millions of years of evolution, mitochondria and chloroplasts have become more specialized

Mitochondria and chloroplasts have striking similarities to bacteria cells.

They have their own DNA used to produce many proteins and enzymes required for their function.

A double membrane surrounds both mitochondria and chloroplasts

The two organelles also reproduce like bacteria, replicating their own DNA and directing their own division

Mitochondrial DNA (mtDNA) has a unique pattern of inheritance.

It is passed down directly from mother to child, and it accumulates changes much more slowly than other types of DNA.

Because of its unique characteristics, mtDNAhas provided important clues about evolutionary history.

For example, differences in mtDNA are examined to estimate how closely related one species is to another.

Conditions on Earth 4 billion years ago were very different than they are today.

The atmosphere lacked oxygen, and an ozone layer did not yet protect Earth from harmful radiation.

Heavy rains, lightening and volcanic activity were common.

Yet the earliest cells originated in this extreme environment.

Today, a group of single-celled organisms called archaeabacteria, or archaea, still thrive in extreme habitats

Archaea are used to study the origins of life on Earth and other planets.

Because archaea inhabit places previously considered incompatible with life, they may provide clues that will improve our ability to detect extraterrestrial life.

Interestingly, current research suggests archaea may be capable of space travel