chapter 3: the biological basis of life

Question 1

proteins

Answer 1

three-dimensional molecules that serve a wide variety of functions through their ability to bind to other molecules

Question 2

nucleus

Answer 2

a structure (organelle) found in all eukaryotic cells; contains dna that, during cell division, is organized into chromosomes

Question 3

molecules

Answer 3

structures made up of two or more atoms; can combine with other molecules to form more complex structures

Question 4

dna (deoxyribonucleic acid)

Answer 4

the double-stranded molecule that contains the genetic code; main component of chromosomes

Question 5

rna (ribonucleic acid)

Answer 5

a single-stranded molecule similar in structure to dna; three forms are essential to protein synthesis: messenger rna (mrna), transfer rna (trna), and ribosomal rna (rrna)

Question 6

cytoplasm

Answer 6

the semifluid substance contained within the cell membrane; nucleus and numerous other kinds of structures involved with cell function are found here

Question 7

protein synthesis

Answer 7

the manufacture of proteins; the assembly of chains of amino acids into functional protein molecules; directed by dna

Question 8

ribosomes

Answer 8

structures composed of a form of rna called ribosomal rna (rrna) and protein; found in a cell’s cytoplasm and are essential to the manufacture of proteins

Question 9

mitochondria

Answer 9

structures contained within the cytoplasm of eukaryotic cells that convert energy, derived rom nutrients, to a form that can be used by the cell

Question 10

mitochondrial dna (mtdna)

Answer 10

dna found in the mitochondria; inherited only from the mother

Question 11

somatic cells

Answer 11

all the cells in the body except those involved with reproduction

Question 12

gametes

Answer 12

reproductive cells (eggs and sperm in animals) developed from precursor cells in ovaries and testes

Question 13

zygote

Answer 13

a cell formed by the union of an egg cell and a sperm cell; contains the full complement of chromosomes (in humans, 46) and has the potential to develop into an entire organism

Question 14

nucleotides

Answer 14

basic units of the dna molecule, composed of a sugar, a phosphate, and one of four dna bases

Question 15

replicate

Answer 15

to duplicate; the dna molecule is able to make copies of itself

Question 16

enzymes

Answer 16

specialized proteins that initiate and direct chemical reactions in the body

Question 17

complementary

Answer 17

in genetics, referring to the fact that dna bases form pairs (base pairs) in a precise manner; one requires the other to form a complete dna base pair

Question 18

hemoglobin

Answer 18

a protein molecule that occurs in red blood cells and binds to oxygen molecules

Question 19

hormones

Answer 19

substances (usually proteins) that are produced by specialized cells and that travel to other parts of the body, where they influence chemical reactions and regulate various cellular functions

Question 20

amino acids

Answer 20

small molecules that are the components of proteins

Question 21

messenger rna (mrna)

Answer 21

a form of rna that’s assembled on a sequence of dna bases; carries the dna code to the ribosome during protein synthesis

Question 22

codons

Answer 22

triplets of messenger rna bases that code for specific amino acids during protein synthesis

Question 23

transfer rna (trna)

Answer 23

the form of rna that binds to specific amino acids and transports them to the ribosome during protein synthesis

Question 24

mutation

Answer 24

a change in dna; changes in dna bases (point mutations) as well as to changes in chromosome number and/or structure

Question 25

gene

Answer 25

a sequence of dna bases that specifies the order of amino acids in an entire protein; a portion of a protein, or any functional product (ex: rna); may be made up of hundreds or thousands of dna bases organized into coding and noncoding segments

Question 26

genome

Answer 26

the entire genetic makeup of an individual or species

Question 27

exons

Answer 27

segments of genes that are transcribed and are involved in protein synthesis; expressed segments

Question 28

noncoding dna

Answer 28

dna that does not direct the production of proteins; may produce other important molecules

Question 29

introns

Answer 29

segments of genes that are initially transcribed and then deleted; not involved in protein synthesis because they aren’t expressed;

Question 30

regulatory genes

Answer 30

genes that influence the activity of other genes; direct embryonic development and are involved in physiological processes throughout life; important to the evolutionary process

Question 31

homeobox genes

Answer 31

evolutionary ancient group of regulatory genes; one type directs segmentation of the body during embryonic development

Question 32

chromosomes

Answer 32

discrete structures composed of dna and proteins found only in the nucleus of cells; visible under magnification only during certain phases of cell division

Question 33

autosomes

Answer 33

all chromosomes except the sex chromosomes

Question 34

sex chromosomes

Answer 34

in mammals, the x and y chromosomes

Question 35

mitosis

Answer 35

simple cell division; the process by which somatic cells divide to produce two identical daughter cells

Question 36

meiosis

Answer 36

cell division in specialized cells in ovaries and testes; involves two divisions and results in four daughter cells, each containing only half the original number of chromosomes; can develop into gametes

Question 37

recombination

Answer 37

the exchange of genetic material between paired chromosomes during meiosis; aka crossing over

Question 38

clones

Answer 38

organisms that are genetically identical to another organism

Question 39

polymerase chain reaction (pcr)

Answer 39

a method of producing thousands of copies of a dna sample

Question 40

human genome project

Answer 40

an international effort aimed at sequencing and mapping the entire human genome, completed in 2003