Term
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Definition
| he was the first to connect inherited human disorders with mendel's laws of inheritence |
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Term
| what did Garrod study patients with? |
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Definition
| patients with Alkaptonuria - rare disease of organic acid metabolism known for darkening of urine from yellow to brown-black after exposure to air |
|
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Term
| what is alkaptonuria also known as? |
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Definition
|
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Term
| what did garrod observe on how alkaptonuria was inherited? |
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Definition
| autosomal recessive - in mendel laws 3:1 ratio. 1/4 to get it |
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Term
| what was Garrod's hypothesis? |
|
Definition
Alkaptonuria patients lack the enzyme necessary for breaking down homogentisic acid due to a defect in a gene
we now know the missing enzyme is homogentisic acid oxidase |
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Term
| what did Beadle and Tatum faff about in 1940? |
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Definition
| the one gene one enzyme hypothesis |
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Term
| beadle and tatum experiment with Neurospora and identified a series of auxotrophic mutants. what are they? |
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Definition
| they are mutant strains that cannot synthesise a particular molecule required for growth (like arginine) therefore will only grown if they are supplied with that molecule |
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Term
| how many classes of arginine auxotrophs did beadle and tatum identify? |
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Definition
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Term
| in beadle and tatums discoveries what did class I auxotrophs require to grow? |
|
Definition
MM + ornithine
MM + Citrulline
MM + Arginine |
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Term
| in beadle and tatums discoveries what did class II auxotrophs require to grow? |
|
Definition
MM + citrulline
MM + arginine |
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Term
| in beadle and tatums discoveries what did class III auxotrophs require to grow? |
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Definition
|
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Term
| what was the interpretation of beadle and tatums experiment? |
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Definition
| the further down the metabolical pathway the block occurs, the FEWER the number of intermediate compounds that will permit the strain to grow |
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Term
| what did beadle and tatums 'one gene - one enzyme' get modified to and why? |
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Definition
| 'one gene - one polypeptide' it was found not all gene products are enzymes, some are stuctural proteins like actin and ribosomal proteins |
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Term
| if a gene codes for a protein, how is the info in the gene sequence get converted into a protein structure? |
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Definition
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Term
| what does gene expression mean? |
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Definition
|
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Term
| what provides the link betwen DNA and protein? |
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Definition
| mRNA - a single stranded RNA molecule that is able to carry genetic information from DNA to protein |
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Term
| there are 2 main stages to gene expression what are they? |
|
Definition
Transcription
and
Translation |
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Term
| what happens in the transcription part of gene expression? |
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Definition
| mRNA is synthesised using one strand of DNA as a template strand. its complimentary strand is known as the coding strand because it has the same sequence as mRNA apart from uracil substitution |
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Term
| which enzyme catalyses transcription? |
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Definition
|
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Term
|
Definition
| assembling amino acids into polypeptides using the genetic information encoded in the mRNA. the information has to be decoded |
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Term
| a series of NON-OVERLAPPING three nucleotide words are known as? |
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Definition
|
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Term
| most amino acids are encoded by more than one codon. what is this known as? |
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Definition
|
|
Term
| how many start codons are there? |
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Definition
|
|
Term
| how many stop codons are there? |
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Definition
|
|
Term
| in which direction are the codons read by the translation machinery? |
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Definition
| 5' to 3' direction along the mRNA |
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Term
| if codons (triplet of nucleotides) do not overlap and each codon specifies an amino acid how many amino acids to 900 nucleotides encode for? |
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Definition
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|
Term
what do these mean?
replication
transcription
translation |
|
Definition
replication - synthesis of DNA
transcription - synthesis of mRNA
translation - synthesis of protein using mRNA as template |
|
|
Term
| what are point mutations? |
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Definition
| mutations that affect one or a few base pairs of DNA |
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Term
| what are the 2 main classes of point mutations? |
|
Definition
1. base pair substitutions
2. Frameshift mutations (caused by insertions and deletions) |
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Term
| base pair substituions can be of 3 types depending on their effcet on translation what are they? |
|
Definition
silent - no change
nonsense - premature termination of translation
missense - amino acid substitution |
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Term
| how are frameshift mutations caused? |
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Definition
| by insertion or deletion of one or two base pairs in the DNA |
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|
Term
true or false
sometimes frameshift mutations cause an immediate stop codon? |
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Definition
| true - this results in a truncated and probably non fucntional protein |
|
|
Term
| will the insertion/deletion of 3 or a multiple of 3 nucleotides cause a frameshift mutation? |
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Definition
| no! will add or remove an amino acid and protein may still function |
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