Download 01 Introduction - U of L Class Index

Biology 1010
IGOR KOVALCHUK
Office hours: 10-12:00 am
Textbook
Biology, 8'th ed., 2008. Campbell, NA, Reece, JB et al.
Benjamin Cummings, Menlo Park, California
Grade composition: two midterms (15 and 20%) and one
final exam (30%).
http://home.uleth.ca/bio
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The Cellular Basis of Life
Introduction to Biology 1010
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Short plan of the lecture
1. Hierarchy of the Living World
2. Evolution, Unity, and Diversity
3. Science is a Process
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Biology – the study of life
Covers research from submicroscopic molecules to the
global distribution of biological communities.
Studies not only living organisms but also ancestral life
forms stretching back nearly four billion years.
Because of new discoveries, biology is in continuous state of
flux.
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Hierarchical Order of Life
Each level of biological structure builds itself on the level
below
Biology is studied on different levels:
- cellular biology;
- molecular biology;
- genetics;
- physiology;
- organism behaviour;
- ecology and environmental studies;
- paleontology.
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Hierarchical Order of Life
• The cell is the lowest structural level in which
all life’s properties, including reproduction,
can occur.
• However, the structure of a cell studied by
cellular and molecular biologists is itself
hierarchical.
• The hierarchy within the cell is either on the
level of the cell structure or reproduction.
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Hierarchical Order of Life
Starting with atoms we can continue in two directions:
-
first, molecules build organelles (such as
chloroplasts, mitochondria etc), and organelles build
a cell;
-
second, molecules build nucleotides, nucleotides
build the DNA, and the DNA builds genes – units of
inheritance, providing continuity from one generation
to the next.
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Hierarchical Order of Life
•
For unicellular organism the cell is the highest level of
hierarchy
but for multicellular it is just an intermediate step in the
chain.
•
The organism either animal or plant exhibit three major
structural levels above the cell.
•
Similar cells are grouped into tissues, several tissues are
arranged in organ, and organs are grouped into organ
systems.
•
Brain (nervous and connective tissues), spinal cord and
nerves build the nervous system.
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Levels of organisation beyond the
individual organism
Population
Localized group of organisms belonging to
the same species
Community
Populations of species living in the same
area
Ecosystem
An energy-processing system of
community interactions that include abiotic
environmental factors such as soil and
water
Large scale communities classified by
predominant vegetation type and distinctive
combinations of plants and animals
Biomes
Biosphere
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The sum of all the planet’s ecosytems
New properties arise with new level of
biological structure
•Emergent property – feature that appear as a result of
interactions between components.
•For example atoms of molecule are able to interact with
each other to certain extent but not able to perform any
specific function within the cell.
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New properties arise with new level of
biological structure
•Protein molecules built from atoms have different
activities (enzymatic, catalytic, etc), which atoms do not
have.
•Cells are much more complex structures functioning as
small independent factories.
•Reductionism – reducing complex systems to simpler
components that are more manageable to study.
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Cells are an organism’s basic units
All organisms consist of cells
Robert Hooke in 1665 – first described and named cells from
oak tree(30x)
Anton van Leeuwenhoek discovered a microbial world in
droplets of pound water.
Mattias Schleiden and Theodor Schwann (1839) called cells
“units of life” – cell theory.
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Cells are an organism’s basic units
The ability of cells to divide to form new cells is the basis for
all reproduction and for the growth and repair of multicellular
organisms.
Some common cell features are:
All cells are enclosed by a membrane that regulates the
passage of materials between the cell and surrounding.
Every cell contains DNA, the heritable material.
Two major kinds of cells – prokaryotic and eukaryotic are
distinguished by their structural organisation.
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Eukaryotic versus prokaryotic cells
The cells of microorganisms commonly called bacteria (and
archaea) are prokaryotic.
All other forms of life are composed of eukaryotic cells.
Major differences
•The presence of nucleus;
•Internal membrane – subdivision into many different
organelles in eukaryotes;
•Separation of the genetic material – DNA into nucleus in
eukaryotes.
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DNA is the basis for continuity of life
The units of inheritance that transmit information from
parents to offspring are called genes
Each DNA molecule is made up of two long chains each
composed of four different building blocks called
nucleotides.
The linear sequence of these four nucleotides encode
the precise information in a gene, the unit of inheritance
from parent to offspring.
All forms of life use essentially the same genetic code.
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Structure and function are correlated
There is a relationship between an organism’s structure
and how it works. Form fits function.
Biological structure gives clues about what it does
and how it works.
Knowing a structure’s function gives insights about
its construction.
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Energy flow and transformation
Both organism and
environment are
affected by the
interaction between
them
Producers
(plants and other
photosynthetic
organisms)
Heat
Chemical
energy
Consumers
(animals, etc.)
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Heat
Dynamic balance in living systems
A
Negative feedback
slows a process down
B
B
Function of hunger
center
C
C
A
negative feedback -
D
D
D
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D
D
D
D
Dynamic balance in living systems
W
W
Positive feedback
speeds a process up
X
X
Function of platelets in
the formation of clot
positive feedback +
Y
Y
Z
Z
Z
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Z
Z
Z
Z
Z
Z
Z Z
Z
Z
Z Z
Evolution, Unity, and Diversity
Diversity: 1.5 mln species are identified and named by
biologists
290 000
plants
52 000
vertebrates
100 000
fungi
Thousands of newly identified species are added to the list
each year.
Estimates for total diversity of life range from about 10 mln
to 100 mln species.
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Evolution, Unity, and Diversity
The unity in the diversity of life forms at the lower levels
of organisation.
It is evident from:
A universal genetic code.
Similar metabolic pathways (e.g., glycolysis)
Similarities of cell structure (e.g., flagella of
protozoans and mammalian sperm cells)
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Three Domains and Five Kingdoms
Domain Bacteria
Domain Eukarya
Domain Archaea
Protista
Unicellular
Prokaryota eukaryotes
and simple
All prokaryotic multicellular
organisms,
relatives
including
Bacteria and
Archaea
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Plantae
Fungi
Carry out
photosynthesis
Defined by
nutritional mode,
they absorb
nutrients after
decomposing
organic material
Animalia
Multicellular
eukaryotes
that ingest
other
organisms
Taxonomy – naming and classifying
diverse species
Kingdom
Animalia
Phylum
Chordata
Class
Mammalia
Order
Carnivora
Family
Felidae
Genus
Species
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Panthera
Pink
panthera
The Origin of Species (1859, Charles Darvin)
Evolution is the one unifying biological topics
Life evolves (via process of “descent with
modification”):
-
every species has an ancestor;
-
similar species (dogs and wolfs) have common early
ancestor since they have branched recently;
-
through very early ancestors all mammals are also
related
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The Origin of Species (1859, Charles Darvin)
Darvin synthesised the concept of natural selection
(mechanism of evolutionary change) from:
Observation 1: Individual variation. Individuals in a
population of any species vary in many heritable
traits.
Observation 2: Struggle for existence. The produced
offspring is far bigger than environment can support.
INFERENCE: Differential reproductive success. Those
individuals with traits best suited to the local environment
leave larger number of surviving fertile offspring.
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Reading
Biology, 8'th ed., 2008. Campbell, NA, Reece, JB et al.
Ch. 1 (1-27)
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Science as a Process
Science is a process of getting knowledge
Create a hypothesis – test it – prove it
Good scientists are people who:
•Ask questions about nature and believe those questions
are answerable.
•Are curious, observant, and passionate in their quest for
discovery.
•Are creative, imaginative, and initiative.
•Are generally skeptics.
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Science is a way of knowing
Scientific method is a process which outlines a series of
steps used to answer questions
•Is not a rigid procedure.
•Based on the conviction that natural phenomena
have natural causes.
•Requires evidence to logically solve problems
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Characteristics of useful hypotheses
Hypothetico-deductive thinking
Hypotheses are possible causes.
Hypotheses reflect past experience with similar questions.
Multiple hypotheses should be proposed whenever possible.
Hypotheses can be eliminated, but not confirmed with
absolute certainty.
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No control – no experiment
In a controlled experiment – control group is the group in
which all variables are held constant.
Controls are necessary basis for comparison with the
experimental group, which has been exposed to a single
treatment variable.
Setting up the best controls is a key element of good
experimental design
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Hypothesis
Test =
experiment or
observations
Support
hypothesis
Reject (may be true)
Test
repeatedly
Accept
Verify
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Hypothesis becomes
theory
Reject
hypothesis
Modify or abandon
hypothesis
Science and technology are functions of
society
We have a love-hate relationship with technology :
Technology has improved our standard of living.
The consequence of using technology also includes the
creation of new problems:
Population growth
Acid rains
Deforestation
Global worming
Nuclear accidents
Ozone holes
Toxic wastes
Endangered species
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