Attributes of Life
16 and 21 November
Introduction to life
 Themes/characteristics of living organisms
 Structural and functional characters
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Introduction
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What defines life?
________________
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Themes
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Hierarchy theory and emergent properties
Structure: “it is the cell”
Continuity of life: function of “information”
Openness of biological systems
Regulatory capacity of living systems
Capacity to reproduce
Capacity to acquire, utilize, and store energy
Diversity and similarity of living systems
Hierarchical Nature of Living
Systems
Community
Population
Organism
Organ
Tissue
Cell
Organelles
Macromolecules
Atoms
Infrastructure
Cell: Structure and Function
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Organism’s basic unit of structure and function
Lowest level of structure capable of performing life’s
activities (e.g., irritability, reproduce, grow, develop,
etc.)
 Most common basic structure of all living organisms
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Cell Theory
Ubiquitous nature of cells
 All cells come from previous cells
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General Cell Structures
Continuity of Life and Information
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Order in any system originates from instructions
serving as a template for organization (e.g.,
Constitution, Bill of Rights)
In living systems, instructions codified in the
DNA
Instructions/inheritance based on the precise,
sequential order of nucleotides (ATCG)
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Example: RAT versus TAR versus ART
Open Systems
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All living organisms are open systems, allowing
organisms to interact with their environment
Processing stimuli
 Responding to stimuli
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“Open” versus a “closed” system
Examples
Orientation of leaves to sun
 Eyes
 Microbes and single cell organisms (e.g., amoeba)
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Examples of Open Systems
Eye
Figure 26.41
Sun-Tracking Plants
26-580
Regulatory Systems
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Interplay of organisms with the environment
requires a well balanced regulatory system
Outcome: homeostasis
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Set point, effectors, control centers and sensors
Analogy: thermostat for heat control
Examples
Enzymes in cells (lab exercise this week)
 Thermostatic control of body temperature
 pH of the cell
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Regulatory Systems: Cybernetics
Positive
Feedback
Set Point
Control
Center/
Sensor
Effector
Negative
Feedback
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Feedbacks (+ and -), homeostasis and cybernetics
Universality of Reproduction
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Reproduction: regenerative process of
making new organisms (not necessarily
copies)
Methods
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Sexual
Asexual (microbes; cell division/mitosis)
Ancillary but important function:
creating new variants
Examples
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Siblings
Geranium plants
Dolly (the sheep)
Energy Utilization
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Three related activities: acquisition, utilization, and
storage
Energy Acquisition
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Energy utilization
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Energy capture (autotrophs; heterotrophs)
Laws of Thermodynamics (1st and 2nd laws)
ATP (adenosine triphosphate) and ADP (adenosine
diphosphate
Energy storage
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Chemical bonds (C-C covalent bonds)
Starch, glycogen and lipids
Energy Utilization
ADP
Catabolism
Biosynthesis/
Anabolism
ATP
Two Sides of a Coin:
Diversity and Similarity
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Diversity is a hallmark of living systems
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1.5 M known species of plants, animals and microbes
100 M+ thought to exist
Similarity is a hallmark of living systems
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Striking similarity at the molecular level (DNA): kinship to
worms, squirrels, birds and pigs (you DNA is ~90% pig)
Examples
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Biochemistry
Structure and morphology
DNA
DNA phylogeny lab (December)
What is Life? “Nuts and Bolts”
Introduction to life
 Themes/characteristics of all living
organisms
 Cardinal structural and functional
characters
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Structural and Functional Characters
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Cells as the physical infrastructure
Biological catalysis: enzymes
Cell membranes
Water as the medium of life
Polymers (C-based polymers)
Compartmentation via organelles
Major types of cells
Cells as the Physical Infrastructure
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Cell theory
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All organisms composed of cells
Cells as smallest unit of organization exhibiting characteristics
of life
Structure
Cell Membrane
Nucleus
Cytoplasm
General Features of a Cell
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Size correlated with function
Upper limit: 0.00001 m (1 x 10-5 m)
 Relationship of volume to distance
 Anything over 1 x 10-5 m is nonfunctional
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Efficacy of transport/diffusion
Diffusion
1 . 10-5 m
Figure 23.5
23-479
Enzymes
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Introduction
Reactions are very slow (not sufficient to sustain life)
 Mechanisms to accelerate specific reactions
preferentially
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Accelerants = Catalysts = Enzymes
Proteins (relate to information brokers)
 Change rate of reactions
 High degree of specificity
 Regenerated
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Enzymes: How They Work
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Base case for
reactions to occur
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Reactants
Products
Energy analysis
(thermodynamics)
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Energy to cause
reaction to occur
(over the “hill”)
“Hill”
Energy
Needed
Reactants
Products
How Enzymes Work
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Efficacy of enzymes: “Hill” height
Mechanism
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Lower the height of the “hill”
Selectivity/specificity
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Protein 3-D structure (1, 2, 3, and 4 protein
conformation)
Conclusion
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Absence of enzyme: minutes to hours to
days to years
Presence of enzyme: 1,000 - 10,000
reactions per second
Increase in rate > 106 orders of magnitude
Membranes: Structure
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Membranes: complex polymer,
with principal monomer (lipid)
being a fatty acid + glycerol (i.e.,
phospholipids)
Lipid bilayer at the molecular level
Phosphate/ Glycerol
(Hydrophilic)
Fatty Acid
(Hydrophobic)
Membranes: Structure
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Lipid bilayer: “fluid membrane” with floating
chunks of proteins and carbohydrates (i.e.,
icebergs)
Lipid Bilayer
Protein Chunk
Proteins in Lipid Bilayer
Membranes: Functions
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Example of hierarchy theory and emergent
properties
Selective permeability
Signaling: cell-to-cell communication
Transport through Membrane:
Selective Permeability
Signaling in/on Membranes
Cystic fibrosis
Vaccinations
Allergies
Water: Medium for Metabolism
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Liquid medium for metabolism and its importance
Role of water (H2O)
Physical properties (e.g., polarity, phases)
 Chemical properties (e.g., pH, solution)
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Exquisite and unique properties of H2O
Biological Macromolecules
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Define polymer…..
Major biomacromolecules of carbon
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Carbohydrates (monomer is ______)
Lipids (monomer is _______ + _______)
Proteins (monomer is ____________)
Nucleic acids (monomer is __________)
“Information brokers”, particularly for nucleic acids
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Analogy to an alphabet
General Cell Structures
Principle of Compartmentation
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Cells are compartmentalized
Elaborate and organized infrastructure
 Analogy to a dorm
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Corridors as endoplasmic reticulum
 Rooms as organelles
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Consequence of not being compartmentalized
Compartmentation
Figure 23.22
23-494
Cell Types
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Prokaryotes
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No typical nucleus
No mitochondria, chloroplasts,
Golgi, or endoplasmic reticulum
DNA, enzymes, metabolize, etc.
Example: bacteria
Eukaryotes
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True nucleus and all the organelles
Plant eukaryotes
 Chloroplast for photosynthesis
and cell wall
Animal eukaryotes
Omissions
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Cell cycle (pp. 478-482)
Controlled methods transport (pp. 464-465)
Non-membraneous organelles (pp. 474-475)
Nuclear component (p. 475)
When you contract a fever, your body
temperature is elevated.
Is fever and inadvertent consequence of the
infection or is it an example of homeostasis?
Each of you has been vaccinated for multiple
childhood diseases. You may or may not have
taken a flu vaccine.
Explain how membrane and information
attributes of living systems underpin the efficacy
of vaccinations.