LIFESCI 4 Lecture Notes - Lecture 16: Nondisjunction, Gamete, Mendelian Inheritance
LIFESCI 4 - Lecture 16 - Molecular Genetics
Molecular Markers
- Despite not knowing the function, they can be used to detect certain things in DNA and
identify different individuals by analysis using the markers
Most of human genome is repetitive sequences
- SNP: Single nucleotide polymorphisms
- Don’t have known function
- Acts as molecular marker
- RFLP: base pair changes that alter a restriction enzyme site
- STR: short tandem repeats
- 1-5 base pair repeats
- E.g CTACTACTACTA
- VTNR: Variable Number Tandem Repeats
- 20-100 base pair repeats
Detection of SNPs:
- DNA sequencing
- RFLPs:
- Restriction digestion / southern blot
- PCR / Gel electrophoresis
- Gel will show heterozygous / homozygous
- ASOs (allele specific oligonucleotides)
- Can detect one nucleotide differences
- PCR followed by blotting → hybridization → find out genotype of individual
- Can see that the fetus is heterozygous by seeing the probes
Combining Molecular Biology with Genetics
- There are 3 restriction sites for morph 1 → 2 fragments
- There are 2 restriction sites for morph 2 → 1 fragment
- Can design a probe to overlap cut site
Southern Blot Detects Size Difference
- Both parental and maternal chromosomes are cut the same way
- 1-1 shows 2 bands (homozygous) for morph 1
- 2 bands because there is one cut and therefore 2 fragments
- 2-2 shows 1 band (homozygous) for morph 2
- 1 band because there is only 1 fragment
- 1-2 shows heterozygous for morph 1 and 2 → .results in 3 bands
RFLPs can be treated like segregating genes
Document Summary
Lifesci 4 - lecture 16 - molecular genetics. Despite not knowing the function, they can be used to detect certain things in dna and identify different individuals by analysis using the markers. Rflp: base pair changes that alter a restriction enzyme site. Pcr followed by blotting hybridization find out genotype of individual. Can see that the fetus is heterozygous by seeing the probes. There are 3 restriction sites for morph 1 2 fragments. There are 2 restriction sites for morph 2 1 fragment. Can design a probe to overlap cut site. Both parental and maternal chromosomes are cut the same way. 1-1 shows 2 bands (homozygous) for morph 1. 2 bands because there is one cut and therefore 2 fragments. 2-2 shows 1 band (homozygous) for morph 2. 1 band because there is only 1 fragment. 1-2 shows heterozygous for morph 1 and 2 . results in 3 bands.
