The Molecules of Cells

organic compounds

Carbon-based molecules are called

hydrocarbons.

Methane and other compounds composed of only carbon and hydrogen are called

straight,

branched, or

arranged in rings.

A carbon skeleton is a chain of carbon atoms that can differ in length and be

isomers.

Compounds with the same formula but different structural arrangements are called

hydroxyl group, carbonyl group, carboxyl group, amino group, phosphate group

These five groups are polar, so compounds containing them are typically hydrophilic (water-loving) and soluble in water.

hydroxyl group

a hydrogen bonded to an oxygen,

carbonyl group

a carbon linked by a double bond to an oxygen atom,

carboxyl group

a carbon double-bonded to both an oxygen and a hydroxyl group,

amino group

a nitrogen bonded to two hydrogen atoms and the carbon skeleton

phosphate group

a phosphorus atom bonded to four oxygen atoms.

methyl group

A sixth group, consists of a carbon bonded to three hydrogen atoms,

is nonpolar and not reactive, but

still affects molecular shape and thus function.

carbohydrates

lipids

proteins

nucleic acids

There are four classes of molecules important to organisms

polymers

They are also called… because they are made from identical or similar building blocks strung together.

monomers

The building blocks of polymers are called

dehydration reactions

Monomers are linked together to form polymers through…which removes water

hydrolysis

Polymers are broken apart by… the addition of water

enzymes

 specialized macromolecules that speed up chemical reactions in cells

nucleotides

DNA is built from just four kinds of monomers called

Carbohydrates

range from small sugar molecules (monomers) to large polysaccharides.

monosaccharides

Sugar monomers are…, such as those found in 

fructose,

glucose, and

honey.

more complex sugars and

polysaccharides

Monosaccharides can be hooked together by dehydration reactions to form

Monosaccharides

main fuels for cellular work, and

used as raw materials to manufacture other organic molecules

disaccharide

Two monosaccharides (monomers) can bond to form a …in a dehydration reaction

two glucose monomers

The disaccharide maltose is formed from

combining a glucose monomer and a fructose monomer

The disaccharide sucrose is formed by 

Polysaccharides 

 are macromolecules, polymers composed of thousands of monosaccharides.

Starch

 is

a polysaccharide,

composed of glucose monomers, and

used by plants for energy storage.

Glycogen

a polysaccharide,

composed of glucose monomers, and

used by animals for energy storage.

Cellulose

is a polymer of glucose and

forms plant cell walls

Chitin

a polysaccharide,

used by insects and crustaceans to build an exoskeleton, and

found in the cell walls of fungi

 hydrophilic

Polysaccharides are usually

lipids

are water insoluble (hydrophobic, or water-fearing) compounds,

are important in long-term energy storage,

contain twice as much energy as a polysaccharide, and

consist mainly of carbon and hydrogen atoms linked by nonpolar covalent bonds

fats,

phospholipids, and

steroids.

We will consider only three types of the lipids:

glycerol and

fatty acids.

A fat is a large lipid made from two kinds of smaller molecules:

triglycerides

Fats are often called … because of their structure.

unsaturated fatty acids

Some fatty acids contain one or more double bonds, forming

saturated fatty acids

Fats with the maximum number of hydrogens are called

trans fat

Hydrogenated vegetable oils are unsaturated fats that have been converted to saturated fats by adding hydrogen.

This hydrogenation creates

Phospholipids

are the major component of all cell membranes.

lipid bilayer 

A phospholipid is ideal for a cell membrane because the hydrophilic phosphate head is in contact with water (both the extracellular space and the intracellular space) and the hydrophobic fatty acid tails form an oily barrier, thus forming the…of the cell

steroids

are lipids in which the carbon skeleton contains four fused rings.

Cholesterol

 is

a common component in animal cell membranes and

a starting material for making steroids, including sex hormones.

proteins

are

involved in nearly every dynamic function in your body and

very diverse, with tens of thousands of different proteins, each with a specific structure and function, in the human body.

enzymes

Probably the most important role for proteins is as 

transport proteins 

 embedded in cell membranes, which move sugar molecules and other nutrients into your cells

defensive proteins

such as antibodies of the immune system

signal proteins 

such as many hormones and other chemical messengers that help coordinate body activities

receptor proteins

 built into cell membranes, which receive and transmit signals into your cells

contractile proteins

 found within muscle cells

structural proteins

such as collagen, which form the long, strong fibers of connective tissues

storage proteins

which serve as a source of amino acids for developing embryos in eggs and seeds.

denaturation

If a protein’s shape is altered, it can no longer function.

In the process of … a protein

unravels,

loses its specific shape, and

loses its function.

Proteins

are made from amino acids linked by peptide bonds

amino acid

all have

an amino group and

a carboxyl group (which makes it an acid).

 peptide bond

Amino acid monomers are linked together in a dehydration reaction,

joining the carboxyl group of one amino acid to the amino group of the next amino acid, and

creating a 

polypeptide

Additional amino acids can be added by the same process to create a chain of amino acids called a 

primary structure

secondary structure

tertiary structure

quaternary structure

A protein’s functional shape results from four levels of structure

he precise sequence of amino acids in the polypeptide chain

The primary structure of a protein

secondary structure

Segments of the chain coil or fold into local patterns called

tertiary structure

The overall three-dimensional shape of a protein is called

quaternary structure

Proteins with more than one polypeptide chain have… The hemoglobin molecule

DNA and RNA 

 are the two types of nucleic acids

gene

The amino acid sequence of a polypeptide is programmed by a discrete unit of inheritance known as a 

RNA (ribonucleic acid)

DNA works through an intermediary,

DNA

deoxyribonucleic acid

 nucleotides

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are composed of monomers called

a five-carbon sugar called ribose in RNA and deoxyribose in DNA

a phosphate group

a nitrogenous base

Nucleotides have three parts

adenine (A), thymine (T), cytosine (C), guanine (G)

DNA nitrogenous bases are

RNA

also has adenine, cytosine, and guanine, but instead of thymine, it has uracil (U).

RNA

 is usually a single polynucleotide strand.

DNA

is a double helix, in which two polynucleotide strands wrap around each other.

T

A pairs with

G

C pairs with