Genetics Lecture 5: Inheritance and Genetic Disease. Flashcards
Genotype
The genetic constitution (make up) of an organism.
i.e. the sum total of all it’s genetic info (e.g. DNA, RNA, Proteins)
Phenotype
The observable characteristics of an organism.
Haploid
An organism or cell having only one complete set of chromosomes or genome.
(Gametes are usually in this state)
Diploid
An organism or cell having 2 complete sets of chromosomes/genomes.
(Somatic cells are usually in this state.)
Dominance
One member of an allelic pair is manifested to the exclusion of another.
Recessive
One member of an allelic pair lacking the ability to manifest itself when the other dominant is present.
Autosomal
Describes a gene or trait which is not carried on the X or Y Chromosome.
Sex-Linked
Describes a gene or trait that is carried on the X or Y Chromosome.
How do genes work?
They operate in pairs (paternal and maternal)
What are Allelles?
Alleles are different form of the same gene.
What determines your Phenotype?
Your Phenotype is determined by the interplay of the allelic products.
What is a Family Pedigree?
It’s one of those sill Mind-Map things that use varying symbols to represent Male or Female, Affected, Carrier of Clean and X linked or Deceased.
They can be used to trace a mutated gene from children to parents. The results are shown on Family Pedigrees.
Dominant Autosomal
Only need 1 bad gene, to be affected
Recessive Autosomal
Need two bad genes, to be affected
Recessive X Linked
Boy can get it as they only have one X Chromosome. Girls can carry it, however need 2 bad copies of the genes to be affected.
Dominant X Linked
Boy and Girls are equally likely to be affected.
What sort of Genetic Disease if Cystic Fibrosis?
Autosomal Recessive.
What goes wrong in the Karyotype for Cystic Fibrosis to occur?
Mutation in the CFTR gene on Chromosome 7.
Explain what happens in Cystic Fibrosis?
Defective secretions by epithelial cells, salt gathers on surface of lung, leads to bacteria growing there, creating problems with the lungs, digestive system and reproducing.
1 in 2000 live births - causes death at 20 - 40.
What sort of Genetic Disease if Marfan’s Syndrome?
Autosomal Dominant
What goes wrong in the Karyotype for Marfan’s Syndrome to occur?
Mutation in fibrillin gene on chromosome 15.
What if the outcome of Marfan’s Syndrome?
Connective Tissue Abnormalities. It also leads to Spinal Deformity, Scoliosis, Arachnodactyly.
1 in 10 000 live births - Life Expectancy Reduced by 30%.
What sort of Genetic Disease if Duchenne Muscular Dystrophy?
X linked Recessive.
What goes wrong in the Karyotype for Duchenne Muscular Dystrophy to occur?
Mutations in the Dystrophin gene Chromosome X.
