CH 10 The Structure and Function of DNA

Question 1

DNA

Answer 1

• was known to be a chemical in cells by the end of the 19th century
• has the capacity to store genetic information
• can be copied and passed from one generation to another

Question 2

molecular biology

Answer 2

study of heredity at the molecular level

Question 3

DNA and RNA are nucleic acids

Answer 3

• they consist of nucleotides
• a nucleic polymer is a polynucleotide
• nucleotides are joined by covalent bonds called a sugar-phosphate backbone

Question 4

DNA stands for

Answer 4

deoxyribonucleic acid

Question 5

four DNA bases

Answer 5

• thymine (T)
• cytosine (C)
• adenine (A)
• guanine (G)

Question 6

Rna bases

Answer 6

uracil (U)

Question 7

model of DNA is like a rope ladder twisted

Answer 7

• ropes at sides represent the sugar phosphate backbones

- each wooden rung represents a pair of bases connected by hydrogen bonds

Question 8

complementary base pairs

Answer 8

• adenine pars with thymine

- cytosine pairs with guanine

Question 9

Watson and Crick’s model

Answer 9

suggested that DNA replicates by a template mechanism

Question 10

DNA polymerases

Answer 10

• are enzymes
• make the covalent bonds between the nucleotides of a new DNA strand
• are involved in repairing damaged DNA

Question 11

DNA provides instructions to

Answer 11

• a cell

- an organism as a whole

Question 12

transcription

Answer 12

the transfer of genetic information from DNA into an RNA molecule

Question 13

translation

Answer 13

the transfer of information from RNA into a protein

Question 14

genetic information in DNA is

Answer 14

• transcribed into mRNA
• translated into polypeptides
• which then fold into proteins

Question 15

flow of information from gene to protein is based on

Answer 15

a triplet code

Question 16

codon

Answer 16

a triplet of bases, which codes for one amino acid

Question 17

genetic code

Answer 17

the set o rules that convert a nucleotide sequence in RNA to an amino acid sequence

Question 18

of the 64 triplets

Answer 18

• 61 code for amino acids and

- 3 are stop codons, instructing the ribosomes to end the polypeptide

Question 19

mutations

Answer 19

is any change in the nucleotide sequence of DNA

Question 20

mutations can involve

Answer 20

• large regions of a chromosome, or

- just a single nucleotide pair, as occurs in a sickle-cell disease

Question 21

mutations may result from

Answer 21

• errors in DNA replication or recombination or

- physical or chemical agents called mutagens

Question 22

Mutations are

Answer 22

• often harmful but
• are useful in nature and the laboratory as a source of genetic diversity, which makes evolution by natural selection possible