10.6-10.16: The Flow of Genetic Information from DNA to RNA to Protein Flashcards
(29 cards)
What is the “molecular chain of command”?
DNA in the nucleus of the cell to RNA to protein synthesis in the cytoplasm.
What are the two main stages of the molecular chain of command?
transcription and translation
What is transcription, in the context of molecular biology?
the synthesis of RNA under the direction of DNA.
What is translation, in the context of molecular biology?
the synthesis of proteins under the direction of RNA.
Review, fill in the blank: Each step in a metabolic pathway is ______ by a specific ______.
catalyzed; enzyme
Enzymes are proteins, but not all proteins…
are enzymes. Ex. keratin, insulin.
Scientist Archibald Garrod in 1909, and scientists George Beadle and Edward Tatum in the 1940s made some very important hypothesises and experiments relating to a specific concept of molecular biology. What concept what that?
That each gene is responsible for programming for a certain polypeptide chain (protein), which performed a certain task or tasks within the organism. To see the specifics of their experiments, go to page 190.
What is DNA –> RNA —> Protein said as?
“DNA makes RNA makes protein”
A good analogy for transcription and translation is…
DNA, RNA and protein all are separate languages, and need to be translated to be able to communicate and do their separate roles.
How are the bases on a strand of RNA related to their corresponding single strand of DNA?
the bases are complementary (with the caveat that A, which is complementary to T, becomes U)
How many types of amino acids are there?
20
Why are three bases in a row necessary to code for 20 different types of protein?
This is a simple counting problem. For two bases, only 4^2 (16) bases could be chosen. But for three options it is 4^3.=64, making it more than enough for three proteins to code for protein.
Continuing the language analogy: what are the triple-bases on RNA, which make individual proteins, like?
words
Because there are 64 options for 20 amino acids, what happens to the extra arrangements?
Nothing. There can be multiple codes for the same protein. For example, AAC and AAT code for same protein.
Define the triplet code
the genetic instructions for the amino acid sequence of a polypeptide chain written in DNA and RNA as a series of nonoverlapping three-base “words”
What are the “nonoverlapping three-base words” found in the triplet code called?
codons.
End of 10.7 Question: What is the minimum number of nucleotides necessary to code for 100 amino acids?
300
How was the “genetic code” cracked? Ie, what experiment led scientists to believing that individual codons coded for proteins?
The Niremberg Experiment: placing an artificially synthesized strand of RNA with only uracil as the base, and placing it in an environment with ribosomes, the only protein produced was phenylalanine (from UUU).
Of the 64 combinations of nucleotide bases, how many code for proteins? What do they exceptions do?
- AUG, which usually codes for methionine, can also provide a signal to start a polypeptide chain. UAA, UGA and UGA only code for ending a polypeptide chain.
In the triplet code, there is redundancy but no ambiguity. What does this mean?
It means that proteins can be coded for by more than one combination of bases, but two proteins can never be coded by the same combination of bases.
The triplet code is…
universal; shared by almost all living organisms.
End of 10.8 Question: Translate the RNA sequence CCAUUUACG into the corresponding amino acid sequence
GGUAAAUGC —> Pro-Phe–Thr
What is a promoter, in the context of molecular biology?
a purposeful genetic binding site for RNA polyermerase. It determines where transcriptions starts and on which strand.
What is the terminator, in the context of molecular biology?
A place on a gene that signals its end (opposite of promoter). Shows RNA polymerase when to end?
