Genetics Flashcards
What’s the human genome?
Complete haploid set of genetic material in an organism
What’s the central dogma of molecular biology?
DNA encodes mRNA which encodes protein
What are male and female chromosomes?
Female XX
Male XY
What are 3 different classes of genetic disease, their abnormality and investigation?
Monogenetic = single gene abnormality (eg cystic fibrosis) and investigate by a molecular genetic test eg PCR
Multifactorial = multiple genes and environmental influences involved (eg heart disease) and investigate using molecular genetic tests to assess risk
Chromosomal = abnormality of chromosome structure or number (eg Down’s syndrome) and investigate using cytogenetics (look at karyotype)
What’s a punnett square used for?
Draw the expected outcomes of matings
Predict the probability of offspring genotype
What are Mendel’s 3 laws of inheritance?
Law of uniformity
Law of segregation
Law of independent assortment
What’s a vertical pattern of inheritance?
Affected offspring must have affected parent
= autosomal dominant
What are some diseases with autosomal dominant inheritance?
Familial hypercholesteroaemia
Adult polycystic kidney disease
Huntington’s disease
Achondroplasia
What does consanguinity mean?
Sharing of blood = matings where the partners have at least one common ancestor = at higher risk of autosomal recessive disease
What’s our genetic load?
The hidden detrimental component of our genome (eg harmful pre-natal mutations and recessive disorders for which we are carriers)
An exception to Mendel’s law is co-dominance - what is it and an example?
Some genes are neither dominant nor recessive over other alleles and are expressed in the phenotype together
AB blood groups are co-dominant but are dominant over type O blood
What are some exceptions to Mendel’s laws of inheritance?
Overdominance Incomplete pentrance Genomic imprinting Sex-linked effects Mitochondrial inheritance Genetic linkage Dynamic mutation
What are examples of sex-linked recessive diseases?
Haemophilia A
Duchenne muscular dystrophy
Red/green colour blindness
Fragile X syndrome
What’s mosaicism?
When different cells within the same individual have different genotypes - usually caused by error in DNA replication and chromosome separation in very early embryo
