Summary of Section 8.2 :)

-=Light Reactions convert light energy into chemical energy=-

Light Energy + Pigments

-sunlight is a type of electromagnetic energy

-electromagnetic energy travels in waves

-distance between two adjecent waves is called a wavelength

-electromagnetic spectrum: the different ranges of wavelengths

-shorter wavelengths have more energy than longer ones

-wavelengths shorter than visible light can damage organic molecules

Pigments + Color

-a substance's color is cause by chemical compounds called pigments

-when light shines on material with pigments, the wavelengths can be absorbed, transmitted or reflected 

-pigments in chloroplasts absorb blue-violet and red-orange light well

-chloroplasts convert the absorbed light energy into chemical energy

-but they cannot absorb green light well

-most of green light is transmitted through leaf or is reflected

-leaves look green because green light is not absorbed

Identifying Chloroplast Pigments

-using paper chromatography, you can observe pigments in a leaf

 

Procedure

1. Press leaf on filter paper

2. Seal paper in a cylinder containing solvents

-solvents will move up the paper

-different pigments will travel at different rates depending on how easily they dissolve and how much they are attracted to the paper 

-chlorophyll a mainly absorbs blue and red light, and reflects green light

-plays big role in light reactions of photosynthesis

-there are "helper pigments" which absorb mainly blue and orange light reflects yellow-green light

 

Harvesting Light Energy

-in the thylakoid membrane, chlorophyll and other molecules are arranges in the groups calles photosystems

-each photosystem contains a few hundred pigment molecules (including chlorophyll a, and b)

-act like light gathering panel

-each time pigment molecule absorbs energy, one of the pigments electrons gains energy

-becomes at an "excited stage"

~unstable

~almost immediately goes back to normal (ground stage) and transfers energy to a molecule next to it

~when at ground state, it "excites" another pigment molecule and that keeps going down the line 

~energy jumps from molecule to molecule until it arrives at the reaction center of photosytem

-reaction center: contains chlorophyll a molecute next to a primary acceptor molecule 

-primary acceptor molecule traps the excited electron from the chlorophyll a molecule

-other molecules can then use energy to create ATP and NADPH 

Chemical Products of Light Reactions

-two photosystems are involved in light reactions

-first photosystem:

traps light energy and transfers the excited electrons to an electron transport chain

electrons are replaces by a splitting molecule of water

release oxygen and hydrogen ions as waste products

-the electron transport chain releases energy for the chloroplast to make ATP 

~connects the two photosystems

-is similar to cellular respiration

-electron transport chain pumps hydrogen ions across membrane

-light-excited electrons travel down the chain

-second photosystem: 

produces NADPH by transferring excited electrons and hydrogen ions to a carrier molecule called NADP+

-input of light energy is shown by the large yellow mallets

-light energy makes electrons excited at the top of the platform in each photosystem

-energy released as the electrons move down the electron transport chain 

-photosystems is used to pump hydrogen ions across a membrane and produce ATP

-light reactions convert chemical energy to NADPH and ATP

Concept Check 8.2

1. Explain why a leaf appears green.

A leaf looks green because the chloroplast pigments don't absorb the green light good, so the green light relflects back on the leaf.

2. Describe what happens when a molecule chlorophyll a absorbs light. 

When it molecule chlorophyll a absorbs light, one of its pigments gains energy and become "excited". The "excited" stage is very unstable, so it almost instantly falls back down to the "ground stage" and transfers its energy to a neighboring molecule. This keeps going down the chain until the energy reaches the reaction center of the photosystem, which will capture the "excited" electron from the chlorophyll a molecule. 

3. Besides oxygen, what two molecules are produced by light reactions?

ATP and NADPH are produces besides oxygen

4. Where in the chloroplast do the light reactions take place?

Light reactions take place in the in thylakoid membranes of the chloroplast.

~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~

Vocabulary for 8.1 + 8.2

chloroplast- cellular organism found in plant cells where photosynthesis occurs

chlorophyll- pigment that gives chloroplast its green color and uses light energy to split water molecules during photosynthesis

thylakoid- disk-shaped sac in the stroma, where light reactions take place

stroma- thick fluid inside the inner membrane of chloroplast

light reactions- chemical reaction that converts sun's energy to chemical energy

Calvin Cycle- cycle in plants that makes sugar from carbon dioxide, high-energy electrons carried by NADPH

wavelength- the distance between two waves that are next to each other 

electromagnetic spectrum- range of electromagnetic waves

pigment- chemical compound that determines substance's color

paper chromotography-technique used to observe different pigments in material

photosystem- cluster of chlorophyll and other molecules in the thylakoid 

Summary of Section 8.1 :)

-=Photosynthesis Uses Light Energy to Make Food=-

The Structure of Chloroplasts

-photosynthesis occurs in a cellular organ called called a chloroplast

-chloroplasts contain chemical contain chlorophylls that give the organelle its green color

-in most plants, the leaves contain the most chloroplasts and that is where photosynthesis occurs the most

-chloroplasts are mostly in the inner layer of the tissue called the mesophyll 

-carbon dioxide goes in and oxygen leaves through tiny pores on the surface of the leaf called stomata 

-the veins carry the nutrients, water and organic molecules to other parts of the plant

-the structure of the chloroplast is the key to its function

~has an inner and other membrane

~inner membrane has fluid called stroma

~in the stroma, there are thylakoids which are disks-shapes sacs

~each thylakoid has a membrane around it

~thylakoids are in stacks called grana

-the structure in the chloroplasts organize chemical reactions that take place during photosynthesis

Photosynthesis 

-opposite of cellular respiration

-electrons from water are lifted by the sunlight energy 

-chloroplast uses those electrons, hydrogen ions and carbon dioxide to produce sugar molecules

this is the equation for photosynthesis

-photosynthesis occur in 2 stages: Light Reactions + Calvin Cycle 

The Light Reactions

-convert sunlight energy -----> chemical energy

-reactions depend on molecules built in the membranes in the thylakoids

Procedure:

1. Chlorophyll molecules in the membranes capture sunlight energy 

2. Chloroplasts use energy to remove the electrons from water

-splits oxygen and hydrogen ions resulting in oxygen becoming a waste product (escapes throught the stomata)

3. Chloroplasts use water's electrons + hydrogen ions = electron carries NADPH

4. Chloroplasts also use the energy to create ATP

Light energy ----> chemical energy in ATP and NADPH

The Calvin Cycle 

-makes sugar from carbon dioxide + hydrogen ions + electrons from NADPH

-enzymes for Calvin Cycle are outside thylakoids and are dissolved in the stroma

-ATP made by light reactions provides energy to make sugar

-does not require light to begin

-requires to inputs supplied by ATP and NADPH

Concept Check 8.1

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

Carbon dioxide + Water = reactants

Glucose + Oxygen =products 

3. Name the two main stages of photosynthesis. How are the two stages related?

The two main stages of photosynthesis are: Light Reactions and the Calvin Cycle. The Light Reactions stage produces chemical energy from light energy in ATP and NADPH while the Calvin Cycle makes sugar from them.

p.106 (1-12,14,15)

1. (c) water

2. (b) carbohydrate

3. (c) hydrophillic

4. (b) lipid

5. (b) side groups

6. (d) substrate

7. (b)Lower  the activation energy of a reaction

8. You might consume pasta the night before a race because pasta has carbohydrates which can 

store energy for later use. 

9. Starch, glycogen, and cellulose are all polysaccharides and all three are made from glucose monomers.

10. Steroids are lipid molecules with four fused carbon rings. Steroids circulate y0ur body as chemical signals and are a starting point for which the body produces other steroids (cholesterol) 

11. Proteins are made out of polypeptides linked to amino acids. 

12. Denaturation causes the protien to lost its shape and lose its ability to function properly.

14. 

a) Water molecule

b) This is called dehydration. Dehydration happens when a monomer is added to the polymer chain and a water molecule is released. 

c) It could attach to the Leucine's OH and Serine's H.

15.

a) Enzyme A performs best at about 37-38 degrees anc enzyme B performs best at about 77-78 degrees. 

b) Enzyme A i found in humans. and enzyme B is thermophilic.

c) It slows down at 40 degrees because a human enzyme cannot be higher than that or else the the human would die. 

Summary of Section 5.5 ;))

-=Enzymes=-

Enzymes and Activation Energy

-to start a chemical reaction:

-it is necessary to weaken chemical bonds in reactant molecules

-this requires for the molecules to absorb energy

activation energy-minimum amount of energy required to start up a chemical reaction

-one way to provide activation energy: heat up the mixture of molecules

-hotter molecules may collide with enough energy to weaken bonds

-cooler molecules collide with less energy

-heating up a cell would cause many unnecessary reactions to occur at once, including reactions that destroy the cell's structures

-instead, cellular reactions depend on the assistance of catalysts

catalysts: compounds that speed up chemical reactions

enzymes

definition-specialized proteins that are main catalysts of chemical reactions in organisms

-provide a way for reactions to occur at cell's normal temperature

-doesn't supply activation energy to the reacting molecules

BUT

-lowers the energy requirement barrier so that the reaction can proceed at normal cell temperature

-each enzyme catalyzes a specific kind of chemical reaction

-at any moment's of a cell's life, the specific enzymes that are present and active determine which reactions occur

How do enzymes work?

-the shape of each enzyme fits the shape of the particular reactant molecules

substrate-a specific reactant acted upon by an enzyme 

active site-region of an enzyme into which a particular substrate fits

-the fit between substrate and enzyme is not rigid

-as the substrate enters, the active site changes slightly which fits the substrate more comfortably

-this places certain function groups of the active site in position to catalyze the reaction

-the tighter grip may also bend the substrate which bends its bonds

Another way that an enzyme can lower activation energy

-by accepting two substrates into adjacent sites

-holding the reactant together helps them to react more easily

So...

enzymes can catalyze the formation of larger molecules into smaller molecules 

-an enzyme's structure and shape is essential to its function

also...

-an enzyme's shape is sensitive to changes in its surrounding environment

So....

-factors of pH and temperature can greatly affect: 

-how well an enzyme works

-or if it can work at all

this is one reason why cells can only survive within certain conditions

Concept Check:

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

The activation energy activates the reactants and triggers the chemical reaction. An enzyme lowers the activation energy to a normal temperature. 

2.Describe how a substrate interacts with an enzyme. 

A substrate enters into the active site of the enzyme, the active site changes shape slightly to fit the substrate more snugly. Then the substrate is converted into products.  

Summary of Section5.4 ;)

-=Proteins=-

protein: a polymer constructed from a set of just 20 kinds of monomers called amino acids.

-are responsible for almost day-to-day fuctioning of organisms

-proteins form structures such as hair and fur, make up muscles, and provide long-term nutrient storage 

-other proteins circulate in blood defend the body from harmful microorganisms

-act as signals, sending messages from one cell to another

-another group of proteins control chemical reactions in a cell

-=Amino Acids=-

definition: a monomer that makes up proteins

-consists of a central carbon bonded to four partners 

-the difference about the each type of amino acid is the "side group" that attaches the fourth bond of the central carbon.

-the side group is responsible for the particular chemical properties of each amino acid

-=Building a Protein=-

polypeptide: chain of linked amino acids 

-cells create protein by making polypeptides

-each link is created by a dehydration reaction between the amino group and the amino acid and the carboxyl group of the next amino acid

-proteins are composed of one or more polypeptide chains

-the body can make a variety of acids in different orders 

-most polypeptides are at least 100 amino acids in length 

-there is a very large number of possible polypeptides

-each protein has a unique sequence of amino acids 

-=Protein Shape=-

-a protein in a single form of amino acids linked together cannot fuction properly

-a fuctional protein consists of one or more polypeptides precisely twisted, folded, and coiled into a unique shape

-some side groups form bonds with each other

-these forces help to fold a polypeptide and keep it folded 

-a protein's shape is also influenced by the surrounding environment, which is usually aqueous

-water attracts hydrophillic side groups

-and rejects hydrophobic groups

-s0o...hydrophillic amino acids are on the outside edges of the protein while the hydrophobic amino acids are clumped in the center of the protein

denaturation: the loss of the normal shape protein due to heat, quality of the environment, or another factor

example: occurs when frying an egg (the egg white changes from a clear liquid to a white solid 

-this is because the polypeptide chains became tangled with one another 

-heating unfolds proteins because...

-most of the forces that keep the folding are weak attractions between pairs of side groups and between side groups and water.

-a protein's function depends on its shape so...

-if a protein loses it shapes (denatures) it won't be able to work properly :( 

Concept Check 

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

Y0u can see the protein that forms fur which keeps animals warm and the protein that forms muscles which keeps the body strong and being able to move. 

2.Relate amino acids, polypeptides, and proteins.

Cells create protein by making polypeptides, which are long chains of amino acids. 

3.Explain how a heat can destroy a protein.

Heat can destroy a protein because most of the folding are weak attractions between pairs of side groups and between side groups and water. The hot molecules collide with enough force to overcome the weak attractions. 

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

One hydrogen atom, an atom in a carboxyl group and and an atom in an amino group are the same in all amino acids. The uniqueness of each amino acid if the side groups that attaches the fourth bond of the central carbon.

Summary of Section 5.3 ;)

unsaturated fat

saturated fat

-=Fats, Lipids and Steroids=-

-=Lipids=-

definition: one of a class of water-avoiding compounds

-lipids act as a wall that surrounds and contains aqueous contents in your cells 

-other lipids molecules circulate in your body as chemical signals to cells 

-some other lipids can be known as fat, which stores energy in your body

hydrophobic: a characteristic of avoiding water molecules

-this is important for the fuctioning of lipids

-=Fats=-

definition: organic compound consisting of glycerol attached to three fatty acids

-some fats can be solid at room temperature

-other can be liquids at room temperature (oils)

-store energy for later use

-fatty tissues cushion the body's organs 

-provides insulation

-if consumed in huge amounts, then its unhealthy (can have heart disease)

saturated fat: a fat which all three fatty acid chains contain the maximum possible number of hydrogen atoms

examples: lard, butter

unsaturated fat: a fat that contains less than the maximum number of hydrogen atoms in one of more of its fatty acids chains

-this is because some of its carbon atoms are double-bonded to each other 

examples: fats in fruits, fish, and vegetables, corn oil, olive oil, vegetable oil..etc

-=Steroids=-

definition: a lipid molecule in which the carbon skeleton forms four fused rings 

-all have a core set of four rings

-differ in the kinds and locations of fuctional groups attached to rings

-are classifies as lipids 

-hydrophobic

-some steroids circulate in body as chemical signals

Cholesterol: an essential molecule found in membranes that surround your cells

-starting point from which body produces other other steroids

-high levels of certain cholesterol in the blood can increase cardivascular diseease. (heart and vessel)

Concept Check:

1.What property do lipids share?

Lipids are all hydrophobic.

2.What are the parts of a fat molecule?

Glycerol(three carbon backbone) attached to three fatty acids which contain hydrocarbon chains.

 

3.Describe two ways that steroids differ from fats.

a)the structure of fats is different from steroids as fats have a three-carbon backbone and steroids have four fused carbon rings 

b)steroids circulate in your body as chemical signals while fats are store energy for later use and cushion your organs.

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

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

Summary of Section 5.2 ;;)

-=Sugars=-

~*~Carbohydrates~*~

Definiton: a compound containing carbon (organic compound) that is made out of sugar molecules 

Carbohydrates provide a good source of energy ;)

Formula : CH2O ( 1 carb0n : 2 hydrogen : 1 oxygen) 

~*~Monosaccharides~*~

Definition: Simple sugars that contains 1 sugar unit 

Examples: Glucose, Fructose, Galactose 

Sugars molecules are used for: 

 

1. for cellular work :

- Cells break down sugar molecules and take their stored energy

2. use carbon skeletons of monosaccharides for making other types of organic molecules 

3. Glucose molecules that are not used immediatly cam be incorporated into larger carbohydrates or can be stored for later use. 

~*~Disaccharides~*~

Definition: when there is a dehydration reaction, cells construct a disaccharide from two monosaccharides

most common disaccharide: sucrose

sucrose : fructose + glucose

once consumed, sucrose can be broken down into:

-glucose 

-fructose

can also store glucose in large molecules for later use.

~*~Polysaccharides~*~

Definition: polymer chains made up of simple sugar monomers (can also be called complex carbohydrates)

Examples: 

**starch: found in plant cells that consists of only sugar monomers

-starch chains serve as sugar stockpiles

-plant and animal cells need sugar for energy to perform work + use as raw material for building other molecules

-when plants break down starch molecules: the stored glucose becomes available

starch can be found in:

-potatoes

-rice

-corn

-wheat

**glycogen: 

Definition: polysaccharide in animal cells 

-like starch, consists of glucose monomers 

BUT: 

a glycogen polymer is more highly branched than a starch polymer

-in humans, most glycogen is stored in muscle and liver cells

-when body needs energy, it breaks the glycogen and releases the glucose

**cellulose: 

Definition: a polysaccharide in a plant

-serves as building material

-protect and stiffen plant

-like starch + glycogen is made out of glucose monomers

-many cellulose chains are linked together with:

hydrogen bonds that make fibers in the tough walls of the plant cells 

-cellulose helps keep your digestion healthy 

-is not a nutrient

-almost all carbohydrates are hydrophillic because:

there are many hydroxyl groups in their sugar units so...

monosaccharides + disaccharides dissolve in water = sugary solutions

starch + cellulose are large molecules so they DO NOT dissolve in water

BUT

they are still hydrophillic (water-loving) 

that's all for now

Concept Check:

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

A monosaccharide ia a simple sugar that contains one sugar unit while disaccharides are made when there is a dehydration reaction. a disaccharide is composed of 2 monosaccharides.

Example of a monosaccharide: glucose, fructose 

Example of disaccharide: sucrose 

2.Compare and contrast starch, glycogen and cellulose. 

-Starch, glycogen and cellulose are all polysaccharides

-all three of them are made out of glucose monomers

-A glycogen molecule is more highly branched than a starch molecule

-starch and glycogen can be digested by people and animals 

-starch and cellulose are both in plants

-cellulose and some forms of starch do not dissolve in water

3.How do animals store excess glucose molecules?

Animals store excess glucose molecules in glycogen.