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Introduction to Biology

Cell Theory

1. All living things are composed of one or more cell.
2. Cells are the units of life
3. New cells come only from preexisting cells by cell division

Seven Characteristics of Life

1. Cells and Organization
2. Energy Use and Metabolism
3. Response to Environmental Changes
4. Regulation and Homeostasis
5. Growth and Development
6. Reproduction
7. Biological Evolution

Unit of Life

Cells are the units of life

Unit of Organization

1. Atoms
2. Molecules and Macromolecules
3. Cells
4. Tissues
5. Organs
6. Organism
7. Population
8. Community
9. Ecosystem
10. Biosphere

Modern Forms of Life

Connected by an Evolutionary History

Modern Forms of Life-Unity

1. All modern forms of life display a common set of characteristics.
2. Based on biological evolution.

Modern Forms of Life-Diversity

1. Diverse environments support diverse organisms.

Vertical Descent with Mutation

1. Progression of changes in a lineage
2. New species evolve from preexisting species by the accumulation of mutations
3. Natural selection takes advantage of beneficial mutations

Horizontal Gene Transfer

1. Genetic exchange between different species
2. Relatively rare
3. Ex: Genes that confer antibiotic resistance are sometimes transferred between different bacteria species


identification, naming, and classification of species based on common vertical descent ancestry.


single-celled organisms that do not have a membrane-bound nucleus

Taxonomic Group


- Domain (largest)
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species (smallest) It describes genetically similar individuals that are capable of mating to produce fertile offspring.


(microbiology) single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll that reproduce by fission


One of two prokaryotic domains of life, the other being Bacteria. Unicellular Prokaryote.


in a modern taxonomic system, a domain made up of all eukaryotes; this domain aligns with the traditional kingdoms Protista, Fungi, Plantae, and Animalia


entire set of genetic information that an organism carries in its DNA

Genome Characteristics

1. Stores information in a stable form: The genome of every organism stores information that provides a blueprint to create its characteristics.

2. Provides continuity from generation to generation: The genome is copied and transmitted from generation to generation.

3. Acts as an instrument of evolutionary change: Every now and then, the genome undergoes a mutation that may alter the characteristics of an organism. In addition, a genome may acquire new genes by horizontal gene transfer. The accumulation of such changes from generation to generation produces the evolutionary changes that alter species and produce new species.


Is the entire protein complement of a cell or organism. Proteins are largely responsible for the structure and function of cells and complete organisms. All of the proteins that a cell or organism can make.

Cytoskeleton (Proteomes)

Proteins are involved in cell shape and movement

Cell Organization (Proteomes)

Proteins organize the components within cells

Enzymes (Proteomes)

Proteins that speed up chemical reactions. Proteins function as enzymes to synthesize and break down cellular molecules and macromolecules.

Transport Proteins (Proteomes)

Proteins facilitate the uptake and export of substances. Protein molecules that help to transport substances throughout the body and across cell membranes

Cell Signaling (Proteomes)

Proteins are needed for cell signaling with other cells and with the environment. The molecular mechanisms by which cells detect and respond to external stimuli and send messages to other cells

Extracellular Proteins (Proteomes)

Proteins hold cells together in tissues.


Science is the observation, identification, experimental investigation and theoretical explanation of natural phenomena.


1. Proposed explanation for a natural phenomenon
2. Educated guess based on previous observations or experimental studies
3. Hypothesis must make predictions that can shown to be correct or incorrect (must be falsifiable)
4. Additional observations or experiments support or reject a hypothesis
5. A hypothesis is never absolutely proven
6. We may not have found the true explanation for a phenomenon.

Hypothesis Example

If exercise is related to weight loss then increasing the amount of daily exercise in someone's routine will cause them to lose weight.

Hypothesis Testing

5 Stage Process

1. Observations are made regarding natural phenomena.

2. These observations lead to a hypothesis that tries to explain the phenomena. A useful hypothesis is one that is testable because it makes specific preditions.

3. Experimentation is conducted to determine if the predictions are correct.

4. The data from the experiment are analyzed.

5. The hypothesis is considered to be consistent with the data, or it is rejected.

Control Group

the group that does not receive the experimental treatment.

Experimental Group

in an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable.

Control Sample

a sample that receives no treatment during an experiment, and demonstrates what happens if no experimental variables are applied.

Experimental Variable

independent variable, the component or factor being tested

Independent Variable

the experimental factor that is manipulated; the variable whose effect is being studied

Discovery Based Science

Experimentation that does not require a preconceived hypothesis. In some cases, the goal is to collect data to be able to formulate a hypothesis.

All life-forms are composed of ____.


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