37 terms

MCDB 101A Midterm 1 Study Guide

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Gene
basic unit of hereditary material
Genome
all chromosomal genes in an organism
Locus
physical location of a gene within a genome
Allele
alternate form of a gene
Genotype
allelic composition of an organism
Phenotype
outcome of given genotype
Wild Type
allelic form of a gene that is most prevalent in "wild" population
Mutation
genetic alteration (usually observed by a change in phenotype)
Mutant
organism that has 1+ mutations
Reversion
second mutation that restores a mutant cell to wild type phenotype
-often occurs at different location of gene/different gene
Haploid
one complete set of genes
Diploid
two complete set of genes
Prototroph
-able to make own AA's, vitamins, nucleic acids, etc...
-can grow fine on minimal media and rich media
Auxotroph
-CANNOT make own AA's, vitamins, etc...
-require rich media OR supplemented minimal media
Merozygote
partial diploid; 2 copies of some genes
Auxotrophic Mutation
mutations in metabolic pathways
-majority are found in genes that encode ENZYMES
-as well as genes encoding TRANSPORT PROTEINS and REGULATORY PROTEINS
Host Range Mutation
a mutation that affects the amount of strains a phage can infect
Plaque
a round, clear area in a lawn of bacteria on a solid medium that results from the lysis of cells by repeated cycles of phage lytic growth
Conditional Mutation
a mutation that results in a wild-type phenotype under one set of conditions but a mutant phenotype under other conditions. Temperature-sensitive mutations are a common type of conditional mutation.
Complementation
trans test
-when two mutants compensate to express wild type phenotypes
1. Two mutations will complement each other only if each is located in a different gene
2. The trans test tells you if two mutations are located in the same or different genes
Recessive Mutation
The phenotype of a recessive mutation will not be visible if a 2nd gene copy is present in the form of a wild type or dominant mutant allele.
Dominant Mutation
The phenotype of a dominant mutation will be visible in the presence of either a wild type or recessive mutation when the latter are present in a 2nd copy of the same gene
-appear to be on the same gene even if on different genes
-mutant alleles suppress phenotype of wild type allele
Alpha Complementation
Proteins with domains that function independently.
-Mutations in different domains of a gene that exhibits alpha complementation may complement each other and appear to be in different genes even though they are actually in the same gene
Recombination
a process by which parents with different alleles give rise to progeny with genotypes that differ from either parent
-CIS TEST tells distance between mutations and relative gene order
-mixing DNA segments by breakage of the double helix and rejoining (can occur between genes or within the same gene). must be homologous to rejoin
Antiparallel
5' to 3'; direction in which complement strand grows
Nucleotide
ribose sugar (ribose in RNA and deoxyribose in DNA), a nitrogenous base, and a phosphate group
Nucleoside
purine/pyrimidine covalently bonded to sugar
Twist
# helix turns
Writhe
# times a dsDNA molecule passes over itself = # supercoils
Linking Number
T + W
Okazaki fragment
short segment of DNA synthesized discontinuously in small segments in the 3' to 5' direction by DNA polymerase
Sigma Factor
binds to promoter and localizes core enzyme to transcription initiation site
Promoter
A DNA region containing specific gene regulatory elements to which RNA polymerase binds for the initiation of transcription
Pribnow box
a part of the promoter sequence in bacterial genomes that is located at about 10 base pairs upstream from the transcription start site. Also called the -10box.
Template Strand
complementary sequence to mRNA synthesized
Coding Strand
identical (except U for T) sequence to mRNA synthesized
Shine Delgarno sequence
A sequence in prokaryotic mRNA's upstream of the start codon that base-pairs with an RNA in the small ribosomal subunit, allowing the ribosome to locate the start codon for correct initiation of translation. Also called the ribosome binding site (RBS)
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