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TULANE / Cell and Molecular Biology / CELL 1010 / What are 2 general approaches to biology?

What are 2 general approaches to biology?

What are 2 general approaches to biology?


School: Tulane University
Department: Cell and Molecular Biology
Course: Intro to Cell & Molecular Biology
Professor: Meenakshi vijayaraghavan
Term: Fall 2016
Cost: 25
Name: Cell 1010, Week 2 Notes
Description: These notes cover week 2 of class and some of the chapter reading.
Uploaded: 09/12/2016
8 Pages 116 Views 1 Unlocks

Cell 1010  

What are 2 general approaches to biology?

Dr. V  

Week 2 Notes for Cell 1010  

Text highlighted in this color means important/high probability of appearing on  an exam.

• Biology is a scientific discipline that seeks to explain the truth through  experimental investigation of natural phenomena.  

•Experiments are conducted utilizing the Scientific Method. Hypothesis vs Theory

• Hypothesis: an educated guess based on past research/literature that leads to  an explanation of a natural phenomena. It is a very specific statement that can  be shown to be correct or incorrect.  

•Theory: broad explanation built on a HUGE body of consistent evidence.  •Both can never be proven to be true.  

Who is dorothy anderson?

2 General Approaches to Biology  

1. Deductive Reasoning  

2. Inductive Reasoning

• Deductive reasoning involves applying general principles in order to predict  specific results.  

•Inductive reasoning observing in order to construct to general principles.  2 Approaches to Experimenting  

1. Discovery Based Science: collecting data without a preconceived hypothesis.  2. Hypothesis Testing: this is the scientific method.  If you want to learn more check out What is the difference between paracellular and transcellular?

• Discovery based science often leads to hypothesis based.

• Five Steps to the Scientific Method

1. Observe  

2. Formulate a testable hypothesis that makes specific claims. 3. Experiments determine if the hypothesis is correct or not.  4. Data is gathered from the experiment and analyzed.  

Enumerate the three subatomic particles.

5. The hypothesis is either accepted or rejected.  

• When you formulate an experiment it is important to only have one variable between the control and experimental sample.  

• Developments discovered in Cystic Fibrosis are an example of discovery based  science leading to hypothesis testing and eventually revolutionizing  discoveries.  

•Cystic Fibrosis: those affected by CF produce thick and sticky mucus that  obstructs the lungs and pancreas. It leads to life threatening lung infections.  • Dorothy Anderson(1935): determined that cystic fibrosis is a GENETIC  disorder. People that have CF have inherited two recessive CFTR genes, one  from each parent.  Don't forget about the age old question of What are the stages of cell cycle?

•CFTR Gene: encodes protein.  

•The search for the CFTR gene was conducted without a preconceived  hypothesis. It is only after scientists discovered that the CFTR gene encodes  proteins that function in the transport of chloride ions across membranes, that  experiments were run with a hypothesis centered around the function of the  gene.  

Chapter 2

•Matter: anything that has mass & occupies space.  

• Atoms are the building blocks of all matter.  

• Element is a specific type of atom that is a pure substance of only one kind of  atom.  

•Three subatomic particles:  

•Protons: positive charge, located in nucleus, same number as electrons  • Neutrons: neutral, found in nucleus, number varies  We also discuss several other topics like If 400.00 g of ch3oh are actually made, what is the percent yield?
We also discuss several other topics like What is the feature analysis theory and the problems associated with it?

• Electrons: negative, found in orbitals, same number as protons  •The atom as a whole does not have a net electrical charge.  If you want to learn more check out Convert the following temperatures from degree fahrenheit to degrees celsius: 300, 70, 32◦f

• Niels Bohr: gave us an image of an atom being like a solar system but we now  understand the electrons are in a cloud like structure not orbiting around the  nucleus.  

• Orbitals: a high probability that an electron can be found here, each one can  hold only 2 electrons.

•S Orbitals: spherical in shape  

•P Orbitals: shaped like a propeller  Don't forget about the age old question of What makes a sample well represented?

•Orbitals are located in the electron shells.

•The electron shell CLOSEST to the nucleus can only hold two electrons. They  spin in a spherical s orbital(1s) in opposite directions.  

•The second electron shell is one spherical s orbital (2s) and three propeller  shaped p-orbitals (2p).

Shell Shell


# of Electrons






# of Electrons


2S^2, 2P^6



3S^2, 3P^6, 3D^10



4S^2, 4P^6, 4D^10, 4F^14


S= Spin P=Principle D=Diffuse F= Fundamental  

•The number and arrangement of electrons of an atom hold the key to its  chemical characteristics.  

• Dmitri Mendeleev: arranged elements based on chemical characteristics (the  periodic table).  

• Valence Electrons: unpaired electrons in the outermost shell. •Octet Rule: many atoms are most stable when they have 8 electrons in their  outermost electron shell (hydrogen does not apply to this rule).  •Inert Atoms: have the outer level at maximum number of electrons.  • Reactive Atoms: have unpaired electrons in the outer level.  • Atomic Mass: an atom’s mass relative to other atoms. It is computed by  obtaining the averages of the weights of different isotopes of an element.  •Mass vs Weight: weight is the gravitational pull on a given mass. • Dalton: unit of measurement for atomic mass that is equal to 1/12 the mass of a  carbon 12 atom.  

•Isotopes: multiple variations of an element that differ in the amount of  neutrons but have the same chemical properties.  

•Carbon, hydrogen, oxygen, and nitrogen are needed to survive. •3 Types of bonds: covalent bond, hydrogen bond, and ionic bond.

•Covalent Bonds: a bond formed when atoms share a pair of electrons. No  charge, fulfill octet rule, no free electrons.  

•Polar Covalent Bonds: when two atoms with different electronegativities form  a covalent bond. This means that the shared electron is closer to the atom with  higher electronegativity. Unequal sharing of the electron!

• Nonpolar Covalent Bonds: bonds formed between atoms with similar  electronegativities. Equal sharing of the electron!

•Water is an example of a polar covalent bond(electrons are more attracted to  oxygen).  

• Hydrogen Bonds: a weak attraction. Arises when one polar molecule becomes  electrical attracted to an electronegative atom in another polar  molecule(partially positive bond).

• An important feature of hydrogen bonds is that individually, they are very  weak and form and break easily. Collectively, they’re strong(they hold DNA  together).  

• Electronegativity: a measure of the capacity of an atom to attract bonded  electrons.

•EX of non-polar covalent bonds: H-H, C-C, O-O, N-N.  

•EX of polar covalent bonds: H-O, H-N, C-O, C-N.  

•Ion: is an atom that has gained or lost an electron  

•Cation: net positive charge(lost an electron)  

• Anion: net negative charge(gained an electron)  

•Ionic Bond: bonds of attraction between a cation and an anion.

•One of the most important properties of molecules is flexibility.  • Free Radical: a molecule with with an atom that has a single unpaired electron  in the outer shell(it has a valence electron).

•Superoxide Anion: together with catalase removes oxygen radicals and  protects cells in the body.  

• Hydrogen Peroxide: a free radical that breaks the membrane of bacteria  affecting the DNA and killing the cell.  

• Anti-Oxidant: provides the free radical with an electron without creating a  bond(now the free radicals can’t create harm because they can’t bond with  anything and are stable).  

•Chemical Reaction: breakage of old bonds and formation of new ones(need a  required concentration of reactants and a source of energy).  

• Heat is often used in chemical reactions because it makes the molecules move  and the reactants collide.  

• Equilibrium: the rate of the formation of products equals the rate of the  reactants. AKA there is no longer a change in the concentrations of products  and reactants.  

Properties of Water

•Solution: solvent + solute  

• Aqueous Solution: water is the solvent.  

•Lipids are hydrophobic(nonpolar) meaning they do not dissolve in water. •Cohesion: a property of water that allows is to move against gravity in plants  without expanding energy because water is attracted to water.

• Adhesion: force of attraction between water and a surface that isn’t  electrically neutral(it clings to surfaces that it can hydrogen bond to).  •Phospholipids in our cells make it so we feel wet when we touch water(ex of  adhesion).  

• Hydrogen bonds in our body absorb heat allowing us to maintain homeostasis.  •2 Characteristics of Water that Help Maintain Homeostasis: 1. High specific  heat 2. high heat of vaporization.

• High Specific Heat: amount of heat one gram of a substance must absorb to  change it’s temperature by one degree celsius.  

• High Heat of Vaporization: the heat needed to vaporize 1 mole of any  substance at it’s boiling point.  

• High Heat of Fusion: the amount of heat energy that is required to cause it to  change from a liquid to a solid state.  

• Water requires a lot of energy to become ice.  

• Hydrophilic vs. Hydrophobic

• Hydrophilic: water loving

• Hydrophobic: water fearing  

• Hydrophobic exclusion: when a nonpolar substance is in water, the water will  push it away because water molecules want to hydrogen bond. • Amphipathic molecule: has a polar head (hydrophilic) and a nonpolar  tail(hydrophobic). When mixed with water, may become MISSILE due to  hydrophobic exclusion (spheres with polar surface).

•Colligative Property of Water: the capacity of water to extend it’s boiling and  freezing point.  

• Dehydration synthesis: occurs during anabolism. It’s the loss of water  molecules during a reaction.  

• Hydrolytic Cleavage: occurs in catabolism. The aid of water in breaking down  molecules.  

• An aqueous environment is necessary in your body in order for reactions to  take place.  

•PH Scale: how acidic or basic a substance is.  

• Acids are an increase in the concentration of hydrogen ions.  •Bases are an increase in the concentration of hydroxide ions.  •PH: negative logarithm of hydrogen ion concentration.  

•1-6= Acidic 7=Neutral 8-14= Basic  

•Protein Denaturation: when proteins lose their quaternary, tertiary and  secondary structure because of stress or compounds such as acids or bases(if  this goes on in a living cell then it can impact the cell severely to the point of  death).  

• Buffer: minimizes ph changes in the fluids of living organisms(made of a weak  acid and it’s related base). EX: Bicarbonate and carbonic acid

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