Cell Biology Preview

1
Chapter One

• A Preview Of Cell Biology
• By Arkan Omais

2
Introduction

• The cell is the basic unit of biology
• Cells are constantly changing
• The convergence of cytology, genetics, and
  biochemistry has made modern cell biology one of
  the most exciting dynamics and disciplines in
  biology

3
The Cell Theory A Brief History

• Robert Hooke (1665) observed compartments in
  cork, under a microscope, and first named the
  cells
• He had observed the compartments formed by cell
  walls of dead plant tissue

4
Advances in Microscopy Allowed Detailed Studies
of Cells

• Two factors restricted progress in early cell
  biology
• Microscopes had limited resolutions, or resolving
  power ( ability to see fine detail)
• The descriptive nature of cell biology the focus
  was on observation, with little emphasis on
  explanation

5
Compound Microscopes

• By the 1830s, compound microscopes were used
  having the following features
• Contain two lenses
• Both magnification and resolution were improved
• Structures only 1µm in size could be seen

6
The Cell Theory Applies to All Organisms

• Using a compound microscope, Robert Brown
  identified the nucleus, a structure inside plant
  cells
• Matthias Schleiden concluded that all plant
  tissues are composed of cells
• Thomas Schwann made the same conclusion for
  animals

7
The Cell Theory

• In 1839, Schwann postulated the cell theory
• All organisms consist of one or more cells
• The cell is the basic unit of structure for all
  organisms
• Later, Virchow (1855) added
• 3. All cells arise only from preexisting cells

8
The Emergence of Modern Cell Biology

• Three strands of biological inquiry weave into
  modern cell biology
• Cytology focuses mainly on cellular structure and
  emphasizes optical techniques
• Biochemistry focuses on cellular morphology and
  function
• Genetics focuses on information flow and heredity
  and includes sequencing of the entire genome (all
  of the DNA) and the numerous organisms

9
Cellular Dimensions

• Cells are measured in micrometer µm also called a
  micron where 1µm 10-6 m
• Plant and animal cells are larger than bacterial
  cells in size by 10- 20 times
• Organelles are comparable to bacterial cells in
  size

10
The Light Microscope

• Earliest tools of cytologists
• Allowed identification of nuclei, mitochondria,
  chloroplasts within cells
• Light microscopy is also called brightfield
  microscopy because white light is passed directly
  through a specimen

11
Improvements of Microscopy

• Microtome (1800s) allowed preparation of very
  thin slices of samples
• Usage of dyes for staining cells
• Improving the limit of resolution
• A greater resolving power
• Electroscope

12
Meanings

• Morphology shape or structure
• Electroscope a scientific instrument that uses
  electric beams to detect and observe the samples
  sharply