BY5.4 - Inheritance Flashcards
What is a Recessive allele?
An allele that is only expressed in the phenotype when present on the genotype in homozygous recessive form
What is an Allele?
Alternative forms of a gene on the same locus on homologous pairs of chromosomes
What is a gene?
A specific sequence of DNA bases which code for a specific polypeptide to be synthesised
What is Genotype?
The combination of alleles found in an induvidual
What is Phenotype?
The appearance of an organism determined by genotype
What is gene expression?
The transcription and translation of a gene, resulting in a functional protein which is part of an individual’s phenotype
What is a dominant allele?
An allele that is always expressed in the phenotype when present in the Genotype
Define Homozygous
Both alleles are the same
Define Heterozygous
both alleles are different
What are Autosomes?
Non-sex chromosomes
What are sex-linked alleles?
Alleles carried on the sex (x and y - mostly x) chromosomes
Why are men more susceptible to sex-linked conditions?
The Y chromosome is small, and is lacking a lot of the genes the X chromosome has.
Therefore in men any recessive allele carried on the X chromosome will be expressed in the phenotype because the genes are unpaired (no dominant gene present - not homologous)
What is the protein thar codes for blood clotting
Factor VIII (8)
What is Mendel’s First Law?
The characteristics of an organism are determined by “factors” (alleles) which occur in pairs.
Only one of the pair of factors can be present in a gamete.
What is Mendel’s Second Law?
Each member of an allele pair may combine randomly with either of another pair
What is Dihybrid Inheritance
The inheritance of 2 genes (4 alleles) from different homologous pairs of chromosomes
What is the Chi squared formula?
Σ((o-e)2 / e)
How do you calculated the expected phenotype number? (E)
Total number of all individuals observed x current phenotype ratio
Total number of phenotype ratios
What are the 3 main characteristics of genes?
1) can Separate and combine
2) can mutate
3) code for production of a specific polypeptide
What is Monohybrid Inheritance?
The Inheritance of one gene (2 alleles) from a Homologous Pair of chromosomes
What is Pure Breeding?
Cross pollinating 2 Identical genotypes
How would you find out if an individual with the dominant characteristic/phenotype is Homozygous dominant or Heterozygous?
1) Take unknown parent plant genotype
2) cross with homozygous recessive genotype (rr)
3) If all F1 phenotypes are dominant, genotype is homozygous dominant
4) If half of the phenotypes are dominant, Genotype is hetrozygous
What is Co-Dominance?
Both alleles are expressed in the phenotype - neither are dominant
How do you show co-dominant alleles in test crosses?
Capital letter for characteristic
Allele letter placed superscript to Characteristic letter
e.g. red coloured petals = Cr
