Cell Theory

• All living things are made up of cells

• Cells are the smallest unit of life that can function independently (if given the right environment)

• All organisms are made up of one or more cells

• Cell is the fundamental unit of life

• All cells come from preexisting cells

Characteristics of Living Organisms

• Organized

• Energy use

• Homeostasis

• Reproduction, growth, and development

• Evolution

Biological Organization

• Atoms (least complex): form the foundation - when they start interacting with each other they form the next level of organization

• Molecules: a combination of different atoms forming a larger structure - can be put together in a wide variety of complexities

• Organelles: small structures that have a specific role of function in the cell

• Cells: made up of thousands of organelles - not all cells have the same composition of organelles - grouping of different organelles together to form that self sustaining unit that can reproduce

• Tissues: different combinations of cells forms different types of tissues

• Organs: different combinations of tissues

• Organ system: combine organs to create an organ system

• Organism: multiple organ systems working together to form a whole living unit

• Population: a collective group in a particular area of the same species

• Community: the interaction between all species in an area

• Ecosystem: all of the living and nonliving interactions in an area

• Biosphere (most complex): our planet earth - interactions between all ecosystems

Life Requires Energy

• Metabolism: all of the chemical reactions that occur inside your cells

• Constant stream of energy required to maintain organized life

• Energy from the environment used to

  • build new structures

  • repair old ones

  • reproduce

• Photosynthesis /cellular respiration

  • Producers extract energy and nutrients from the nonliving environment

  • Consumers obtain energy by eating other organisms

  • Decomposers are consumers that obtain nutrients from dead organisms and organic wastes

• Not all life gets energy the same way

• Law of entropy: energy is constantly lost as it travels through the atoms and molecules that make us up; process of energy lost

Energy Flow

• Broad categories

  • Producer/autotroph: extract energy and nutrients from nonliving environment

    • Plants and some microbes

  • Consumer/Heterotrophs: eat other organisms for nutrients

    • Humans and other animals

  • Decomposer: obtain energy from wastes or dead organisms

    • Fungi and many bacteria

Life Maintains Homeostasis

• Homeostasis: state of internal constancy or equilibrium (things can happen that disrupt your homeostasis)

Life Reproduces Itself, Grows, and Develops

• Mitosis

  • Asexual: organism produces offspring virtually identical to itself

    • Bacteria, some plants, fungi, and animals

    • Genetically identical population

• Meiosis

  • Sexual: genetic material from 2 individuals unites to form new third individual

    • Benefit of tremendous variation

    • Genetically diverse population

• Most reproduction on our planet is asexual

• Mitosis (cell division) is occurring all the time in our body: mainly used for cell renewal and repair; constantly making new cells

• For single celled organisms, mitosis is their only form of reproduction, hence why it’s called asexual reproduction -> essentially cloning themselves

• Sexual reproduction has the greatest evolutionary advantage

• The less variety in a species, the less ability they have to adapt to changing conditions in their environment and they die off

Life Evolves

• Some organisms seem “perfectly” adapted to their environments

• When you see a species in its environment, the reason it has the phenotypes or traits is due to the fact that it’s the most advantageous for that environment, and has adapted over time because of its advantages.

• Recent issue of climate change: environments are changing so fast, species don’t have time to adapt and survive -> causes ecosystems to collapse