8.2

8.2 Summary
LIGHT REACTION
-light energy
-electromagnetic energy travel in waves
-Wavelength- distance between 2 waves
-electromagnetic spectrum: range of type of rays (short to large)
-pigments: chemical compounds that causes color.
-chloroplast allows some to pass through and others to reflect
-green reflects, causing the color of the leaves.
-paper chromatography can be used to observe the different pigments in a leaf.
-photosystems contain hundreds of pigment molecules, which act like light gathering panels
-when energy is absorbed, electron gain and lose energy while the energy bounce from place to place and is finally trapped by the primary electron acceptors.

8.2 Vocabulary
Wavelength is the distance between 2 adjacent waves.
Electromagnetic spectrum is the range in types of electromagnetic energy from the short gamma rays to the long radio waves.
Pigments are what make a substance’s color.
Paper chromatography is a laboratory technique that can be used to observe the different pigments in a green leaf.
Photosystems are clusters within the thylakoid membrane hat chlorophylls and other molecules are arranged in.

8.2 Concept Check
1. Explain why a leaf appears green.
A leaf appears green because chloroplast pigments do not absorb green light well, causing the green light to bounce back (reflect) and not to be absorbed.
2. Describe what happens when a molecule of chlorophyll a absorbs light?
When a molecule of chlorophyll absorbs light, one of the pigment’s electrons will gain energy, but since the high energy stage is unstable, it will fall to a low energy state again, which will transfer its energy to the next electron. After a while, the energy will arrive at the center of the photosystem, which will cause the electron accepter to trap the excited electron from the chlorophyll a molecule.
3. Besides oxygen, what two molecules are produced by the light reactions?
Besides oxygen, NADPH and ATP and produced by light reactions.
4. Where in the chloroplast do the light reactions take place?
The light reactions take place in the thylakoid membranes in the chloroplast.

8.1

8.1 Summary
PHOTOSYNTHESIS
-takes place in chloroplast which contain chlorophylls (green color)
-Chloroplasts are in mesophyll cells.
-Structure is important to the function of chloroplasts
-inner membrane — encloses thick fluid of stroma with thylakoids inside
-outer membrane
-carbon dioxide + water = glucose + oxygen
-electrons in water are boosted uphill by the energy of sunlight. Produces sugar molecules with carbon dioxide and hydrogen.
-2 stages
-Calvin cycle
-light reaction

8.1 Vocabulary
Chloroplast is the cellular organelle where photosynthesis takes place at
Chlorophylls are compounds that chloroplasts contain, which gives these organelles a green color.
Stroma is the thick fluid that the inner membrane of a chloroplast contains.
Thylakoids are disk-shaped sacs that are suspended in the stroma.
Light reaction converts the energy of the sunlight to chemical energy.
Calvin cycle makes sugar from the atoms in carbon dioxide plus the hydrogen ions and high-energy electrons carried by NADPH.

8.1 Concept Check
1. Draw and label a simple diagram of a chloroplast that includes the following structures: outer and inner membranes, stroma, thylakoids.
2. What are the reactants for photosynthesis? What are the products?
Reactants of photosynthesis are carbon dioxide and water; the products are glucose and oxygen.
3. Name the two main stages of photosynthesis. How are the two stages related?
The 2 main stages of photosynthesis are the light reaction and the Calvin cycle.
They are related because they happen in the photosynthesis process, transfer one substance into another and transfers substances between the 2 processes.

Chapter 5 Review

pg 106 #1-12,14,15

Multiple Choice
1. Which of the following is not an organic molecule? c. water
2. Which of the following terms includes all the other terms on this list? b. carbohydrate
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.Lipid
5. The 20 amino acids vary only in their b. side groups
6. A specific reactant an enzyme acts upon is called the d. substrate.
7. An enzyme does which of the following? b. lowers the activation energy of a reaction

Short Answer
8. Besides satisfying your hunger, why else might you consume a big bowl of pasta the night before a race?
Besides satisfying hunger, I would also eat a bowl of pasta the night before the rece because I want to have energy in my body for the next day, and the carbohydrates I take in are a good source of energy.
9. How are glucose, sucrose, and starch related?
Glucose, sucrose and starch are related because they are all sugars and carbohydrates.
10. What are steroids? Describe two functions they have in cells.
Steriods are lipid molecules in which the carbon skeleton forms 4 fused rings. The 2 functions they have in cells are that they serve as a chemical signal that circulated the body and form membranes that surround a cell.
11. How are polypeptides related to proteins?
Polypeptides are related to proteins because protein is formed when amino acids are linked together into the chain called polypeptides.
12. How does denaturation affect the ability of a protein to function?
Denaturation affect the ability of a protein to function because a protein can unravel and lose it's normal shape due to unfavorable enviornment changes.

Applying ConceptsAnalyzing Information
14. Analyzing Diagrams
The reaction below shows two amino acids joining together.
a. One product of this reaction is represented by a question mark. Which molecule is it?
The molecule represented by a question mark is a water molecule.
b. What is this kind of reaction called? Explain.
This kind of reaction is called a dehydration reaction because water(H20) is removed for the chemical bond to form.
c. If an amino acid were added to this chain, at what two places could it attach?
If an amino acid was added to this chain, it could be attached to the OH part at the left and the H part at the right. 15. Analyzing Graphs
Use the graph to answer the questions below.
a. At which temperature does enzyme A perform best? Enzyme B?
Enzyme A performs the best at 38 degrees, while enzyme B performs best at 78 degrees.
b. Knowing that one of these enzymes is found in humans and the other in thermophilic (heat-loving) bacteria, hypothesize which enzyme came from which organism.
Enzyme A is found in thermophilic bacterias and Enzyme B is found in humans.
c. Propose a hypothesis that explains why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40°C.
The rate of reaction catalyzed by enzyme A slows down at temperatures above 40 degrees because it's reaction has finished.

5.5 Summary

Enzymes
Chemical reaction starts by weakening bonds by absorbing energy as the activation energy
Activation Energy is the energy that activates reactants and triggers a chemical reaction.

Chemical reactions may occur faster by heating the molecules, so they can collide with more energy to weaken the bonds. But it can also cause unnecessary reactions to happen.
That’s why cellular reaction depends on catalysts (compounds that speed up chemical reactions). The main kind is a specialized protein in organisms called enzymes.

Enzymes make it possible for reactions to occur at a normal temperature, because it lowers the activation energy required.
Different enzymes catalyze a specific kind of chemical reaction because the shape of each enzyme fits the shape of only particular reactant molecules.

Substrate is the specific reactant acted upon by an enzyme.
Active site is the place where the substrate fits into on an enzyme; it changes slightly after the substrate enters. So the bonds can be weakened by the grip, thus making them easier to break and react.

Key characteristic of Enzymes: Recycling ability.

Enzymes can also lower the activation energy by putting the 2 reactants side by side, forming a big molecule from small molecules.

Function of enzymes depends on its structure and shape, that’s why it can only function in certain conditions.


Concept Check 5.5
1. Explain the role of activation energy in a reaction. How does an enzyme affect activation energy?
Activation energy is the energy that activates the reactants and triggers a chemical reaction.
Enzymes lower the activation needed to a normal temperature.

2. Describe how a substrate interacts with an enzyme
Substrates interacts with an enzyme by locating itself in to an enzyme’s activation site, after it enters the site, the shape of the activation site may change slightly and make the substrates change.

5.4 Summary

Proteins!!
Proteins are polymers constructed from a set of 20 kinds of amino acids. They are very important for the functions of cells.

An amino acid monomer is made up of a central carbon atom bonded to 4 partners.
Partners all amino acids have:
1 hydrogen atom
1 carboxyl group
1 amino group
Unique partner:
The side group is differ in different amino acids, also called “R-group”

Polypeptide: a chain that is made from proteins created by cells that are linked together by amino acids.
-Links are created by dehydration
-There are 1 or more polypeptide chains in a protein

Protein shape
Proteins are made of one or more polypeptides twisted, folded and coiled into a unique shape.
Denaturation is the process in which proteins loses its normal shape due to a change of environment such as pH and temperature.


Concept Check 5.4
Give at least 2 examples of proteins you can “see” in the world around you. What are their functions?

Examples of proteins I can "see" include fur, which makes animals warmer during the winter, and muscles which makes humans stronger.
Relate amino acids, polypeptides and proteins.

Amino acids makes polypeptides, and polypeptides makes up proteins.
Explain how heat can destroy a protein.

If the temperature of a protein or the enviornment the protein is in suddenly changes, then the protein will be influenced and lose it's normal shape, and therefore it is destroyed.

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

Three of the central carbon's partners, the hydrogen atom, the carboxyl group partner and the amino group partner are the same in all amino acids, but each amino acid has a side group and that part is unique.

5.3 Summary

Lipids, Fats, and Steroids!!!

Lipids are water-avoiding compounds such as oil, they are hydrophobic (afraid of water).
-act as a boundary that surrounds and contains watery contents of your cell.
-circulate body as chemical signals
-fats that store energy in body

Fats contain 3 carbon backbone called glycerol attached to 3 fatty acids which contain long hydrocarbon chains. They cushion organs to provide the organs with insulation.
-Some are solid at room temperature
-Oils are liquids at room temperature

Saturated Fat is a fat in which all three fatty acid chains contain the maximum possible number of hydrogen atoms. (Most animal fats are saturated)
Unsaturated Fat is a fat that has less than the maximum number of hydrogen atoms in one or more of its chains. (The fats in fruits, vegetables and fish)

Steroid: is a lipid molecule in which the carbon skeleton forms 4 fused rings.
-they are hydrophobic
-different from fats in structure and function

Cholesterol is a steroid that is found in membranes surrounding cells
-starting point from which the body produces other steroids.
-high cholesterol levels can cause cardiovascular diseases.


Concept Check 5.3
What properties do lipids share?
Lipids share the property of fearing water, or hydrophobic.
What are parts of a fat molecule?
A fat molecule is made up of a glycerol attached to 3 fatty acids.
Describe 2 ways steroids differ from fats.
Steroids differ from fats in it's structure and function.
What does the word unsaturated fat on a food label mean?
The word unsaturated fat on a food label means that the food contains less than the maximum number of hydrogen atoms in one or more of it's fatty acid chains.

5.2 Summary...

Section 5.2
This section mainly discusses the important CARBOHYDRATES that provide living things energy or “fuel”.
Carbohydrates are organic compounds that are made up of sugar molecules. Sugar molecules are molecules that contain carbon, hydrogen and oxygen, in a ratio of 1:2:1.Since sugar molecules are the fuels for our cellular work, it is very important to take in enough carbohydrates everyday.

Glucose, fructose and galactose are monosaccharides, a sugar unit that simple sugars contain, they are found in many sweet things we eat. After a dehydration process, the monosaccharides will become a disaccharide which can be stored in the body for later use.

Starch is a polysaccharide, or long polymer chains made up of simple sugar monomers, found in plant cells and are made up of glucose monomers.
Glycogen is also a type of polysaccharide, but it is found in animals and it gives the human body energy after it’s broken down.
Cellulose, another type of polysaccharides in plants are the building material of plants. Humans and animals find it hard to digest this, so it passes though our digestive system without changing.

*Almost all carbohydrates are hydrophilic.

Concept Check 5.2
Explain the difference between a monosaccharide and a disaccharide.

The difference between a monosaccharide and a disaccharide is that a monosaccharide is made up of only 1 sugar unit, while a disaccharide is made up of many sugar monomers.
Compare and contrast starch, glycogen, and cellulose.

Starch consists entirely of glucose monomers, and are used as food for humans, glycogen is more highly branched than starch and is stored as granules for later energy use. Cellulose is the building material, it also keeps the digestive system healthy.
How do animals store excess glucose molecules?

Animals store excess glucose molecules because it is the main fuel supply for cellular work. Also glucose molecules that are not used immediately can be incorporated into larger carbohydrates or used to make fat molecules.

That’s all for this section:)