Class notes
Class notes The Diversity of Life
- Course
- The Diversity of Life
- Institution
- University Of Saskatchewan (USask )
Lecture notes of 63 pages for the course The Diversity of Life at USask (bio 120 uofs notes)
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What is biology?• The word biology is formed by combining the greek "bios" meaning life and the suffix "logy"
meaning science of, knowledge of, or study of.
Life Around Us
• Birds, frogs and rodents;
• Trees, bushes, grass;
• Insects;
• Honeybees, spiders;
Communities of macroscopic and microscopic forms of life in the soil;
• Earth worms, bacteria and other organisms
What is LIFE?
Biology is the study of life.
• The characteristics that distinguishes objects that have signaling and self sustaining
processes from those that do not.
• Either because such functions have ceased or else because they lack such functions and
are classified as inanimate;
• At first the distinction might seem intuitively obvious:
• a person is alive but a rock is not.
Life as an Integrative
Level of Organization.
• Water; the essential molecule of Life.
• Atoms may combine in specific ways to form assemblies called molecules
• Carbon based molecules of life are called organic molecules
• "Organic" derives from "Organism."
• Atom
• Molecule
• Macromolecule
• Cell
• Tissue
• Organ
• Organ system
• Organism
• Population
• Community
• Biosphere
•
Life is the result of different emergent properties.
• Includes complex and ordered interaction among parts that are unique to life.
• The properties of the new parts (molecules) are not always additive or equal to the
sum of the properties of the
components.
• At each level, new properties and rules emerge that cannot be predicted by
observations and full knowledge
Of the lower levels.
There is no unequivocal definition of life.
• Current understanding of life is descriptive
, • Properties distinguish a vital and functioning being from a dead body, but do not
define life.
• Only the structural or functional complexity of an organisms more than the sum of the
parts define life.
What is an organism?
• Broadly defined as "an assembly of molecules functioning as a more or less stable with
whole that exhibits
The properties of life.
• Unicellular
• Multicellular
In Greek, organon for instrument, Latin for Organum:
Terms directly related "organization"
Only living organisms manufacture large and complex molecules
• Macromolecules- a large molecule or macromolecule, composed of many repeated
subunits termed monomers.
• Many monomers bond together from polymers (In Greek poly means many)
• Carbohydrates (starch)
• Proteins (enzyme)
• Nucleic acids (DNA)
• Organic macromolecules interact to create a cell, the basic unit of life
• Some cells exist as unicellular organisms, while others work together to form multicellular
organisms.
Inside more complex organism, cells may form tissues, organs, organ systems.
Biologists define life by listing characteristics of living things
Energy Use and Metabolism
• Metabolism: chemical reactions
• Display order and have a complex chemistry
• Harness and utilize energy :
• Autotrophs: synthesize own organic molecules
▪ Produce own energy, use photosynthesis
• Heterotrophs: ingests organic molecules
▪ Produced by autotroph, depend on autotroph to get energy
• All living organisms react to external or internal stimulus (respond to stimuli)
• Stimuli: any change in the environment
Reproduction
• The process of making the next generation; Life will create more life otherwise it will
Go extinct.
• Sexual reproduction involves two parents and the fusion of gametes, haploid sex cells
from each parent;
Offspring are genetically unique.
• Increases genetic variation within species.
• Asexual reproduction involves only one parent: no fusion of gametes, Offspring are all
genetically identical to the parent.
• Maintain homeostasis (body temp, water lvl, blood ph, glucose lvl)
• State of steady internal physical and chemical conditions maintained by living systems
, (input sent via afferent pathway) Control center (output sent via afferent
pathway) > Effector (response to change) > Homeostasis (imbalance corrected)
> Receptor (change detected)
• Grow and change; characteristics
• Evolve and Adapt to Environment:
• Adaptation: Process of becoming adjusted to an environment
• Structural, physiological or behavioral traits that improve an organism's
likelihood of survival
And thus to reproduce.
• Pass their traits onto their offspring
Chapter 2
All organisms are made up of cells
• All have similar cell structures
The Cell Theory:
• Most cells are small ranging from about 1 to 100 micrometers
(millionths of a meter μm: 10-6) in diameter.
Evidences that support the main tents of the modern "Cell Theory"
In 1665 Robert Hooke saw something like this looking through his crude Microscope
Schleiden and Schwann 1838-1839 proposed the "cell theory" : the cell is the basic
functional and structural unit of all living things
The basic structural and functional unites of all living organisms, carry out the essential
process of life.
Rudolf Virchow used the work of Robert Remak to popularize the idea that all cells
come from other cells.
These proposals developed into the cell theory.
1. All organisms are compose of one or more cells;
2. The cells is the basic structural and functional unit of all organisms.
---If cells are broken open, the property of life is lost.
--- They are unable to grow, reproduce or respond to outside stimuli in a
coordinated,
potentially independent fashion.
3. cell arise only from the division of pre-existing cells (cell division)
• Cytology: study of cell Microscopy, examination of cells from the body under a
microscope.
The end of "spontaneous generation"
• From the time of the ancient romans until the late 19th century, it was generally accepted
that some life forms arose "spontaneously" from non-living matter. Such "spontaneous
generation"
• Theory of spontaneous generation died in 1869 (Louis Pasteur), discovered pasteurization
and developed a vaccination.
• Since the first cells were seen in the late 1600s, scientists have advised increasingly sophisticated
ways of observing them;
• To view objects and areas that cannot be seen with the naked eye;
• Not within the resolution range of the normal eye;
• Looking at slices of cork observed tiny compartments that he named cellulae;
, • By the resemblance to cells of a honeycomb
• Optical;
• Electron;
• Transmission and
• Scanning
• Fluorescent microscopy
• Causing them to emit light of longer wavelengths
• Advantages: allow in vivo
Difference: Source of elimination
First microscope: Zacharias Jansen, invented telescope/microscope
First cells seen in cork (Robert hooked); dead cell walls of plant cells.
Anton van Leeuwennhoek "father of microbiology" ; bacteria, sperm cells
Two Branches of microscope:
• Optical
• Electron
Magnification:
• Ratio between the size of an image produced by a microscope and its actual size
• How much bigger you can make an object appear dependent upon the lens system
Resolution:
• Ability to observe two adjacent objects as distinct from one another
• Measure of the clarity of the image or ability to differentiate between two dots
dependent upon the wavelength of light used.
Contrast:
• How different one structure looks from another
• Enhanced by dyes
View:
• Inside or outside of the cell, type of light
Electron microscopy
• Uses an electron beam
• Resolution 2 nm
• Transmission electron microscopy (TEM);
o – Beam of electrons transmitted through sample;
o – Thin slices stained with heavy metals;
o – Some electrons are scattered while others
pass through to form an image;
• Scanning electron microscopy (SEM) – Sample coated with heavy metal;
– Beam scans surface to make 3D image.
Transmission electron microscopy (TEM)
A beam of electrons is focused on a thin section of a specimen in a vacuum. Electrons that
pass through form the image; structures that scatter electrons appear dark. TEM is used
primarily to examine structures within cells. Various staining and fixing methods are used to
highlight structures of interest
• Structures that scatter electrons appear dark
Microscopy Terminology
Magnification
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