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1. Which of the following is not an organic molecule?
a. cellulose
b. sucrose
c. water
d. testosterone


2. Which of the following terms includes all the other terms on this list?
a. polysaccharide
b. carbohydrate
c. monosaccharide
d. glycogen


3. Which term is most appropriate to describe a molecule that dissolves easily in water?
a. hydrocarbon
b. hydrophobic
c. hydrophilic
d. organic


4. Cholesterol is an example of what kind of molecule?
a. protein
b. lipid
c. amino acid
d. carbohydrate


5. The 20 amino acids very only in their
a. carbozyl groups
b. side groups
c. amino groups
d. lipid groups


6. A specific reactant an enzyme acts upon is called the
a. catalyst
b. sucrase
c. active site
d. substrate


7. An enzyme does which of the following?
a. adds heat to a reaction, speeding it up
b. lowers the activation energy of a reaction
c. cools a reaction, slowing it down
d. raises the activation enevergy of a reaction


8. Besides satisfying your hunger, why else might you consume a big bowl of pasta the night before a race?
It is because pasta consists whole loads of energy in it which will help me to use the energy during race.


9. How are glucose, sucrose, and starch related?
They are all monosaccharides.


10. What are steroids? Describe two functions they have in cells.
A female sex hormone and a male sex hormone and the structural formation of steroid differs in its fuction.


11. How are polypeptides related to proteins?
Proteins are the main factor that build up the polypeptides.


12. How does denaturation affect the ability of a protein to function?
denaturation change the portein's shape and make it not to function in proper way.


14. The reaction below shows two amino acids joining together.
a. One product of this reaction is represented by a question makr. Which molecule is it?
Water molecule
b. What is this kind of reaction called? Explain.
Dehydration reaction is the reaction taking place while water molecule is released when bonds are created.
c. If an amino acid were added to this chain, at what two places could it attach?
Side groups and amino groups.


15. Use the graph to answer the questions below.
a. At which temperature does enzyme A perform best? Enzyme B?
Enzyme A: 37 degrees
Enzyme B: 77 degrees


b. Knowing that one of these enzymes is found in humans and the other in thermopilic(heat-loving) bacteria, hypothesize which enzyme came from which organism.
Enzyme A: human
Enzyme B: thermophilic bacteria


c. Propose a hypothesis that explains why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40˚C.
The reaction is almost to the end.

Chapter 5.5 summary

- Activation energy

- Catalysts is compounds that speed up chemical reactions.

- The main catalysts of chemical reactions in organisms are specialized proteins called enzymes.

- Enzymes provide a way for reactions to occur at the cell's normal temperature, it doesn't suppy activation energy to the reacting molecules but lowers the energy requirement barrier.

- A specific reactant acted upon by an enzyme is called the enzyme's substrate, it fits into a particular region of the enzyme called the active site.

- Enzyme lowers activation energy by accepting two reactant molecules into adjacent sites.

Chapter 5.4 summary

- A protein is a polymer constructed from a set of just 20 kinds of monomers called amino acids.

- Each amino acid monomer consists of a central carbon atom bonded to four partners.

- Three of the central carbon's partners are the same in all amino acids. One partner is a hydrogen atom and two others are a carboyl group and an amino group.

- Cells create proteins by linking amino acids together into a chain called a polypeptide.

- Proteins are composed of one or more polypeptide chains.

- Most polypeptide chains are at least 100 amino acids in length.

- A protein in the simple form of amino acids linked together cannot function properly.

- Denaturation is loss of normal shape of an protein due to heat or other factor.

- Hot molecules collide with enough force to overcome these weak attractions.

Concept Check 5.4

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

Cheese and beef.

2. Relate amino acids, polypeptides, and proteins.

Polypeptide and protein are made up of amino acids.

3. Explain how heat can destroy a protein.

The process called denaturation of the protein. Heating unfolds protein because most of the forces that maintain folding are weak attractions between pairs of side groups. Hot molecules collide with enough force to overcome these week attractions.

4. Which parts of an amino acid's structure are the same in all amino acids? Which part is unique?

A protein in the simple form of amino acids linked together cannot function properly. A functional protein consists of one or more polypeptides precisely twisted, folded, and coiled into unique shape.

Chapter 5.3 Summary

- Oil's inability to mix with water is typical of the class of water-avoiding compunds called lipids.

- Water-avoiding molecules are said to be hydrophobic.

- Lipids act as a boundary that surrounds and contains the aqueous contents of your cells.

- A fat consists of a tree-carbon backbone called glycerol attached to three fatty acids, which contain long hydrocarbon chains.

- A saturated fat is a fat in which all three fatty acid chains contain the maximum possible number of hydrogen atoms.
- An unsaturated fat contains less than the maximum number of hydrogen atoms in one or more of its fatty acid chains because some of its carbon atoms are double-bonded to each other.

- A lipid molecule in which the carbon skeleton forms four fused rings

- Cholesterol is an essential molecule found in the membrances that surround your cells.

Concept checks 5.3

1. What property do lipids share?

water-avoiding molecules

2. What are the parts of a fat molecule?

glycerol

3. Describe two ways that steroids differ from fats.

They are different from fats in structure and function. Some steroids circulate in your body as chemical signals. Perhaps the best-known steroid is chloesterol. It is an essential molecule found in the membranes that surround your cells. It is also the starting point from which your body produces other steroids.

4. What does the term unsaturated fat on a food label mean?

Means that it contains less than the maximum number of hydrogen atoms in one or more of its fatty acid cahins.