Ch 1 - The Fundamental Units of Life

Question 1

archaeon

Answer 1

microscopic organism that is a member of one of the two divisions of prokaryotes; often found in hostile environments such as hot springs or concentrated brine (see also bacterium)

Question 2

bacterium

Answer 2

microscopic organism that is a member of one of the two division of prokaryotes; some species cause disease. the term is sometimes used to refer to any prokaryotic microorganism, although the world of prokaryotes also includes archaea, which are only distantly related to each other

Question 3

cell

Answer 3

the basic unit from which a living organism is made; an aqueous solution of chemicals, enclosed by a membrane, that has an ability to self-replicate

Question 4

chloroplast

Answer 4

specialized organelle in algae and plants that contains chlorophyll and serves as the site for photosynthesis

Question 5

chromosome

Answer 5

long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism; become visible as a distinct entity when a plant or animal cell prepares to divide

Question 6

cytoplasm

Answer 6

contents of a cell that are contained within its plasma membrane but, in the case of eukaryotic cells, outside the nucleus

Question 7

cytoskeleton

Answer 7

system of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell shape and the capacity for directed movement. its most abundant components are actin filaments, microtubules and intermediate filaments.

Question 8

cytosol

Answer 8

contents of the main compartment of the cytoplasm, excluding membrane-enclosed organelles such as endoplasmic reticulum and mitochondria. the cell fraction remaining after membranes, cytoskeletal components and other organelles have been removed

Question 9

DNA

Answer 9

double stranded polynucleotide formed from two separate chains of covalently linked deoxyribonucleotide units. it serves as the cell’s store of genetic information that is transmitted from generation to generation.

Question 10

electron microscope

Answer 10

instrument that illuminates a specimen using beams of electrons to reveal and magnify the structures of very small objects, such as organelles and large molecules

Question 11

endoplasmic reticulum (ER)

Answer 11

labyrinthine membrane-enclosed compartment in the cytoplasm of eukaryotic cells where lipids and proteins are made

Question 12

eukaryote

Answer 12

an organism whose cells have a distinct nucleus and cytoplasm

Question 13

evolution

Answer 13

process of gradual modification and adaptation that occurs in living organisms over generations

Question 14

fluorescence microscope

Answer 14

instrument used to visualize a specimen that has been labeled with a fluorescent dye; samples are illuminated with a wavelength of light that excite the dye, causing it to fluoresce

Question 15

genome

Answer 15

the total genetic information carried by all the chromosomes of a cell or organism; in humans, the total number of nucleotide pairs in the 22 autosomes plus the X and Y chromosomes

Question 16

Golgi apparatus

Answer 16

membrane-enclosed organelle in eukaryotic cells that modifies the proteins and lipids made in the endoplasmic reticulum and sorts them for transport to other sites

Question 17

homologous

Answer 17

describes genes, chromosomes or any structures that are similar because of their common evolutionary origin. can also refer to similarities between protein sequences or nucleic acid sequences

Question 18

micrometer

Answer 18

unit of length equal to one millionth (10 to the power -6) of a meter

Question 19

microscope

Answer 19

instrument for viewing extremely small objects. some use a focused beam of visible light and are used to examine cells and organelles. others use a beam of electrons and can be used to examine objects as small as individual molecules.

Question 20

mitochondrion

Answer 20

membrane-enclosed organelle, about the size of a bacterium, that carries out oxidate phosphorylation and produces most of the ATP in eukaryotic cells

Question 21

model organism

Answer 21

a living thing selected for intensive study as a representative of a large group of species. examples include the mouse (representing mammals), the yeast Saccharomyces cerevisiae (representing unicellular eukaryote) and Escherichia coli (representing bacteria)

Question 22

nucleus

Answer 22

in biology, refers to the prominent, rounded structure that contains the DNA of a eukaryotic cell. in chemistry, refers to the dens, positively charged center of an atom

Question 23

organelle

Answer 23

a discrete structure or subcompartment of a eukaryotic cell that is specialized to carry out a particular function. examples include Golgi apparatus and mitochondria

Question 24

photosynthesis

Answer 24

the process by which plants, algae and some bacteria use the energy of sunlight to drive the synthesis of organic molecules from carbon dioxide and water

Question 25

plasma membrane

Answer 25

the protein-containing lipid bilayer that surrounds a living cell

Question 26

prokaryote

Answer 26

major category of living cells distinguished by the absence of a nucleus; includes the archaea and the eubacteria (commonly called bacteria)

Question 27

protein

Answer 27

macromolecule built from amino acids that provide cells with their shape and structure and performs most of their activities

Question 28

protozoan

Answer 28

a free-living, nonphotosynthetic, single-celled, motile eukaryote

Question 29

ribosome

Answer 29

large macromolecular complex, composed of RNAs and proteins, that translates a messenger RNA into a polypeptide chain

Question 30

RNA (ribonucleic acid)

Answer 30

molecule produced by the transcription of DNA; usually single-stranded, it is a polynucleotide composed of covalently linked ribonucleotide subunits. serves a variety of informational, structural, catalytic and regulatory functions in cells