Exam 3 Flashcards
Describe chromosome theory of inheritance
states that genes are located on the same chromosomes
Describe incomplete dominance
Where the F1 hybrid has an appearance in between the phenotypes of the two parents (blended)
What is codominance?
When both alleles are expressed in the phenotype (both show)
What is polygenic Inheritance?
The addative effects of 2 or more genes on a single phenotype…In other words…traits determined by two or more genes
Name 3 internal and external conditions which influence phenotype
Temperature, Chemicals, and Nutrition
What are homologous chromosomes and what do they form?
Chromosomes that pair up during meiosis I which form a tetrad or bivalent
Describe mutation
change in DNA that makes up a gene
Are most human disorders recessive or dominate?
recessive
What is a family pedigree?
It shows the history of a trait in a family
Describe sex linked genes
Any genes located on the X chromosome
What are two main causes of chromosomal abnormalities?
Changes in chromosome structure and number
What are the 4 ways the chromosomal structure can change?
1 - Deletion
2 - Inversion
3 - Translocation
4 - Duplication
Describe nondisjunction
Errors in meiosis which results in abnormal chromosome numbers
Describe complete dominance
For dominance to be complete, a single copy of the
dominant allele must be enough to produce its phenotypic
effect in a heterozygote
Can phenotype be affected by environment?
Yes
What is the relationship between alleles, genes, and homologous chromosomes for the chromosome therory of inheritance?
Genes are at a specific loci
Alleles of a gene are at the same locus
In homologous chromosomes one gene is inherited from each parent
Describe loci / locus
The physical location of a gene on a chromosome
Loci is plural
Describe “origin of alleles” concept
Different alleles originally arose from mutations
What is the relationship between mendel’s laws and the movement of chromosomes during meiosis?
The law of segregation is when homologous chromosomes separate from each other during meiosis resulting in each gamete receiving just one chromosome from each parent
The law of independent assortment is baed on different tetrads lining up on the metaphase plate independent of each other
What are linked genes?
Genes found close together on the same chromosome
How do linked genes and independent assortment relate?
Independent assortment explains inheritance patterns of two genes found on different chromosomes. We can tell if two genes are linked because they would no longer be able to sort independently
Who was Thomas Hunt Morgan and what organism did he study?
He discovered that genes were inherited together by cross breeding fruit flies (imagine a man “hunting” for fruit flies
What are carriers?
When someone has one of the disease alleles but does not show that trait. They will always be heterozygous
Can there be carriers for an autosomal dominant disorder?
NO because it is impossible to be a carrier for a dominant disorder