Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
35 Cards in this Set
- Front
- Back
|
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. |
|
|
Knock-out Allele |
A mutant allele that does not function at all, or an organism homozygous for such a mutation. Also called a null allele or a loss-of-function allele. |
|
|
Beadle and Tatum |
Knocked out genes by damaging them (using high energy radiation) and observed the phenotype to see what the gene did. One of the most common research strategies used in studying gene function today. |
|
|
One-gene, One-enzyme Hypothesis |
Beadle and Tatum's hypothesis that each gene is responsible for making one protein, in most cases an enzyme that catalyzes a specific reaction. There are now many exceptions to this hypothesis. |
|
|
Adrian Srb and Norman Horowitz |
Tested the one-gene one-enzyme hypothesis using a genetic screen. Found a correlation between a specific genetic defect and a defect at a specific point in a metabolic pathway. This gave evidence that the hypothesis is correct. |
|
|
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. |
|
|
The Genetic Code Hypothesis |
Crick proposed that the sequence of bases in DNA might act as a code, such that different combinations of bases specified the 20 amino acids. Proved incorrect because DNA is not directly translated into amino acid sequence of proteins. |
|
|
Messenger RNA (mRNA) |
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. Its discovery was evidence of the messenger RNA hypothesis. |
|
|
Central Dogma |
The hypothesis by Francis Crick that information in cells flows in one direction: DNA codes for RNA and RNA codes for proteins. There are some exceptions. |
|
|
How do genes code for proteins? |
The sequence of bases in DNA specifies the sequence of bases in RNA, which specifies the sequence of amino acids in a protein. |
|
|
Transcription |
The process by which RNA is made from a DNA template by RNA polymerase. |
|
|
Translation |
The process by which proteins and peptides are syntehsized from messenger RNA. |
|
|
The relationship among DNA, RNA, and proteins |
However, many genes code for RNA molecules that do not function as mRNAs and are not translated into proteins. |
|
|
Reverse Transcriptase |
An enzyme of retroviruses (RNA viruses) that can synthesize double-stranded DNA from a single-stranded RNA template. In these RNA viruses, information flow from RNA to DNA. |
|
|
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. Suggested by George Gamow because a three base code would give 4x4x4=64 amino acids. |
|
|
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. |
|
|
Francis Crick and Sydney Brenner |
Confirmed that codons are three bases long. |
|
|
Marshall Nirenberg and Heinrich Matthaie |
Created a method for synthesizing RNAs of known sequence. Were able to determine many of the codes. |
|
|
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. |
|
|
The important properties of the genetic code |
- It is redundant: most amino acids are coded by more than one codon - It is unambiguous: one codon never codes more than one amino acid - It is universal: all codons specify the same amino acids in almost all organisms - It is conservative: when several codons specify the same amino acid, the first two bases in those codons are identical |
|
|
How to use the genetic code to predict an amino acid sequence |
1. Transcribe the bottom strand of DNA using the base pair rules where RNA uses U instead of T paired with A. 2. Translate the RNA code using the genetic code chart |
|
|
Mutation |
Any permanent change in an organism's DNA. |
|
|
Point Mutation |
A mutation that results in a change in a single nucleotide pair in a DNA molecule. |
|
|
Missense Mutation |
A point mutation that causes a change in the amino acid sequence of a protein. Also called replacement mutation. |
|
|
Silent Mutation |
A mutation that does not detectably affect the phenotype of the organism. |
|
|
The Three Categories of Mutations |
1. Beneficial 2. Neutral: mutation that has no effect on fitness 3. Deleterious |
|
|
Nonsense Mutation |
Change in a nucleotide that results in an early stop codon. |
|
|
Frameshift Mutation |
Addition or deletion of a nucleotide. |
|
|
Inversion |
A mutation in which a segment of a chromosome breaks from the rest of the chromosome, flips, and rejoins with the opposite orientation as before. |
|
|
Translocation |
A type of mutation in which a piece of a chromosome moves to a nonhomologous chromosome. |
