Gene Function Flashcards
(29 cards)
Prototrophic strain
can grow on minimal medium (is
able to make its own arginine and other amino acids)
Auxotrophic strain
requires nutritional supplementation
One Gene-One Polypeptide Hypothesis
an extension based on the
fact that not all proteins are made of up one polypeptide subunit
Two Key Processes in Gene Function
Transcription and Translation
Function of a Gene
our genes contain instructions that tell your cells to make molecules called proteins.
One Gene-One Enzyme Hypothesis
genes encode enzymes
One Gene-One Protein Hypothesis
an extension based on the fact
that not all proteins are enzymes
What process is initiated by the start codon?
the translation of the first amino acid in the polypeptide chain.
What process is terminated by the stop codons?
a signal to terminate protein synthesis.
In what way is the genetic code “redundant”?
the same amino acid residue can be encoded by multiple, so-called synonymous, codons.
In what way is the genetic code “universal”?
every known living organism has genes made of DNA.
In what way is the genetic code “non-overlapping”?
one amino acid can be coded by several different codons; however, each codon ONLY codes for one amino acid, not more. Hence the unambiguity of the genetic code.
Hershey Chase Experiment
-studied E-Coli
-location of radioactive protein (capsid or intracellular)
-Conclusion: DNA hereditary material
Deoxyribonucleotide contains:
deoxyribose sugar, phosphate group, nitrogenous base
How do deoxyribonucleotides link?
a hydroxyl group on the 3’ carbon of one deoxyribose and the phosphate group attached to the 5’ carbon of another deoxyribose are joined by a covalent bond (phosphodiester bond)
Null alleles
alleles that do not function at all
Beadle and Tatum experiment
-used a model organism in their work, mold Neurospora crassa.
-exposed crassa cells to radiation
-analyzed the cells, looking for mutant that failed to make specific compounds.
-inspired the one gene, one enzyme hypothesis.
Central Dogma
DNA-> RNA -> Proteins
Reading frame
sequence of codons. A single base pair deletion will throw off the whole frame, but a set of three (whole codon) can be removed and still produce functional proteins.
Start codon
AUG
Stop Codon
UAA, UAG, and UGA
Key properties of the genetic code:
-it is redundant
-it is unambiguous
-is non-overlapping
-is nearly universal
-is conservative
Point mutations
mutation that alters the sequence of one or a small number of base pairs.
missense mutations
point mutations that change the identity of an amino acid in a protein
