Gene Expression Flashcards
gene expression
Overall process by which the information encoded in genes is converted into an active product, most commonly a protein. Includes transcription and translation of a gene and in some cases protein activation.
loss of function alleles
A mutant allele that does not function at all, or an organism homozygous for such a mutation.
one gene, one enzyme hypothesis
The hypothesis that each gene is responsible for making one (and only one) protein, in most cases an enzyme that catalyzes a specific reaction. Many exceptions to this hypothesis are now known.
metabolic pathway
An ordered series of chemical reactions that build up or break down a particular molecule. Often, each reaction is catalyzed by a different enzyme.
genetic screen
Any of several techniques for identifying individuals with a particular type of mutation. Also called a screen.
What do genes do?
They contain the instructions for making proteins
messenger RNA
An RNA molecule that carries encoded information, transcribed from DNA, that specifies the amino acid sequence of a polypeptide.
RNA polymerase
One of a class of enzymes that catalyze synthesis of RNA from ribonucleotides, using a DNA template. Also called RNA pol.
central dogma
The long-accepted hypothesis that information in cells flows in one direction: DNA codes for RNA, which codes for proteins. Exceptions are now known (e.g., retroviruses).
Transcription
The process by which RNA is made from a DNA template.
Translation
The process by which proteins and peptides are synthesized from messenger RNA.
What are some changes to central dogma since its inception?
- sometimes info flows from RNA to DNA
- many genes code for RNA molecules that do not function as mRNA..they are not all translated into proteins
reverse transcriptase
An enzyme of retroviruses (RNA viruses) that can synthesize double-stranded DNA from a single-stranded RNA template.
genetic code
The set of all 64 codons and the particular amino acids that each specifies.
triplet code
A code in which a “word” of three letters encodes one piece of information. The genetic code is a triplet code because a codon is three nucleotides long and encodes one amino acid.
codon
A sequence of three nucleotides in DNA or RNA that codes for a certain amino acid or that initiates or terminates protein synthesis.
reading frame
The division of a sequence of DNA or RNA into a particular series of three-nucleotide codons. There are three possible reading frames for any sequence.
start codon
The AUG triplet in mRNA at which protein synthesis begins; codes for the amino acid methionine.
stop codon
One of three mRNA triplets (UAG, UGA, or UAA) that cause termination of protein synthesis. Also called a termination codon.
point mutation
A mutation that results in a change in a single nucleotide pair in a DNA molecule.
missense mutation
A point mutation (change in a single base pair) that causes a change in the amino acid sequence of a protein.
replacement mutations
Same as missense mutation
silent mutation
A mutation that does not detectably affect the phenotype of the organism.
What are the three categories of mutation?
1) Beneficial
2) Neutral
3) Deleterious-harmful
