Chapter 17: Gene Expression (from gene to protein) Part 1

Question 1

Gene Expression

Answer 1

process by which genes direct protein synthesis, by means of transcription and translation

Question 2

Archibald Garrod

Answer 2

suggested that genes dictate phenotypes by enzymes that catalyze specific chemical reactions

Question 3

“one gene-one enzyme” hypothesis

Answer 3

function of a gene is to dictate the synthesis of an enzyme

Question 4

transcription

Answer 4

synthesis of RNA using information in the DNA, writes the blueprint for the protein

Question 5

translation

Answer 5

synthesis of a polypeptide using the information in the mRNA, ribosomes are starts of translation, builds the protein

Question 6

mRNA

Answer 6

carries genetic message from the DNA to the protein-synthesizing machinery of the cell, synthesized from transcription

Question 7

Ribosomes Primary transcript

Answer 7

Initial RNA that’s produced from transcription prior to processing

Question 8

Triplet Code

Answer 8

Series of non-overlapping 3 nucleotide words, called codons. Basically the gene sequence.

Question 9

Codon

Answer 9

mRNA based triplets, read 5’-3’, specifies a particular amino acids to be placed at the corresponding place on a polypeptide

Question 10

Template strand of DNA

Answer 10

3’-5’, used to translate into mRNA

Question 11

Coding strand of DNA

Answer 11

nucleotides here are exactly the same as mRNA triplets, except where T is replaced by U

Question 12

Discuss/Explain the progress of knowledge from Garrod’s “genes code for enzymes” to the “one gene- one polypeptide” hypotheses.

Answer 12

Garrod hypothesized that inherited disease reflect an inability to make a particular enzyme. Later, research supported that gene’s do dictate the production of enzymes in the “one gene-one polypeptide” hypothesis: the functions of a gene is to dictate the production of a specific enzyme. Biochemists learned that cells make and break molecules via metabolic pathways (reactions catalyzed by specific enzymes). Tatum and Beadle supported this hypothesis further with an experiment, in which they caused genetic mutations to molds and discovered that the mutations were unable to synthesize arginine. Meaning that the mutated genes changed the “blue-print” to exclude the enzyme that synthesizes arginine. One gene dictates the synthesis of one polypeptide (protein).

Question 13

Describe the difference between protein synthesis in prokaryotes (bacteria) and eukaryotes.

Answer 13

In prokaryotes, translation can happen before transcription is finished, because there are no bound membranes keeping everything in one spot. So the RNA being synthesized is being translated as it is created. In eukaryotic cells, there are very specific steps. The RNA and mRNA is made in the nucleus, the RNA is capped with a poly A tail, then 10-35 more nucleotides are added at the end. Then the mRNA slips through a pore into the cytoplasm to meet the ribosomes.

Question 14

Using a codon chart, be able to create a strand of mRNA to a polypeptide.

Answer 14

.

Question 15

What are the 3 stages of DNA transcription.

Answer 15

Intiation: promoters define starting point on a strand Elongation of the codes: RNA polymerase unzips at 10-20 bases at a time, nucleotides are added to the 3’ end of RNA
Termination of reading that DNA:

Question 16

What are the purposes for the alteration at the ends of mRNA?

Answer 16

Not sure. Still researching it. They think the poly A tail and the 5’ cap are there for 3 reasons: to facilitate the transfer into the cytoplasm through pores in the nucleus, to protect rna from hyrolytic enzymes, help RNA attach to the 5’ end of other ribosomes

Question 17

Reading Frame

Answer 17

Correct groupings that codons are in for polypeptide production

Question 18

Promoters

Answer 18

Signal the transcription start point on a strand and extend several dozen nucleotide pairs upstream

Question 19

Transcription Factors

Answer 19

mediate the binding of RNA polymerase (unzips your genes) and the initiation of transcription. kinda like glue for the rna polymerase

Question 20

Transcription initiation complex

Answer 20

the completed assembly of all the transcription factors and the RNA polymerase bound to a promoter (TATA box)

Question 21

TATA box

Answer 21

Series of triplets, used as a promoter, on the DNA strand. Series of Thymine Adenine.

Question 22

RNA processing

Answer 22

“cleaning up” the pre-RNA. Sequences of nucleotides that aren’t used for polypeptide synthesis are removed

Question 23

Introns

Answer 23

Intervening sequences (non-coding), won't code for a polypeptide.
Cleaned up by RNA processing/splicing

Question 24

Exons

Answer 24

Express genes, translated into other

Question 25

RNA splicing

Answer 25

Removes introns, joins to clean RNA molecule

Question 26

Splicosomes

Answer 26

Protein complex with smaller RNAs. Splices RNA introns.

Question 27

Ribozymes

Answer 27

RNA molecules that function as enzymes