Thursday, October 30, 2008

Hey guys, today in class we took the in class essay for chapters 5 and 8 and finished up Lab 2. We have Chapter 12 Vocab due next week so here are the words:

Density Dependent Inhibition: The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another.
Cyclin: A cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle
.
Cleavage: The process if cytokinesis in animal cells, characterized by pinching of the plasma membrane. Also, the succession of rapid cell growth during early embryonic development that converts the zygote to a ball of cells.
Centrosomes: Structure present in the cytoplasm of animal cells, important during cell division; functions as a micro tubule-organizing center. A centrosome has two centrioles.
Centromere: The specialized region of the chromosome where two sister chromatids are most closely attached.
Kinetochore: A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle.
Sister Chromatid: Either of the two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms. While joined, two sister chromatids make up one chromosome; chromatids are eventually separated during mitosis or meiosis II.
Gamete: A haploid reproductive cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.
MPF: (Maturation-promoting factor [M-phase-promoting factor]); a protein complex required for a cell to progress from late interphase to mitosis. The active form consists of cyclin and a protein kinase.

Cell Plate: A double membrane across the mid line of a dividing plant cell, between which the new cell wall forms during cytokinesis.
Cytokinesis: The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II.

ROOTS:

Centro- the center
Mito- a thread
Meta- between
Telos- an end
Soma- body
Pro- before
Meio- less
Mal- bad or evil
Inter- between
Gen- produce
Gamet- a wife and husband

In class we talked about possible factors that could explain the large variances in the group data. One factor that could account for the drastic differences is the way in which each group their reaction chamber during each experiment. We found that leaving the chamber completely submerged under the water resulted in a slower reaction while holding the chamber at more of a vertical angle resulted in a faster reaction. Another factor is the way in which our enzyme-the catalase (yeast)- was prepared. On the first day (Wednesday), Ms. Lyon prepared the yeast with warm water which caused the oxygen gas to take over the water during the reaction very quickly. Whereas on the second day (Thursday), Ms. Lyon prepared the yeast with cold water which resulted in a much slower reaction.

Here is a video to help you better understand Feedback Inhibition - a method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

*I did not know how to upload a video but here is the URL: http://www.youtube.com/watch?v=zl2KYhgZ_u8

Multiple Choice Questions for the Unit Exam on Wednesday!!

1. What determines if an enzyme can act on a specific substrate?
a) temperature
b) pH
c) if the active site of an enzyme fits the substrate properly
d) the specific three-dimensional configurations of enzymes
e) C and D are correct

2. When an enzyme is added to a solution where the substrate and product are in equilibrium, what will happen?
a) More product would be formed
b) More enzyme would be formed
c) The free energy of the system would change
d) Nothing-it would stay at equilibrium
e) The reaction would change from endergonic to exergonic

3.
All of the following are true about exergonic reactions except:
a) energy is released
b) products have less free energy than reactants
c) G is negative
d) reactants have less free energy than products
e) they are spontaneous


4. What is the fastest way to obtain products from an enzyme saturated with substrate?
a) add more substrate
b) add more enzyme
c) heat the solution
d) add a noncompetitive inhibitor
e) B and C are correct

5. The structural level of a protein least affected by a disruption in hydrogen bonding is:
a) primary
b) secondary
c) tertiary
d) quaternary
e) disruption of hydrogen bonds does not affect proteins

answers: E, D, D, B, A

Jordan

Unit Review!

Hi AP BIOLOGY!!! I MISS YOU GUYS SO SO SO... MUCH! I hope you all are doing great and getting lots of A's! 
Well there is a Unit 2 test on Wednesday (yikes) so here are some multiple choice questions to help you review! 
Chapter 2
1. How do isotopes differ from each other?
a) ability to form ions
b) number of protons
c) number of valence electron 
d) number of electrons
e) number of neutrons

2. Oxygen has an atomic number of 8. Therefore, it must have
a) 8 protons
b) 8 electrons
c) 16 neutrons
d) Only A and B
e) A, B, and C

3. Which of the following is a trace elements that is essential to living organisms?
a) hydrogen
b) nitrogen
c) carbon
d) oxygen
e) iron

4. The mass number can be approximated by adding together the number of
a) neutrons and electrons
b) protons and neutrons
c) protons and electrons
e) isotopes of the atom

5. Which four elements make up approximately 96% of living matter?
a) carbon, oxygen, sulfur, calcium
b) carbon, sulfur, phosphorus, hydrogen
c) oxygen, hydrogen, calcium, sodium
d) carbon, sodium, chlorine, magnesium
e) carbon, hydrogen, nitrogen, oxygen

ANSWERS: E, D, E, B, E

Chapter 4

1. How many electron pairs does carbon share to full its outter shell?
a) 1
b) 3
c) 2
d) 4
e) 5

2. What type of bonds does carbon form?
a) hydrogen
b) covalent
c) ionic
d) only A and B
e) A, B, and C are correct

3. Why are hydrocarbons not soluble in water?
a) they are hydrophilic
b) the C-H bond is nonpolar
c) they are less dense than water
d) the C-H bond is polar
e) they are large molecules

4. What is true about geometric isomers?
a) they are variations in arrangement around a double bond
b) they are mirror images
c) they have different molecular formulas
d) they have the same chemical properties
e) their atoms and bonds are arranged in different sequences

5. Organic chemistry is the study of
a) oxygen
b) water
c) all matter
d) carbon compounds
e) functional groups


ANSWERS: D, B, B, A, D

Chapter 5

1. Carbohydrates function in animal as
a) energy-storage
b) functional units of lipids
c) sites of protein synthesis
d) enzymes in the regulation of metabolic processes
e) a component of triglycerides

2. Amino Acids differ because of their
a) amino group
b) R group
c) tertiary structure
d) carboxyl groups
e) A and B are correct

3. Which of the following are polysaccharides?
a) glycogen and starch
b) glucose and sucrose
c) uracil and thymine
d) RNA and DNA
e) cholesterol and triacylglycerol

4. Which of the following is true of start and cellulose?
a) They can both be digested by humans
b) they are both structural components of the plant cell wall
c) They are geometric isomers
d) they are both polymers of glucose
e) they are both used for energy storage in plants

5. Which of the following lipids is most important in the cell membrane?
a) fat
b) oil
c) wax
d) triglyceride
e) phospholipid

ANSWERS: A, B, A, D, E

Chapter 8

1. Which term describes the process of breaking down large molecules into smaller ones?
a) catabolism
b) catalysis
c) anabolism
d) dehydration
e) metabolism

2. Which is true about catabolic pathways?
a) they consume energy to build up polymers from monomers
b) they do not depend on enzymes
c) they release energy as they degrade polymers to monomers
d) they lead to syntheses of catabolic compounds
e) A and B are correct

3. Anabolic pathways
a) release energy as they degrade polymers to monomers
b) do not depend on enzymes
c) depend on enzymes
d) consumes energy to build up polymers from monomers
e) B and C are correct

4. The transfer of free energy from catabolic pathways to anabolic pathways is best called
a) entropy
b) cooperativity
c) bioenergetics
d) feedback regulation
e) energy coupling

5. Which of the following would decrease the entropy within a system?
a) digestion
b) dehydration reactions
c) hydrolysis
d) respiration
e) catabolism

ANSWERS: A, C, E, E, B 

Great! well I hope that mini test helps you study!
MISS AND LOVE YOU ALL!!!!

Tuesday, October 28, 2008

Lab 2 Enzyme Catalyst

Hey guys! Today in class we took the 8.2 quiz. Since our essay was canceled, (thanks Ms. Lyon!) we prepped for the lab.

Lab 2: Enzyme Catalyst (Factors Influencing Enzyme Activity)

Enzymes are biological catalysts capable of speeding up chemical reactions by lowering activation energy. One benefit of enzyme catalysts is that the cell can carry out complex chemical activities at relatively low temperatures.


Regions that play important roles in catalytic activity
  1. Active Site: The area of the enzyme which binds to the substrate(s) and aids in the chemical reaction.
  2. Allosteric Site: Involved in forming the proper 3D shape when linked with specific cofactors.

These regions allow enzymes to be highly specific in terms of the reactions they will catalyze and under the condition they work best.


Enzyme Reactions

Enzymes combine reversibly with specific substrates to form an enzyme-substrate complex. This then forms the products of the reactions.

The equation for enzyme reactions is as follows:

Enzyme + Substrate → Enzyme-Substrate Complex → Enzyme + Product


It is important to remember that the enzyme is not consumed in the reaction and can recycle to work with additional substrate molecules. Each enzyme is specific for a particular reaction because its amino acid sequence is unique, which causes it to have a unique 3D structure. The active site is the part of the enzyme that interacts with substrate, so that any substance that blocks or changes the shape of the active site affects the activity of the enzyme.


Factors Influencing Enzyme Activity include

1. Time course of enzyme activity
2. Enzyme concentration
3. Temperature
4. pH
5. Substrate Concentration
6. Ionic concentration

Any of these factors, if altered from the optimal state, will influence the way the enzyme reacts with the substrate.


Some conclusions you should make

1. The rate of a reaction is determined by measuring the accumulation of one of the products or by measuring the disappearance of the substrate (reactant).
2. The rate of a reaction is the slope of the linear (straight) part of the graph that describes the accumulation of product (or decrease in substrate) as time progresses.
3. Reaction rate may be affected by temperature, pH, substrate concentration, and enzyme concentration.


Multiple Choice Questions

1. If an enzyme is added to a solution where its substrate and product are in equilibrium, what would occur?
a. Additional product would be formed
b. additional product would be formed
c. the reaction would change from endergonic to exergonic
d. the free energy of the system would change
e. nothing; the reaction would stay at equilibrium

2. In describing enzyme feature, enzymes:
a. are composed primarily of polypeptides, which are polymers of amino acids.
b. can bind prosthetic groups such as metal ions that participate in enzyme reactions
c. have defined structures.
d. bind their substrates at active sites.
e. all statements are true

3. Which of the following is not a true type of enzyme inhibition?
a. allosteric inhibition
b. competitive inhibition
c. noncompetitive inhibition
d. denaturation inhibition
e. feedback inhibition

Monday, October 27, 2008

Essay Postponed GO FIELD HOCKEY

I will figure out something. We still have 8.2 quiz, but we will postpone essay.
I am way too excited!!!!!
Mrs. Lyon

Chapter 8 Enzymes

Section 8.4 Enzymes
Catalysts: are substance that can change the rate of a reaction without being altered themselves in the process.
Enzymes are proteins that are biological catalysts.


  • Enzymes= speed up reactions by lowering amount of energy needed for reaction to occur. * NO ENERGY IS ADDED
  • Protein with a specific sites.
- Have active sites
  • Both catabolic (polymer) & anabolic (monomer)

  • Enzymes can be recycled and re-used
The activation energy of a reaction is the amount of energy it takes to start s reaction (amount of energy it takes to break bonds or reactant). The reactant that the enzyme acts on is called the substrate.

Structure of Enzyme
Enzyme has an active site where the substrate binds.









  • The enzyme and substrate form a complex called enzyme- substrate complex, which is then converted into products. The products are released from the enzyme.
- Products are the result of substrates binding to the enzyme.
-Ex. If the substrate binds in one piece then the result could be two products or if the substrate is in two pieces then the product could be one. (This is a simple example).











Each Enzyme has an optimal temperature and pH
There are some substances that inhibit the actions of enzymes.

  • Competitive inhibitors: are reversible inhibitors that compete with the substrate for the active site on the enzyme.

  • Noncompetitive inhibitors: bind to other site on the enzyme (not the active site)














- Result of binds is that it changes the shape of enzyme= preventing substrate or competitive inhibitor from binding.


* Competitive and Noncompetitive can NEVER work together to take over an enzyme.

Section 8.5 Regulation of enzyme activity help control metabolism
Many enzymes regulators bind to an allosteric site (specific site) on the enzyme away from the active site.

  • Bound= either stimulate or inhibit enzyme activity.
Cooperativity: is the binding of one substrate molecule, which can stimulate the binding or activity at other active sites.
  • This mechanism amplifies the response of enzymes to substrates.
In feedback inhibition, the end product of a metabolic pathway allosterically inhibits the enzyme for a previous step in the pathway.

ATP
is the immediate source of energy that drives most cellular work.
  • The 3 main kinds of work are:
  1. Mechanical work







  • Examples:

- Muscle contractions
- Movement of chromosomes during cellular reproduction.

2. Transport work







  • Examples:

- Pumping of substances across the membrane

3.Chemical work.












  • Examples:

- Pushing of endergonic reactions

- Synthesis of polymers from monomers


* All enzymes are proteins but all proteins are not enzymes.

Multiple choice questions

1. Which of the following characteristics are not associated with allosteric regulation of an enzyme's activity?
a. A mimic of the substrate competes for the active site.
b. A naturally occurring molecule stabilizes a catalytically active conformation.
c. Regulatory molecules bind to a site remote from the active site.
d. Inhibitors and activators may compete with one another.
e. The enzyme usually has a quaternary structure.

2. If an enzyme has been inhibited noncompetitive,
a. The delta G for the reaction it catalyzes will always be negative.
b. The active site will be occupied by the inhibitor molecule.
c. Raising substrate concentration will increase inhibition.
d. More energy will be necessary to initiate the reaction.
e. The inhibitor molecule may be chemically unrelated to the substrate.

3. The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. Which of the following best explains why this decrease occurs?
a.The allosteric inhibitor binds to the active site, preventing the substrate from binding.
b.The allosteric inhibitor causes free energy change of the reaction to increase.
c.The allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site.
d.The allosteric inhibitor lowers the temperature of the active site.
e.The allosteric inhibitor binds to the substrate and prevents it from binding at the active site.




Answers:

1.a, 2.e, 3.c

Created by Alyssa Hamilton

Friday, October 24, 2008

8.1

Metabolism-the totality of an organism's chemical reactions

Metabolic pathway
- begins with a specific molecule that is altered in to a final product

Catabolic pathway
- releases energy and breaks down complex molecules into simpler compounds
(ex. cellular respiration)

anabolic pathway- absorbs energy to build complicated molecules from simpler ones
(ex. protein synthesis from amino acids)

bioenergetics- the study of how energy flows through living organisms

energy- capacity to cause change; ability to rearrange collection of matter

kinetic energy- relative motion of obejects

potential energy-energy that is not kinetic; energy that matter possess because of its ocation or structure

The study of energy transformations the occur in matter is called thermodynamics, and there are two basic laws of thermodynamics. The first law of thermodynamics (even bioenergetics) states that the energy of the universe is constant and that energy can be transferred and transformed, though it cannot be created or destroyed.

*Also called the Principle of Conservation of Energy



Everything Works continuously! When there is system within a certain surrounding, things come in and out and there are lots of transformations, but nothing gets outside barrier of Universe. So energy is constant, just transformations are different.
Living Cells covert organized energy into heat.

Example: By turning on a fan, you convert mechanical energy to kinetic energy

The second law of thermodynamics states that very energy transfer of transformation increases entropy, or the amount of disorder or randomness, in the Universe.

Another definition to the second law-For any process to occur spontaneously, it must increase the entropy of the universe.



- When you eat a protein or any polysaccharide, it is broken down and energy is released (catabolic)

-You are getting ready play a big game, and you play the sport to release energy (catabolic)
Afterwards, you eat to absorb energy (anabolic)

-An example of entropy is a messy room... it takes energy to clean it up
-Another example, a cheetah eating a gazelle to convert food into chemical energy, to go and catch more prey
*With each input there is an output

-An aside: The energy drinks that rock stars drink contain monosccharides which break down fast in the body. Really you need to eat polysaccharides for some time before a big game. The energy drinks just give you a rush of silly energy and then you pass out.

8.2

The free energy change of a reaction tells us whether or not the reaction occurs spontaneously
Unstable systems are rich in free energy, G. They have a tendency to change spontaneously to more stable state, and it is possible to harness this “downhill” change to perform work

Example: A diver has more potential energy (free energy to utilize) right before they dive and that transforms to kinetic energy during dive (heat is released when someone dives).
-Up on the diver platform=positive Delta G which indicates a greater work capacity but instability

Free energy is defined as the part of a system’s energy that us able to perform work when the temperature of a system is uniform. Free energy is depicted as G. The symbol for the total energy of a system is H, and the symbol for entropy is S. The relationship between the change in free energy, change in energy, change in entropy, and temperature is as follows”

Delta G=Delta H – T Delta S
Total-heat= final

In order for a chemical reaction to occur spontaneously (going down), the system must experience either a decrease in H (energy) or an increase in S (entropy)

Keep in mind that nothing, not a car, a washer, a dryer, are 100% efficient because heat is still released

An exergonic reaction is one in which energy is released (Delta G is negative). The greater the decrease in free energy, the greater the amount of work that can be done. The products have less free energy than he reactants
**Exergonic is spontaneous with a negative delta G (potential)


href="http://www.estrellamountain.edu/faculty/farabee/biobk/exergonic.gif">




An endergonic reaction is one that requires energy in order to proceed. Endergonic reactions absorb free energy from the surroundings. This reaction is “uphill” which uses energy.
**Endergonic is non-spontaneous with a positive delta G (kinetic)
href="http://www.emc.maricopa.edu/faculty/farabee/BIOBK/activationener.gif">


Review of reactions

Exergonic Reactions

energy released=catabolic
- Delta G (free energy)
spontaneous
downhill
H (energy) must decrease
gives up order (TS must increase)
system becomes more stable

Endogonic Reaction
energy absorbed=anabolic
+Delta G (free energy)
non spontaneous
uphill
system becomes less stable


8.3
ATP Is very important molecule, because it is primary source of enrgy for the cell. Also known as adenosine triphosphate, ATP is made up of the nitrogenous base adenine, bodnded to ribose and a chain of three phosphate groups. When a phosphate group is hydrolyzed, energy is released in an exergonic reaction

Work in the cell is done by the release of a phsphate group from ATP. When ATP tranfers one phosphate group through hydrolysis, it become ADP (adenosine triphosphate).

The ATP cycle in the cell involves the use of energy that’s released from catabolic reaction re-phosphorylate ADP to form ATP. Energy is released when ATP is then dephosphorylates and exergonic reaction to power important cellular processes


Practice questions

1. Which of the following best describes a pathway which absorbs energy to build complicated molecules from simpler ones?

a) anabolic pathway
b) thermodynamic pathway
c) catabolic pathway
d) metabolic pathway

2. Which reaction process with a net release of free energy?

a) endergonic reaction
b) decomposition reaction
c) exergonic reaction
d) hydrolysis reaction

3. In which reaction is there a positive delta G (the quantity of energy required to drive a reaction)?

a) endergonic reaction
b) metabolic reaction
c) exergonic reaction
d) thermal energy reaction







Answers: 1.a, 2.c, 3.a
Functional Groups...a review

Functional groups are specific arrangements of atoms commonly attached to carbon skeletons. These functional groups are also called chemical groups. They can affect molecular function by being directly involved in chemical reactions. An example is the molecules shape.

The hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, and methyl groups are the most important functional groups in biological processes. 

The hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, and phosphate gruops are hydrophilic and have an increase in the solubility of organic compounds in water. 
The methyl group is not reactive and often acts as a recognizable tag on biological molecules.

Hydroxyl Group:

In a hydroxyl group a hydrogen atom is bonded to an oxygen atom, and this is bonded tothe carbon skeleton of an organic molecule. This bond is -OH and sometimes may be seen as HO-.




The name of the compound is alcohols. Ethanol is an example of this.



Functional properties:
-It is polar
-Can form hydrogen bonds with water molecules and helps dissolve organic compounds

Carbonyl Group:

This group consists of a carbon atom bonded to an oxygen atom by a double bond. The bond looks like -C=O.


In the carbonyl group there is two compound groups, ketones and aldehydes.
Ketones are when the carbonyl group is within the carbon skeleton.
Aldehydes are when the carbonyl group is at the end of the carbon skeleton.

An example of a ketone is acetone.


An example of an aldehyde is propanal.


Functional properties:
-A ketone and aldehyde can be structural isomers with different properties
-These groups are found in sugars: 
  aldoses(containing an aldehyde)
  ketoses(containing a ketone)

Carboxyl Group:

A carboxyl group is when an oxygen atom is double-bonded to a carbon atom that is also bonded to an -OH group. -COOH is a carboxyl group.



The names for the compounds are carboxylic acids or organic acids.

An example of a carboxyl group is acetic acid.


Functional properties:
-Has acidic properties
-It is found in cells in the ionized form with a charge of 1- 

Amino Group:

This group consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton.


The name of a compound is amines.

An example is Glycine.


Functional properties:
-Acts as a base
-Ionized with a 1+ charge, under cellular conditions

Sulfhydryl Group:

Sulfhydryl group has a sulfur atom bonded to an hydrogen atom, it resembles a hydroxyl group in shape.


The compound name for this is Thiols. 

An example is cysteine. 


Functional properties:
-Two sulhydryl groups can react by forming a covalent bond
-Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair

Phosphate Group:

In this group a phosphorous atom is bonded to four oxygen atoms . One oxygen atom is bonded to the carbon skeleton.


The name compound is organic phosphates.

An example of this is glycerol phosphate.


Functional properties:
-Contributes a charge to the molecule it is a part of
-Has the potential to react with water, therefore releasing energy

Methyl Group:

This group has a carbon bonded to three hydrogen atoms. It may be attached to a carbon or a different atom.


The compound name of this is methylated compounds. 

An example is 5-methyl cytidine.


Functional properties:
-It can affect expressions of genes
-Arrangements of methyl groups in male and female sex hormones affects their shape and function


Quiz:
1. Which function is true about the amino group?
a)has acidic properties
b)acts as a base
c)affects expression of genes

2. Which chemical group could be defined as an aldehyde
a)a carbon atom joined to an oxygen atom by a double bond at the end of the carbon skeleton
b)a carbon atom joined by an oxygen atom by a double bond in the middle of the carbon skeleton
c)can be a structural isomer 
d)Both b and c

3. Which action could produce a carboxyl group?
a) a carbon atom double bonded to an oxygen atom
b)a carbon atom double bonded to an oxygen atom and also bonded to a nitrogen atom
c)a carbon atom double bonded to an oxygen atom and the carbon atom is also bonded to an -OH group

Thursday, October 23, 2008

CHAPTER 8: AN INTRODUCTION TO METABOLISM


CONCEPT 8.1:
AN ORGANISM'S METABOLISM TRANSFORMS MATTER AND ENERGY, SUBJECT TO THE LAWS OF THERMODYNAMICS

The following information concerns how
energy is used, how it moves, how it is released, and the laws that govern it.

ORGANIZATION OF THE CHEMISTRY OF LIFE INTO METABOLIC PATHWAYS



Metabolism (from the Greek metabole, change) is the collection of chemical reactions that occur in an organism. Aided by enzymes, it follows intersecting pathways, which may be catabolic (breaking down molecules, releasing energy), or anabolic (building molecules, consuming energy).

  • A metabolic pathway begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product. Each step of the pathway is catalyzed by a specific enzyme.
Energy is fundamental to all metabolic processes, and a basic knowledge of energy is necessary to understand how the living cell works. Bioenergetics, is the study of how energy flows through living organisms.


FORMS OF ENERGY

Energy
is defined as the capacity to do work. Things that move are said to possess kinetic energy. An object at rest can possess potential energy if it has stored energy as a result of its position or structure. Chemical energy is stored in molecules, and the amount of chemical energy a molecule possess depends on its chemical bonds.


Heat or thermal energy, is kinetic energy associated with the random movement of atoms or molecules. Light is also a type of energy that can be harnessed to perform work, such as powering photosynthesis in green plants.


Preview of vocabulary for next section:
(1) Potential Energy: energy that is not kinetic; energy that matter possess because of its location or structure.
(2) Chemical Energy: refers to the potential energy available for release in a chemical reaction. Recall that catabolic pathways release energy by breaking down complex molecules.
(3) Thermodynamics: the study of energy transformations that occur in a collection of matter.


MULTIPLE CHOICE QUESTIONS:

1. Energy can be ______ or _______ but neither created nor destroyed.
a.
distorted; transferred
b. transferred; altered
c. transferred; transformed

2. Choose the phrase that best completes this sentence:
A major pathway of catabolism is _______, in which the sugar glucose and other organic fuels are broken down in the presence of oxygen to carbon dioxide and water.
a. metabolism
b. cellular respiration
c. through bio synthetic pathways

3. Chose the ending that best completes this statement:
Energy is_________
a. the ability to rearrange a collection of matter.
b. an emergent property that of life that arises from interactions between molecules within the orderly environment of the cell.
c. breaking down complex molecules to simpler compounds.


Answers: 1c, 2b, 3a


Tuesday, October 21, 2008

Nucleic Acids-Informational Polymers

-The last group of important biological molecules we'll discuss is the nucleic acids. The two nucleic acids are DNA(deoxyribonucleic acid) and RNA(ribonucleic acid).


- DNA is the moecule of heredity. It is what is inherited from cell to cell, parent organism to offspring. DNA moleculesare very long; thay are polymers of nucleotide monomers. Nucleotides are made up of three parts: a nitrogenous base,a five carbon sugar called a pentose, and a phosphate group.








-There are two types of nitrogenous bases, purines, and pyrimidines. The purines are adenine(A), and guanine(G) and the pyrimidines are cytosine(C), Thymine(T), Uracil(U).

-Thymine is found ONLY in DNA, and uracil is found ONLY in RNA. In DNA, adenine always pairs with thymine, and cytosine always pairs with guanine.

*All Girls are Pure (A & G are Purines)*

*Hook-ups: A & T, C & G*

-4 groups of Amino Acids:
  • Polar- they can dissolve in water (-OH, O, SH)

  • Nonpolar- they do not dissociate (HC)

  • Acidic-(COO-)

  • Basic- Amine group with + charge

-In DNA,, the pentose sugar is deoxyribose, and in RNA, the pentose sugar is ribose. Deoxyribose has one less oxygen than ribose.


-In DNA and RNA, the nucleotides are joined by phosphodiester bonds. In DNA, two polynucleotide chains wrap around each other. In a helical shape, whereas RNA is a single polynucleotide.



-Size of the carbon skeleton varies from 3 to 7 carbons.

  • Trimose= 3

  • Pentose=5

  • Hexose=6



Questions:

1. Each chromosome contains one long DNA molecule that usually carries how many genes?

A) One hundred

B) One Thousand

C) Several

2. When a cell reproduces itself by dividing, its DNA molecules are:

A)attached on to others

B) Copied & passed along

C)newly rebuilt into something different

3. What carries protein-coding instructions from DNA to protein-synthesizing machinery?

A) DNA

B) RNAC) Both

D) Neither

*Answers: 1. c, 2. b, 3. b