Living things have 5 functional traits in common:
- Growth: for unicellular organisms, an increase in cell size prior to reproduction; for multicellular organisms, an increase in an organism's size as the number of cells making up the organism increases.
- Reproduction: the process of producing new organisms. [Offspring are similar, but not necessarily identical, to their parents in general structure, function, and properties.]
- Homeostasis: the maintenance of a relatively constant internal environment. [Organisms maintain a stable internal environment, even when the external environment changes.]
- Sense & Response to Stimuli: organisms respond to stimuli in many ways - they may move toward a food source or away from a threatening predator.
- Ability to Obtain & Use Energy: all living organisms require an input of energy to power their activities, and chemical reactions convert that energy into usable forms. [Organisms obtain energy from food (which they either produce themselves or consume from the environment).] [The sum total of all these reactions is metabolism.]
Chemical reactions convert that energy into usable forms. Metabolism is the sum total of all of the chemical reactions taking place in the cells of a living organism that allow it to obtain and use energy.
At its most basic level, all life is composed of chemicals.
Matter is anything that takes up space and has mass.
All matter on Earth is made up of elements- chemically pure substances that cannot be chemically broken down.
Elements exist as atoms- the smallest units of an element that cannot be chemically broken down into smaller units.
The nucleus is the dense core of an atom.
Protons are positively charges subatomic particles found in the nucleus of an atom.
Neutrons are electrically uncharged subatomic particles found in the nucleus of an atom.
Electrons are negatively charged subatomic particles with negligible mass.
Periodic Table of Elements:
Each element is placed in order by its atomic number - the number of protons found in the nucleus of its corresponding atom.
Carbon is a versatile component of life's molecules.
Carbon is the fourth most common element in the universe and the second most common element in your body.
Just 6 elements make up the bulk of you:
- Oxygen (65%)
- Carbon (18.5%)
- Hydrogen (9.5%)
- Nitrogen (3.3%)
- Phosphorous (2%)
- Sulfur (2%)
When atoms are linked by covalent bonds, they form molecules. Carbon atoms have 4 potential binding sites and can therefore bind up to 4 different atoms.
Organic molecules have carbon-based backbones and at least one C-H bond. (Glucose: C6H12O6)
Inorganic molecules lack carbon-based backbones and C-H bonds. (Carbon Dioxide: CO2)