Orientation to Biology

By the end of this class you should understand: The organization of the fields of science Characteristics common to all living things The organization of living things, and humans in particular

Biology is an Integrated Science To understand biology well, one must also understand: – Chemistry – Physics – Math – Statistics

Organization of Living Things All living things are highly organized into levels of organization More complex organisms are organized into more levels – Some living things are only one cell – Some living things do not have organs

Smallest “unit” of life? A cell is the smallest thing that is alive – It is made of things that are not alive – It meets all the criteria of being alive Huge variety of cells

Consider a car A car is made of many parts Each part is made of materials Only the complete car will drive around – Cells are alive but made of nonliving things

Quick check! What are some characteristics of life?

Characteristics of Life Maintain homeostasis (WTF is that?) Acquire energy and raw materials Excrete waste products Respond to environment Grow and reproduce Made of macromolecules (WTF are those?)

WTF are these? Homeostasis: the process of maintaining a constant internal environment despite changes in external environment – Example: body temperature Macromolecules: large molecules made mostly with carbon – Refers to nucleic acids, proteins, sugars, and fats

Homeostasis Homeostasis is maintained through negative feedback loops – When a signal is received, it produces something that blocks the original signal Temperature homeostasis is the easiest to understand – ALL conditions in our bodies are similarly controlled

Negative Feedback Loops Sweat glands activated Shivering begins Stimulus Body temperature rises BALANCE Information sent along the afferent pathway to control center Information sent along the afferent pathway to control center Afferent pathway Afferent pathway Efferent pathway Efferent pathway Information sent along the efferent pathway to effectors Information sent along the efferent pathway to effectors Stimulus Body temperature falls Receptors Temperature-sensitive cells in skin and brain Receptors Temperature-sensitive cells in skin and brain Effectors Sweat glands Effectors Skeletal muscles Control Center (thermoregulatory center in brain) Control Center (thermoregulatory center in brain) Response Evaporation of sweat Body temperature falls; stimulus ends Response Body temperature rises; stimulus ends

Macromolecules Macromolecules perform all the major functions of life in our cells – Macromolecules perform their functions because of the atoms that make them up – The study of atoms is called chemistry – The study of macromolecules is often called biochemistry (chemistry of living things) This will be Wednesday’s topic!