BIO Test 1

atomic number

number of protons in the nucleus of an atom

valence electron

an electron in the outermost electron shell

ionic bonds

a chemical bond resulting from the attraction between oppositely charged ions

surface tension

a measure of how difficult it is to stretch or break the surface of a liquid

electronegativity

attraction of an atom for the electrons of a covalent bond

buffer

a substance that minimizes changes in the concentrations of H+ and OH- in a solution

enantiomers

mirror images of each other and differ in shape due to the presence of an asymmetric carbon

structural isomer

differ in the covalent arrangement of their atoms

nucleotide

building blocks of nucleic acids consisting of a pentose, a nitrogenous base, and phosphate groups

ester linkage

bond between hydroxyl and carboxyl groups

peptide bond

covalent bond between the carboxyl group on one amino acid and the amino acid group on another, formed by a dehydration reaction

plasmodesmata

cytoplasm that passes through the cell walls of adjacent plant cells and allows communication between them

endosymbiosis theory

states that mitochondria and plastids originated as prokaryotic cells engulfed by a host cell, which then evolved into a single organism

scanning electron microscope

a microscope that uses an electron beam to scan the surface of a sample, coated with metal atoms, to study details of its topography

transmission electron microscope

a microscope that passes an electron beam through very thin sections stained with metal atoms to study the internal structure of cells

what four elements make up 96% of living matter?

carbon, oxygen, hydrogen, nitrogen

radioactive isotopes

unstable - the nucleus decays spontaneously, giving off particles and energy

examples of radioactive isotopes

when carbon-14 decays, a neutron decays into a proton and the atom transforms into a nitrogen atom (also radioactive tracers as tools in medicine)

what is the difference between an essential element and a trace element?

essential elements are required by living organisms in large amounts, while trace elements are required by living organisms in minute amounts

trace element examples

iron, iodine, zinc

potential energy

energy that matter possesses because of its location or structure

which has more potential energy: an electron in the first energy shell or an electron in the third energy shell?

third energy shell because the more distant an electron is from the nucleus, the greater its potential energy

which subatomic particle determines the atom’s identity?

protons

which subatomic particle is directly involved in chemical reactions between atoms?

electrons

nonpolar covalent bonds

two atoms with a similar electronegativity share electrons equally

polar covalent bonds

two atoms that differ in electronegativity do not share electrons equally

why is water considered a polar molecule?

the oxygen molecule has a partial negative charge and the hydrogen molecules have partial positive charges, resulting in unequal sharing of electrons

what is the importance of stanley miller’s experiment?

he identified a variety of organic molecules and supported the idea of abiotic synthesis of organic compounds

what unique feature of carbon allows it to support life on earth?

it can form diverse molecules by bonding to four other atoms, enabling the formation of large, complex molecules

what property of lipids makes them hydrophobic?

their molecular structure, which consists mostly of nonpolar hydrocarbons (nonpolar molecules are hydrophobic)

disaccharide

double sugar consisting of two monosaccharides joined together by a glycosidic linkage formed by a dehydration reaction

examples of disaccharides and their monosaccharides

maltose (glucose), sucrose (glucose and fructose), lactose (glucose and galactose)

what makes different hormones have different effects on the human body?

the different functional chemical groups attached to the carbon skeleton

dehydration reaction

two molecules are covalently bonded to each other with the loss of a water molecule

hydrolysis

chemical reaction that breaks bonds between two molecules by the addition of water

saturated fatty acids

fatty acids in which all carbons in the hydrocarbon tail are connected by single bonds

unsaturated fatty acids

fatty acids that have one or more double bonds between carbons in the hydrocarbon tail (creating a kink in the hydrocarbon chain)

what is the monomer of carbohydrates?

monosaccharides

what is the monomer of lipids?

fatty acids

what is the monomer of proteins?

amino acids

what is the monomer of nucleic acid?

nucelotides

hydroxyl functional group

OH

carbonyl functional group

CO (double bond)

carboxyl functional group

COOH

amino functional group

H2N

sulfhydryl functional group

SH

phosphate functional group

PO4

methyl functional group

CH3

RNA

directs protein synthesis and gene regulation

DNA

directs RNA synthesis and provides directions for its replication

differences between RNA and DNA

the nucelotides in RNA are made up of ribose and the nucleotides in DNA are made up of deoxyribose, DNA is generally double-stranded and RNA is generally single-stranded

primary structures of proteins

linear sequences of amino acids (determine protein shape)

secondary structures of proteins

regions of repetitive coiling or folding of the polypeptide backbone, including alpha and beta pleated sheets

what causes the formation of secondary structures of proteins?

hydrogen bonds between the repeating constituents of the polypeptide backbone

tertiary structures of proteins

three-dimensional shapes stabilized by interactions between side chains

what causes the formation of the tertiary structures of proteins?

hydrophobic interactions among the side chains

prokaryotic cells

distinct cells in bacteria and archaea

eukaryotic cells

distinct cells in eukarya, such as plants and animals

differences between prokaryotic and eukaryotic

prokaryotic cells do not have membrane-bound organelles and eukaryotic cells do have membrane-bound organelles, most DNA in prokaryotic cells is located in the nucleoid and most of the DNA in eukaryotic cells is located in the nucleus

structures in both prokaryotic and eukaryotic cells

plasma membrane, cytosol, chromosomes, ribosomes

structures unique to plant cells

chloroplasts and cell walls (mitochondria in both)

rough endoplasmic reticulum function

protein synthesis

smooth endoplasmic reticulum function

lipid synthesis

golgi apparatus function

post office

lysosome function

digestion

peroxisome

oxidation

mitochondria

cellular respiration (energy conversion)

chloroplasts

photosynthesis (capture light energy)