Molecular Techniques Flashcards
Summarise how DNA codes for a phenotype
DNA sequence codes for an gene which encode for a protein
Pairs of chromosomes in diploid organisms
At a locus, alleles from both chromosomes combine to produce a genotype
Genotype and environmental influences produce phenotype
What polymorphism?
Variation in a gene for multiple alleles
What are functional (coding) genes?
Exons, transcribed and translated part of the genome.
What are the non-coding parts of DNA (neutral markers)?
Introns, part of the genome that isn’t transcribed, no direct function.
Neutral to selection.
Highly polymorphic
Provides many highly informative markers.
What are the 3 types of DNA?
Nuclear - bi-parentally inherited, e.g autosomes and sex chromosomes - X = both sexes and Y = males
Chloroplast
Mitochondrial - maternally inherited
What are some examples of DNA markers?
Microsatellite repeats e.g CTTT10
Single Nucleotide Polymorphisms (SNPs)
How can DNA markers be applied in practise?
Marking individuals
Sampling - 100% ethanol, dried, specialised buffers
Polymerase chain reaction (PCR) - used to amplify targeted regions of DNA
How to molecular techniques allow us to identify species?
Distinguishes between similar species using DNA barcoding:
- Short, easy to amplify, sections of DNA
- Lots of variation between species, but little within
- Same section used across all species
- Library of species barcodes to compare to
Prey species can be identified using gut contents and faecal samples.
How can sex be determined?
Amplify section of DNA on sex chromosome.
Allele on W chromosome shorter than Z.
Size separation electrophoresis gel shows females (WZ) with two bands and males (ZZ) with one.
How can chronological age be determined using DNA methylation?
Methyl groups attach to DNA preventing that region from being transcribed
Key DNA loci show increased methylation with age
Determine age structure of populations
How can chronological age be determined using telomeres?
Telomere attrition with cell replication
Shorten with age
May cause senescence
How can biological age be determined using telomeres?
Oxidants erode telomeres which are products of metabolism and affected by stresses.
Higher oxidants shorten telomeres with:
- Infection
- Reproductive effort
- Psychological stresses
Telomere length can predict future lifespan
Generic currency to measure cost of different behaviours
How can infections like Endosymbionts be identified?
Wolbachia bacteria infect invertebrates can be identified using PCR of ribosomal DNA.
60% of insects infected
Transmitted in egg cytoplasm, so only female hosts
Female bias in offspring, override sex determination, parthenogenesis, kill male eggs
In Acraea butterflies, skews sex ratio to mainly female, reversing the sex that competes for a mate, results in female lekking
What are the problems with determining parentage through observations?
Difficult to watch individuals or groups
Mating may be secretive or difficult to observe
Females may copulate with different mates
Offspring from multiple females may be mixed
Solved through molecular techniques
How can reproductive success be determined?
Assessment of reproductive success determines adaptive significance of behaviours
Male reproductive skew drives sexual dimorphism, higher variance in males than females.
Selection greater in males, invest more into secondary sexual characteristics and behaviours
