Ch 17: Gene Expression from Gene to Protein

Question 1

What is gene expression?

Answer 1

the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce and products, proteins or non-coding RNA, and affect a phenotype

Question 2

What are the two processes in gene expression?

Answer 2

transcription and translation

Question 3

What does DNA dictate?

Answer 3

the synthesis of proteins

Question 4

What do proteins link?

Answer 4

genotype and phenotype

Question 5

What is the one-gene-one enzyme hypothesis?

Answer 5

the function of a gene is to dictate production of a specific enzyme

Question 6

What is the newest name for the one-gene-one protein hypothesis?

Answer 6

it is now restated as the one-gene-one polypeptide hypothesis

Question 6

What did Archibald Garrod first suggest?

Answer 6

he suggested that genes dictate phenotypes through enzymes that catalyze specific chemical reactions

Question 7

What is translation?

Answer 7

the synthesis of a polypeptide using information in the mRNA

Question 7

What is RNA?

Answer 7

the bridge between genes and protein synthesis

Question 8

What is transcription?

Answer 8

the synthesis of RNA using information in DNA

Question 8

Where does transcription occur?

Answer 8

in the nucleus

Question 9

What does transcription produce?

Answer 9

mRNA and primary transcripts

Question 10

Where does translation take place?

Answer 10

in the cytoplasm (ribosomes)

Question 11

How many total amino acids are there?

Answer 11

only 20 amino acids

Question 12

What is the flow of information from gene to protein based on?

Answer 12

the reading of a codon, or a triplet code

Question 13

What is a template strand?

Answer 13

template for ordering the sequence of complementary nucleotides in an RNA transcript

Question 14

During translation, what direction are the codons read?

Answer 14

5’ —-> 3’

Question 15

What is a coding strand?

Answer 15

nontemplate strand, nucleotides are identical to codons except that T is present in the DNA in place of U in the RNA

Question 16

What are the two type of amino acids?

Answer 16

61 code for amino acids, while only 3 are “stop” signals that end transcription

Question 17

What is the reading frame?

Answer 17

the correct order in which the codons must be read in for the specified polypeptide to be produced

Question 17

What is the function of the RNA polymerase?

Answer 17

catalyzes RNA synthesis, pries the DNA strands apart, and joins together RNA nucleotides

Question 17

What is the one difference between DNA polymerase and RNA polymerase?

Answer 17

RNA polymerase does not need a primer

Question 18

What is a start point?

Answer 18

an area that is signaled by a promoter for transcription to start

Question 18

What is a promoter?

Answer 18

a specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing RNA at an appropriate place

Question 18

What is a terminator?

Answer 18

specific sequences of DNA that end transcriptions

Question 18

What is a transcription unit?

Answer 18

a region of DNA that is transcribed into an RNA molecule

Question 18

What are the three stages of transcription?

Answer 18

initiation, elongation, termination

Question 19

What is a TATA box?

Answer 19

a promoter that is crucial in forming the initiation complex in eukaryotes

Question 19

What are the functions of transcription factors?

Answer 19

they guide the binding of RNA polymerase and the initiation of transcription

Question 20

What is a transcription initiation complex?

Answer 20

the completed assembly of transcription factors and RNA polymerase II bound to a promoter

Question 21

What end of an RNA strand are nucleotides added to?

Answer 21

the 3' end

Question 22

What is RNA processing in Eukaryotic cells?

Answer 22

enzymes in the eukaryotic nucleus modify pre-mRNA before the genetic messages move to the cytoplasm where certain interior sections of the molecule are cut out and the remaining parts spliced together

Question 23

How are each end of a pre-mRNA molecule modified?

Answer 23

the 5' end receives a modified nucleotide 5' cap and the 3' end gets a poly-A tail

Question 24

What are the functions of a 5'cap and a poly-A tail?

Answer 24

they seem to facilitate the export of mRNA to the cytoplasm, they protect mRNA from hydrolytic enzymes, and they help ribosomes attach to 5' end

Question 25

What are introns?

Answer 25

non-coding stretches of nucleotides

Question 26

What are exons?

Answer 26

non-coding stretches of nucleotides that are eventually expressed and translated into amino acid sequences

Question 27

What are spliceosomes?

Answer 27

they remove introns, made of proteins and several small RNAs that recognize the splice sites

Question 28

What are ribozymes?

Answer 28

catalytic RNA molecules that function as enzymes and can splice RNA

Question 29

What are the three properties of RNA that enable it to function as an enzyme?

Answer 29

it can form a three-dimensional structure because of its ability to bas-pair, some bases in RNA contain functional groups that participate in catalysis, and RNA make hydrogen bonds with other nucleic acid molecules

Question 30

What is alternative RNA splicing?

Answer 30

some genes encode more than one kind of polypeptide depending on which segment is treated as exon during splicing

Question 31

What are domains?

Answer 31

modular structures in proteins that consist of regions

Question 32

What is exon shuffling?

Answer 32

it may result in the evolution of new proteins by mixing and matching exons between different genes