Inheritence (SB3) Flashcards
What is a gene
A section of DNA that codes for a characteristic
What is an allele
A version of a gene that can code for different versions of the characteristic
What is an example alleles can be found in
If there is a gene for eye color, that gene has several alleles for different colors like blue and brown eyes
What is the ‘phenotype’
Physical observable characteristics
What is the ‘genotype’
The alleles that code for the phenotype
What does every person inherit two of
Two genes, one from the mother’s egg cell and one from the father’s sperm cell
What can the genes inherited from the parents be
Two of the same alleles or two different ones
What happens if there are two different alleles
In most cases, only one is expressed in the phenotype
What is the allele that is expressed in the phenotype called
The dominant allele
What is the allele that is ignored in the phenotype called
The recessive allele
What must happen in order for a recessive allele to be expressed in the phenotype
There must be two recessive alleles
What is it called if the genotype has two of the same allele
Homozygous (dominant or recessive)
What is it called if the genotype has two different alleles
Heterozygous
What is a ‘family pedigree’ diagram
Used to trace the pattern of inheritance of a specific character (usually a disease) through generations of a family.
It can be used to work out the probability that someone in the family will inherit the genetic disorder.
In ‘family pedigree’ diagrams what do the square and circle shapes represent
The square represents males and the circle represents females
In ‘family pedigree’ diagrams what do the red and blue colors represent
Red is affected and blue is unaffected individuals
In ‘family pedigree’ diagrams, what do horizontal lines show
Show that they have produced children
