Genetics Flashcards
(17 cards)
Co-Dominant Alleles
When two alleles are EQUALLY dominant.
They are both expressed in the phenotype.
Monohybrid Inheritance
The inheritance of a single gene.
Punnet Squares
Used to describe patterns and predict probabilities of outcomes of monohybrid crosses. Also called genetic diagrams.
Allele
A form of a gene.
Dominant: It will always be displayed phenotypically.
Recessive: It will only be displayed phenotypically if there are two.
Genotype
The combination of alleles an individual has for a particular gene. e.g. homozygous(recessive/dominant) & heterozygous
e.g what alleles the individual has
Phenotype
An individual’s physcial appearance based on their alleles. (also whether they are dominant or recessive). e.g. blood type or colour of eyes
Homozygous
When the individual has 2 of the same allele. It can be dominant (BB), or recessive (bb).
Heterozygous
When the individual has 2 different alleles. e.g. (Bb).
Pedigree Charts
Mutations (T)
A rare random change in the genetic code of a gene, that can produce a different form of the gene (allele).
They can produce changes that are beneficial, neutral and harmful.
What changes do mutations produce?
Beneficial - may give the organism some advantage over other individuals of the same species.
Neutral - has no obvious effect. Most mutations are neutral.
Harmful - causing early death of embryo, or making the individual less able to survive.
What are mutations caused by?
- Ionising radiation such as gamma rays, X rays and UV radiation
- Mutagens such as chemicals in tobacco smoke
Different types of mutation
Insertion Mutation: DNA is added
Deletion Mutation: DNA is removed/deleted
Inversion Mutation: DNA base pairs are inverted
Substitution Mutation: single bases are added
What is sickle cell disease?
A genetic disorder.
The faulty allele is recessive.
Symptoms: tiredness, shortness of breath, painful joints
What is cystic fibrosis?
A genetic disorder.
The faulty allele is recessive.
Symptoms: difficulties breathing due to mucus, lung infections, weight loss
What is polydactyly?
A genetic disorder, the sufferer has extra digits.
Caused by dominant allele.
What is Huntington’s disease?
A genetic disorder, dominant.
The symptons appear in middle age and sufferers gradually lose control of their muscles. First appears as twitching, then they gradually become more forgetful and find it difficult to understand things. It is eventually fatal.
