CHAPTER 12

Question 1

genetic material must be…

Answer 1

able to store information that pertains to the development, structure, and metabolic activities of the cell or organism

stable, so it can be replicated with high accuracy during cell division and be transmitted from generation to generation

able to undergo rare changes, called mutations, that provide the genetic variability required for evolution to occur

Question 2

DNA contains 4 different types of nucleotides

Answer 2

2 purine bases, adenine and guanine, which have a double ring

2 pyrimidine bases, thymine and cytosine, which have a single ring

Question 3

chargaff’s rules

Answer 3

the amount of a, t, g, and c in dna varies from species to species

in each species, the amount of a = t and the amount of g = c

Question 4

double helix

Answer 4

dna is a double helix with sugar-phosphate backbones on the outside and paired bases on the inside

Question 5

complementary base pairing

Answer 5

means that a purine is always bonded to a pyrimidine

Question 6

what direction?

Answer 6

dna must always be read in the 5’ to 3’ direction, thus is usually replicated in this direction

Question 7

dna replication

Answer 7

refers to the process of copying a dna molecule

Question 8

semiconservative replication

Answer 8

each daughter dna double helix contains an old strand from the parental dna double helix and new strand

Question 9

what are the pairings

Answer 9

a pairs with t and g pairs with c

Question 9

dna helicase

Answer 9

separates double stranded dna into single strands

Question 9

dna primase

Answer 9

synthesizes short rna primers

Question 9

dna polymerase

Answer 9

synthesizes dna in the leading and lagging strands; removes rna primers, filling the gaps with more dna; and proofreads newly made dna

Question 9

single stranded binding protein

Answer 9

binds to single stranded dna and prevents it from reforming a double helix

Question 9

origin of replication

Answer 9

the place where replication begins, a specific site on the bacterial chromosome

Question 9

dna ligase

Answer 9

covalently attaches adjacent okazaki fragments in the lagging strand

Question 10

termination region

Answer 10

where replication stops

Question 10

replication fork

Answer 10

there is a v shape wherever dna is being replicated, this is called the replication fork

Question 10

rna (ribonucleic acid)

Answer 10

a polymer composed of nucleotides. the nucleotides in rna, however, contain the sugar ribose and the bases adenine, cytosine, guanine and uracil

Question 10

gene expression

Answer 10

the flow of dna to rna and then on an expressed protein

Question 11

messenger rna (mrna)

Answer 11

takes a message from the dna in the nucleus to the ribosomes in the cytoplasm

Question 12

transfer rna (trna)

Answer 12

transfers amino acids to the ribosomes

Question 13

ribosomal rna (rrna)

Answer 13

along with ribosomal proteins, makes up the ribosomes, where polypeptides are synthesized

Question 14

transcription

Answer 14

a process by which an rna molecule is produced based on a dna template.

Question 15

translation

Answer 15

the mrna transcript is read by a ribosome and converted into the sequence of amino acids in a polypeptide

Question 16

central dogma

Answer 16

the flow of info from dna to rna to protein to the trait is known as the central dogma of molecular biology

Question 17

genetic code

Answer 17

universal code that allows for conversion of dna and rna’s chemical code to a sequence of amino acids in a protein

Question 18

codon

Answer 18

the coding unit, made up of 3 nucleotides

Question 19

promoter

Answer 19

defines the start of transcription, the direction of transcription, and the strand to be transcribed

Question 20

initiation of transcription

Answer 20

the binding of the rna polymerase to the promoter

Question 21

mrna transcript

Answer 21

the stop sequence causes rna polymerase to stop transcribing the dna and to release the mrna molecule, now called an mrna transcript

Question 22

pre-mrna

Answer 22

contains a mix of exons (protein coding regions) and introns (non-protein coding regions)

Question 23

ribozyme

Answer 23

enzyme made of rna rather thann just pprotein used to cut and remove the introns

Question 24

anticodon

Answer 24

the opposite end of the molecule contains this, which is a group of 3 bases that is complimentary and antiparallel to a specific mrna codon

Question 25

polyribosome

Answer 25

the entire complex of mrna and multiple ribosomes, which greatly increases the efficiency of translation

Question 26

initiation

Answer 26

the step that brings all the translation components together

Question 27

the start codon

Answer 27

AUG

Question 28

elongation

Answer 28

the stage during protein synthesis when a polypeptide increases in length one amino acid at a time

Question 29

termination

Answer 29

the final step in protein synthesis, the polypeptide and the assembled components that carried out protein synthesis are separated from one another

Question 30

proteomics

Answer 30

dedicated to understanding the structure of proteins and how they function in metabolic pathways