5.5 Enzymes are proteins that speed up specific reactions in cells

1. Enzymes and Activation Energy
a. To start a chemical reaction, you need to weaken chemical bonds in the reactant molecules.
b. The activation process above requires the molecules to absorb energy.
c. Start-up energy is called the activation energy because it activates the reactants.
d. Hotter molecules may collide with enough energy to eaken bonds while cooler molecules collide with less energy
e. Cellular reaction depends on the cataylsts, which are compounds that speed up the chemical reaction. The main catalyst is proteins called enzymes.
f. Enzymes provide a way for reactions to occur at the cell's normal temperature.
- enzymes do not supply the activation energy, instead, it lowers the energy barriers so the reaction can speed up.
g. Each enzyme catalyzes a specific kind of chemical reaction.

2. How enzymes work
a. The shape of each enzyme fits the shape of only particular reactant molecules.
b.Subtrate is a specific reactant acted upon by an enzyme. The subtrate fits into a active site.
c. Active site changes shape when subtrate enters.
d.The tighter the grip, the subtrate will be weakened in its bonds.
e. Enzymes can lower activation energy by accpeting two reactant molecules into adjacent sites.

Concept Check:
1. Explain the role of activation energy ina reaction. How does the enzyme effect the activation energy?
- The activation energy activates the reactants and the enzymes can lower its energy barriers so that the reaction can speed up.
2. Describe how subrate interacts with an enzyme.
-Together, they lower the activation energy so that the reaction could proceed.

5.4 Proteins perform most function in cells

The functions of Protein

protein is a polymer conrtucted from a set of just 20 kinds of monomers called amino acids.

Proteins are responsible for almost all of the day to day functioning of organisms.

Amino acids

amino acids consists of a central carbon atom bonded to four partners. The side of amino acid serine contains a hydroxyl group that attracts water.

Building a Protein

*a polypeptides are cells that create protein by linking amino acids together into a chain.

Our body can make variety of proteins by arranging different amino acids in different orders.

Protein shape

Protein in a simple form of amino acids can not function properly.

* the protein's shape is influenced by the surrounding environment , which is aqueous.

Denaturation is a process in which an unfavorable change in temperature or other qualities of environment can cause a prtoein to unravel and lose its shape.

Concept check.

1.Give at least two examples of proteins you can see in the world around you. What are their functions?

-I see animal coats and muscles. They help you keep warm and stay healthy.

2.Relate two amino acids, polypeptides and proteins.

-Polypeptides help produce proteins. Proteins are produced by the linking of amino acids.

3.Which parts of an amino acid's sturcture are the same in all amoni acids?Which part is unique?

-They all containn hydroxyl groups. They attracts water

5.3 lipids include fats and steroids.

characteristics of lipids

*lipids are compounds that water trys to ignore. The water avoiding molecules are said to be hydrophobic, whcih also meant water fearing.

Lipids act likea boundary that surrounds and contains the aqueous contents of your cell.

*Some lipids are signals to cells or fats store energy.

Fats

* fat consist of a three carbon backcone called glycerol attched to three fatty acids, which includes long hydrocarbon chains.

*saturated fat is a fat in which all the three fatty acids chains contain the maximum possible number of hydrogen atoms.

*unsaturated fat contains less than the maximum number of hydrogen atoms in one or moreof its fatty acid chains because some of its carbon atoms are doubled bonded to each other.

Steriods

steriods are lipid molecules in which the carbon skeleton forms four fused rongs is called a steriod.

* steriods are classified as lipids because they are hydrophobic, but they are veru different from fats in structure and function. Soem circu;ate your body as a chemical signal.

cholestrol is an essential molecule found in menbranes that surround your cell.

concept check

1. What property do lipids share?

-they share hydrophobic.

2. What are the parts of a fat molecule?

-It contains three glycerol and three fatty acids.

3. Descrive two ways that steroids deffer from fat.

- Steroids are different from fat in structure and function

4. What does the term unsaturated fat mean?

-It means that that the acid chain contains less than the maximum number of hydrogen atoms in one or more of its fatty acid chains.

5.1 Carbon skeleton and functional groups:

Carbon skeleton and functional groups
Carbon has only four highest electrons in its energy level. total holds eight electrons.
* Carbon can form up to four bonds with other atoms. Example: carbon and hydrogen=hydrocarbon ( fuels).
* Methane: natural gas to heat homes. *hydrophlic-water-loving.
Monomers and polymers
*biomolecules may be composed of hundreds or even millions of atoms.
Every living thing's cells has thousands of different kinds of polymers. (polymers are built out of 50 kinds of monomers. For example, the spider's web, which is made from protein, is an example of polymer). Life's largest molecules: CARBOHYDRATES, LIPIDS, PROTEINS,NUCLEUR ACID( or DNA).
Building and breaking Polymers
organisms make polymers. * breaks to monomers so available for cells.
Each time a monomer is added to a chain, it releases the water molecules ( dehydration reaction).
* water is removed to build polymers, water is added to break it down.

Concept check

1.

2. Explain the connection between monomers and polymers

-polymers is a chain that is made up of a lot of monomers.

3.What molecule is released durig conrtuction of a polymer. What is this reaction called?

-The dehydration reaction is the name. It releases de- water (hydro)

5.2 carbohydrates provide fuel and building material

Summary 5.2

A. Sugars
1. carbohydrates: organic coumpound made from sugar molecules.
2. contains elememts: carbon, hydrogen. oxygen in ratio of 1 carbon: 2 hydrogen: 1. oxygen.
*Formula: CH2O
3. at core of most sugar molecules in nature are carbon skeletons that has a ring shape.

B. Monosaccharides.
monosaccharides are simple sugar that contains just one sugar unit.
Examples: glucose, fructose, galactose.
1. Glucose exists in both straight chained and ring shaped form.
2. Sugar moleclues, glucose, are the main supply for the cellurar work.
3. Cells break glucose down and extract their stored energy.
4. Cells also use carbon skeletons of monosaccharides as raw material for manufactoring other kinds of organic molecules.
5. glucose molecules that is not used by cells are usually transported into larger carbohydrates or used to make fat molecules.

C. Disaccharides
disccharides are "doubled sugar" from two monosaccharides
Surcose: example of disaccharide. It linked glucose and fructose.
1. Surcose is a bog carbohydrate in plant sap. It nourishes all the part of the plant.

D. Polysaccharides
polysaccharides are long polymer chains made up of simple sugar monpmers. They are also known as complex carbohydrates.
1. Starch is a kind of polysaccharide found in plant cells that contains glucose monomers.
2. Plant cells and animal cells need sugar for energy to perform work.
3. potatoes, rice, and corns are all examples of foods rich in starch.
4. For animals, it is not starch but glycogen. They are more highly branched than starch. You can find them in liver and muscle cells.
* Cellulose serves as a building materials. It protects and stiffen cells. Cellulose from cells are known as fibers. Cellulose helps your digestive system stay healthy but does not provide nutrients.

concept check

1. Explain the difference between a monosaccharide and a disccharide. Give an example of each.

-the monosaccharide only contains one sugar unit while disaccharide contains two. Glucose is a monosaccharide and surcose is disaccharide.

2.Compare and conrast starch, glycogen, and cellulose.

-starch,glycogen, and cellulose all makes the body strong and consist glucose. The difference is that glycogen is more highly branched than starch and cellulose serves as building materials.