The Human Genome And Disease Flashcards
What are mutations
A permanent change in DNA sequences that can be inherited or acquired
What are somatic and Germaine mutations
Germaine mutations are mutations that are inherited and are passed on via the gametes
Somatic mutations are caused by DNA damage/modification/incorrect replication. Somatic mutations are not passed on
What do mutations do
Mutations/variation are a driving force for evolution
Mutations can have beneficial or deleterious effects on the organism
The vast majority of mutations have no effect at all
Outcome of mutations can also depend on environmental factors, and other genes
Outline dominance vs recessive alleles
Dominant alleles cause a phenotype when heterozygous (or homozygous dominant)
Recessive alleles cause a phenotype when homozygous recessive
Outline loss of function vs gain of function
Loss of function mutations may cause gene to not work as well as normal or not work at all
Gain of function mutations may cause gene to work to well, or do something different
Are loss of function mutations generally dominant or recessive
Loss of functions are generally recessive, as the normal copy of the gene exists on the other chromosome hitch can replace the lost function
Are gain of function mutations generally dominant or recessive
Gain of function mutations are generally dominant because having an allele that works too well or does something else will not be replaced by the normal copy of the gene
What does x linked recessive inheritance refer to
Genetic conditions associated with mutations in genes on the X chromosome
What are the characteristics and examples of x linked recessive chromosomes(mutations)
Fathers cannon pass on X linked traits to their son (as they pass on Y chromosome)
No Male to Male transmission
Most often effects males (due to possession of only one X chromosome)
Examples are Haemophilia A and B
What are the characteristics and examples of Autosomal Dominant genes
Occurs commonly in a pedigree
Affected individuals have an affected parent
Males and females equally likely to inherent
Examples are widows peak and Huntingtons disease
What are the characteristics and examples of Autosomal recessive genes
Typically none seen in every generation of an affected family
Passed on by two asymptomatic carriers
Males and females equally likely to inherit
Examples include inability to taste PTC, Cystic fibrosis
What is the basic process to determine inheritance patterns
Examine the pedigree and look for individuals that break the above rules (male to male transmission rules out x linked)
Identify carriers who do not have the condition, if there are none, might mean dominant
Find the inheritance pattern that explains all the disease occurrence in a pedigree
What are polygenic disorders
Polygenic disorders involve several genes acting together or environmental factors interacting with genes
E.g. obesity, diabetes, rheumatoid arthritis, gout, bipolar disorder
Outline what is meant by most genes being probabilistic
For most diseases, having a disease related variation does not mean you will get the disease
Such diseases come about through a combination of variants and the environment
Genes increase the probability of a certain effect. Most genes are not deterministic
