Trimester Review Session 11/18/15 WARNING: THIS REVIEW POWERPOINT IS NOT ALL-INCLUSIVE! You should still study your notes, and old tests and quizzes

What is Biology? Biology is the science that seeks to understand the living world.

Characteristics of Living Things Made up of units called cells Can reproduce Are based upon a universal genetic code Can grow and develop Obtain and use nutrients and energy Respond to their environment Maintain a stable internal environment Change over time (as a group)

Maintain a stable internal environment Homeostasis: process by which organisms maintain a stable internal environment Usually involves feedback mechanisms – Such as the blood sugar example – sweating – Think of a thermostat

REPEAT! 0 Remember, any good experiment must be able to be repeated with the same results!

Share your results 0 Good communication is key for any scientist. 0 Be able to explain… 0 what you did, 0 what you tested, 0 what you observed, and 0 what it means.

Hypothesis, Theory, or Law? 0 Hypothesis: educated guess, based on observation 0 You can never PROVE a hypothesis…your data can just support or contradict it 0 EXAMPLE—You observe each morning that your trashcan is overturned with the garbage spilled about the yard. You form a hypothesis that raccoons are responsible. Through testing, you can either support or contradict your hypothesis.

Hypothesis, Theory, or Law? 0 Theory: summarizes a hypothesis or group of hypotheses that are supported with repeated testing 0 Can be disproven 0 Describes how and why something happens 0 Think of a theory as an accepted hypothesis

Hypothesis, Theory, or Law? 0 Law: explains natural phenomena 0 They are short, sweet, and always true 0 Cannot ever be shown to be wrong 0 Does not explain why

Question 1

Question 3

Some quality bonding time… Ionic Bonds 0 Electron transfer due to electrical attraction between ions 0 Form cations (+) and anions (-) Covalent Bonds 0 Electron sharing 0 Can be polar (unequal sharing) or nonpolar (equal sharing) Electronegativity: “greediness” for electrons; attraction of an atom for electrons in a covalent bond

The Macromolecules 0 Carbohydrates 0 Nucleic Acids 0 Proteins 0 Lipids

Primary Structure 0 Amino acid sequence

Secondary Structure Coiling or folding of the a.a. sequence due to hydrogen bonds

Tertiary Structure Irregular contortions from interactions between side chains (aka R groups) This involves… – Hydrogen bonding – Ionic bonding – Hydrophobic interactions

Quaternary Structure Grouping of polypeptide chains

Denaturation A poor environment may result in denaturation (breaking of a protein) – Cooking an egg – Getting a fever

ENERGY IN REACTIONS Make a bond  release energy Break a bond  absorb energy Chemical reactions that release energy often occur spontaneously (naturally)

ENERGY-ABSORBING REACTION ENDERGONIC/ENDOTHERMIC

ENERGY-RELEASING REACTION EXERGONIC/EXOTHERMIC

ACTIVATION ENERGY Activation energy: the energy needed to get the reaction started

LOWERING Ea Increases the speed of the rxn!!!

ENZYME-SUBSTRATE COMPLEX Substrates: the reactants of enzyme- catalyzed reaction Active site: place on an enzyme where the substrates bind SHAPE DETERMINES FUNCTION!!!!

LOCK-AND-KEY MODEL The fit between an enzyme and its substrate is so precise, it is compared to a lock and key

INDUCED FIT MODEL Enzyme changes shape slightly to “hug” the substrate

REGULATION OF ENZYME ACTIVITY pH Temperature [Enzyme] [Substrate] Regulating proteins—turn enzymes “on” or “off”

[ENZYME]  [enzyme]= greatly  reaction rate

[SUBSTRATE]  [substrate]=  reaction rate to a certain point Eventually, the enzyme becomes saturated with substrate, reaches its maximum speed

Km=amount of substrate to reach half the max rxn rate Vmax=max rxn rate Vmax/2=1/2 max rxn rate

Cell Theory 1.All living things are made of cells 2.Cells are the basic unit of structure and function in living things 3.All cells are produced from existing cells