Patterns of inheritance Flashcards
What is chlorosis
When plant leaves appear yellow due to a lack of chlorophyll
What are the environmental causes of chlorosis
- Lack of light
- Mineral deficiencies (iron and magnesium)
- Viral infections
Genotype vs Phenotype
- Genotype= the genetic make up of an organism
- Phenotype= the observable characteristics of an organism
Homozygous vs heterozygous
- homo= 2 identical alleles, either homozygous recessive or homozygous dominant
- hetero= 2 different alleles for a characteristic, dominant allele expressed
Genes coding for continuous and discontinuous variation
- continuous controlled by many genes= polygenes
- discontinuous controlled by 1 or 2 genes
What is monogenic inheritance
- the inheritance of a single gene
- shown in punnet squares
What is co-dominance, how is it written
-2 alleles are equally dominant, both expressed in the phenotype
- 1 letter to represent genes, other letters at top right to represent alleles
What alleles are dominant and recessive for blood group
- A and B are co-dominant
- O is recessive
What are sex linked genes
- characteristics that are determines by genes carried on the sex chromosomes
Cause, symptoms of haemophilia
- sex linked genetic disorder
- blood clots too slowly
- caused by an absence of protein blood clotting factor VIII
- affects males only- inherit the recessive, faulty allele and no dominant one as only 1 X chromosome
What is dihybrid inheritance
- shows the inheritance of 2 genes on the same chromosome
Expected ratio of dihybrid inheritance
9:3:3:1
What is linkage
- when different genes are located on the same chromosome
What is autosomal linkage
- when genes that are linked are found on 1 of the other pairs of chromosomes
What is a recombinant offspring
- organisms have different combinations of alleles to both their parents
What is recombinant frequency, how to work it out
- a measure of the crossing over that happens in meiosis
- number of recombinant offspring/ total number of offspring
What does the chi-squared test measure
whether the difference between observed and expected values is significant
When to reject the null hypothesis for the chi-squared test
-if the value of x^2 is greater than or equal to the critical value
- indicates a significant difference
What is epistasis
the interaction of genes at different loci
