, CHAPTER 1
INTRODUCTION TO THE STUDY OF CELL AND MOLECULAR
BIOLOGY
OBJECTIVES
Identify the three tenets of cell theory.
Explain the importance of the fundamental properties shared by all cells.
Compare the structures and functions of prokaryotic and eukaryotic cells.
Distinguish the structures and functions of viruses and viroids.
Differentiate a colony of individual single-celled organisms from a multicellular organism.
Describe how tissue engineering can create cell-based replacement organs.
LECTURE OUTLINE
(1.1) The Discovery of Cells
I. Cell and molecular biology is reductionist, based on the view that knowledge of the parts of the whole can
explain the character of the whole.
A. The reductionist view can lead to replacement of the wonder and mystery of life by the need to explain
everything in terms of the workings of the "machinery" of living systems which many consider a loss.
B. It is hoped that one can replace this loss by an equally strong appreciation for the beauty and complexity
of the mechanisms underlying cellular activity.
Microscopy
I. Cell biology began as a result of the discovery that curved glass surfaces can bend light and form images.
A. Spectacles were first made in Europe in the 13th century.
B. First compound (double-lensed) microscopes were made by the end of the 16th century, microscopes
provide a magnified image of a tiny object.
C. By the mid-1600s, a handful of scientists had used handmade microscopes to uncover a previously
unseen world that could not be seen with the naked eye.
II. Robert Hooke (1665), English microscopist who at age 27 became curator of the Royal Society, England's
foremost scientific academy, is generally credited with the discovery of cells.
A. In describing the chambers in cork, part of the bark of trees, he called them cells (cellulae) since they
reminded him of cells occupied by monks living in a monastery.
1. Found them while trying to explain why cork stoppers could hold air in a bottle so effectively; cork
is part of the bark of trees.
1
, 2. He said "“I took a good clear piece of cork, ….., I cut a piece of it off, and . . . then examining it with
a Microscope, me thought I could perceive it to appear a little porous . . . much like a Honeycomb.”
3. He called the pores cells.
B. Was looking at the empty cell walls of dead plant tissue that had no internal structure, the walls
originally made by the living cells they surrounded.
III. Anton van Leeuwenhoek (1665-1675) was Dutch seller of clothes and buttons and in his spare time he
ground lenses and made simple microscopes of remarkable quality.
A. For 50 years, he sent letters to the Royal Society of London describing his microscopic observations,
and included in his letters a rambling discourse on his daily habits and the state of his health.
B. He was the first to describe living single cells, and his results were checked and confirmed by Hooke.
1. Saw “animalcules” in pond water darting back and forth, the first to do this, using the scopes that he
made.
2. First to describe various forms of bacteria from tooth scrapings and water in which pepper was soaked.
C. His initial letters to the Royal Society describing what he saw were met with skepticism so the Society
sent its curator, Robert Hooke, to confirm the observations.
1. Hooke confirmed Leeuwenhoek's findings and soon Leeuwenhoek was a worldwide celebrity.
2. He was visited in Holland by Peter the Great of Russia and the queen of England.
Cell Theory
I. The 1830s is when the full and widespread importance of cells was realized.
A. Matthias Schleiden, German lawyer turned botanist (1838) concluded that, despite differences in various
tissue structures, all plant tissues were made of cells and that plant embryos arise from single cell.
B. Theodor Schwann, German zoologist (1839) and colleague of Schleiden's, realized the cellular basis of
animal life and concluded that plants and animals are similar structures.
1. Published a comprehensive report on the cellular basis of animal life.
C. Schwann concluded that the cells of plants and animals are similar structures and then proposed the first
two tenets of the cell theory.
1. All organisms are composed of one or more cells.
2. The cell is the structural unit of life for all organisms.
D. However, the Schleiden-Schwann view of cell origin was less insightful, as both agreed that cells could
arise from noncellular materials that was eventually disproved by others; however, it took time due to their
prominence.
1. It took a number of years before observations by other biologists were accepted to demonstrate that
cells did not arise in this manner any more than organisms arose by spontaneous generation.
E. Rudolf Virchow, a German pathologist (1855), made good case for and added third tenet of Cell Theory
derived from his cell division observations that ran counter to Schleiden-Schwann view of cell origins.
1. Cells can arise only by division from a preexisting cell.
F. Since the discovery of DNA as the genetic material, a fourth tenet of cell theory is sometimes added.
1. Cells contain genetic information in the form of DNA, and that information is passed from parent to
daughter cell.
(1.2) Basic Properties of Cells
2
, I. Life is the most basic property of cells, and they are the smallest units to exhibit this property.
A. Unlike the parts of a cell, which deteriorate if isolated, whole cells can be removed from a plant or
animal and cultured in a lab where they will grow and reproduce for extended periods of time.
1. If mistreated, they may die.
2. Death can be considered one of the most basic properties of life, as only a living entity can die.
3. Cells within the body generally die by their own hand, by an internal program that causes cells that
are no longer needed or cells that pose a risk of becoming cancerous to eliminate themselves.
B. George and Martha Gey, Johns Hopkins Univ. (1951) developed the first human cell culture, HeLa cells,
donated by Henrietta Lacks from her malignant tumor.
1. Descendants from this sample are still grown in labs today.
2. Descended by cell division from this first cell sample.
C. Cultured cells are simpler to study than cells in body, and cells grown in vitro (in culture, outside the
body) have become an essential tool of cell and molecular biologists.
1. Much of what we know about cells has been obtained using cells grown in lab cultures.
Cells Are Highly Complex and Organized
I. Complexity is evident when encountered, but hard to describe, so think of complexity in terms of order and
consistency.
A. If a structure is more complex, a greater number of parts must be in the proper place and there must be
less tolerance of errors in the nature and interaction of its parts.
1. Also, more regulation or control must be exerted to maintain the system.
2. Cell activities can be remarkably precise, as DNA duplication has error rate <1 mistake every
10,000,000 nucleotides incorporated, and most errors quickly fixed by elaborate repair mechanism that
recognizes defect.
B. Each level of structure in cells has a great level of consistency from cell-to-cell, and each cell type has a
consistent appearance in EM; its organelles have a particular shape and location in all individuals of
species.
1. Organelles have consistent macromolecular composition arranged in a predictable pattern.
2. Epithelial cells that line the intestine are tightly connected to each other like bricks in wall.
a. Cell apical ends (face intestinal lumen) have long processes (microvilli) that facilitate nutrient
absorption.
b. Microvilli project outward from apical surface because they contain internal skeleton made of
filaments composed of protein (actin) monomers polymerized in characteristic array.
c. At basal ends, intestinal cells have many mitochondria that provide energy to fuel membrane
transport.
d. Each mitochondrion is composed of defined pattern of internal membranes, which, in turn, are made
of consistent array of proteins, including the electrically-powered protein that makes ATP.
C. Cells achieve organization at many different levels using physical processes that are essentially random.
1. Even though living cells are highly complex and ordered, it is evident that random, stochastic events
play a critical role in all cellular activities.
2. Many molecules in living cells are in constant state of random movement, propelled by thermal energy
from environment, and cells have evolved capacity to utilize this movement in highly directed ways.
3
INTRODUCTION TO THE STUDY OF CELL AND MOLECULAR
BIOLOGY
OBJECTIVES
Identify the three tenets of cell theory.
Explain the importance of the fundamental properties shared by all cells.
Compare the structures and functions of prokaryotic and eukaryotic cells.
Distinguish the structures and functions of viruses and viroids.
Differentiate a colony of individual single-celled organisms from a multicellular organism.
Describe how tissue engineering can create cell-based replacement organs.
LECTURE OUTLINE
(1.1) The Discovery of Cells
I. Cell and molecular biology is reductionist, based on the view that knowledge of the parts of the whole can
explain the character of the whole.
A. The reductionist view can lead to replacement of the wonder and mystery of life by the need to explain
everything in terms of the workings of the "machinery" of living systems which many consider a loss.
B. It is hoped that one can replace this loss by an equally strong appreciation for the beauty and complexity
of the mechanisms underlying cellular activity.
Microscopy
I. Cell biology began as a result of the discovery that curved glass surfaces can bend light and form images.
A. Spectacles were first made in Europe in the 13th century.
B. First compound (double-lensed) microscopes were made by the end of the 16th century, microscopes
provide a magnified image of a tiny object.
C. By the mid-1600s, a handful of scientists had used handmade microscopes to uncover a previously
unseen world that could not be seen with the naked eye.
II. Robert Hooke (1665), English microscopist who at age 27 became curator of the Royal Society, England's
foremost scientific academy, is generally credited with the discovery of cells.
A. In describing the chambers in cork, part of the bark of trees, he called them cells (cellulae) since they
reminded him of cells occupied by monks living in a monastery.
1. Found them while trying to explain why cork stoppers could hold air in a bottle so effectively; cork
is part of the bark of trees.
1
, 2. He said "“I took a good clear piece of cork, ….., I cut a piece of it off, and . . . then examining it with
a Microscope, me thought I could perceive it to appear a little porous . . . much like a Honeycomb.”
3. He called the pores cells.
B. Was looking at the empty cell walls of dead plant tissue that had no internal structure, the walls
originally made by the living cells they surrounded.
III. Anton van Leeuwenhoek (1665-1675) was Dutch seller of clothes and buttons and in his spare time he
ground lenses and made simple microscopes of remarkable quality.
A. For 50 years, he sent letters to the Royal Society of London describing his microscopic observations,
and included in his letters a rambling discourse on his daily habits and the state of his health.
B. He was the first to describe living single cells, and his results were checked and confirmed by Hooke.
1. Saw “animalcules” in pond water darting back and forth, the first to do this, using the scopes that he
made.
2. First to describe various forms of bacteria from tooth scrapings and water in which pepper was soaked.
C. His initial letters to the Royal Society describing what he saw were met with skepticism so the Society
sent its curator, Robert Hooke, to confirm the observations.
1. Hooke confirmed Leeuwenhoek's findings and soon Leeuwenhoek was a worldwide celebrity.
2. He was visited in Holland by Peter the Great of Russia and the queen of England.
Cell Theory
I. The 1830s is when the full and widespread importance of cells was realized.
A. Matthias Schleiden, German lawyer turned botanist (1838) concluded that, despite differences in various
tissue structures, all plant tissues were made of cells and that plant embryos arise from single cell.
B. Theodor Schwann, German zoologist (1839) and colleague of Schleiden's, realized the cellular basis of
animal life and concluded that plants and animals are similar structures.
1. Published a comprehensive report on the cellular basis of animal life.
C. Schwann concluded that the cells of plants and animals are similar structures and then proposed the first
two tenets of the cell theory.
1. All organisms are composed of one or more cells.
2. The cell is the structural unit of life for all organisms.
D. However, the Schleiden-Schwann view of cell origin was less insightful, as both agreed that cells could
arise from noncellular materials that was eventually disproved by others; however, it took time due to their
prominence.
1. It took a number of years before observations by other biologists were accepted to demonstrate that
cells did not arise in this manner any more than organisms arose by spontaneous generation.
E. Rudolf Virchow, a German pathologist (1855), made good case for and added third tenet of Cell Theory
derived from his cell division observations that ran counter to Schleiden-Schwann view of cell origins.
1. Cells can arise only by division from a preexisting cell.
F. Since the discovery of DNA as the genetic material, a fourth tenet of cell theory is sometimes added.
1. Cells contain genetic information in the form of DNA, and that information is passed from parent to
daughter cell.
(1.2) Basic Properties of Cells
2
, I. Life is the most basic property of cells, and they are the smallest units to exhibit this property.
A. Unlike the parts of a cell, which deteriorate if isolated, whole cells can be removed from a plant or
animal and cultured in a lab where they will grow and reproduce for extended periods of time.
1. If mistreated, they may die.
2. Death can be considered one of the most basic properties of life, as only a living entity can die.
3. Cells within the body generally die by their own hand, by an internal program that causes cells that
are no longer needed or cells that pose a risk of becoming cancerous to eliminate themselves.
B. George and Martha Gey, Johns Hopkins Univ. (1951) developed the first human cell culture, HeLa cells,
donated by Henrietta Lacks from her malignant tumor.
1. Descendants from this sample are still grown in labs today.
2. Descended by cell division from this first cell sample.
C. Cultured cells are simpler to study than cells in body, and cells grown in vitro (in culture, outside the
body) have become an essential tool of cell and molecular biologists.
1. Much of what we know about cells has been obtained using cells grown in lab cultures.
Cells Are Highly Complex and Organized
I. Complexity is evident when encountered, but hard to describe, so think of complexity in terms of order and
consistency.
A. If a structure is more complex, a greater number of parts must be in the proper place and there must be
less tolerance of errors in the nature and interaction of its parts.
1. Also, more regulation or control must be exerted to maintain the system.
2. Cell activities can be remarkably precise, as DNA duplication has error rate <1 mistake every
10,000,000 nucleotides incorporated, and most errors quickly fixed by elaborate repair mechanism that
recognizes defect.
B. Each level of structure in cells has a great level of consistency from cell-to-cell, and each cell type has a
consistent appearance in EM; its organelles have a particular shape and location in all individuals of
species.
1. Organelles have consistent macromolecular composition arranged in a predictable pattern.
2. Epithelial cells that line the intestine are tightly connected to each other like bricks in wall.
a. Cell apical ends (face intestinal lumen) have long processes (microvilli) that facilitate nutrient
absorption.
b. Microvilli project outward from apical surface because they contain internal skeleton made of
filaments composed of protein (actin) monomers polymerized in characteristic array.
c. At basal ends, intestinal cells have many mitochondria that provide energy to fuel membrane
transport.
d. Each mitochondrion is composed of defined pattern of internal membranes, which, in turn, are made
of consistent array of proteins, including the electrically-powered protein that makes ATP.
C. Cells achieve organization at many different levels using physical processes that are essentially random.
1. Even though living cells are highly complex and ordered, it is evident that random, stochastic events
play a critical role in all cellular activities.
2. Many molecules in living cells are in constant state of random movement, propelled by thermal energy
from environment, and cells have evolved capacity to utilize this movement in highly directed ways.
3
