BIOLOGY MIDTERM ONE

matter

anything that takes up space and has mass, made up of elements

element

cannot be broken into a simpler substance

compound

substance consisting of two or more different elements in a fixed ratio eg: NaCl sodium chloride

oxygen, carbon, hydrogren, nitrogen

essential elements that make up 96% of human body

trace elements

required by living organisms in small quantities

atom

smallest unit of matter that still retains its properties

atomic nucleus

protons and neutrons at the center of the atom.

atomic number

number of protons in an atom which is unique to the element.

mass number, atomic mass

sum of number of protons and neutrons, mass number approximates the atomic mass.

isotopes

atoms with differing numbers of neutrons. an element usually a combination of different isotopes

radioactive isotope

unstable isotope where the nucleus decays spontaneously giving off particles and energy

potential energy

energy possessed because of structure or location, electrons have it given their arrangement around the nucleus

chemical behavior of an atom

depends largely on the number of electrons in the outermost shell>>>> valence shell

valence electrons

electrons in the outer shell aka valence shell

molecule

2 or more atoms joined by a covalent bond

double bond

sharing of two pairs of electrons between two atoms

electronegativity

attraction of a particular atom for the electrons of of a covalent bond.

• the greater the electronegativity the more strongly it pulls the shared pair of electrons towards itself.

nonpolar covalent bond

the electron pair is shared equally in a covalent bond because the elements have equal E-negativity

polar covalent bond

unequal sharing of the electron pair if one of the atoms is more E-neg than the other.

ion

charged ion or particle. it has either gained or lost an electron.

cation

positively charged ion

anion

negatively charged ion

ionic bond

attraction between a cation and an anion.

hydrogen bond

when water molecules are close together, their positive and negative regions are attracted to the oppositely-charged regions of nearby molecules. this is a weak interaction

Adhesion

clinging of one substance to another

surface tension

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

kinetic energy

energy of motion

temperature

measure of heat intensity and also represents the average kinetic energy of molecules.

heat transfer

heat passes from warmer to cooler substances until the two are the same temperature.

specific heat

the amount of heat that must be absorbed or lost for 1 g of substance to change temp 1 deg C

evaporation

transformation from a liquid to gas

solution

homogeneous mixture of two or more substances

solvent

dissolving agent within a solution

solute

substance that is dissolved in the solvent.

hydrophilic

any substance that has an affinity for water,

colloid

large molecules that do not dissolve in water but rather remain suspended in the aqueous solution.

hydrophobic

substances without an affinity for water, generally nonionic and nonpolar eg oil

mole (mol)

represents the exact number of objects 6.23 * 10^23.

molarity

the number of moles of solute per liter of solution

acid

substance that increases the hydrogen ion concentration of a solution.

base

substance that reduces the hydrogen ion concentration of a solution.

isomer

compounds with the same numbers of the same elements but have a different shape and therefore different properties.

light microscope

visible light passed through the specimen and then through glass lenses, which magnify the image as it is projected into the eye or into a camera.

magnification

ratio of an objects image size to its real size

resolution

measure of clarity of the image. it is the minimum distance two points can be separated but still distinguished.

contrast

accentuates differences in the parts of a sample

organelles

membrane enclosed structures within eukaryotic cells

electron microscope

focuses a beam of electrons through the specimen or onto its surface.

scanning electron microscope

good for the detailed study of topography . electron beam scans the surface and excites the electrons

transmission EM

used to study internal structure of cells. aims an E beam through a very thin section of specimen which has been stained with heavy metals.. this has revealed many organelles.

nucleoid

DNA concentrated in a region but is not bound, occurs in prokaryotic cells.

"eukaryote"

means true nucleus in greek aka they have a real nucleus.

cytoplasm

region generally between the nucleus and the plasma membrane. organelles are suspended in euks.

cell size

eukaryotic cells tend to be larger than prokaryotic cells.

plasma membrane

selective barrier found in all cells that allows for the passage of enough oxygen, nutrients, and wastes to service cell.

microvilli

long thin projections from the surface which increase cellular surface area.

in animal cells but not in plant cells

nucleus

contains most of the genes of a eukaryotic cell.

nuclear envelope

encloses the nucleus and separates the contents from the cytoplasm. this is a double membrane. envelope is perforated by pore structure

chromosomes

structures that carry the genetic information. each eukaryotic species has a unique number of chromosomes

chromatin

complex of DNA and proteins making up chromosomes

nucleolus

-dense granules and fibers adjoining part of the chromatin. -this is where ribosomal RNA (rRNA) is synthesized.

ribosomes

consist of rRNA and proteins; carry out protein synthesis.

vesicles

little sacs made out of membrane material which is transports stuff

endoplasmic reticulum

network of membranous tubules and sacs called cisternae. ER membrane is continuous with the nuclear envelope.

smooth ER

lacks ribosomes

functions include

1. synthesis of lipids

2. metabolism of carbohydrates

3. detox of drugs and poison

4. storage of calcium ions

rough ER

studded with ribosomes

functions include the production of secretory proteins. teh rough ER keeps these separate from proteins that will remain in the cytosol.

also membrane factory of the cell by adding phospholipids and proteins to its own membrane

glycoproteins

many secretory proteins are these.

starch

polymer of glucose monomers as granules within cellular structures

glycogen

storage within animal cells typically in the muscles or liver and releases glucose when the demand for sugar rises via hydrolysis.

cellulose

major component of cell walls. can not be digested by humans

microfibrils

units of cellulose molecules that are bonded

chitin

used by arthropods (insects, crustaceans etc) to build their exoskeleton.

types of lipids

fats, phospholipids, steroids

triacylglycerols

fats or oils

saturated fatty acid

as many H as possible, no double bonds. most animal fats

unsaturated fatty acids

at least one double bond. double bonds are typically cis and cause a kink in the tail.

polypeptides

polymer of amino acid monomers

amino acid

have an amino group and a carboxyl group as well as an H and a side chain called "R" and there are many different side chains.

peptide bond

resulting covalent bond between amino acids

shape of protein

polypeptides spontaneously fold and assume the functioal structure of that protein.

primary structure

unique linear chain of amino acids

secondary structure

based off of hydrogen bonds formed b/w the repeated constituents of the polypeptide backbone

alpha helix

coil held together by H bonds bw every 4th amino acid

beta pleated sheet

pleats created by H bonds bw parallel polypeptide backbones

tertiary structure

shape determined by the interactions of the side chains

hydrophobic interaction

hydrophobic side chains tend to cluster together, held by van der waals interactions

gene

unit of inheritance

DNA and RNA

made up of sugar (ribose), nitrogenous bases

virus

gene packaged in a protein coat and sometimes a membranous envelope. They cannot reproduce without a host

genomes of viruses

can be either single or double stranded DNA or RNA and are identified as either DNA or RNA in the name

viral envelope

derived from membrane of the host cell consist of host phospholipids and membrane proteins as well as glycoproteins and proteins of the virus.