Biochemistry of Cells

ORGANIC MOLECULES:

• Normally found in living systems

• Contain C (carbon)

• Usually in rings or long chains

• Often attached to other atoms such as Hydrogen, Oxygen and Nitrogen.

Uses of Organic Molecules• Canadians consume

an average of 140 pounds of sugar per person per year

Cellulose, found in plant cell walls, is the most abundant organic compound on Earth

Uses of Organic Molecules

• A typical cell in your body has about 2 meters of DNA

A typical cow produces over 200 pounds of methane gas each year

(see video)

cowsandmethane.rm

Touching on Water• About 60-90 percent of an

organism is water

Water is used in most reactions in the bodyWater is called the universal solvent

Carbon-based Molecules

• Although a cell is mostly water, the rest of the cell consists mostly of carbon-based molecules

Organic chemistry is the study of carbon compounds

Carbon is a Versatile Atom

• It has four electrons in an outer shell that holds eight

Carbon can share its electrons with other atoms to form up to four covalent bonds

Hydrocarbons

• The simplest carbon compounds …

Contain only carbon & hydrogen atoms

Carbon can use its bonds to::

• Attach to other carbons

Form an endless diversity of carbon skeletons

Large Hydrocarbons:

• Are the main molecules in the gasoline we burn in our cars The

hydrocarbons of fat molecules

provide energy for our bodies

Shape of Organic Molecules

• Each type of organic molecule has a unique

three-dimensional shape

The shape determines its function in an

organism

Functional Groups are:• Groups of atoms that give properties to the

compounds to which they attach

Gained Electrons Lost Electrons

Common Functional Groups

Giant Molecules - Polymers

• Large molecules are called polymersPolymers are built from smaller molecules called monomersBiologists call them macromolecules

Examples of Polymers• Proteins

Lipids

Carbohydrates

Nucleic Acids

Most Macromolecules are Polymers

• Polymers are made by stringing together many smaller molecules called monomers

Nucleic Acid

Monomer

Linking MonomersCells link monomers by a

process called dehydration synthesis (removing a

molecule of water)

This process joins two sugar monomers to make a double

sugar

Remove H

Remove OH

H2O Forms

Breaking Down Polymers

• Cells break down macromolecules by a process called hydrolysis (adding a molecule of water)

Water added to split a double sugar

Macromolecules in Organisms

• There are four categories of large molecules in cells:Carbohydrates

Lipids

Proteins

Nucleic Acids

•CARBOHYDRATES1. Energy

2. Fuel for CNS

3. Fuel for the Muscular System

4. Spare Proteins

5. Supply Dietary Fiber

Carbohydrates• Carbohydrates include:• Small sugar molecules

in soft drinks• Long starch molecules

in pasta and potatoes

Carb Classification

• Known as saccharides

Characteristics of Carbohydrates

• Consist of carbon, hydrogen, & oxygen• Energy containing molecules• Some provide structure• Basic building block is a monosaccharide

(CH2O)n ; n = 3,5,6

• Two monosaccharides form a disaccharide

• Many form polysaccharides!

Monosaccharides:• Called simple sugars

Include glucose, fructose, & galactoseHave the same chemical, but different structural formulas

C6H12O6

Monosaccharides• Glucose is found in

sports drinksFructose is found in fruitsHoney contains both glucose & fructoseGalactose is not found in nature

Isomers• Glucose &

fructose are isomers because they’re structures are different, but their chemical formulas are the same

Rings

• In aqueous (watery) solutions, monosaccharides form ring

structures

Cellular Fuel

• Monosaccharides are the main fuel that cells use for cellular work

ATP

Disaccharides• A disaccharide is

a double sugarThey’re made by joining two monosaccharides

Involves removing a water molecule (dehydration)

Disaccharides

• Common disaccharides include:

Sucrose (table sugar) Lactose (Milk Sugar) Maltose (Grain sugar)

Disaccharides• Sucrose is composed of

glucose + fructose

Maltose is composed of glucose + glucoseLactose is made of galactose + glucose

GLUCOSE

Hydrolysis of a Disaccharide:

Polysaccharides

• Complex carbohydratesComposed of

many sugar monomers linked togetherPolymers of monosaccharide chains

Examples of Polysaccharides

Starch

Glycogen

Cellulose

Glucose Monomer

Starch

• Starch is an example of a polysaccharide in plants

Plant cells store starch for energy

Potatoes and grains are major sources of starch in the human diet

Glycogen• Glycogen is an example of a

polysaccharide in animals• 2/3 muscles; 1/3 liver• Acts as a carb reserve!

Cellulose

• Cellulose is the most abundant organic compound on Earth

It forms cable-like fibrils in the tough walls that enclose plants

It is a major component of wood

It is also known as dietary fiber

Cellulose

SUGARS

Dietary Cellulose

• Most animals cannot derive nutrition/energy from fiberThey have

bacteria in their digestive tracts that can break down cellulose

Another important Polysaccharide:

• CHITIN:• Glucose subunits• Partly derived from

non-sugars (nitrogen)• Composes

exoskeletons of insects

• Similar in structure to cellulose

Sugars in Water

• Simple sugars and double sugars dissolve readily in water

They are hydrophilic, or “water-loving”

WATER MOLECULE

SUGAR MOLECULE

INTERACTIVE CARBOHYDRATES:

• RECAP: Let’s Take another LOOK!

• http://www.bbc.co.uk/education/asguru/biology/02biologicalmolecules/index.shtml

Carb Digestion: (1-4 hrs) Cracker

• In the Mouth: • Saliva (salivary amylase) hydrolyzing starch to shorter

polysaccharides and maltose• Do you think much carb digestion takes place in the

mouth?• In the Stomach:• Bolus is continually broken down by acid, but its juices

contain no enzymes to digest carbohydrates.• Fibers linger in the stomach (satiety)• In the Small Intestine – PERFORMS MOST OF THE

WORK!!• Pancreatic amylase enters and breaks down further.

Digestion cont…

• On the Outer Membranes of the Intestinal Cells:• SPECIFIC ENZMES DISMANTLE DISACCHARIDES!• Maltase breaks maltose into • _________ +________• Sucrase breaks sucrose into • ___________ + _______• Lactase breaks lactose into • ___________ + ________• At this point, all polysaccharides and disaccharides

are broken down into mono’s – mainly glucose (but some fructose and galactose as well)

Carb Absorption

• Nutrient absorption takes place in the SI

• Glucose and galactose leave the cells lining the SI by active transport

• Fructose leaves by facilitated diffusion, which slows its entry and produces a smaller rise in blood sugar.

Carbohydrate Overview Video

• Thursday – Carbohydrate Lab

• Friday – Research Day

• Monday after March Break – carb overview (begin Lipids)

• Tuesday after March Break – carb quiz