ap bio unit `1

what elements make up most (96%) of living matter?

carbon, hydrogen, oxygen, nitrogen

covalent bond

sharing of a pair of valence electrons by 2 atoms

electronegativity

atom's attraction for the electrons in a covalent bond

polarity

unequal sharing of electrons

chemical bonds

the attractive forces that hold atoms together

hydrogen bond

A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule (usually nitrogen or oxygen)

van der waals interactions

attractions between molecules that are close together as a result of asymmetrically distributed electrons accumulating in a part of a molecule by chance

why is structure of water important?

allows it to interact with other molecules

what allows water molecules to form hydrogen bonds with each other?

polarity

why is water polar?

electrons of the polar covalent bonds spend more time near oxygen than the hydrogen due to oxygen's electronegativity, giving oxygen a partial negative charge

what makes water able to facilitate an environment for life?

cohesive behavior

ability to moderate temperature

expansion upon freezing (less dense)

versatility as a solvent

cohesion

hydrogen bonds holding water molecules together, helps for transport against gravity in plants by leading them to stick together

adhesion

attraction between different substances

in case of plants, between water and plant cell walls

surface tension

measure of how hard it is to break surface of a liquid

water has a high surface tension due to its hydrogen bonds at surface between air and water

temperature moderation in water

absorbs heat from warmer air and releases it to cooler air due to its high specific heat

specific heat

amount of heat that must be absorbed or released for 1g of the substance to change its temperature by 1 celsius

water - 1 cal/g/C

Why does water have a high specific heat?

hydrogen bonds

evaporative cooling

helps stabilize temperatures in organisms and bodies of water

do substances less dense than water float or sink?

float (ex: ice)

why is water a versatile solvent?

polarity

hydrophobic

no affinity for water

hydrophilic

affinity for water

organic compound

compound containing carbon

macromolecules

carbohydrates, lipids, proteins

why is carbon so versatile?

has 4 valence electrons which can form covalent bonds with many different elements

carbon's most frequent partners (building code of living molecules)

hydrogen, oxygen, and nitrogen

hydrocarbon

An organic molecule consisting only of carbon and hydrogen.

functional groups

the components of organic molecules that are most commonly involved in chemical reactions

what gives molecules unique properties

The number and arrangement of functional groups

atp

(adenosine triphosphate) main energy source that cells use for most of their work

polymer

A long molecule consisting of many similar or identical monomers linked together.

monomers

building blocks of polymers

dehydration synthesis (condensation reaction)

a chemical reaction in which two or more molecules combine resulting in the loss of a water molecule

hydrolysis

A chemical process that splits a molecule by adding water.

enzymes

Proteins that speed up chemical reactions

carbohydrates

sugars and polymers of sugars

monosaccharides

simple sugars (glucose, fructose, galactose)

Polysaccharides

Carbohydrates that are made up of more than two monosaccharides

glucose

C6H12O6, most common monosaccharide

what do monosaccharides serve as

major fuel for cells and material for building molecules

disaccharide

A double sugar, consisting of two monosaccharides joined by dehydration synthesis.

glycosidic linkage

A covalent bond formed between two monosaccharides by a dehydration reaction.

roles of polysaccharide

storage and structure

what determines structure and function of polysaccharides?

sugar monomers, position of glycosidic linkages

starch

A storage polysaccharide in plants consisting entirely of glucose.

glycogen

storage polysaccharide in animals, stored in liver and muscle cells by humans

cellulose

polysaccharide consisting of glucose monomers that reinforces plant-cell walls

chitin

structural polysaccharide found in exoskeleton of arthropods and cell wall of many fungi

lipids

Energy-rich organic compounds, such as fats, phospholipids, and steroids, that are made of carbon, hydrogen, and oxygen.

main feature of lipids

hydrophobic

why are lipids hydrophobic

consist mainly of hydrocarbons which have nonpolar covalent bonds

important types of lipids

fats, phospholipids, steroids

makeup of fats

glycerol and fatty acids

glycerol

a three-carbon alcohol with a hydroxyl group attached to each carbon

fatty acid

carboxyl group attached to long carbon skeleton

triglyceride

a lipid made of three fatty acid molecules and one glycerol molecule

Why do fats separate from water?

because water molecules form hydrogen bonds with each other and exclude the fats

What joins the glycerol and fatty acid molecules?

ester linkages

saturated fatty acid

max number of hydrogen atoms possible and NO DOUBLE BONDS, solid at room temp

unsaturated fats

ONE or MORE double bonds, liquid at room temp

major function of fats

energy storage

phospholipid makeup

glycerol, 2 fatty acids, and a phosphate group

fatty acid tails hydrophobic, phosphate group and its attachment form hydrophobic head

major part in cell membrane

steroids

lipids characterized by a carbon skeleton consisting of four fused rings

cholesterol

important steroid found in animal cell membranes

protein functions

defense, storage, transport, cellular communication, movement, structural support

catalysts

speed up chemical reactions without being consumed

polypeptides

unbranched polymers built from the same set of 20 amino acids

protein

biologically functional molecule consisting of one or more polypeptides, contains carbon, hydrogen, oxygen, nitrogen

amino acids

organic molecules with carboxyl and amino groups

R groups

groups that give different amino acids different properties

peptide bonds

link amino acids

carboxyl end, C-terminus

The end of a polypeptide chain that has a free carboxyl group.

amino end, N-terminus

end of polypeptide chain with a free amino end

protein's structure determines

function

4 stages of proteins

primary, secondary, tertiary, quaternary (occurs when protein is made of 1+ polypeptide chain)

primary structure

unique sequence of amino acids

secondary structure

coils and folds in polypeptide chain which form alpha helices and beta pleated sheets

tertiary structure

the overall, three-dimensional shape of a polypeptide due to interactions of R groups

quaternary structure

results from interactions between multiple polypetide chains

slight change in primary structure does what

affects protein structure and function

sickle cell disease

results from single amino acid substitution into hemoglobin

denaturation

loss of a protein's native structure, biologically inactive

what can lead to a protein to unravel

pH changes, salt concentration, temperature

x-ray crystallography

determines 3d protein structure

gene

sequence of DNA that codes for amino acid sequence of polypeptide

nucleic acid

macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

2 types of nucleic acids

deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)