ch 9 molecular structure of dna & rna

Question 1

molecular genetics

Answer 1

an examination of dna structure and function at the molecular level

Question 2

dna (deoxyribonucleic acid)

Answer 2

the genetic material; double stranded structure with repeating units of deoxyribonucleotides

Question 3

rna (ribonucleic acid)

Answer 3

a nucleic acid that is composed of ribonucleotides; in living cells, rna is synthesized via the transcription of dna

Question 4

transformation

Answer 4

1. when a bacterial cell takes up a plasmid vector or segment of chromosomal dna from the environment
2. when a normal cell is converted into a malignant cell

Question 5

DNase

Answer 5

an enzyme that cuts the sugar phosphate backbone in dna

Question 6

RNase

Answer 6

an enzyme that cuts the sugar phospate backbone in RNA

Question 7

protease

Answer 7

an enzyme that digests the polypeptide backbone in a protein

Question 8

bacteriophage (phage)

Answer 8

a virus that infects bacteria

Question 9

nucleic acid

Answer 9

rna or dna; macromolecule that is composed of repeating nucleotide units

Question 10

nucleotide

Answer 10

the repeating structural unit of nucleic acid, composed of a sugar, one to three phosphates, and a nitrogen-containing base

Question 11

strand

Answer 11

in dna or rna, a long linear polymer formed of nucleotides covalently linked together

Question 12

double helix

Answer 12

the arrangement in which two strands of dna (or sometimes stands of rna) interact with each other to form a double stranded helical structure

Question 13

deoxyribose

Answer 13

the sugar found in dna

Question 14

ribose

Answer 14

the sugar found rna

Question 15

purine

Answer 15

a type of nitrogenous base that has a double ring structure; examples are adenine and guanine

Question 16

pyrimidine

Answer 16

a type of nitrogenous base that has a single ring structure; examples are cytosine, thymine, and uracil

Question 17

adenine (A)

Answer 17

a purine base found in dna and rna; base pairs w thymine in dna

Question 18

guanine (G)

Answer 18

a purine base found in dna and rna; base-pairs with cytosine in dna

Question 19

thymine (T)

Answer 19

a pyrimidine base found in dna; base pairs with adenine in dna

Question 20

cytosine (C)

Answer 20

a pyrimidine base found in dna and rna; base pairs with guanine

Question 21

uracil (U)

Answer 21

a pyrimidine base found in rna

Question 22

nucleoside

Answer 22

structure in which a base is attached to a sugar but no phosphate is attached to the sugar

Question 23

phosphodiester linkage

Answer 23

in dna or rna stand, a linkage in which a phosphate group connects two sugar molecules

Question 24

backbone

Answer 24

the portion of a dna or rna strand that is composed of covalently linked phosphate and sugar molecules

Question 25

directionality

Answer 25

in dna & rna, refers to the 5' to 3' orientation of nucleotides in a strand; in proteins, refers to the linear arrangement of amino acids from the n-terminal to c-terminal

Question 26

chargaff's rule

Answer 26

observation that in dna, amount of A and T are equal and amounts of G and C are equal

Question 27

base pair (bp)

Answer 27

the structure in which two nucleotides in opposite strands of dna hydrogen bond with each other; for example, an AT base pair is a structure in which an adenine-containing nucleotide in one dna stand hydrogen bonds with a thymine-containing nucleotide in the complementary strand

Question 28

at/gc rule

Answer 28

in dna, the phenomenon in which an adenine base in one strand always hydrogen bonds with a thymine base in the opposite strand, and a guanine always hydrigen bonds with a cytosine

Question 29

complementary

Answer 29

describes sequences in which two dna strands that match each other accordign to the at/gc rule; antiparallel

Question 30

antiparallel

Answer 30

refers to an arrangement in a double helix in which one strand is running in the 5' to 3' direction, while the other strand runs 3' to 5'

Question 31

base stacking

Answer 31

in dna, the orientation of base pairs in which the flat sides of the bases are facing each other

Question 32

grooves

Answer 32

in dna, the indentations where the atoms of the bases are in contact with the water in surrounding cellular fluid; in B dna, there is a minor groove and major groove

Question 33

minor groove

Answer 33

a narrow indentation in the dna double helix in which the bases have access to water

Question 34

major groove

Answer 34

a wide indentation in the dna double helix in which the bases have access to water

Question 35

B dna

Answer 35

the predominant form of dna in living cells; right handed dna helix with 10 bp per turn

Question 36

Z dna

Answer 36

a left handed dna double helix that is found occasionally in living cells

Question 37

dna methylation

Answer 37

a regulatory mechanism in which an enzyme covalently attaches a methyl group (–CH3 to a base in DNA; in eukaryotes, the base is cytosine; in prokaryotes both adenine and cytosine can be methylated