cell bio

What do living things do?

Maintain homeostasis

Growth and development

Maintain PH levels/acidity

Cellular respiration

Who discovered Cell Theory?

Robert Hooke (English Scientist in1665)

Who laid bases for Cell Theory?

Botanist Matthias Schleiden and zoologist Theodor Schwann in Germany

Cell Theory

says that cells are the universal building blocks for all living things.

1500

Light microscope was invented

1665

Hooke identifies cells

1839

Schleiden and Schwann’s cell theory

1950s

Electron microscope invented

Polar covalent bond made of

partial positive + (oxidized) and partial negative charge - (reduced)

Elements in the cells

• About 25 elements are essential to life (known to be)

• Carbon, hydrogen, nitrogen, and oxygen make up 96% of all living matter.

Trace elements

elements that are only needed in small amounts

O (oxygen), C (carbon), H (hydrogen), N (nitrogen), C (calcium), P (phosphorus), P (potassium).

chemical bonds

Weak or strong electrical attraction that holds atoms in the same vicinity

molecule

a grouping of two or more atoms held together by chemical bonds.

covalent bonds

• atoms share electrons.

• Two types of covalent bonds

• Can be nonpolar (equal sharing, ex, CH4)

• Can be polar (unequal sharing, ex, H2O)

Ionic bonds

• electrons are transferred

• Creates ions

• Cations = positive

• Anions = negative

• Opposites attract!

• Compounds formed by ionic bonds are called ionic compounds or salts.

Whether an atom forms a covalent or ionic bond depends

electronegativity of the atom involved.

electronegativity

attraction of an atom for electrons. The more electronegative an atom is, the stronger it pulls electrons to the nucleus.

• When two atoms are very unequal in electronegativity, the more electronegative one may strip away electrons, forming an ionic bond.

• Electronegativity increases as you move from left to right across the periodic table until you reach the noble gases (these are inert/chemically unreactive)

In water, ionic bonds get…

• Because the ions are separated and shielded from each other by water molecules. The sphere of water molecules around each dissolved ion is called the hydration shell.

• Important because all organisms familiar to us are mostly water, and most cells are *70-95% Water.

• Many things dissolve in water, like molecules such as proteins. Water is a universal solvent/solvent for life.

weaker bonds

Two molecules in a cell contact each other → may stick together temporarily because of chemical bonds weaker than covalent bonds. Have brief contact.

hydrogen bonds

Hydrogen bonds, which are strongly bound to one electronegative atom, are also attracted to another electron-donating atom.

Van der Waals interactions

attraction of positive and negative regions of molecules that are caused by the motion of electrons. Electrons are in constant motion, so they accumulate by chance in one part of a molecule. These changing regions of partial charge enable atoms and molecules to interact and form bonds. 

• These interactions are very weak and only occur when molecules or parts of the same molecules are in proximity.

Hydroxyl

• OH

• Compound name: Akohols

Carboxyl

• Carboxylic acids