Biochemistry

Reviewing the 4 macromolecules of life!!!Objectives

1. Describe the structure and functions of carbohydrates, lipids, proteins and nucleic acids

2. Describe the structure and function of the cells membrane (phospholipid bilayer)3. Describe the process of diffusion, osmosis and facilitated diffusion

Quiz

1. State 1 of the 3 major concepts from the ‘Cell Theory’. (1 mark)

2. What is the difference between chromosomes and genes? (1 mark)

3. State one way that DNA is different from RNA. (1 mark)

4. What is the function of the cell membrane? (1 mark)

• There are four molecules unique to cells referred to as “molecules of life”

• They are: 1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids (DNA & RNA)

Reviewing ConceptsAtoms Molecules

Cells Tissues Organs Organ systems

ORGANISM

• These molecules are all organic molecules, because they all contain carbon and hydrogen.

• They are referred to as macromolecules, because they are formed of smaller sub-units.

Review Concepts

1. Carbohydrates • Sugars: contain C, H, O• These are our primary source of

energy

• When food containing carbohydrates is eaten, they are broken down by digestive enzymes into monosaccharides (sugars), the smallest sub-unit of carbohydrate that cells can use.• examples of CHO’s are: Bread, Rice, Cereals,

Pasta, Vegetables, Fruit, Legumes (beans), Honey, Sugar, Cookies, Crackers, muffins, Candy, Juice, Pop

Carbohydrates (cont’d)

a) Monosaccharides-single sugars, Ex. fructose, galactose, glucose

• When macromolecules are being BUILT (several smaller molecules are joined), a water molecule (H2O) is removed. • This is referred to as a Dehydration Reaction.

Dehydration Reaction

b) Disaccharides- double sugars: result of two

monosaccharides joining together through a dehydration reaction, ex. maltose, sucrose

c) Polysaccharides (‘many sugars’)-complex: result of 3 or more monosaccharides linking together-need to be digested before we can absorb themex. glycogen, starch, cellulose (in plants)

The Fats of Life: LIPIDS

• Fats, oils, cholesterol, hormones• Composed of C,H,O but not water soluble• Store the most energy: these are energy

storing molecules!

Three types of fats

1. Triglycerides

2. Phospholipids (plasma membrane)

3. Sterols (from hormones)

1. TRIGLYCERIDES• Most common fat in plants and animals,

used in storage• A molecule of 3 fatty acids attached to a

glycerol backbone:

fatty acid

fatty acid

fatty acid

2. PHOSPHOLIPIDS

-structural components of cell membrane

hydrophobic tailhydrophilic phosphate head

The Plasma membrane – phospholipid bilayer

The Cell Membrane

function• - controls the passage of molecules in and out

of the cell • - selectively permeable or semi-permeable;

allows only certain molecules or ions to enter or leave the cell

• - allows inside of cell to be different than its environment

Plasma Membrane (cont’d)

3. STEROLS• Cholesterol is a natural component of cell

membranes• used by cells to make steroid hormones, vitamin

D, bile salt

Third Group of Macromolecules: PROTEINS

• The functional molecules– Help chemical reactions take place (ex. enzymes)– Repair and maintain the cell– Transport materials around the body

– Ex. enzymes, hemoglobin, hair

There are 7 classes or categories of body proteins: (this will not be on the test)

• STRUCTURAL – eg. collagen in tendons, ligaments; keratin in hair

• CONTRACTILE eg. actin and myosin in muscle cells• STORAGE eg. ovalbumin in the developing embryo• DEFENSIVE eg. antibodies in blood plasma• TRANSPORT eg. hemoglobin inside red blood cells transports

O2

• SIGNAL eg. hormones, neurotransmitters• ENZYMES eg. enzymes which control all metabolic reactions

Categories of Proteins

• the basic unit or sub-unit or building block of a protein molecule is an AMINO ACID

• there are 20 different amino acids each with its’ own name e.g. glycine

• amino acids are linked together in a long chain to form a protein

Amino Acids (a.a.)

• Proteins are "un-branched chains of amino acids"

• Amino acids link together during protein synthesis through peptide bonds to form a POLYPEPTIDE– Most functional proteins will contain hundreds and

thousands of amino acids linked together

• when proteins are exposed to extremes of heat or pH, they undergo an irreversible shape change called denaturation• loss of shape means loss of function• e.g. Alzheimer’s disease – formation of

unusual protein plaques and tangles that disrupt brain function

Denaturation

Your Task• Create a table to summarize the structure, function

and give an example of each of the 3 types of macromolecules we have just discussed.

• You will need to include a spot for nucleic acids as well.

• For homework, read about nucleic acids in your hand out. Summarize the structure and function of nucleic acids and state the two types of nucleic acids as examples.• Homework: Answer the questions on your hand out. There will be a QUIZ on this tomorrow.

Macromolecule Review