Final Test Flashcards
What is a gene?
Basic unit of hereditary
What is a chromosome?
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
What is a locus?
A specific region or spot on a chromosome where a gene is found
What is an allele?
One or two on more forms of a given gene
What is a dominant allele?
Relationship between to alleles in which one allele masks the effect of the other (recessive) allele
What is a recessive allele?
Allele expressed only in the homozygous state - bb- when in the heterozygous state- Bb - it is masked by the dominant allele
What is homozygous?
Both alleles being the same at one locus =BB or bb
What is heterozygous?
2 different alleles at one locus = Bb
What is a genotype?
Genetic makeup of an organism
What is a phenotype?
The observable makeup of an organism
What is the use of test crosses?
To find out he genotype of an unknown that shows a dominant phenotype you cross it with a homozygous recessive and this will tell you if the unknown is heterozygous or homozygous dominant
How is the punnett square used?
Used to determine all the possible combinations of offsprings from two parents
What is the law of independent assortment?
The Principle of Independent Assortment describes how different genes independently separate from one another when reproductive cells develop.
What is the law of segregation?
Each individual carries a pair of factors (2 alleles) for each trait that segregate during the formation of gametes.
What is codominance?
Full expression of both alleles
AB blood group
What is incomplete dominance?
When the phenotype of the heterozygote is intermediate between the 2 parental extremes
What is polygenic inheritance?
Polygenic inheritance concerns a pattern of inheritance in which the interactions of two or more functionally similar genes determine phenotype.
these are examples of traits that exhibit polygenic inheritance; they are governed not by interactions among two or more genes
What is sex linked inheritance?
If a gene is present on one sex chromosome but not on the other, its pattern of inheritance is sex linked.
How do mutations affect human diseases?
Cause genetic disorders
Cancer
Prevent proteins from works properly
What is the relationship between human disease and recessive alleles?
Recessive inheritance means both genes in a pair must be abnormal to cause disease.
Example: Diseases like sickle cell anemia come from homozygous recessive alleles ss
What is hemophilia? How is it caused?
If a gene is present on one sex chromosome but not on the other, its pattern of inheritance is sex linked.
Hemophilia
a medical condition in which the ability of the blood to clot is severely reduced, causing the sufferer to bleed severely from even a slight injury
What is sickle cell anemia ? How is it caused?
These cell have a change in r- group this produces hemoglobin that stick together and form fibers which then get stuck in capillaries (small blood cells)
Sickle cell disease is caused by a mutation of a single nucleotide located within a restriction sequence in the human Beta globin gene .