Upgrade to remove ads
Only $35.99/year

Human Molecular Genetics - Topic 1,2,3

Terms in this set (13)

Define Chargaff's Rules.
In a DNA molecule, total number of purines is equal number of pyrimidines.
Describe the three types of DNA conformation.
- B-form: Most common, right handed, smooth backbone
- A-form: Rare, right handed, shorter & wider
- Z-form: Transient, left handed, irregular backbone
State what happens during interphase.
- G1: Chromosomes are not duplicating or dividing
- S: DNA synthesis, duplication of chromosomes into sister chromatids
- G2: Synthesis of proteins required for mitosis.
What is the consequence of nondisjunction?
- Inviable gametes of embryos
- Abnormal chromosome numbers in viable individuals
List the three types of Down Syndrome.
- Trisomy 21
- Mosaic Down Syndrome
- Translocation Down Syndrome
State the techniques used to collect fetal tissues.
- Amniocentesis: Involves sampling and testing of amniotic fluid which contains cells of baby
- Chorionic villi sampling: Involves testing of tissue sample taken from placenta
- Fetal cell sorting: Fetal cells in maternal bloodstream are sampled and distinguished by fluorescence activated cell sorter
State the causes of reciprocal translocation.
- Chromosome breaks
- Abnormal crossing over between non-homologous chromosomes
Define uniparental disomy and why is it rare.
- Inheritance of two chromosomes or chromosome parts from same parent
- Rare because it requires simultaneous occurrence of two rare events namely
a) non disjunction of same chromosome in both sperm and egg.
b) trisomy followed by chromosome loss
List the two main ways by which polyploidy happens.
- Fertilization of one egg by two sperm
- Fusion of haploid and diploid gametes
What are the most frequent types of trisomies seen in newborns?
- Trisomy 21 (Down syndrome)
- Trisomy 18 (Edwards syndrome)
- Trisomy 13 (Patau syndrome)
State the differences between mitochondrial and nuclear genome.
- Mitochondrial genome contains few non coding DNA sequence while nuclear genome contains 93% non coding DNA sequence
- Mitochondrial genome is not enveloped and not packaged into chromatin, nuclear genome is packaged into chromatin
- Small mito. genome is unable to independently produce all of the proteins needed for functionality, mito. rely heavily on imported nuclear gene products
Define heteroplasmy.
A condition where mtDNA sequence is not the same in all copies of genome. Thus, a mitochondrion will have different alleles for the same gene.
What is the purpose of testcross?
Can determine whether recombination has occurred during gamete formation in the heterozygous parent.
Sets with similar terms