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Chapter 1

BIO152H5 Chapter Notes - Chapter 1: Natural Environment, Maple Leaf, Emergence

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Maria Arts

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Chapter 1-Introduction: Evolution and the Themes of Biology
Concept1.1: Studying the diverse forms of life reveals common themes
New properties emerge a t each level in the biological hierarchy
o Study of life extends from the microscopic scale of molecules to the global scale of the entire
living planet
Emergent properties
o Zoom out from molecular level, novel properties emerge at each step
Properties that are not present at the preceding level
o Due to the arrangement and interactions of parts as complexity increases
Photosynthesis occurs in intact chlorophyll but now in a disorganized test tube
mixture of chlorophyll and other chloroplasts molecules
Requires specific organization of these molecules in the chloroplast
A blow to the head will disrupt architecture of a human brain, the mind may cease
to function properly
All brain tissue is still present
A box of bicycle parts won’t be enough to transport you
Need to assemble the parts in a specific way
Graphite and diamond consists of pure carbon
Depends on arrangement of these carbons
Properties of life
o Order
A sunflower starts off as a little seed, and then grows into an intricate flower
o Evolutionary adaptation
Pygmy sea horse camouflage
Adaptations evolve over many generations by the reproductive success of
those individuals with heritable traits best suited for their environment
o Response to environment (stimuli)
Venus flytrap
Closes rapidly in response to something landing on open trap
o Regulation (homeostasis)
Blood flow through blood vessels in ears helps maintain a constant body
Adjusts heat exchange with surrounding air
o Energy processing
Obtains fuel in the form of nectar from flowers
Uses chemical energy stored in food to power flight and other work
o Growth and development
Inherited information carried by genes controls the pattern of growth and
A Nile crocodile egg will always grow up to be a Nile crocodile
o Reproduction
Organisms reproduce their own kind
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Levels of biological organization
o Biosphere
Consists of all life on earth and all the places where life exists
All ecosystems make up the biosphere
The Earth
o Ecosystems
Organisms interact with abiotic factors
Soil, water, atmospheric gases and light
o Communities
Entire array of organisms inhabiting a particular ecosystem
Consists of multiple populations
Different plants and animals
o Populations
Consists of all the individuals of a single species living within the bounds of a
specified area
School of fish
o Organisms
Individual living things
o Organs and organ systems
Architecture of more complex organisms
Organs are organized into organ systems
Cooperate in a larger function
Consist of multiple tissues
Maple leaf
o Tissues
Made up of a group of cells that work together to perform a specialized function
Tissue of a leaf
o Cells
Life’s fundamental unit of structure and function
Unicellular and multicellular organisms
Multicellular organisms have a division of labor among specialized cells
o Organelles
Functional components present in cells
o Molecules
Chemical structure consisting of two or more small chemical units called atoms
The power of limitations and reductionism
o Cannot fully explain a higher level of order by breaking it down into its parts
o Something as complex as an organism or a cell cannot be analyzed without taking it apart
o Reductionism- the approach of reducing complex systems to simpler components that are
more manageable to study
Study the molecular structure of DNA that had been extracted from c ells
How this molecule could serve as the chemical basis of inheritance
Central role of DNA in cells and organisms became better understood when
scientists were able to study the interactions of DNA with other molecules
o Biologist must balance the reductionist strategy with the larger-scale, holistic objective of
understanding emergent properties
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The parts of cells, organisms and higher levels of order work together
Systems Biology
o A system is a combination of components that function together
o An approach to model the dynamic behaviour of whole biological systems based on a study
of the interactions among the system’s parts
o Enables us to pose new kinds of questions
o Successful models help scientists predict how a change in one variable will affect other
components and the whole system
How might a drug that lowers blood pressure affect the functioning of organs
throughout the human body?
How might a gradual increase in atmospheric carbon dioxide alter ecosystems in the
entire biosphere
Organisms interact with other organisms and the physical environment
o In an ecosystem, each organisms interacts continuously with its environment
Both other organisms and physical factors
Life requires energy transfer and transformation
o Moving, growing, reproducing and other activities of life are work
Requires energy
o Organisms often transform one form of energy to another
Use sunlight to convert carbon dioxide and water to sugar and oxygen
Chemical energy in sugar is passed along to consumers
Structure and function are correlated at all levels of biological organization
o A screwdriver is used to tighten or loosen screws while a hammer is used to pound in nails
o How a device works is correlated to its structure
Shape of wings
Hollow bones
No teeth
o Everything helps allow bird to fly
The cell is an organism’s basic unit of structure and function
o In life’s structural hierarchy, the cell has a special place as the lowest level of organization
o Activities of organisms are based on the activities of cells
Movement in eyes based on muscle and nerve cells
Recycling carbon is the cumulative product of cellular activities
o All cells share certain characteristics
Every cell is enclosed by a semi-permeable membrane that regulates the passage of
materials between cell and surroundings
Every cell is enclosed by a membrane
o Two types of cells
Microorganisms such as bacteria and archaea are prokaryotic
Generally smaller than eukaryotic cells
DNA is not separated from the rest of the cell by enclosure in membrane-
enclosed organelles
Subdivided by internal membrane into various membrane-enclosed
organelles in the nucleus which contain cell’s DNA
Other organelles located in cytoplasm
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