Homework Questions 8/9/08

Review Questions

1.) Wich of the followinf is NOT organic molecule?

C. Water

2.) Which of the following terms includes all the other terms on this list?

D. Polyssacharides

3.) Which term is most appropriate to describe a molecule that dissolves easily in water?

C. Hydrophilic

4.) Cholesterol is an example of what kind of molecule?

B. Lipids

5.) The 20 amino acids vary only in their...

C. Amino groups

6.) A specific reactant an enzme acts upon is called the ...

D. Substrate

7.) An enzyme does which of the following ?

B. Lowers the activation energy of a reaction


8.) Besides satisfying your hunger, why else might you consume a big bowl of pasta the night before a race?


I might consume a bowl of pasta because pasta provides me carbohydrates which i need to give me energy.

9.) How are glucose,sucrose and starch related?


They are related because they are all sugars, and they all contained in a plant. Sucrose is a major carbohydrate in a plant sap; starches are made up of glucose monomer that are found in plant cells.



10.) What are steriods? Describe 2 functions they have in cells.


Steriods are lipid molecules which contain carbon skeletons that forms four fused rings. The 2 different functions effect the appearance between male and female, estrogen for femals and testosterone for male.

11.) How are popypeptides related to proteins?

Proteins are made by the link of amino acids which makes a chain, this chain is called a polypeptide.

12.) How does denaturation affect the ability they have in cells?

Denaturation affect the ability they have in cells because once they unravel, it caused the cells to not function properly.


14a.) One product of this reation is represented by a question mark. Which molecule is it?

Hydrogen Molecule .

b.) What kind of reaction is this called? Explain

It is a Dehydration reaction because two hydrogen and oxygen molecules are released so that they can bond together.

c.) If an amino acid is added to this chain, at what two places could it attach?

I think it would be added at the OH and H.

15a.) At which temperature does enzyme A perfom best? Enzyme B?

Enzyme A: 37 celcius
Enzyme B: 77 celcius

b.) Knowing that one of these Enzymes is found in humans and other inthermophilic (heat-loving) bacteria, hypothesize which enzyme came from which organism.

I think that enzyme A is found in humans, since a normal temperature for a human would be about 37 celcius. And enzyme B could be found in baterica, due to its high temperature.

c.) Propose a hypothesis that explains why the rate of reaction catalyzed by a enzyme A slows down at temperatures above 40 celcius

In my opinion, i think enyme A slows down because it might be too hot for it to function properly, and therefore the rate of reaction decreases.

Summary on Concept 5.5

Enzymes and Activation Energy

• To start a chemical reaction it is necessary to weaken chemical bonds in their reactant molecules. This activivation requires molecules to absorb energy.


• The energy that "starts up" the reaction is called activation energy.


• Heating up cells could cause a reaction that can destroy the cells delicate structures.


• Catalysts are compounds that speed up a reaction.


• The main catalysts of chemical reactions are specialized proteins called Enzymes.

How Enzymes work

• A specific reactant acted upon an enzyme is called an enzymes substrate.


• The Substrate fits in a particular region of the enzyme called the active site.


• A way inwhich a enzyme can lower activitation energy is by accepting two reactant molecules (substrates) The composition of these reactants allows them to react more easily.


• An enzymes structure and and shape are important to its functions.


• Like proteins, an enzyme's shape is sensitive to changes in its surrounding enviroment.

Concept Check

1.)Explain the role of activation energy in a reaction. How does an enzyme affect activation energy?

The activation energy plays a role in starting a reaction. Enzymes act as a catalyst of a chemical reaction, which means that enzymes speeds up the process of a chemical reaction.

2.)Describe how a substrate interacts with an enzyme.

As the substrate enter the active site, the shape of the active site changes so that the subtrate can fit tightly. When they fit together, it places certain functional groups that would catalyze the reaction.

Summary of Concept 5.4

The Functions of Proteins

• A protein is a polymer constructed by 20 kinfd of monomers called amino acids.
• Proteins are responsible for the functioning of organisms.

Amino Acids

• An amino acid consists of carbon atoms which are bonded to four pairs.


• The side group of amino acid serine contains a hydroxyl group that attracts water.

Building a Protein

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


• And each link is created by a dehydration reaction between the amino group and the carboxyl group.


• Proteins are composed of one or more polypeptide chains.


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


• Most polypettide chains are at least 100 amino acids in length.

Protein Shape

• A protein in the simple form or amino acids connected together cannot function properly.


• A Proteins shape is influenced by the surrounding enviroment.


• Water attracts hydrophilic side groups and rejects hydropobhic ones.


• A change in pH, tempreture and other quality of the enviroment can cause a protein to unravel and lose it normal shape. This process is called denaturation of proteins.

Concept Checks

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

Animal muscle and hair are two examples of proteins. Muscles allows animals to move freely, and hairs protect their skin.

2.)Relate amino acids, polypeptides and proteins.

Proteins are created by the combination of amino acids, forming a chain called polypeptide.

3.)Explain how heat can destroy a protein

Heat can destroy a protein because the heat causes the weak attractions of molecules to collide, causing it to lose its shape.

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

An amino group, carboxyl group and a hydrogen atom are similar. The fourth bond is unique because it is reponsible for the chemical properties of each amino acid.

Summary of 5.3

Characteristics of Lipids

• Lipids are water-avoiding compunds.

• Water-avoiding molecules are said to be Hydrophobic (water fearing)

• Fats consists of three carbon backbone called Glycerol attached to three fatty acids, which contains hydrocarbon chains.

• Saturated fat is fat which all three fatty acid chains contain the maximum number of hydrogen atoms.

• Unsaturated fat is fat that contains less maximum number of hydrogen atoms.

• A lipid molecule in which carbon skeletons form four fused rings is called a steriod.

• Cholesterol is an essential molecule found in membranes that surround your cells.

Concept Checks

1.) What property do lipids share?

Lipids are "water-avoiding" molecules. (Hydrophobic)

2.)What are the parts of a fat molecule?

Fat consists of three carbon backbones called glycerol, which are connected to three fatty acids.

3.)Describe two ways that steroids differ from fats.

Steroids are differnt from fats because of there structure and function.

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

Foods labeled unsaturated fat could mean that the product has less than the maximum number of hydrogen atoms. These food are healthier than product with saturated fat.

Summary of 5.1

Carbon Skeletons and Functional Groups

• Carbon has only 4 electrons in it s highest occupied energy level.



• Carbon's energy level is so high that it can hold 8 electrons, which allows it to form 4 bonds.



• Carbon can form bonds with other carbon atoms, producing a variety of skeletons.

• Carbon-based molecules are called Organic Molecules.



• Non-carbon-based molecules are called inorganic molecules.



• Molecules composed of carbon and hydrogen are known as Hydrocarbons.



• Small moleculer units are called Monomers.



• Linked monomers are form chains called Polymers.



• 4 main catagories of life large molecules: carbohydrates, lipids, proteins, and mucleic acids.

Building and Breaking Polymers

• When a monomer is added to a chain, a water molecule is released. This process is called dehydration reaction.



• Cells break bonds between monomers by adding water. This reaction is called a hydrolysis reaction.

Concept Check

1.)Draw a molecule that has a three carbon skeleton and a hydroxyl group on the middle carbon.

2.)Explain the connection between monomers and polymers.

Polymers are chains linked by monomers

3.)What molecule is released during construction of a polymer? What is this reaction called?

Water is lost each time a monomer is added; this reaction is called a dehydration reaction.

4.)Draw at least three ways in which five carbon atoms could be joined to make different carbon skeletons.

Section 5.2 Summary

Sugars

• A carbohydrate is an organic compound composed of sugar molecules.
• Sugars contain carbon, hydrogen, and oxygen.
• Simple sugars containing just one single sugar unit are called monosaccharides
• An example of a monosaccharide, Gulcose, form in straight-chains and in ring-shaped forms.

• Disaccharides also known as "double sugar" construct from two monosaccharides.
• Polysaccharides are long chains made up of simple sugar monomers.
• Plants need energy to perform work.
• Animals and humans store sugar in form of a polysaccharide called glycogen.
• Cellulose work as a building material.
• Cullulose helps us keep our digestive system in our body healthy

Concept Check

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

Monosaccharides are simple sugars that contain just one unit, for example, gluscose and galactose. Dissacharides are constructed by two monosaccharides, an example of this is sucrose.

2.)Compare and contrast starch, glycogen, and cellulose.

Starch, glycogen and cellulose are all glucose monomers. Glycogen is used as a storage for excess sugar in a animals body. In addition, cellulose is used in plants to help stiffen plants, and preventing it from falling. Starch acts as a source of energy for animals and humans, we need starch in order to perform work.

3.)How do animals store excess glucose molecules?

Animals store excess gluclose molecules in a glycogen;when our body needs energy, it breaks down the glycogen granules which causing it to releasing glucose.