Inheritance Flashcards
What is a gene with more than one allele called?
polymorphic
alleles are either?
dominant or recessive
Monogenetic condition
disease caused by one single gene
Second law of mendelian inheritance
- alleles of different genes divided across gametes independently
- parental traits = Gen 2
- not always true
- applies to genes that are on diff chromosomes
Non- mediated inheritance
multiple alleles, incomplete dominance, co- dominance, pleiotropic allele,
Co- dominance alleles
produce phenotypes that both appear in heterozygotes
Pieotrophic allele
one allele has multiple phenotypic effects
Epistasis
One gene alters the phenotypic expression of another gene
Polygenic traits
Traits controlled by multiple genes
Incomplete penetrace
variable phenotypic expression of a genotype
Example of polygenic trait
height in humans
Two processes introduce variation
Mutation, recombination
what is a mutation
a heritable change in the genetic information of a cell or organism
What is recombination
the rearrangement of genetic material. this happens during sexual reproduction
spontaneous causes of mutation
- chemical reactions that alter nucleotides
- errors in DNA replication
- errors during meiosis
induced causes of mutation
damaging chemicals
- ionising or UV radiation
what are induced mutations caused by?
mutagens
Frame shift point mutation
insertion or deletion of one or two bases will alter the reading frame
Missense point mutation
changes a codon into one that specifies a different amino acid, the amino acid sequence of the encoded protein is affected
Synonymous (silent) point mutation
there is a redundancy in the code as there 64 codons but only 20 amino acids
- amino acid is unaffected
nonsense point mutation
changes a codon that specifies an amino acid into a stop codon
- translation is terminated prematurely
- resulting in a truncated protein
Chromosomal mutations can be due to;
- deletion
- duplication
- inversion
- insertion
- translocation
Molecular characteristic of the mutation
point mutation
chromosomal mutation
Function of the encoded protein
silent, loss or gain of function
a mutation can be silent because…(encoded)
- mutation doesn’t alter the amino acid sequence
- mutation causes change in the sequence that has no effect on the function of protein
Loss of function mutation (encoded)
- results in a change in the amino acid sequence that impairs normal protein function
- shows recessive inheritance
Gain of function… (encoded protein)
- change leads to abnormal functioning protein
- shows dominant inheritance as wild type allele encoding for normal protein is often not able to prevent the abnormal activity of mutant protein
