AP Biology Units 1-4

Covalent bond

a bond between atoms in which the electrons between the atoms are shared

Ionic bond

a bond between atoms that involves a transfer of valence electrons from the less electronegative atom to the more electronegative atom

Nonpolar covalent bond

A covalent bond in which the two atoms equally share the electrons

Polar covalent bond

A covalent bond in which two atoms unequally share the electrons

Electronegativity

The ability of an atom to attract electrons

Hydrogen bond

The intermolecular electrostatic attraction that occurs between a hydrogen atom that is bonded to a more electronegative atom (NOF) on a different molecule

Adehesion

The attraction of a water molecule to a different type of (hydrophilic) molecule

Cohesion

The attraction of a water molecule to another water molecule

Capillary action

The movement of water up a narrow tube because of its adhesive and cohesive properties. Important in the movement of water up the xylems of plants

Specific heat

The quantity of heat required to raise the temperature of one gram of a substance one degree C. Water has a very high specific heat, which leads to the ability of sweat to provide a cooling function and the ability of large bodies of water to stabilize climate

Density of ice

Because of water's ability to form hydrogen bonds, the crystalline structure of ice takes up more volume than an equivalent mass of liquid water; therefore, the density of ice is less than the density of liquid water, and ice floats

Solvent

The liquid in which a solute is dissolved to form a solution. The solvent is the most prevalent material in a solution. Water's ability to form hydrogen bonds makes it a good solvent for both ions and polar molecules

Solute

The solid, liquid, or gas dissolved in a solute to make a solution. One solution may have multiple solutes

Surface tension

The tension in the surface of a liquid caused by its cohesive properties. Water has a high surface tension due to hydrogen bonds

CHONPS

carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur

Organic molecules

Chemical compounds in which one or more atoms of carbon are covalently bonded to atoms of other elements

Carbohydrates

A sugar molecule or polymer of sugar molecules used primarily for energy or to give structure to living organisms (CHO). Monomer is monosaccharide such as glucose or fructose. Polymer is polysaccharide (glycogen, cellulose)

Disaccharide

Two sugar monomers that are connected via glycosidic linkage (ex: sucrose)

Glycogen

A polysaccharide formed from multiple glucose monomers that is used for energy storage in animals

Starch

A polysaccharide formed from multiple glucose monomers that is used for energy storage in plants

Cellulose

A polysaccharide formed from multiple glucose monomers connected with a very sturdy beta glycosidic linkage that is used for structural support in plant cells

Lipids

Biological molecules that are largely nonpolar and include fatty acids, steroids, and phospholipids. Functions include energy storage, insulation, cell signaling, and membrane structure

Fatty acids

A lipid with a long carbon chain attached to a carboxylic acid group. Nonpolar and support plasma membrane structure. Can be saturated (H attached to C in all available places) or unsaturated (double bonded C, causes kink in structure)

Polypeptide

A chain of amino acids. Amino acids consist of a central carbon with a carboxyl group, amino group, and an R group. R group determines amino acid properties. Can fold based on charge, polarity, or affinity to water

Primary structure

sequence of amino acids in a polypeptide chain

Secondary structure

arrangement of amino acids in a polypeptide chain driven by hydrogen bonding between the amino acids in the polypeptide chain. Form alpha helices and beta sheets

Tertiary structure

Driven by interactions between R groups in a polypeptide chain. Can include hydrophobic interactions, hydrogen bonding, or disulfide bridges

Quaternary structure

Interactions between protein subunits (ex: hemoglobin and collagen)

Denatured

A protein that has been changed in shape to the point it can no longer function. Due to temperature or pH

Nucleic acids

molecules that can store or transmit genetic information and contain a sugar-phosphate backbone and nitrogenous bases. Monomer is nucleotides.

DNA vs. RNA

DNA: deoxyribose (H), ACGT, located in nucleus, double helix structure, greater stability

RNA: ribose (OH), ACGU, located in nucleus and cytoplasm, single stranded, lower stability

Amphipathic

describes molecules such a phospholipids that have both polar and nonpolar components

Glycolipids

lipids with added carbohydrate groups. Function in cell recognition

Glycoproteins

proteins with added carbohydrate groups. Function in cell recognition

Steroids

Function as ligands in cell signaling. Cholesterol is a steroid that can help regulate the flexibility of cell membranes

Purines

A type of nitrogenous base that contains two fused hydrocarbon rings. Adenine and guanine

Pyrimidines

A type of nitrogenous base that contains one hydrocarbon ring. Cytosine, thymine, and uracil

Components of prokaryotic cells

cytosol, plasma membrane, cell wall, capsule, pili, ribosomes, genetic material. NO membrane-bound organelles

Components of eukaryotic cells

cytosol, plasma membrane, ribosomes, genetic material, nucleus, membrane bound organelles

Ribosomes

contain rRNA and are responsible for translation of proteins from the mRNA transcript

Plasma membrane

made of a phospholipid bilayer in which various proteins are embedded. control what enters and exits the cell

nucleus

the membrane-enclosed organelle that contains the genetic material of the cell. also includes the nucleolus where ribosomes are synthesized.

Nucleoid

A dense region of DNA in a prokaryotic cell.

rRNA

makes up ribosomes

Rough ER

contains ribosomes and functions in protein synthesis. part of the endomembrane system

Smooth ER

does not contain ribosomes and functions in lipid synthesis, Ca2+ storage, and cell detoxification

Golgi complex

a stack of small membranous sacs that functions in the packaging and modifications of proteins in a cell. usually located close to the ER

Lysosomes

vesicles that contain hydrolytic enzymes. function in digestion, apoptosis, and the destruction of pathogens within the cell

Vacuoles

Vesicles in the cell that serve a storage function. In plant cells, the central vacuole stores water and can give a plant cell its rigidity. Other vacuoles can store food or other material for a cell

Mitochondria

where cellular respiration occurs. Outer membrane and inner membrane with cristae (folds). Matrix is inside the inner membrane, intermembrane space is between the membranes. synthesizes ATP. Have their own DNA and ribosomes, reproduce on their own

Chloroplasts

where photosynthesis occurs. outer membrane, inner membrane, thylakoids (light dependent), stroma (light independent). have their own DNA and ribosomes. reproduce on their own

Centrosomes

cellular structures made of microtubules that help organize the spindle fibers during cell division

amyloplasts

plastids in plant cells that store glucose polymers as starch

peroxisome

an organelle found in eukaryotic cells that contains peroxidase and other hydrolytic enzymes that break down toxins in the cell

Cytoskeleton

The network of filaments and fibers that give a cell its shape and can be used to move items throughout the cell. Includes microtubules, intermediate filaments, and actin filaments

Cilia/flagella

Cellular appendages specialized for locomotion

Endosymbiosis theory

The theory that the first organelles were originally independent living cells that formed symbiotic relationships with larger cells. For example, mitochondria may have been smaller prokaryotic cells that could produce ATP. These smaller cells were engulfed by larger cells, which provided protection for the smaller cells and ATP for the larger cells. Evidence includes mtDNA and cpDNA, as well as that mitochondria and chloroplasts have their own ribosomes, which resemble prokaryotic ribosomes

Compartmentalization

The division of cellular function among different organelles, allowing each organelle to perform its function more efficiently than if the molecules involved in that function were free-floating in cytosol. Adds more surface area for more reactions and allows separate environments (ex: lysosomes with a low pH)

Surface area to volume ratio

The surface area of a cell divided by its volume. Cells with larger surface area to volume ratios can exchange materials more efficiently with their environments than cells with smaller surface area to volume ratios.

Phospholipid bilayer

A double layer of amphipathic phospholipids that forms the plasma membrane. The hydrophobic lipid portions of the phospholipids are found in the interior of the plasma membrane, and the hydrophilic phosphate portions are found on the inner and outer surfaces of the plasma membrane, in contact with the aqueous environments outside the cell and in the cytosol

Fluid mosaic model

A way of describing the structure of the plasma membrane in which the plasma membrane consists of a phospholipid bilayer in which proteins with various functions are embedded. In the plasma membrane, the proteins can move to suit the changing needs of the cell and are, therefore, fluid

Aquaporins

Specialized protein channels in the cell membrane through which the passage of water can occur

Cell wall

The relatively rigid layer of carbohydrates surrounding the cell membrane in plant, bacterial, and fungal cells. The composition of cell walls gives cells extra support

Diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration. No energy is required, so it is a form of passive transport

Osmosis

Movement of water from areas of higher water potential to areas of lower water potential

Passive transport

Movement of molecules down their gradient that does not require energy

Active transport

Movement of molecules against their gradient that requires the input of energy

Sodium-potassium pump (Na/K pump)

A protein in the cell membrane involved in the active transport of sodium and potassium ions against their concentration gradient. Three sodium ions are pumped out of the cell for every two potassium ions pumped into the cell, resulting in a difference in membrane potential

Facilitated diffusion

Passive transport o f a molecule that requires a protein of channel. The rate of facilitated diffusion is limited by the number of transport channels available

Cotransport

Transport of a molecule against the concentration gradient by coupling its movement with the movement of a different molecule down its gradient. Symport = same direction, Antiport = different directions

Isotonic

Two solutions have the same solute concentration

Hypertonic

A solution has a higher solute concentration relative to another solution. Have low water potentials. Shriveled red blood cell or plasmolyzed plant cell

Hypotonic

A solution that has a lower solute concentration relative to another solution. Have high water potentials. Lysed red blood cell or turgid plant cell

Water potential

The potential energy of water in a solution. The higher the concentration of water in a solution, the greater its water potential. Water tends to move away from high water concentrations and towards low water concentrations. Sum of pressure potential and solute potential

Solute potential

The water potential that is due to the concentration of solutes in a solution. -iCRT. i is ionization constant of solute, C is solute concentration, R is pressure constant, and T is temperature. The solute potential of distilled water is 0 bars

Pressure potential

The hydrostatic pressure of water in a solution. In solutions in open containers in equilibrium with the atmosphere, pressure potential is 0 bars

Ionization constant

The number of particles or ions a molecule forms when dissolved. Most covalent compounds have an ionization compound of 1, whereas ionic salts often have more (KCl has an i of 2)

Osmolarity

The concentration of total solutes in a solution. Solutions with a higher osmolarity have a lower water potential. Solutions with a lower osmolarity have a higher water potential

Contractile vacuole

A specialized type of vacuole found in some freshwater protozoan that pumps excess water out of the cell

Coenzymes

Organic molecules that bind to enzymes and enhance the efficiency of enzymes. Many vitamins function as coenzymes.

Endergonic

Describing a chemical reaction in which the free energy of the products of the products is greater than the free energy of the reactants. Considered energetically unfavorable

Exergonic

Describing a chemical reaction in which the free energy of the products is lower than the free energy of the reactants. Considered energetically favorable

Activation energy

The minimum amount of energy required to energize the reactants to a transition state from which a chemical reaction can occur. The higher the activation energy, the slower the rate of the chemical reaction

Coupled reaction

A pair of chemical reactions in which the energy released from an exergonic reaction is used to drive an endergonic reaction

Heterotrophs

Organisms that obtain energy and nutrients from other organisms

Autotrophs

Organisms that can produce organic molecules from inorganic molecules using energy from photons or from other inorganic molecules

Photoautotrophs

Autotrophs that use photons of light energy to construct complex organic molecules from inorganic molecules

Chemoautotrophs

Autotrophs that use energy from inorganic chemical reactions to construct complex organic molecules from inorganic molecules

Light-dependent reactions

The series of chemical reactions in photosynthesis that requires photons of light energy and produces ATP, NADP, and O₂. Occur on the thylakoid membrane

Light-independent reactions

The series of chemical reactions is photosynthesis that uses ATP, NADPH, and CO₂ to produce G3P. Occure in the stroma

Photophosphorylation

The use of photons of light to excite electrons and build proton gradients, which can be used by ATP synthase to generate ATP

Chlorophylls

The major light-absorbing pigments in green plants used in photosynthesis. Absorb specific wavelengths of light energy to excited electrons that power the light-dependent reactions of photosynthesis

Accessory pigments

Minor pigments in photosynthesis that capture light energy from wavelengths of light different from those wavelengths from which chlorophyll captures light energy. Examples include xanthophylls and carotenes

Photosystems II and I

Complexes of light-absorbing pigments and proteins that absorb photons at 680 nm and 700 nm of light (red and blue, reflects green) to excite electrons that power the light-dependent reactions of photosynthesis

Photolysis

The use of photons of light energy to split water molecules into molecular oxygen, electrons, and protons in photosynthesis

Chemiosmosis

The use of proton gradients and the enzyme ATP synthase to generate molecules of ATP

ATP synthase

The enzyme that catalyzes the formation of ATP using a proton gradient

NADP⁺ reductase

The enzyme that catalyzes the reduction of NADP⁺ to NADPH during the light-dependent reactions of photosynthesis

Carbon fixation

The first part of the calvin cycle in which inorganic CO₂ is added to the five-carbon molecule RuBP to form a six-carbon intermediate

Reduction (calvin cycle)

The second part of the calvin cycle in which ATP and NADH from the light-dependent reactions are used to produce the three-carbon molecule G3P, which is a building block of organic molecules