Intro to Biology / Chemistry of Life

Science

  • Method of observation, measurement, and experimentation used to acquire knowledge
    and the body of knowledge obtained via this method

  • Scientific method – first half of the “definition” of science

    • Objective

    • Based around testing hypotheses

    • Results are repeatable

  • Scientific knowledge – second half of the “definition” of science

    • Always expanding

    • New knowledge refines understanding

Biology

Bio = life ology = study of

Species - the largest group of organisms capable of producing fertile offspring

Biological Diversity = biodiversity - diversity/variety of organisms

Important because

Reductionism vs. Emergent Properties

Reductionism - breaking down complex systems into simple components

  • analyzing components

Holistic - examining the whole of a complex system

  • emergent properties can be observed

    • emergent properties = novel properties that emerge due to the interaction of components

    • object is greater than the sum of its parts

Characteristics of Life

Body

  • separate self from environment

  • maintain homeostasis

  • cell or cells

Metabolism

  • obtaining and using energy and nutrients

  • Photo- / Chemo - synthesis and respiration

Inheritable information

  • pass the ability to survive to offspring

  • method of reproduction

  • DNA

Carbon-based

  • All organic molecules have a carbon skeleton

Liquid Water

  • the most abundant substance in living things

Life

What is alive and what is not alive is not always clear

ex) viruses - not alive, require a host to survive and reproduce

Living things are composed of nonliving things

  • cells are made of molecules, molecules are made of atoms

Elements

Element - a substance that cannot be broken down to other substances by chemical reactions

The periodic table lists all known elements

Atoms

  • the smallest unit of matter that retains the properties of an element

  • subatomic particles - do NOT retain the properties of the element

Atoms retain element

Subatomic does not retain the element

Nucleus - composed of protons and neutrons, contains most of the mass of the atom

Electron cloud - composed of electrons, orbits the nucleus

Atomic number = number of protons

Atomic mass - average mass number

Mass number - number of protons + neutrons

Electron orbitals

Electrons are located in electron orbitals

  • The electron orbitals compose the electron cloud

  • Area outside of the nucleus

Have distinct shapes and represent where the electrons can be found 90% of the time 

Atoms usually contain 1 or more electrons located in electron orbitals, which are organized into electron shells

Represents most of the space of an atom

The number of orbitals and the number of electrons determine the chemical reactivity of the element

Compound

A substance formed by the combination of 2 or more different elements in a fixed ratio.

Emergent properties

2H hydrogen + O oxygen = H2O Water

Molecules

  • 2 or more atoms held together by chemical bonds

    • the smallest unit of a compound that retains the properties of the compound

    • elements can form molecules without forming compounds

Molecular Bonds

  • hold atoms together - form molecules

  • Chemical Bond - an attractive force that links atoms together in a molecule

  • Molecular bonds

    • covalent bond

    • ionic bond

  • Chemical reactions - occur when molecule bonds are formed or broken

Covalent Bonds

  • when atoms share 1 or more pairs of electrons

  • 2 atoms can share more than 1 pair of electrons

  • Single bonds - atoms share 1 pair of electrons

    • CH4 (methane), each hydrogen has a single bond with the carbon

  • Double bonds - atoms share 2 pairs of electrons

    • O2 (oxygen), the oxygen atoms share a double bond

  • Triple bonds - atoms share 3 pairs of electrons

    • N2 (nitrogen), the nitrogen atoms share a triple bond

  • Multiple bonds are stronger and harder to break than single bonds

Polar and nonpolar covalent bonds

  • Nonpolar covalent bond - the electrons are shared equally

  • Polar covalent bond - the electrons are not shared equally

    • The electrons are closer to the nucleus of 1 atom than to the nucleus of the other atom

    • creates a slight negative charge near the more electronegative atom and a slight positive charge near the electronegative atom

Ionic Bonds

  • Ions form when an atom gains or loses an electron, giving it a net electric charge

  • Cations - positive ions - have more protons than electrons

    • Na+, H+

  • Anions - negative ions - have more electrons than protons

    • CL-, F-

  • Opposite charges are attracted to one another

  • Ionic bond - forms as a result of the electrical attraction between ions of opposite charges

  • NaCl - sodium chloride