Molecular markers Flashcards
What’s a molecular marker ?
Segment of DNA that is found at a specific site along a chromosome and has properties that enables it to be uniquely recognized using molecular tools (PCR, gel electrophoresis, sequencing…)
True or false : molecular markers can code for protein
false
True or false : we can use molecular markers to help track genetic variation, polymorphisms or patterns of inheritance
True
True or false : most individuals of one population have the same molecular markers
False. Markers vary between individuals of the same population
True or false : molecular markers are codominant
True
True or false : molecular markers can be mapped by recombination frequency, juste like phenotypic markers
True
Name how we can use molecular markers (what are they useful for ?)
- Genetic mapping and linkage analysis
- Selective breeding
- Population genetics and evolutionary studies
- Medical genetics and disease association studies (identify diseases)
- Forensic sciences (fingerprinting, paternity tests)
- Conservation biology (assess diversity)
What does PCR stand for ?
Polymerase chain reaction
Explain how PCR works
Uses 1 chromosome, 2 primers, some nucleotides and a polymerase that copies DNA
- The primers are attached to the denatured DNA
- Temperature is raised
- Polymerase copies the region surrounded by the 2 primers
- gives 2 new molecules
- Repeat a bunch of times to get a large number of copies
What are the 3 steps of PCR ?
- Denaturation of parental DNA
- Annealing of DNA primers
- Extension
How can we visualize and measure the size of the DNA fragments that are amplified through PCR ?
- Place the sample on an electrophoresis gel
- The negatively charged DNA migrates inside gel towards the positive charge
- we compare the height at which our sample migrates to the height of the pathogen we’re testing for
What’s the restriction fragment lenght polymorphism (RFLP)?
polymorphism generated when specific DNA sequences are recognized and cut (or not cut) by restriction enzymes
Complete : most sequences recognized by restriction enzymes are ___
palindromes (can be read in both direction)
What are variable number of tandem repeats (VNTR) ?
Short, repeated DNA sequences (2-100 nucleotides) found in the genome and present in tandem (repeated many times in a row)
name 2 types of VNTR and their number of base pairs
- Minisatellite : 6-100bp
- Microsatellite : 1-6bp
What’s a SNP (single-nucleotide polymorphism) ?
A site in a genome where a single nucleotide is polymorphic among different individuals
Which technique is widely used in the mapping of disease-causing alleles and genes that contribute to quantitative traits ?
SNPs
Name one diseased caused by a SNP
Sickle cell anemia (A switched for a T –> synthesizes a valine instead of a glutamine)
What field of study does the analysis of genetic variations to find links between SNPs and causal genes ?
Genome-Wide Association Studies (GWAS)
True or false : SNPs are harmful
False, they can be either harmful or beneficial
