Bio Mid Term 1

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Virus

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package of nucleic acid wrapped in a protein coat that must use a host cell's machinery to reproduce itself

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Bacteriophage

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virus that infects bacteria; also called a "phage"

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lytic cycle

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a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses

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lysogenic cycle

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a viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA

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HIV (human immunodeficiency virus)

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virus that destroys helper T cells and causes AIDS

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prokaryotic cell

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cell lacking a nucleus and most other organelles

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bacteria

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domain of prokaryotic organisms that are biochemically and genetically distinct from archaea

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bacillus

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a rod-shaped bacterium

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coccus

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a spherical bacterium

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autotroph

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organism that makes its own food

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heterotroph

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organism that obtains food by eating other organisms

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binary fission

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mode of prokaryote asexual reproduction in which each daughter cell receives an identical copy of the parent cell's chromosome

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endospore

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dormant cell formed by certain bacteria that can survive very harsh conditions

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pathogen

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a disease-causing organism or virus

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antibiotic

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medicine that kills or slows the growth of bacteria

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vaccine

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dose of a disabled or destroyed pathogen (or part of a pathogen) used to stimulate a long-term immune defense against the pathogen

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pigment

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chemical compound that determines a substance's color

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photosynthesis

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process by which plants use the sun's energy to convert water and carbon dioxide into sugars

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chlorophyll

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pigment that gives a chloroplast its green color; uses light energy to split water molecules during photosynthesis

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ATP: (adenosine triphosphate)

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main energy source that cells use for most of their work

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light reactions

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chemical reactions that convert the sun's energy to chemical energy; take place in the membranes of thylakoids in the chloroplast

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electron transport chain

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sequence of electron carrier molecules that transfer electrons and release energy during cellular respiration

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catalyst

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agent that speeds up chemical reactions

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enzyme

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specialized protein that catalyzes the chemical reactions of a cell

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substrate

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specific reactant acted on by an enzyme

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active site

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region of an enzyme into which a particular substrate fits

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nucleotide

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building block (monomer) of nucleic acid polymers

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cell theory

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generalization that all living things are composed of cells, and that cells are the basic unit of structure and function in living

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cell wall

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strong wall outside a plant cell's plasma membrane that protects the cell and maintains its shape

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nucleus

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in an atom, the central core that contains protons and neutrons; in a cell, the part that houses the cell's genetic material in the form of DNA

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eukaryotic cell

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cell with a nucleus (surrounded by its own membrane) and other internal organelles

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nuclear envelope

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double membrane that surrounds a cell nucleus

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nucleolus

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ball-like mass of fibers and granules in a cell nucleus

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chromosome

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condensed threads of genetic material formed from chromatin as a cell prepares to divide

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cytoplasm

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region of a cell between the nucleus and the plasma membrane

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organelle

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part of a cell with a specific function

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mitochondria

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cellular organelles where cellular respiration occurs

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chloroplast

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organelle found in some plant cells and certain unicellular organisms where photosynthesis takes place

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ribosome

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cluster of proteins and nucleic acids that constructs proteins in a cell

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Golgi

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cellular organelle that modifies, stores, and routes cell products

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lysosome

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membrane-bound sac containing digestive enzymes that can break down proteins, nucleic acids, and polysaccharides

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vacuole

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membrane-bound sac that buds from the endoplasmic reticulum or the Golgi apparatus

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diffusion

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net movement of the particles of a substance from where they are more concentrated to where they are less concentrated

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selectively permeable membrane

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membrane that allows some substances to pass more easily than others and blocks the passage of some substances altogether

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hypertonic

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having a higher concentration of solute than another solution

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hypotonic

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having a lower concentration of solute than another solution

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isotonic

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having a solute concentration equal to that of another solution

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endocytosis

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process of taking material into a cell within vesicles that bud inward from the plasma membrane

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exocytosis

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process of exporting proteins from a cell by a vesicle fusing with the plasma membrane and spilling the proteins outside the cell

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osmosis

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passive transport of water across a selectively permeable membrane

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active transport

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movement of molecules across a membrane requiring energy to be expended by the cell

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facilitated diffusion

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pathway provided by transport proteins that helps certain molecules pass through a membrane

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tissue

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cooperating unit of many similar cells that perform a specific function

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organ

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unit consisting of several tissues that together perform a specific task

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radioactive isotope

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isotope in which the nucleus decays (breaks down) over time, giving off radiation in the form of matter and energy

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compound

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substance containing two or more elements chemically combined in a fixed ratio

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molecule

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two or more atoms held together by covalent bonds

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covalent bond

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chemical bond that forms when two atoms share electrons

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ionic bond

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chemical bond that occurs when an atom transfers an electron to another atom

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ion

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atom that has become electrically charged as a result of gaining or losing an electron

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chemical reaction

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breaking of old and formation of new chemical bonds that result in new substances

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reactant

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starting material for a chemical reaction

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product

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material created as a result of a chemical reaction

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solvent

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substance in a solution that dissolves the other substance and is present in the greater amount

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solution

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uniform mixture of two or more substances

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acid

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compound that donates H+ ions to an aqueous solution and measures less than 7 on the pH scale

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base

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compound that removes H+ ions from an aqueous solution and that measures more than 7 on the pH scale

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pH scale

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a range of numbers used to describe how acidic or basic a solution is; ranges from 0 (most acidic) to 14 (most basic)

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polymer

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long chain of small molecular units

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monomer

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small molecular unit that is the building block of a larger molecule

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carbohydrate

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organic compound made of sugar molecules

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monosaccharide

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sugar containing one sugar unit

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disaccharide

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sugar containing two monosaccharides

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polysaccharide

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long polymer chain made up of simple sugar monomers

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lipid

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one of a class of water-avoiding compounds

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cholesterol

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steroid molecule present in the plasma membranes of animal cells

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protein

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polymer constructed from a set of 20 amino acid monomers

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amino acid

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monomer that makes up proteins; contains carboxyl and amino functional groups

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controlled experiment

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experiment that tests the effect of a single variable

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variable

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any factor in an experiment that is not constant (any factor that can change)

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unicellular

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consisting of a single cell

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multicellular

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consisting of many cells

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asexual reproduction

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process in which a single cell or set of cells produces offspring that inherit all their genetic material from one parent

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sexual reproduction

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process in which genetic material from two parents combines and produces offspring that differ genetically from either parent

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metabolism

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all of a cell's chemical processes

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homeostasis

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internal stability or "steady state" maintained by the body

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atom

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smallest particle of an element

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proton

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subatomic particle with a single unit of positive electric charge

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neutron

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subatomic particle that has no charge (is electrically neutral)

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electron

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subatomic particle with a single unit of negative electric charge (-)

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atomic number

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number of protons in an atom's nucleus; is unique for each element

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element

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pure substance that cannot be broken down into other substances by chemical or physical means

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isotope

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one of several forms of an element, each containing the same number of protons in their atoms but a different number of neutrons

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pseudoscience

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A theory, methodology, or practice that is considered to be without scientific foundation.

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scientific method

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a method of research in which a problem is identified, relevant data are gathered, a hypothesis is formulated from these data, and the hypothesis is empirically tested.

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dependent variable

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a variable in a logical or mathematical expression whose value depends on the independent variable

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independent variable 

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a variable in a functional relation whose value determines the value or values of other variables

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control variable

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any factor that remains unchanged and strongly influences values; also, a factor held constant to test the relative impact of an independent variable

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anabolism

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constructive metabolism; the synthesis in living organisms of more complex substances from simpler ones

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catabolism

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destructive metabolism; the breaking down in living organisms of more complex substances into simpler ones, with the release of energy

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resolution

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the ability of a microscope or telescope to measure the angular separation of images that are close together

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limit of resolution 

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the capacity of an optical system to resolve point objects as separate images.

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-SEM
-TEM

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-scanning electron microscope.
-transmission electron microscope

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physical property

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any property used to characterize matter and energy and their interactions

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chemical property

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a characteristic of a substance that becomes known during a chemical reaction; also, a characteristic depending on the arrangement of the atoms in the molecule

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phase change

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a change from one state (solid or liquid or gas) to another without a change in chemical composition

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energy level/shell/orbital

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any of up to seven energy levels on which an electron may exist within an atom, the energies of the electrons on the same level being equal and on different levels being unequal.

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atomic mass 

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the mass of an isotope of an element measured in units formerly based on the mass of one hydrogen atom taken as a unit

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isomer

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a compound displaying isomerism with one or more other compounds.

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chemical bond

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Any of several forces or mechanisms, especially the ionic bond, covalent bond, and metallic bond, by which atoms or ions are bound in a molecule or crystal.

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mixture

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an aggregate of two or more substances that are not chemically united and that exist in no fixed proportion to each other.

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suspension

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the state in which the particles of a substance are mixed with a fluid but are undissolved.

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-organic compound
-inorganic compound

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-any compound of carbon and another element or a radical
-any compound that does not contain carbon

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polymerization

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the act or process of forming a polymer or polymeric compound.

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glucose

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a monosaccharide sugar that has several forms; an important source of physiological energy

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sucrose

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a crystalline disaccharide the sugar obtained from the sugarcane, the sugar beet, and sorghum, and forming the greater part of maple sugar; sugar.

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glycerol

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a sweet syrupy trihydroxy alcohol obtained by saponification of fats and oils

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fatty acid 

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any of a class of aliphatic acids, esp. palmitic, stearic, or oleic acid, consisting of a long hydrocarbon chain ending in a carboxyl group that bonds to glycerol to form a fat.

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peptide bond 

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a covalent bond formed by joining the carboxyl group of one amino acid to the amino group of another, with the removal of a molecule of water.

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nucleic acid

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any of a group of long, linear macromolecules, either DNA or various types of RNA, that carry genetic information directing all cellular functions: composed of linked nucleotides.

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cell membrane

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the semipermeable membrane enclosing the cytoplasm of a cell.

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retrovirus

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Any of a group of viruses, many of which produce tumors, that contain RNA and reverse transcriptase, including the virus that causes AIDS.

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parasite

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an organism that lives on or in an organism of another species, known as the host, from the body of which it obtains nutriment.

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spirillum

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any of several spirally twisted, aerobic bacteria of the genus Spirillum, certain species of which are pathogenic for humans.

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conjugation

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the reproductive process in ciliate protozoans in which two organisms of different mating types exchange nuclear material through a temporary area of fusion

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dark reaction 

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the phase of photosynthesis, not requiring light, in which carbohydrates are synthesized from carbon dioxide.