Question | Answer |
What is a linkage group? | A set of genes that do assort independently |
What did Beadle and Tatum contribute to molecular biology? | The one gene: one polypeptide hypothesis |
What cause a recessive mutation? A dominant mutation? | Loss of function by the polypeptide product. Gain of function |
How does one test whether a gene is essential? | using a null mutation |
What is a null mutation? | one that completely eliminates function |
What do leaky mutations do? | Do not affect the function of the gene product, they are not shown in the phenotype because sufficient activity remains |
What is a polymorphic distribution? | Distribution of alleles in which no individual allele can be considered the sole wild type (blood type) |
What is polymorphism? | The simultaneous occurance of the population of alleles showing variations at a given position |
What is frameshift mutation? | insertion or deletion |
What are combinations of mutations? | They together insert or delete three bases (or multiples of three) that do not change the reading of the triplets beyond the last site of mutation |
What is conlinearity? | Bacterial gene has a continuous length of 3N nucleotides that encode N amino acids, Gene is colinear with both mRNA and polypeptide products |
What is an antisense strand? | The template strande, to which mRNA is complementary |
What is a sense stand? | The coding strand to which mRNA is identical |
How can introns be detected? | The presence of additional regions |
How are genes compared with their RNA products? | restriction mapping or electron microscopy |
What are paralogs? | genes that share common ancestory due to gene duplication |
what is an example of a paralog? | alpha and beta globin genes (variability in introns) |
Are positions of introns conserved? | yes when homologous genes are compared among different organisms |
what can vary with the introns? | the length |
How long are typical exons? | short, encoding <100 amino acids |
What are genes like in yeasts compared to multicellular eukaryotes? | uninterrupted in yeast |
in which type of organism are introns typcically short? | unicellular eukaryotes |
What is alternative initiation or termination? | Allows two proteins to be generated where one is equivalent to a fragment of the other |
what is an overlapping gene? | part of one sequence occurs within another sequence |
what is alternative splicing? | removal of introns and combining of exons, or removal of introns and one or more exons |
what is a gene family? | a group of genes that encode related or identical products as a result of gene duplication events |
what is an ortholog? | related genes in different species |
what is a homolog | related genes in the same species, such as alleles on homologous chromosomes or multiple genes in the same genome sharing common ancestory |