Characteristics of Life Our Environment is made of living and non-living things biotic abiotic

Characteristics of Life     CHARACTERISTICS OF LIFE   Living things have characteristics that make them different from non-living things.   Although some non-living things show some of these characteristics, none show all of them.  

Organization Organization- * living things are highly organized * specialized structures perform specific functions  

  Organization *basic unit of organization in living things is the cell   *all organisms are made of cells -multicellular: many celled (ex.plants, animals) - unicellular: single celled (ex. Bacteria

Organization *Every cell in an organism displays the characteristics of life  

Organization The majority of organisms consist of many more than one type of cell. There are about 200 different types of cells -- many highly specialized – that make up the tissues and organs of the human body Surprisingly, however, every nucleus of every cell has the same set of genes

Energy II. Energy *living things use energy for life processes (ex. grow, fly, reproduce)   * Organisms take in energy from their environment and use it.

  Growth * All living things grow and develop   * growth = increase in size *development = change in form   *The amount of growth/development varies among living things.

  Reproduction IV. Reproduction * living things come from other living things (biogenesis)   * Reproduction involves making new cells   * The new cells can be part of an existing organism or part of a new organism

Reproduction *reproduction is necessary for the survival of the species   *reproduction can result in the an exact duplicate of a parent or in an offspring with variations  

Response and Adaptation     V. Response and Adaptation * Responding to stimuli is a characteristic of all living things (ex. movement, color change)

Response and Adaptation * Adaptation is and entire population of organisms responding to long term changes in their environment   *Adaptations are passed from one generation to the next  

Response and Adaptation *Each species has unique adaptations that allow it to survive in it’s environment.

Homeostasis Living things are made of cells. Cells work best when their surroundings are kept constant. Organisms have many mechanisms that keep the cells surroundings constant even though your external environment is changing. This is homeostasis.

Ex. Thermoregulation – keeping constant body temperature (endotherms, warm blooded animals) To survive, grow and multiply living cells depend on various chemical reactions within the cell. In living cells these reactions are helped by substances called enzymes which are special types of proteins. Enzymes speed up reactions without being used up. Without enzymes the reactions would be too slow to support life processes.

Human enzymes work best at 37°C (body temperature). If you are too hot or too cold the brain sends nerve impulses to the skin, which has three ways to either increase or decrease heat loss from the body's surface

1. Hairs on the skin trap more warmth if they are standing up than if they are lying flat. Tiny muscles in the skin can quickly pull the hairs upright to reduce heat loss, or lay them down flat to increase heat loss. Ex. Goosebumps 2. Glands under the skin secrete sweat onto the skin in order to increase heat loss by evaporation if the body is too hot. Sweat secretion stops when body temperature returns to normal. 3. Blood vessels supplying blood to the skin can swell or dilate (called vasodilation) - so that more heat is carried by the blood to the skin where it can be lost to the air; or shrink down again (called vasoconstriction) - to reduce heat loss through the skin once the body temperature has returned to normal Homeostasis is very important because when it fails organisms become ill and may die Can you think of other conditions that living things need to keep constant?

Universal Genetic Code All living things contain DNA DNA codes for the proteins that carry out all of the chemical reactions in your body (metabolism). The genetic code is the same for all living organisms

Reflection Questions 1.What are the characteristics of life? 2. What characteristics of life does a flame have? What does it lack? 3. What is the difference between growth and development? 4. Give an example of an organism and an adaptation it has to it’s environment. 5. What is homeostasis?