cell bio 1

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

• Compound name: Akohols

Carboxyl

• Carboxylic acids

amino

• amines

sulfhydryl

• thiols

phosphate

• organic phosphates

Stanley Miller (1953)

studied —> Demonstrate spontaneous formation of organic compounds in primitive Earth conditions

Cells are…?

organic and 70-95% water

How many Macromolecules classes are there?

four.

What are the four classes of macromolecules?

Carbohydrates, lipids, proteins, nucleic acids.

How are macromolecules arranged?

chainlike molecules

Macromolecules are arranged in chainlike structures that are called…?

polymers.

A polymer is…?

long molecule consisting of similar/identical building blocks linked by covalent bonds.

sugars are the subunit of…

polysaccharides and oligosaccharides

Fatty acids are the subunit of…

fats and membranes lipids

amino acids are the subunit of…

proteins

nucleotides are the subunit of…

nucleic acids (DNA, RNA)

How many carbons are in ribose and glucose?

5,6

carbohydrates can exist as…

linear structure, but sugar monomers form rings in water.

isomer

same chemical formula but differ in the arrangement of atoms.

small changes are important…

like when molecules act as ligands for proteins.

Deoxyribose

a five-carbon sugar found in DNA.

Disaccharide

sugar formed by two monosaccharides and a glycosidic bond.

example of disaccharides

Sucrose

sucrose is made of

glucose and fructose

A monosaccharide has how many carbons?

6

cellulose

a polysaccharide made by some organisms, such as plants. Humans can’t digest.

polysaccharide

made of many monosaccharides linked together

Amylose, amylopectin, glycogen are all…

polysaccharides

Humans (and animals) make which polysaccharide…

Glycogen (energy storage)

Monosaccharides are linked by…

glycosidic bonds

A glycosidic bond has what type of bond?

covalent bond (shares electrons)

Lipids are made of what…

fatty acids

fatty acids have a…

• hydrophilic carbon acid head

• hydrophobic hydrocarbon tail

triglycerides

• Composed of one glycerol and three fatty acids.

• Fatty acids link to glycerol by dehydration synthesis.

• These are commonly called fat molecules (triglycerides).

There are how many types of fatty acids?

1. Unsaturated fats

2. Saturated fats

Saturated fats

• Fully saturated with hydrogens (no double bonds).

• Long, straight (linear) tails.

• Pack closely together → solid at room temperature.

Unsaturated fats

• Not fully saturated with hydrogens (one or more double bonds).

• Double bonds cause a bend (kink) in the tail.

• Cannot pack closely → liquid at room temperature (e.g., corn oil).

Omega - 3 fatty acid is a…

A type of polyunsaturated fatty acid (has multiple double bonds).

three types of omega-3 fatty acids

Alpha-linolenic acid (ALA)

Eicosapentaenoic acid (EPA)

Docosahexaenoic acid (DHA)

Alpha-linolenic acid (ALA)

• 18 carbons

• 3 double bond

Eicosapentaenoic acid (EPA)

• 20 carbons

• 5 double bonds

Docosahexaenoic acid (DHA)

• 22 carbons

• 6 double bonds

What is cholesterol?

A steroid.

Are steroids…?

lipids characterized by carbon skeleton consisting of four fused rings.

Many hormones are produced from…

cholesterol.

nucleotides are…

building blocks of nucleic acids (DNA and RNA)

nucleotide components are

• Phosphate group(s)

• Sugar

• Nitrogenous base

There are two types of nitrogenous bases…

• pyrimidines

• purines

pyrimidines (single ring)

• Cytosine, thymine, uracil

• DNA: cytosine, thymine

• RNA: cytosine, uracil (uracil replaces thymine

purine (double ring)

Adenine and guanine

Different sugars in each nucleotide. DNA contains…

deoxyribose

Different sugars in each nucleotide. RNA contains…

ribose

function of nucleotides…

• Energy transfer by breaking phosphate groups (e.g., ATP).

• Form coenzymes when combined with other groups.

• Act as small intracellular signaling molecules in the cell.

Enzymatic proteins

ex: digestive enzymes

structural proteins

ex: silk fibers, collagen, feathers, hair keratin.

storage proteins

ex: ovalbumin in egg whites

transport proteins

ex: hemoglobin

hormonal proteins

ex: insulin

receptor proteins

ex: receptors in nerve cell membranes

contractile and motor proteins

ex: actin and myosin in muscles

defensive proteins

ex: antibodies combating bacteria and viruses.

proteins are…

polymers made of amino acid subunits

A polymer of amino acids is called…

polypeptide

polypeptide can range from how many amino acids?

a few to over 1,000

polypeptides have a what sequence?

unique.

protein consists of one or more…

polypeptides

polypeptides can be folded into…

a specific shape (conformation)

all amino acids have…

• Amino group (–NH₂)

• Central carbon

• Hydrogen atom

• Carboxyl group (–COOH)

What truly makes each amino acid different…?

The R group, or side chain.

How many common amino acids are in cellular proteins?

twenty (you’re twenty???)

families of amino acids are grouped into families according to whether their side chains are…

acidic, basic, uncharged polar, nonpolar

acidic side chains

aspartic acid, glutamic acid

basic side chains

lysine, arginine, histidine

why are basic side chains basic?

because it positive charge stabilized by resonance.

uncharged polar side chains

asparagine, glutamine, serine, threonine,tyrosine

uncharged polar side chains have…

have hydroxyl group as a side chain

nonpolar side chains

alanine, valine, leucine, isoleucine, proline, methionine, tryptophan, glycine, cysteine, phenylanine

all amino acids have…

weak acids and bases

acids

release protons (hydrogen ions) when dissolve in water. increase H+ concentration.