Transcript Lecture 1 PPT

Introduction to Cell Biology
Course #72108 (2011)
7 weeks (14 meeting) Cell Biology, Molecular Biology
Amir Eden
Dep. Of Animal & Cell Biology
Life Science Institute
Room: 3-564
Phone: 6584981
Course website: http://moodle.huji.ac.il
Enter course # 72108
http://moodle.huji.ac.il
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Reference
• Life: The Science of Biology, Seventh Edition, by
William K. Purves, David Sadava, Gordon H. Orians,
and H. Craig Heller.
Free website: http://bcs.whfreeman.com/thelifewire/
Animated Tutorials
Activities and Flashcards
Interactive Quizzes
Online Quizzes
Suggested Readings
Glossary by Chapters
Glossary
Math for Life
Survival Skills
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Reference
Biology, 8th Edition
By: Campbell & Reece
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• Essential Cell Biology,
Second Edition
Bruce Alberts, Alexander Johnson,
Julian Lewis, Martin Raff, Dennis Bray,
Karen Hopkin, Keith Roberts, Peter
Walter
• Garland 2003
Reference
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Aim
• Introduction to basic principles of biology at all levels
(Molecular Cellular, Organisms)
• The lectures are designed for first year students in
biology having heterogeneous previous knowledge
• More “in-depth” course in cell biology called:
“Advanced Cell Biology” (72373)
will be given in second year.
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How to succeed in this course
• Read, Read & Read! Comprehensive knowledge is achieved only by
reading the books and listening to the lectures.
• Understand what you read.
• Lectures can be downloaded from the moodle site, and most material can
be read in text-books (Academon / Library).
• Important concepts are stated on the slides. Make sure you remember and
understand these statements
• Do not hesitate to ask questions (raise your hand, ask me after the class or
at my office)
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How to succeed in this course
NEW:
• Video recording of lectures
NEW:
• Online exercise
Introduction to Biology,
The Science of life
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An Evolutionary Framework for Biology
Outline of today’s talk
• What is Life?
• Biological Evolution: Changes over Billions of
Years
• The Evolutionary Tree of Life
• Major Events in the History of Life on Earth
• Levels of Organization of Life
• Biology is a Science
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What is Life?
• Life can be defined as an organized (genetic)
unit capable of metabolism, reproduction,
and evolution.
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What is Life? Metabolism
• An organism’s metabolism is its total
chemical activity.
• Metabolism involves thousands of individual
chemical reactions.
• These reactions must be coordinated for an
organism to function.
• The internal environment of an organism
must remain within a given range of physical
and chemical conditions for that organism to
remain healthy.
• Homeostasis is the maintenance of a
relatively stable internal condition, such as
temperature.
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What is Life? Reproduction & Evolution
• Reproduction can be by duplication or by mating.
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What is Life? Reproduction & Evolution
• Reproduction with variation is a major characteristic of life.
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What is Life? Reproduction & Evolution
• The combination of reproduction and duplication errors
(leading to variation) results in biological evolution.
• Variations in the physical environment have helped drive
the diversification of life.
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What is Life? Reproduction & Evolution
• The differences among living things that enable them to
live in different kinds of environments and adopt different
lifestyles are called adaptations.
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Microbial adaptation
Hot springs
Possible microfossil in
Martian meteorite
ALH84001
Deep vent
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Biological Evolution:
Changes over Billions of Years
• Count George-Louis Leclerc de Buffon (1707–
1788) wrote Natural History of Animals and
suggested the possibility of evolution.
• Buffon observed the similarity of different
mammals’ limbs and suggested that the limbs of
mammals were inherited from a common
ancestor.
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Biological Evolution:
Changes over Billions of Years
• Jean Baptist de Lamarck, a student of Buffon,
suggested a mechanism:
 With continued use, some structures
become larger from generation to
generation, whereas others become
smaller from disuse
• Though Lamarck made important
contributions, this theory of acquired structures
is not accepted by scientists today.
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Biological Evolution:
Changes over Billions of Years
• In 1858, both Charles Darwin and Alfred Russel Wallace
independently developed and proposed the theory of
evolution by natural selection:
• The world is ancient
• Living things evolve - ancestral forms were different
from organisms we find today
• Differences or variations among individuals influence
how well those individuals survive and reproduce in
changing environments.
• Traits that increase the probability that their bearers will
survive and reproduce are passed on to the next
generation. According to survival and reproductive
success
• Two major forces: Variation + Selection
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What is Life? Reproduction & Evolution
• The differences among living things that enable them to
live in different kinds of environments and adopt different
lifestyles are called adaptations.
If variation happens to produce a
useful change,
Selection will fix it in the right
environment
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The Evolutionary Tree of Life
• All organisms on Earth today descended from an
original unicellular organism that lived around 4
billion years ago.
• Major evolutionary events have led to more
complex organisms with larger quantities of
information and more complex mechanisms for
using it.
• Genetically independent groups, called species,
have evolved. (~30 million sp.)
• All organisms alive today have survived because
of appropriate adaptations to their environments.
A Provisional Tree of Life
Prokaryotic cells
Eukaryotic cells
Autotrophs =
self-feeders
Protists
mostly unicellular
Heterotrophs=
other feeders
Molds,
mushrooms,
yeasts
Heterotrophs=
other feeders
Kingdom
Kingdom
Kingdom
Figure 1.3 Life’s Calendar
Life’s Calendar
Earth
Chemical evolution Origin of Life
Forms
3.8 Billion
(Cells)
4.5 Billion
years ago
years ago
Oldest
(microbial)
fossils
Photosynthesis
Evolves
2.5 Billion
years ago
Biological evolution
Oxygen, Ozone
Eukaryotic
cells
evolve
Multicellular
Organisms
1 Billion
Years ago
Abundant
life
1 day = 150 million years
1 week = 1 billion years
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Life’s Calendar
Earth
forms
Origin of Life
Oldest
fossils
Photosynthesis
evolves
Eukaryotic
cells
Multicellular
Abundant
life
Cell specialization
Sexual reproduction
Aquatic life
Abundant
fossils
First land
plants
First land
animals
Forests
Insects
Dinosaurs
dominant
First
mammals
Birds
Flowering
plants
Rise of
Mammals
First hominids
Homo sapiens
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Life’s Calendar
Earth
forms
Origin of Life
Oldest
fossils
Photosynthesis
evolves
Eukaryotic
cells
Recorded history
fills the
last 5 seconds
Modern humans
of day 30.
appeared in the
last 10 minutes
of day 30.
Multicellular
Abundant
life
Aquatic life
Abundant
fossils
First land
plants
First land
animals
Forests
Insects
First
mammals
Dinosaurs
dominant
Birds
Flowering
plants
Rise of
Mammals
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Major Events in the History of Life on Earth
• Life arose from nonlife.
• Chemical evolution led to the appearance of life about 4 billion years ago.
• Random inorganic chemical interactions eventually produced molecules that had the
property of acting as templates to form similar molecules.
• Around 3.8 billion years ago certain molecules became enclosed in compartments, or
cells.
• Cells capture energy and replicate themselves, two fundamental characteristics of life.
• For 2 billion years, all organisms were unicellular (prokaryotes), confined to the
oceans.
• About 2.5 billion years ago some prokaryotes acquired the ability to photosynthesize.
• The energy of sunlight was captured, and oxygen was generated as a waste product.
• Oxygen increased in concentration in the atmosphere, making aerobic metabolism
possible.
• Another effect of oxygen was O3 (ozone) accumulation in the upper atmosphere.
• Ozone has the property of preventing excess ultraviolet light from the sun from
reaching Earth.
• Around 800 million years ago, ozone accumulation shielded the landmass from
radiation enough to allow the movement of organisms to land.
• Some prokaryotic cells became large enough to attach, engulf, and digest smaller
cells.
• About 1.5 billion years ago, some cells had surviving smaller cells within them: These
were early eukaryotic cells.
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Major Events in the History of Life on Earth
• Two developments made the evolution of multicellular
organisms possible:
 The ability of a cell to change its structure and function
to meet the challenges of a changing environment
 The ability of cells to stick together after they have
divided and to act in a coordinated manner
• Once organisms became multicellular, it became possible
for certain cells to specialize.
• Sexual recombination, the combining of genes from two
cells, appeared early in the evolution of life.
• Sex increased the rate of evolution:
 Organisms that exchange genetic information produce
offspring that are genetically variable.
 Because environments are constantly changing,
organisms that produce variable offspring have an
advantage over those that produce genetically identical
clones.
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Levels of Organization of Life
• Biology can be visualized as a hierarchy of units
that include molecules, cells, tissues, organs,
organisms, populations, communities, and the
biosphere.
• To understand organisms, biologists must study
them at all levels of organization, from low to high.
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From Molecules to the Biosphere: The Hierarchy of Life
Atoms are the basic building blocks of all matter.
Atoms
Molecule
Molecules are made up of atoms.
Molecules in turn can be organized into cells.
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From Molecules to the Biosphere: The Hierarchy of Life
Cells of many types are the
working components of living organisms.
Cell (Neuron)
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From Molecules to the Biosphere: The Hierarchy of Life
A tissue is a group of many cells
with similar and coordinated functions.
Tissue (ganglion)
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From Molecules to the Biosphere: The Hierarchy of Life
Organs combine several tissues that function together.
Organs form systems, such as the nervous system.
Organ (brain)
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From Molecules to the Biosphere: The Hierarchy of Life
An organism is a recognizable, self-contained individual
made up of organs and organ systems.
Organism (fish)
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From Molecules to the Biosphere: The Hierarchy of Life
A population is a group of many organisms
of the same species.
Population (school of fish)
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From Molecules to the Biosphere: The Hierarchy of Life
Communities
consist of populations
of many different
species.
Community
(coral reef)
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From Molecules to the Biosphere: The Hierarchy of Life
Biological communities exchange energy with one another,
combining to create the biosphere of Earth.
Biosphere
From Molecules to the Biosphere
Full understanding
crosses levels
(Pesticides,
Herbicides,
Prozac )
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Requires:
Engineering
Computing
Mathematics
Statistics
Chemistry
Physics
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Biology is a Science
• The hypothesis-prediction (H–P) system - a
conceptual tool for scientific research:
 Making observations
 Asking questions
 Forming hypotheses, or tentative answers to
the questions
 Making predictions based on these
hypotheses
 Testing the predictions by making additional
observations or conducting experiments
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The scientific method
• Gastritis (Ulcer)
Using the comparative & experimental methods to Test a Hypothesis
The Nobel Prize in Physiology or Medicine 2005
Barry J. Marshall
J. Robin Warren
"for their discovery of the bacterium Helicobacter
pylori and its role in gastritis and peptic ulcer
disease"
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The scientific method
• Step 1: Making observations:
 Scientists observed bacteria in the stomach
 Scientists isolated and grew a bacterium that
lives in the acidic environment of the human
stomach
Helicobacter pylori
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The scientific method
• Step 2: Asking questions:
 Are these good or bad bacteria?
 Are they important in Gastritis (Ulcer)?
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The scientific method
• Steps 3 and 4: Formulating hypotheses and making
predictions:
• Hypothesis: Helicobacter pylori is causing Ulcer
• Predictions:
• Prediction I: Patients with ulcer should have the
bacterium
• Prediction II: Infection with the bacterium should
cause ulcer
• Prediction III: Killing the bacterium should cure
ulcer
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Comparative method for testing a hypothesis
• Most tests of hypotheses are of two types:
 Controlled experiments
 The comparative method
• Step 5: Testing hypotheses:
Prediction I: Patients with ulcer
should have the bacterium
comparative study
Screen healthy people
and people with Ulcer
for Helicobacter pylori
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Controlled experiment for testing a hypothesis
• Prediction II: Infection with the bacterium should
cause ulcer
• Prediction III: Killing the bacterium should cure
ulcer
Controlled experiment:
Infect a person with the bacterium
and see if he develops Gastritis or
Ulcer
Give the person antibiotics to kill
the bacteria and see if he is cured
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Biology is a Science
The H-P method is self correcting:
• If the results of continued testing support the
hypothesis, it may come to be considered a
theory.
• If the results do not support the hypothesis, it may
be modified or abandoned.
• Reproducibility is important
Using controlled experiments to Test a Hypothesis
• Jean Baptist de Lamarck suggested:
 With continued use, some structures become
larger from generation to generation, whereas
others become smaller from disuse
Using controlled experiments to Test a Hypothesis
• The case of the midwife toad by Arthur Koestler
• 1920s an Austrian scientist named Paul Kammerer
reported that midwife toads forced to mate in the
water developed pads within a few generations
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Biology is a Science
• It is important to distinguish science from
nonscience.
• Science begins with observations and the
formulation of hypotheses that can be tested and
that will be rejected if significant contrary evidence
is found.
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Biology is a Science
The study of biology has major implications for human life.
• Currently, biological science is positioned at the forefront of
many ethical, ecological, social, and medical challenges and
dilemmas.
 In-Vitro Fertilization
 Viagra
 Global warming
 Cloning
 Forensics
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Please recall or learn from book
• Atom, Atom structure, Proton, Neutron, Electron
• Elements, Periodic table, Isotopes, Orbitals
• Molecules,Chemical bonds & interactions
• Isomers, Optical isomers
• Chemical reactions, Reactants, Products, Bond
energy
• Mole, Molar
• pH, Buffers
Chapter 2 in “Life” or in “Biology” or in “Cell Biology”