unit 1 biology

12th grade ap biology

qualitative

observations with senses

quantitative

measured using instruments

inductive reasoning

derive generalizations based on a large number of specific observations (general)

deductive reasoning

specific results are derived from general premises (specific)

hypothesis

- predictions that can be tested by recording more observations or experiments
- if, then, because statement
- if: independent variable
- then: dependent variable
- because: explanation
- results can support or refute hypothesis

null hypothesis

- H₀
- researcher tries to disprove, reject, or nullify
- start with this one

alternative hypothesis

- H₁, H₂, etc.
- normal "if then because" statement

control groups

- helps eliminate experimental errors and biases of researchers
- positive and negative control

positive control

ensures that there is an effect when there should be an effect

negative control

nothing is expected to happen (placebo or water)

essential elements

carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur

trace elements

required in very small quantities

covalent bonds

- two or more nonmetal atoms share electrons
- single, double, and triple bond
- nonpolar and polar covalent

nonpolar covalent

electrons are shared equally between two atoms

polar covalent

electrons are not shared equally between two atoms

ionic bonds

metal transfers electrons to nonmetal
- cation: positively charged ion
- anion: negatively charged ion

hydrogen bonds

- partially positive hydrogen atom in one polar covalent molecule will be attracted to an electronegative atom in another polar covalent molcule
- weak attraction
- h-bonds between water make it more structured than most liquids

intermolecular bond

forms between molecules

properties of water

- polarity
- cohesion
- adhesion
- capillary action
- temperature control
- density (floating ice)
- universal solvent

polarity

unequal sharing of electrons make water a polar molecule

cohesion

- attraction of molecules for other molecules of the same kind
- h-bonds increase cohesive forces
- allows for the transport of water and nutrients against gravity in plants
- responsible for surface tension

adhesion

- the clinging of one molecule to a different molecule
- allows water to cling to the cell wall to resist the downward pull of gravity

capillary action

- the upward movement of water due to the forces of cohesion, adhesion, and surface tension
- occurs with adhesion > cohesion

temperature control

water has a high specific heat due to h-bonds, which means water resists changes in temperature

importance of high specific heat

- moderates air temperature: water absorb heat during the day and release heat at night
- stabilizes ocean temperature: benefits marine life
- organisms can resist changes in their own internal temperature

evaporative cooling

- water has a high heat of vaporization (ex: sweating)
- moderates earth's climate
- stabilizes temp in lakes and ponds
- prevents terrestrial organisms from overheating
- prevents leaves from becoming too warm in the sun

density (floating ice)

as water solidifies, it expands and becomes less dense due to h-bonds

solvent

- water is a universal solvent
- solvent: dissolving agent
- solute: being dissolved
- solution: homogenous mix of 2+ substances
- "like dissolves like": water will form h-bonds with the sugar or protein to dissolve it

organic compounds

compounds that contain carbon and hydrogen

carbon

- 4 valence electrons
- can form single, double, or triple covalent bonds
- can form long chains
- shape determines function

carbon chains

- can use its valence electrons to form covalent bonds to other carbons
- hydrocarbons: organic molecules consisting only of carbon and hydrogen
- form the skeletons of most organic molecules (length, branching, double bond, presence of rings)

functional groups

chemical groups attached to the carbon skeleton that participated in chemical reactions

macromolecules

- carbohydrates, proteins, nucleic acids, lipids
- nitrogen is an important element for building proteins and nucleic acids
- phosphorus is important for building nucleic acids and some lipids

macromolecules

- polymers: chain like macromolecules of similar or identical repeating units that are covalently bonded together
- monomers: repeating units that make up polymers
- dehydration/condensation reaction
- hydrolysis

dehydration/condensation reaction

bonds two monomers with the loss of H₂O (A + B -> AB + H₂O)

hydrolysis

breaks the bonds in a polymer by adding H₂O (AB + H₂O -> A + B)

carbohydrates

- CHO
-carbonyl group and hydroxyl group (OH)
- monomer: monosaccharides
- polymer: polysaccharides
- disaccharides:two monosaccharides joined together by covalent bonds

monosaccharides

- most common: glucose (nutrients and fuel for cells, used in cellular respiration)
- can serve as building blocks for amino acids or as monomers for di & polysaccharides

disccharides

- most common: sucrose (monomers are glucose and fructose)
- plants transfer carbohydrates from roots to leaves in this form

polysaccharides

- many sugars joined via dehydration reactions
- storage: plants store starch to store excess glucose and animals store glycogen in liver and muscle cells
- structural: cellulose (tough substance that forms plant cell walls) and chitin (forms exoskeleton of arthoropods)

proteins

- CHONS
- molecule consisting of polypeptides folded into a 3D shape
- shape determines function
- monomer: amino acid
- polymer: polypeptide
- function: antibody, enzyme, messenger, structural, transport/storage

amino acids

- amino and carboxyl group and R (side chain) group
- side chains can be grouped as nonpolar (hydrophobic), polar (hydrophilic), or charged/ionic (hydrophilic)
- side chains interact, which determine the shape and function

peptide bonds

formed by positioning a carboxyl group next to an amino group of another amino acid

polypeptides

- many amino acids linked by peptide bonds
- when a polypeptide twists and folds (because of R interaction), it forms a protein

levels of protein structure

- all levels of structure determine protein's function
- primary
- secondary
- tertiary
- quaternary

primary

- linear chain of amino acids
- determined via genes
- dictates secondary and tertiary forms

secondary

coils and folds due to h-bonds within polypeptide backbone

tertiary

- 3D folding due to interactions between the side chains of the amino acids
- covalent bond formed between sulfur atoms of two cysteine monomers

quaternary

association of two or more polypeptides

nucleic acids

- CHONP
- monomer: nucleotides
- polymer: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
- function: store, transmit, and express hereditary information

nucleotides

- nitrogenous base
- five carbon sugar (pentose)
- phosphate group

nitrogenuous base

pyrimidines and purines

pyrimidines

- one ring with 6 atoms (cytosine, thymine, uracil)
- single ring

purines

- one ring with 6 atoms bonded to one ring with 5 atoms (adenine, guanine)
- double ring

five carbon sugar

- sugar is bonded to the base
- DNA: deoxyribose (without oxygen)
- RNA: ribose

phosphate group

added to the 5' carbon of the sugar to form a nucleotide

polynucleotides

- phosphate groups link adjacent nucleotides (phosphodiester linkage)
- directionality is 5' to 3'

DNA

- two polynucleotides
- double helix
- strands are antiparallel
- held together by h-bonds between bases
- adenine + thymine

RNA

- single stranded polynucleotide
- adenine + uracil

cytosine and guanine

stronger because there are more h-bonds

lipids

- CHO(P)
- monomer: glycerol and fatty acids
- polymer: no true polymer
- types: fats, phospholipids (only one with phosphorus), steroids

glycerol

- classified as an alcohol
- hydroxyl groups

fatty acids

- long carbon chains
- carboxyl group

fats

- 3 fatty acids join to a glycerol via ester linkage
- saturated: no double bond, linear, solids
- unsaturated: one or more double bonds, bent, liquids

ester linkage

bond between a hydroxyl and carboxyl group

phospholipids

- major component of cell membrane
- two fatty acids attached to a glycerol and a phosphate
- assemble as a bilayer in H₂O (tails=hydrophobic; head=hydrophilic)

steroids

lipids that have four fused rings