What Does it Mean to Be Alive? What Are The Characteristics of Life?

Exploring LIFE Biology – The study of Life What does it mean to be ALIVE? How do you know if something is ALIVE?

Is Fire ALIVE?

Characteristics of Life! All living things share basic properties  Eight Characteristics of Life C  Composed of cells (+1) H  Homeostasis A  Adaptation R  Reproduce R  Respond to the environment G  Growth & Development E  Energy (metabolism) D  DNA /RNA (genetic material)

All Living Things are Made Up of Cells Living organisms consist of organic (carbon-containing) molecules  organized to form cells Cells  Life’s basic units of structure and function

Unicellular Organisms Entire organism is made up of one single cell Bacteria and protists

Multicellular Organisms The organism is made up of many cells Cells have specialized functions within the organism

All Organisms Maintain Homeostasis Homeostasis = ability of an organism to maintain relatively constant, stable state of internal conditions EXAMPLES: Body temperature Blood volume pH balance Water balance All organ systems contribute to homeostasis

All Living Things Adapt to Their Environment Through Evolution Adaptation A trait (or process) that enables organisms to become better suited to their environment Species obtain adaptations through evolution, which occurs over great periods of time

Evolution Gradual change in a species over time Species differ greatly in their adaptations to the many distinct environments on Earth Both the unity and diversity of organisms can be explained by the mechanisms of evolution and natural selection….more on that later 

An Example of Adaptation Desert plants have succulent waxy leaves and stems to store water and reduce water loss

All Living Things Reproduce Reproduction is the process of producing new organisms. Two types: Asexual Reproduction A single parent organism reproduces by itself Ex: binary fission in bacteria

Sexual Reproduction Two different parent organisms contribute genetic information Involves the combination of male and female sex cells

Respond to the Environment Living things respond to the environment by reacting to a stimulus (a thing or event that produces a specific reaction)

All Living Things Respond to Their Environment Example: A plant’s leaves and stems grow toward light Organisms react to stimuli: Light Temperature Odor Sound Gravity Heat Water Pressure

ALL ORGANISMS GROW & DEVELOP Growth & Development ALL ORGANISMS GROW & DEVELOP

All Living Things Grow Growth means to get bigger in size

All Living Things Develop Development involves a change in the physical form or physiological make-up of an organism

ENERGY: All living organisms obtain & use energy for all body processes: growth and development, damage repair, , transport, and reproduction

Energy: Two types of Living Organisms 1. PRODUCERS: - Plants, algae, and other photosynthetic organisms that produce their own “food” for energy (from CO2, H2O, & the sun) - Entire ecosystems depend on producers 2. CONSUMERS: - Organisms that obtain nutrients and energy from consuming the food made by producers

Metabolism All chemical reactions occurring within an organism Anabolism + Catabolism = Metabolism

Anabolism Process of building up complex substances from simpler substances Building up cells and cellular components Photosynthesis

Catabolism Process of breaking down complex substances into simpler substances to release energy Digestion Cellular Respiration

All Organisms Pass Along Hereditary Traits Genes carry hereditary information Genes are composed of DNA Heredity is the reason offspring resemble their parents Mutations change DNA code and can be passed from generation to generation

Characteristics of Life - RECAP C  Composed of cells (+1) H  Homeostasis A  Adaptation R  Reproduce R  Respond to the environment G  Growth & Development E  Energy (metabolism) D  DNA /RNA (genetic material)

Organisms Viruses Metabolism Do not metabolize Grow and Develop No Growth and Development Sexual or Asexual Reproduction Must use the machinery of cells to reproduce Composed of cells DNA or RNA and a protein coat – no cells Maintains Homeostasis Does not maintain Homeostasis

STRUCTURE OF A VIRUS CAPSID (protein coat) DNA or RNA

How is life classified? Taxonomy = biological classification binomial nomenclature Two-word “scientific” name (Genus & species)

Benefits of Classifying Accurately & uniformly names organisms Prevents misnomers such as “starfish” & “jellyfish” that aren't really fish Uses same language (Latin or some Greek) for all names Sea”horse”??

Prokaryotes – The first Cells Cells that lack a nucleus or membrane-bound organelles Includes bacteria Simplest type of cell Single, circular chromosome copyright cmassengale

copyright cmassengale Prokaryotes Nucleoid region (center) contains the DNA Surrounded by cell membrane & cell wall (peptidoglycan) Contain ribosomes (no membrane) in their cytoplasm to make proteins copyright cmassengale

copyright cmassengale Eukaryotes Cells that HAVE a nucleus and membrane-bound organelles Includes protists, fungi, plants, and animals More complex type of cells copyright cmassengale

copyright cmassengale Eukaryotic Cell Contain 3 basic cell structures: Nucleus Cell Membrane Cytoplasm with organelles copyright cmassengale