2A: overview of central dogma

Question 1

what is the central dogma?

Answer 1

universal information flow from DNA to RNA to protein (process of conversion of genotype into phenotype)

Question 2

what is transcription? (general)

Answer 2

process by which information encoded in DNA is made into a complementary RNA copy

Question 3

what is translation? (general)

Answer 3

the use of information encoded in RNA to assemble amino acids into polypeptides (proteins)

Question 4

what is the template strand?

Answer 4

the strand that is used to make complementary RNA in transcription (the strand read by RNA polymerase)

Question 5

what is the coding strand?

Answer 5

the coding strand is opposite of the template strand and has the exact same sequence of bases as the RNA formed in transcription (except has T instead of U)

Question 6

which strand of DNA is shown on chromosomal maps?

Answer 6

the coding strand

Question 7

how do we find out which strand is entirely coding and which is entirely template?

Answer 7

we don’t. each strand of DNA has sections where it is coding and where it is template

Question 8

what is the process of transcription?

Answer 8

RNA polymerase creates RNA sequence (called mRNA) complementary to template DNA. follows same basic rules as DNA replication

Question 9

where is reverse transcriptase found?

Answer 9

in viruses with RNA genomes (such as HIV/AIDs)

Question 10

what is the process of infection by an RNA virus?

Answer 10

① virus’s genome (RNA) enters host cell along with reverse transcriptase (enzyme)
② reverse transcriptase generates ssDNA from virus’s RNA genome
③ second strand of DNA is synthesized, using first strand as template (so its now dsDNA)
④ dsDNA integrated into host DNA as a provirus (which is like a prophage)
⑤ the DNA is transcribed into mRNA, and then translation occurs

Question 11

what makes RNA viruses impossible to make a vaccine for?

Answer 11

their use of reverse transcripase. reverse transcriptase is extremely bad at proofreading, which results in a high rate of mutation

Question 12

did RNA or DNA evolve first? reasoning?

Answer 12

RNA because besides being able to store genetic information, it can also catalyze reactions, like an enzyme.

Question 13

what are ribozymes?

Answer 13

RNA catalysts that can catalyze reactions on the RNA molecules that lead to their own synthesis

Question 14

how were the jobs of information storage and catalysis taken by DNA and catalysts (proteins) from RNA?

Answer 14

DNA and proteins just do a better jobs at those tasks than RNA. DNA is much more stable than RNA and proteins are more efficient at catalysis and are able to make shorter chains with more variety than RNA

Question 15

why is DNA better than RNA at storing information?

Answer 15

it is more stable and being double stranded allows the complementary strand to be used as a template to repair the other strand if it is damaged

Question 16

where does transcription and translation occur in prokaryotes?

Answer 16

cytoplasm (this allows transcription and translation to occur at the same time)

Question 17

where does transcription and translation occur in eukaryotes?

Answer 17

transcription: in nucleus
translation: in cytoplasm

Question 18

what did Garrod study and what did this show?

Answer 18

he studied the disease that makes your pee black and his work on it was the first to show a specific relationship between genes and metabolism

Question 19

what was Beadle and Tatum’s experiment?

Answer 19

they studied 3 auxotrophic mutants of Neurospora crassa that did not grow in medium without arginine supplements. they put all 3 mutants into mediums with no supplements, mediums with ornithine supplement, mediums with citrulline supplement, and mediums with arginine supplement, and kept track of growth.

Question 20

what did Beadle and Tatum conclude from their experiment?

Answer 20

they concluded that the biosynthesis of arginine occurs in a series of steps, and each step is controlled by a gene that codes for the enzyme for the step.

Question 21

what are the two types of RNA genes encode for?

Answer 21

➞ coding RNA

➞ noncoding RNA

Question 22

what does coding RNA do? what RNA is coding RNA?

Answer 22

codes for proteins/polypeptides.

mRNA is coding RNA

Question 23

what does noncoding RNA do? what RNA is noncoding RNA?

Answer 23

noncoding RNA does not code for a protein.

tRNA, rRNA, snRNA, and microRNA are all noncoding RNA

Question 24

how many nucleotides are required to code for 20 different amino acids?

Answer 24

3

Question 25

what is a 3-letter code of DNA called?

Answer 25

a triplet

Question 26

what is a 3-letter code of RNA called?

Answer 26

a codon

Question 27

how does genetic code (codons) compare in different organisms?

Answer 27

its universal

Question 28

what is the process of translation?

Answer 28

① an mRNA associates with a ribosome (particle on which amino acids are linked into polypeptide chains)
② as ribosome moves along the mRNA, the amino acids specified by the mRNA are joined one by one to form the polypeptide coded for by the mRNA