Unit 4- Biochemistry, Energy, & Enzymes

4a- Chemistry + Carbon Compounds

Chemistry Review

• What makes an atom stable?– 8 valence electrons; full outer

energy level, or shell• What can an atom do to

become stable?– Form bonds with other atoms

Chemistry Review• Two types of bonds?

– Ionic Bonds: attraction of oppositely charged ions– Covalent Bonds: form by sharing electrons; causes the

outer energy levels to overlap

Chemistry Review• Bonds between atoms are built and broken causing

substances to combine and recombine as different molecules during chemical reactions.

• Essential functions of a cell involve chemical reactions that take place between many different types of molecules– All of the chemical reactions within a cell are referred to

as the cell’s metabolism.

Building Blocks of Cells

• Living things are organized…• All organisms are composed of

organic molecules – Organic Molecules- contain

carbon atoms

The Role of Carbon• A carbon atom has 4 electrons in its valence shell.• Carbon can form covalent bonds with as many as 4

other atoms.– Can also bond with other carbon atoms to form a single,

double or triple bond (sharing 1, 2, or 3 electrons)

– Allows carbons to form straight chains, branched chains, or rings

Large Carbon Molecules (Biomolecules, Macromolecules)

• Most organic molecules are made of smaller units (monomers) that bond to form larger molecules (polymers)– Energy is stored in the bonds that link these units together– The amount of energy varies with the type of molecule formed.

• Polymer: a molecule that consists of repeated, linked units. – Units may be identical or structurally related

Large Carbon Compounds

• Example: Starches are complex carbohydrates formed by long chains of simple sugars, like glucose– Glucose= monomer; Starch= polymer

Molecules of Life

• There are four types of organic compounds necessary for life (aka biomolecules)– Carbohydrates– Lipids– Proteins– Nucleic Acids

Carbohydrate Structure

• Contain: Carbon, Hydrogen, & Oxygen• Structures:

– Monosaccharides – 1 ring (simple sugars)• Glucose (cell’s primary source of energy)

– Disaccharides – 2 rings• Sucrose (table sugar)

– Polysaccharides – 3 or more rings (complex carbohydrates)• Amylose (component of starch)• Cellulose (structural carbohydrate in plants)

Role of Carbohydrates• In Plants

– Carbohydrates are synthesized during the process of photosynthesis

– The plants then:• Use them as a source of energy• Store them in the cells.

Role of Carbohydrates• In Animals

– Consumed as sugars, starches, and fiber– When complex carbohydrates are consumed, digestion breaks

the bonds between the larger carbohydrate molecules so that individual simple sugars can be absorbed into the bloodstream through the walls of the intestines.• The bloodstream carries the simple sugars to cells

throughout the body• Once inside the cells, they are used as fuel in the process of

cellular respiration, releasing energy that is stored as ATP.– If an organism has a greater supply of carbohydrates than

needed for its energy requirements, the extra energy is converted to fats and stored by the body.

Functions of Carbohydrates• Energy Source

– Glucose in cells is the primary source of energy - fuel for cellular respiration

• Energy Storage (short term)– Glycogen in the liver of animals– Starch in the structures of plants

• Structural Support– Cellulose forms cell walls in plants

• An important source of fiber for animals to stimulate the digestive system• The C, H, & O that make up carbohydrates serve as raw

materials for the synthesis of other small organic molecules, such as amino acids & fatty acids.

Lipids• Contain: Carbon, Hydrogen, &

Oxygen• Includes fats (triglycerides),

phospholipids, steroids, & waxes

• A triglyceride is a lipid made up of a glycerol & 3 fatty acids

• The high number of C-H bonds makes lipids very energy rich.

glycerol three fatty acids

Role of Lipids• Fats

– Important to organisms for energy when carbohydrates are scarce, but when there is no shortage of food, stored fat accumulates.

– Functions:• providing long-term energy storage• cushioning of vital organs• insulation for the body

– Fats are insoluble in water.

Role of Lipids

• Phospholipids– Major component of cell

membranes.• Steroids

– Can serve as raw materials necessary for the production of some vitamins, some hormones, and cholesterol

• Waxes– Lipids that form waterproof

coatings for plants and animals

Proteins• Proteins are molecules composed of chains of amino

acids– Contain: Carbon, Hydrogen, Oxygen, & Nitrogen &

sometimes Sulfur• 20 different amino acids

– 10 amino acids are made in the human body– Humans need to consume the other 10 amino acids from

sources such as nuts, beans, or meat.• Failure to obtain enough of even 1 of the 10 essential AA’s results

in degradation of the body’s proteins.

Protein Structure

• Two amino acids bond to form a dipeptide.– This covalent bond is called a peptide bond

• Polypeptide: long chain of amino acids• Proteins are composed of one or more

polypeptides.– The sequence of amino acids determines the proteins

shape & function.• ~100,000 different proteins in the human body

Role of Proteins• Proteins are the major structural & functional material of body

cells. (workhorse molecules)– Because of the variety of shapes & structures of protein molecules,

proteins have a wide variety of functions– Involved in almost every function in the human body

• Functions:– Structural proteins- used for support such as connective tissue & keratin

that forms hair & finger nails.– Transport proteins- move many substances throughout the body

• Example: hemoglobin transports oxygen from the lungs to the other parts of the body to be used by cells in cellular respiration.

– Hormone proteins- coordinate body activities• Example: insulin regulates the amount of sugar

in the blood.– Contractile proteins- help control movement

• Example: proteins in the muscles which help control contraction.

– Enzymatic proteins- accelerate the speed of chemical reactions • Example: digestive enzymes break down food in

the digestive tract.

Nucleic Acids

• Nucleic Acids are long chains of nucleotides– Nucleotides contain: Carbon, Hydrogen, Oxygen,

Nitrogen, & Phosphorus– Nucleotides are made up

of three parts• Five carbon sugar• Phosphate group• Nitrogen base

Function of Nucleic Acids

• Carry and transmit genetic information – Two Types:

• DNA – holds genetic code for an organism• RNA – makes a copy of DNA in order to make a protein

Calorie Comparison• Energy stored in organic molecules

determines the caloric value• Lipids have the greatest chemical

bond energy over carbohydrates & proteins

• Calorie comparisons:– Proteins 4 Calories per

gram– Lipids 9 Calories per gram– Carbohydrates4 Calories per gram