quantitative genetics, mapping and bioinformatics Flashcards
quantitative genetics
study of traits that can be described numerically
complex traits
phenotypes determined by both genes and influenced by environmental factors
what is the importance of quantitative genetics?
understanding key characteristics for animal and plant breeders, understanding human disease, and understanding environmental adaptation
continuous traits
vary continuously, do not fall into discrete categories
Meristic traits
can be counted and expressed in whole number
threshold traits
inherited quantitatively but are expressed qualitatively in terms of phenotype
polygenic inheritance
transmission of traits that are governed by 2 or more genes
quantitative trait loci mapping
genes are mapped by identifying molecular markers that are close by
what is heritability
proportion of phenotype variance attributed to genetic variation
heritability= 1 when
all the variation is due to genetics
heritability = 0 when
all the variation is due to environment
broad sense heritability
accounts for all genetic variation that may affect the phenotype
narrow sense heritability
estimated from the additive effects of alleles
cryogenic mapping
genes are mapped based on location of visible bands, uses microscopy
linkage mapping
genes are mapped based on locations relative to one another, uses crosses and recombinant offspring
physical mapping
make libraries of chromosomal DNA, use overlapping clones to identify all parts of a chromosome
Ion Torrent DNA sequencing
measures proton released, one nucleotide at a time
Single Molecule Real Time Sequencing (SMART)
fluorochromes attached to phosphate, fast and long reads, less accurate, detecting methylation and other base modifications
illumina DNA sequencing
each base fluorescently labeled with terminators attached, small reads
Bioinformatics
genomes too large to examine without the help of a computer, it is a computer science concerned with acquisition, storage and analysis of biological data
Basic Local Alignment Search Tool (BLAST Search)
software app used to compare a segment of genetic DNA to sequences in the major databases and identify portions that align with or are the same as existing sequences
blastn
nucleotide vs nucelotide database
blastx
translated nucleotide vs protein database
blastp
protein vs protein database
tbalstn
protein vs translated nucleotide
tblastx
translated nucleotide vs translated nucelotide
Baldt results
ranked alignments with similar sequences
similarity score
sum of identical matches/total # of bases or amino acids aligned
E value
statistical analysis comparing result with random chance- smaller the better
homologs
closely related genes (high DNA similarity)
homologs- Orthologs
genes at the same locus in different species inherited from common ancestor
homolog- Paralog
related genes within or between a species- comes from duplication events in a genome
sanger sequence
method for determining the nucleotide sequence of DNA by elongating the small fragments sequence
