1. Foundations of Life and Biological Inquiry
Biology, the study of life, explores all living things from the smallest cells to
complex ecosystems. Scientists in biology search for patterns and connections,
using a set of unifying themes to guide their understanding of the natural world.
What is Life? � Life is characterized by several core properties: � Order: Liv-
ing things have organized, purposeful structures (like cells, tissues, organs). �
Energy Processing: All organisms use and transform energy (like plants with
sunlight, humans with food). � Growth & Development: Organisms grow
and change based on genetic instructions. � Response to Environment: Liv-
ing things detect and react to stimuli (like plants growing towards light). �
Regulation: Maintaining homeostasis, or internal balance (like body tempera-
ture). � Reproduction: Passing genetic material to offspring, whether sexual
or asexual. � Evolutionary Adaptation: Populations change over generations
to better survive in their environment.
Hierarchy of Organization � Biology studies life across many levels, from tiny
molecules to the entire planet: � Biosphere: All of Earth’s environments
supporting life. � Ecosystem: Communities of living things interacting with
nonliving things (like forests, oceans). � Community: All organisms in a
specific area. � Population: Individuals of a single species in an area. �
Organism: An individual living thing. � Organs/Organ Systems: Body parts
that carry out specific functions. � Tissues: Groups of similar cells performing
a function. � Cells: The smallest units of life. � Organelles: Functional
structures within cells (like the nucleus, mitochondria). � Molecules: Chemical
structures (proteins, DNA, etc.) essential for life.
The Process of Science � Science is a way of solving problems and answering
questions about the natural world: � Observation: Gathering facts by watch-
ing, measuring, or experimenting. � Hypothesis: A testable explanation for
an observation. � Experimentation: Testing hypotheses under controlled con-
ditions. � Data Analysis: Gathering and interpreting results. � Conclusion:
Supporting or refuting the hypothesis based on data.
Biologists perform these steps over and over, building on previous knowledge to
expand our understanding of life’s complexity .
2. Chemistry of Life
All living things are made of chemicals, and their survival depends on the inter-
actions between those chemicals!
Atoms & Elements � All matter is made of atoms, the smallest units of elements.
� Key elements in biology: carbon (C), hydrogen (H), oxygen (O), and nitrogen
(N)—these make up about 96% of living matter. � Elements combine to form
molecules, the building blocks of cells (e.g., water, proteins, DNA).
Water—The “Universal Solvent” � Water molecules are polar: they have slightly
charged ends, allowing them to dissolve many substances. � Hydrogen bonds
1
, between water molecules give water its unique properties: high boiling point,
surface tension, and ability to stabilize temperature. � Water is essential for
many biological reactions—life on Earth depends on it!
Acids, Bases & pH � Acid: Adds H� ions to a solution (e.g., stomach acid). �
Base: Removes H� ions, often adds OH� ions (e.g., baking soda). � The pH scale
(0–14) measures acidity; cells must keep pH stable for proteins and enzymes to
function.
Major Biological Molecules � Carbohydrates: Sugars and starches for energy
and structure. � Proteins: Made from amino acids—used in everything from
muscles to enzymes. � Lipids: Fats, oils, and membranes—energy storage and
cell structure. � Nucleic acids: DNA and RNA—store and transmit genetic
information.
Biological chemistry is the foundation for everything else you’ll study in biology.
Master these basics, and you’re set for success!
3. Cell Structure and Function
Cells are the basic units of life—everything in biology starts here!
Two Main Cell Types � Prokaryotic Cells: No nucleus. Simpler and smaller (e.g.,
bacteria, archaea). � Eukaryotic Cells: Have a nucleus and membrane-bound
organelles. Make up plants, animals, fungi, protists.
Common Features of All Cells � Plasma Membrane: The cell’s flexible “skin” that
controls what goes in and out. � Cytoplasm: Gel-like inside filling, where cell
parts float and many reactions happen. � DNA: Genetic info—even prokaryotes
have DNA, just not inside a nucleus. � Ribosomes: Protein factories—build all
the proteins cells need.
Eukaryotic Cell Organelles (“Tiny Organs”) and Their Jobs � Nucleus: Stores
DNA, the cell’s “control center.” � Mitochondria: Make ATP (cellular energy)
by breaking down food—“powerhouse of the cell.” � Chloroplasts: Found only in
plants/algae—do photosynthesis (convert solar energy into food). � Endoplasmic
Reticulum (ER): � Rough ER: Has ribosomes, makes and folds proteins. �
Smooth ER: Makes lipids, processes toxins. � Golgi Apparatus: “Post office” of
the cell—sorts and ships proteins. � Lysosomes: Clean-up crew—digest waste,
old cell parts (mainly in animal cells). � Vacuoles: Storage for water, nutrients,
or waste (big in plant cells).
Cell Membrane Structure � Phospholipid bilayer: Two-layered wall with proteins
“floating” in it—selectively lets materials in/out. � Proteins and carbohydrates
in the membrane help with transport, identification, and cell signaling.
Fun Fact: Your body’s eukaryotic cells work together in tissues and organs, but
even single-celled prokaryotes can do a LOT with very little!
4. Energy, Enzymes, and Metabolism
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Biology, the study of life, explores all living things from the smallest cells to
complex ecosystems. Scientists in biology search for patterns and connections,
using a set of unifying themes to guide their understanding of the natural world.
What is Life? � Life is characterized by several core properties: � Order: Liv-
ing things have organized, purposeful structures (like cells, tissues, organs). �
Energy Processing: All organisms use and transform energy (like plants with
sunlight, humans with food). � Growth & Development: Organisms grow
and change based on genetic instructions. � Response to Environment: Liv-
ing things detect and react to stimuli (like plants growing towards light). �
Regulation: Maintaining homeostasis, or internal balance (like body tempera-
ture). � Reproduction: Passing genetic material to offspring, whether sexual
or asexual. � Evolutionary Adaptation: Populations change over generations
to better survive in their environment.
Hierarchy of Organization � Biology studies life across many levels, from tiny
molecules to the entire planet: � Biosphere: All of Earth’s environments
supporting life. � Ecosystem: Communities of living things interacting with
nonliving things (like forests, oceans). � Community: All organisms in a
specific area. � Population: Individuals of a single species in an area. �
Organism: An individual living thing. � Organs/Organ Systems: Body parts
that carry out specific functions. � Tissues: Groups of similar cells performing
a function. � Cells: The smallest units of life. � Organelles: Functional
structures within cells (like the nucleus, mitochondria). � Molecules: Chemical
structures (proteins, DNA, etc.) essential for life.
The Process of Science � Science is a way of solving problems and answering
questions about the natural world: � Observation: Gathering facts by watch-
ing, measuring, or experimenting. � Hypothesis: A testable explanation for
an observation. � Experimentation: Testing hypotheses under controlled con-
ditions. � Data Analysis: Gathering and interpreting results. � Conclusion:
Supporting or refuting the hypothesis based on data.
Biologists perform these steps over and over, building on previous knowledge to
expand our understanding of life’s complexity .
2. Chemistry of Life
All living things are made of chemicals, and their survival depends on the inter-
actions between those chemicals!
Atoms & Elements � All matter is made of atoms, the smallest units of elements.
� Key elements in biology: carbon (C), hydrogen (H), oxygen (O), and nitrogen
(N)—these make up about 96% of living matter. � Elements combine to form
molecules, the building blocks of cells (e.g., water, proteins, DNA).
Water—The “Universal Solvent” � Water molecules are polar: they have slightly
charged ends, allowing them to dissolve many substances. � Hydrogen bonds
1
, between water molecules give water its unique properties: high boiling point,
surface tension, and ability to stabilize temperature. � Water is essential for
many biological reactions—life on Earth depends on it!
Acids, Bases & pH � Acid: Adds H� ions to a solution (e.g., stomach acid). �
Base: Removes H� ions, often adds OH� ions (e.g., baking soda). � The pH scale
(0–14) measures acidity; cells must keep pH stable for proteins and enzymes to
function.
Major Biological Molecules � Carbohydrates: Sugars and starches for energy
and structure. � Proteins: Made from amino acids—used in everything from
muscles to enzymes. � Lipids: Fats, oils, and membranes—energy storage and
cell structure. � Nucleic acids: DNA and RNA—store and transmit genetic
information.
Biological chemistry is the foundation for everything else you’ll study in biology.
Master these basics, and you’re set for success!
3. Cell Structure and Function
Cells are the basic units of life—everything in biology starts here!
Two Main Cell Types � Prokaryotic Cells: No nucleus. Simpler and smaller (e.g.,
bacteria, archaea). � Eukaryotic Cells: Have a nucleus and membrane-bound
organelles. Make up plants, animals, fungi, protists.
Common Features of All Cells � Plasma Membrane: The cell’s flexible “skin” that
controls what goes in and out. � Cytoplasm: Gel-like inside filling, where cell
parts float and many reactions happen. � DNA: Genetic info—even prokaryotes
have DNA, just not inside a nucleus. � Ribosomes: Protein factories—build all
the proteins cells need.
Eukaryotic Cell Organelles (“Tiny Organs”) and Their Jobs � Nucleus: Stores
DNA, the cell’s “control center.” � Mitochondria: Make ATP (cellular energy)
by breaking down food—“powerhouse of the cell.” � Chloroplasts: Found only in
plants/algae—do photosynthesis (convert solar energy into food). � Endoplasmic
Reticulum (ER): � Rough ER: Has ribosomes, makes and folds proteins. �
Smooth ER: Makes lipids, processes toxins. � Golgi Apparatus: “Post office” of
the cell—sorts and ships proteins. � Lysosomes: Clean-up crew—digest waste,
old cell parts (mainly in animal cells). � Vacuoles: Storage for water, nutrients,
or waste (big in plant cells).
Cell Membrane Structure � Phospholipid bilayer: Two-layered wall with proteins
“floating” in it—selectively lets materials in/out. � Proteins and carbohydrates
in the membrane help with transport, identification, and cell signaling.
Fun Fact: Your body’s eukaryotic cells work together in tissues and organs, but
even single-celled prokaryotes can do a LOT with very little!
4. Energy, Enzymes, and Metabolism
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