AP Biology: Units 1-2

Observation

Observation

regarding a phenomena (which leads to a question)

Question

regarding a cause or variable which might influence the observed phenomena

Hypothesis

The predicted relationship between the variable and the observed phenomena

IF (cause) THEN (effect)

Independent Variable

the manipulated variable

Dependent Variable

which will change as a result

Confounding Variables

might influence dependent variable so must be controlled (kept constant)

Replication

obtain a larger sample of data which is likely to be more representative of natural variations

Statistical analysis

reduce the effect of outliers on the overall data pool

Scaled, titled graph

Title: Dependent vs. Independent

Conclusion

Explains how the data does or does not support the hypothesis

Matter

has mass and takes up space 

Matter is made of…

elements

Atomic number

number of protons and electrons 

Atomic mass 

protons + neutrons

Where are protons and neutrons located?

nucleus

electrons found in

specific orbitals or energy levels 

types of orbitals 

* s-orbital holds 2e^- 

* p_x, p_y & p_z  orbitals hold 2e- each

octet rule

principle in chemistry that states that atoms tend to gain, lose, or share electrons in order to achieve a stable electron configuration with eight valence electrons (8e^- in outer level is stable) 

What does the location of electrons determine?

effect the chemical reactivity by determining bonding activity 

Covalent Bonds

atoms share a pair of valence e^- 

Ionic Bonds

an e^- is transferred from one atom to another 

Oxidation

a substance loses electrons, resulting in an increase in its oxidation state

Reduction

involves the gain of electrons or the loss of oxygen, resulting in a decrease in the oxidation state of an atom, ion, or molecule

What does the movement of electrons between energy levels do?

Energy can be stored or released; commonly used to transfer energy in cellular reactions like photosynthesis and respiration

e^- elevated to higher level

energy is stored

e^- drop to lower level

energy is released

Water 

Oxygen forms one covalent bond with each of the 2 hydrogens by sharing e^- pairs

What shape does a water molecule have?

Tetrahedron because exposed protons repel and unshared electrons repel

Water is dipolar because…

oxygen is more electronegative and pulls e- away from hydrogen (un-bonded e^- create negative pole)

Water creates an…

 electrostatic attraction between opposite charges that forms lots of Hydrogen bonds between water molecules

cohesion

stick to each other  (surface tension)

adhesion

stick to other  polar molecules (your finger)

Water is important for…

capillary action

Capillary action

draw water up the tubular structures of plants

Water’s high specific heat

can absorb a lot w/o change in temp (slow to change temp-homeostasis)

Water’s high heat of vaporization

resist evaporation (so sweating takes a lot of heat away)

Water stabilizes…

temperature homeostasis of body and ecosystems

Hydration shell

refers to the sphere of water molecules that surround dissolved ions or polar molecules in a solution, formed due to the attraction between the charged or polar solute particles and the water molecules

Dissolve

forms hydrogen bonds w/ other charged or polar molecules so they dissociate ionic compounds & can’t re-associate

Dissolving is important for

transportation all molecules carried, dissolved sugars, salts, gases in blood & body fluids and plants

hydrophobic

nonpolar, insoluble

hydrophilic

polar, soluble

Hydrophobic exclusion

water molecules push nonpolar molecules away - exclude

Water is important for maintaining

cell membranes (phospholipids), nucleic acids and folding protein

Because oxygen _____________________ very strongly (it is very ________________________ or ______________________) it leaves the remaining ________________ from the _____________ exposed so creates a partial ____________________ charge all of which makes this molecule ______________________.

attracts these electrons; electronegative; electron loving; proton; hydrogen; positive; polar

Because ___________ does ________ attract the electrons as strongly (it is __________________)  the ________________in the ___________ are not as _____________ so no _________________ is created.  This molecule therefore is ____________ or __________________ (water fearing) and _______________.

carbon; not; less electronegative; electrons; hydrogen; attracted; partial charge; nonpolar; hydrophobic; insoluble

Because ___________________ is ______________________ it attracts the _________________  so hydrogen’s protons _________ exposed creating a partial ____________________ charge.  This molecule is therefore ____________ and will be ______________________ and ______________________. 

nitrogen; more electronegative; hydrogen electrons; are; positive; polar; hydrophilic; soluble

(Ionically Bonded Molecules)

Because electrons are ________________ in this molecule, it becomes ____________________ (which is even more than just ________________).  These molecules will therefore both _______________ and ____________________.

transferred; fully charged +/-; partially charge; soluble, hydrophilic

Hydrophobic molecules are

uncharged and nonpolar; bonded covalently w/low electronegative atoms

Hydrophilic molecules are

charged and or polar; bonded ionically or covalently w/elements of high electronegativity

pH

negative logarithm of H⁺ concentration that a substance makes as it dissociates in solution

Acids

molecules that release an excess of H⁺ hydrogen ions when they dissociate in solution

Bases

molecules that release an excess of OH^- ions when they dissociate in solution

Neutral (7)

H+ = OH-

Buffers

Compounds that can both absorb and release H⁺ so that pH remains relatively constant

Buffers example

CO₂ in blood creates a buffer to prevent pH changes

Bicarbonate buffering system

-Add a base (take up H⁺)the buffer responds by producing more

-Add acid (releases H⁺) the buffer absorbs them 

Dehydration Synthesis

the process that allows cells to remove a hydrogen from one molecule and a hydroxyl group from another (forming water) and bond the remaining subunits together 

(Dehydration synthesis)

monosaccharide + monosaccharide →

di- and polysaccharides + water

(Dehydration synthesis)

amino + amino→

Polypeptides & larger proteins + water

(Dehydration synthesis)

glycerol + 3 fatty acids →

Triglyceride + 3 water

Hydrolysis

the process of inserting a hydrogen and hydroxyl group into a pre-existing bond to break the two sub-units apart

(Hydrolysis)

di- and polysaccharides + water →

monosaccharide + monsaccharide

(Hydrolysis)

polypeptides & larger proteins + water →

amino acid + acid

(Hydrolysis)

triglyceride + 3 water

glycerol + 3 fatty acids

Carbohydrates types

Monosaccharides, disaccharides, polysaccharides

Monosaccharides (one sugar) functions

-Ready energy due to many C-H bonds 

-Rapidly available- monos don’t need hydrolysis to get to blood

-Transport sugar in animals due to –OH groups which are polar so dissolve readily in blood 

Isomers

molecules with same molecular or empirical formula but different structural formula

Monosaccharides examples

Glucose or galactose; fructose

Disaccharides (two sugars) functions

Transportation of sugars in plants because of a lot of –OH groups w/ high electronegative O that makes molecules polar so they will dissolve in water

Disaccharides examples

Glucose+fructose=sucrose

Glucose+glucose=maltose (boned by dehydration synthesis)

Polysaccharides (many sugars) functions

-Storage – polys can be retrieved later because alpha glucose forms linkage that enzymes can digest

-Structural – can’t be broken down and used for energy because it is made of beta glucose that have bond angles you can’t digest

Polysaccharides examples

Amylose (plants), glycogen (animals), cellulose (plants), chitin (exoskeletons of anthropods/fungi)

Amylose & glycogen are

Digestible – made of alpha glucose isomers form 1-4 linkage that can digest

Cellulose & chitin

Indigestible- made of beta glucose isomers that you can’t digest

Lipids

All are long chains of C-H bonds, so they are nonpolar & hydrophobic

Lipids types

Triglyceride, phospholipids, terpenes, prostaglandins, steroids

Triglyceride functions

-Long term storage because many C-H bonds

-Saturated – no double bonds, lie flat. Solid fats – animal fats

-Unsaturated – double bond kink fatty acids – won’t be flat so stay liquid – plant oils

Triglyceride examples

fats & oils

Glycerol

3 carbon alcohol

3 Fatty Acids

Long chain of C w/H

Phospholipids functions

Cell membrane – barrier to entrance into the cell by charged or water soluble because lipids are nonpolar (hydrophobic exclusion)

Outside cell

hydrophilic

Fatty acids

hydrophobic

Inside cell

hydrophilic

Terpenes functions

Pigments like chlorophyll – tail acts as anchor that holds polar chlorophyll to membrane inside chloroplast (in order to gather maximum amount of light)

Terpenes examples

non-polar tails, long chains of carbons with methyl groups

Prostaglandins functions

-Stimulate smooth muscle

-Vasodilatation

-Uterine contraction

-Affect wide range of cells b/c soluble in membranes

Prostaglandins examples

Ring with long chain of carbons

(Don’t need membrane receptors because they are soluble in the cell membrane – so they can affect a wide range of cells)

Steroids functions

-Add flexibility to cell membrane in cold conditions 

-Affect wide range of cells b/c soluble in membranes

Steroids examples

-Cholesterol (which is made into reproductive hormones like estrogen and testosterone)

(Don’t need membrane receptors because they are soluble in the cell membrane – so they can affect a wide range of cells)

Peptide Bonding

between amino acids

Peptide bond

C-N-C

Primary

sequence of amino acids varies as coded in DNA

Secondary

folding due to H-bond between polar groups on amino acids; two patterns of H bonding

Two types of secondary folding

Beta pleated sheet & alpha helix

beta pleated sheet

2 parallel strands, bonds form across strands

alpha helix

single strand spirals, H bonds form above and below

Motif

describes protein secondary structure – alpha, alpha, beta etc.

Tertiary

occur when protein interacts with water – hydrophobic R-groups fold to inside and hydrophilic R-groups go to outside