Biology Grade 12

Intramolecular bonds

bonds between atoms of the same molecule

3 types of intramolecular bonds

covalent, polar covalent, and ionic

Covlent bonds

share valence electrong between two non-metals, electronegative less than 0.4

Polar Covalent bonds

valence electrons are shared unequally between two non-metal atoms, electronegativity between 0.4 and 1.8

Ionic bonds

transfer of an electron from a metal to a non metal, electronegativtiy above1.8

Hydrogen bonding

weak intramolecular bond between a slightly positive hydrogen of one molecule and a slightly negative atom of a different molecule

Cohesion

intermolecular attraction between water bonding molecules

Adhesion

intermolecular attraction between water and polar or ionic substances

Capillary Action

Adhesion plus cohesion, the flow of liquid through narrow spaces defying gravity

Water properties

hydrogen bonding, universal solvent, high specific heat capacity, surface tension, density

Water as the universal solvent

water dissolves polar and ionic molecules due to its polarity

Water’s high specific heat capacity

for water to increase in temperature, water molecules must be made to move faster within the water; requires breaking of hydrogen bonds which requires heat

Surface tension

water forms strong bonds with other water, the top molecules repel the non-polar air, the top layer becomes more dense than the water below

Water’s density

ice is less dense then water because when water freezes it crystalizes the space between molecules so each molecule is hydrogen bonded to 4 other molecules

Molecule

2 or more atoms joined by chemical bonds

Macromolecule

large polymer made up of repeating units

Monomer

repeating unit

monomer of carbohydrate

monosaccharides

monomer of protiens

amino acids

Monomer of nucleic acids

nucleotides

Monomer of lipids

not polymers because not made of repeating units

Dehydration synthesis

removal of water to add monomer units

Hydrolysis

addition of hydroxide and hydrogen groups of water to b reak bond between monomers

Primary structure of protien

chain of amino acids

Protien structure

amino group, alpha carbon, carboxylic acid group, “R” group

Polarity of protien

determined by R group

Four levels of protien structure

primary (sequence), secondary (coiling by H bonding), tertiary (folding by R-group interactions), and quaternary (two or more chains)

Polarity and size of lipids

non-polar and large

Polarity and size of carbohydrates

polar, monosaccharides and disaccharides are small

polarity and size of nucleic acids

polar and large

Main function of carbohydrates

energy source

main function of proteins

speeding up chemical reactions and cell movements

main functin of nucleic acids

genetic information

main function of lipids

energy storage

elements of carbohydrates

carbon, hydrogen, and oxygen

elements of proteins

carbon, hydrogen, oxygen, and nitrogen

elements of nucleic acids

carbon, hydrogen, oxygen, nitrogen, and phosphorus

elements of lipids

carbon, hydrogen, and oxygen

fatty acids

used for cellular functions and energy storage

saturated fats

made of saturated fatty acids with single bonds in their hydrocarbon chain, solid at room temperature, linear, and derived from animals

unsaturated fats

made of unsaturated fatty acids with double bonds in their hydrocarbon chains, liquid at room temperature, bent, and derived from plants

triglyceride

a fat, three fatty acid chains linked to a glyerol molecule

DNA

stands for dioxyribose nucleic acid. polymer made of repeating nucleotides

nucleotide structure

phosphate group, sugar, and nitrogenous base

two categories of nitrogenous bases

purines and prymidines

Purines

adenine and guanine, double ring structures

Prymidines

thymine (uracil) and cytosine, one ring structure

DNA base bonds

Adenine bonds to Thymine (or Uracil in RNA), Guanine bonds to ctyosine

DNA vs RNA

DNA: single stranded, has thymine, uses deoxyribose

RNA: single stranded, has uracil, uses ribose

Enzymes

protiens (end in ase)

enzyme function

speed up chemical reactions

Enzyme substrate complex

enzyme and substrate

How enzymes work

substrate binds to activ site of enzyme, reaction occurs, products are released, enzyme is ready for another reaction

Other molecule catalysts

cofactors and coenzymes

cofactors

non protein molecules or inorganic ions

coenzymes

organic cofactors

Factors affecting enzyme activity

substrate concentration, enzyme concentration, temperature, and pH

How substrate concentration affects enzyme activity

increased concentration means more chances of finding an active site, more product is made

How enzymme concentration affects enzyme activity

increased concentration of enzymes means more active sites and increased enzyme activity

How temperature affects enzyme activity

increased temperature means more particle movement, if the temperature becomes too high the hydrogen bonds break, the enzyme denatures and the active site no longer exists

How pH affects enzyme activity

enzymes require a specific pH to function

Enzyme regulation

competitive inhibition, non-competitive inhibition, and feedback inhibition

Competitive inhibition

prevents product from being made by physically blocking the active site

Non-competitive inhibition

inhibitior binds to an allosteric site (not active site)

Feedback inhibition

product is the inhibtior, binds to allosteric site and changes the shape of the enzyme so no more product can be formed

Cell membrane function

control traffic in and out of the cell

Cell membrane structure

selectively permable, made of phospholipids, proteins, and other macromolecules arranged as a bilayer

selectively permable

allows some substances to cross more easily than others

phospholipid structure

made of non-polar fatty acid tails and polar phosphate group head

membrane fat composition

fat percentage affects flexibility of membrane the membrane must be flexible for function

Ways to change flexbility of membrane

percent of fatty acids (more = more liquid) and amount of cholesterol in membrane (more=less liquid)

Membrane protiens

protien determines membrane function, 3 types: peripherol proteins, integral proteins, and transmembrane proteins

peripheral proteins

loosely bound to surface of membrane, cell surface identity marker (antigen), hydrophilic

integral proteins

penetrate lipid bilayer, hydrophobic

transmembrane protein

specific type of intergal protein, transport proteins, both hydrophobic and hydrophilic

Functions of membrane proteins

transporter, enzyme activity, cell surface receptor, cell surface identity marker, cell adhesion, and attachment to the cytoskeleton

Membrane carbohydrates

play a keep role in cell-cell recognition, basis for rejection of foreign cells by immune system

cell-cell recognition

ability to distinguish one cell from another

Passive transport

no energy required, movement from high to low concentration

Types of passive transport

diffusion and facilitated diffusion

Simple diffusion

movement of small particles across a selectively permable membrane until equilibrium is reached, high to low concentration, no energy

Molecules that can pass through membrane in diffusion

lipids, oxygen, and carbon dioxide

Molecules that can’t pass through membrane in diffusion

polar moleculs, ions, sats, and larger molecules

Facilited diffusion

diffusion through protein channels (diffusion with help)

Channels through cell membrane

membrane becomes semi-permable with protein channels, specific channels alow specific materials across

Active transport

cells may need to move molecules against concentration gradient (low to high), shape change transports solute from one side of membrane to other, uses energy

Moving large molecules

done using endocytosis and exocytosis

Endocytosis

bringing large molecules into the cell

Types of endocytosis

phagocytosis (cellular eating) and pinocytosis (cellular drinking)

Exocytosis

a cell expels waste from a vacuole

Concentraion of water

direction of osmosis is determined by comparing total solute concentration; hypertonic, hyptonic, isotonic

Hypertonic

more solute, less water

Hypotonic

less solute, more water

Isotonic

equal solute, equal water

Osmosis

diffusion of water from high concentration of water to low concentraon of water

Animal cell in hyptonic solution

water enters cell, cell lyseed

animal cell in isotonic solution

water equally enters and exits cell, cell normal

anima cell in hypertonic solution

water leaves cell, cell shrivels

plant cell in hyptonic solution

water enters cell, cell is turgid (normal)

plant cell in isotonic solution

water equally enters and exits cell, cell is flaccid