Topic 3.1 Genes Flashcards
Gene
A gene is a heritable factor that consists of a sequence of DNA and influences a specific trait. (extra info. The position of a gene on a chromosome is the locus)
Alleles
Alleles are the alternate forms of a gene that code for the different variation of a specific trait. Alleles for specific gene variations will differ by only a few bases by only a few bases. (extra info. New Allels may be formed as a result of gene mutations)
Genome
A genome describes the totality of the genetic information in an organism. It includes all genes and non-coding sequences.
Human Genome Project
The human genome project was complete in 2003 and mapped the entire base sequence of human genes. (extra info. The human calls typically have have 46 chromosomes. The human genome consists of 3~billion base pairs. It contains roughly 21,000 genes (although estimates vary) The genomes of other sequences may vary.)
What is a mutation
A gene mutation is a change in the base sequence of a section of DNA coding for particular characteristics. A gene mutation may be beneficial, detrimental or neutral.
Type of Gene Mutation Description
Somatic - Occurs in a body cell and affects a tissue
Germline - Occurs in a gamete and affects offspring
Types of mutation
Substitution (either silent, missense or nonsense)
Frameshift (insertions or deletions)
Cause of Gene Mutations
Mutations can arise spontaneously as copying errors during DNA replication or can be induced my mutagenic agents.
Genetic Comparisons
There is no Clear correlation between genetic complexity and chromosomes numbers, genome size or the number of genes.
Cause of Sickle cell anemia
Base Substitution: GAG → GUG (6th condon: hemoglobin beta)
Amino acid change: Glutamic acid → Valine (Glu → Val)
Consequences of Sickle Cell Anemia
Alters Hemoglobin structure (forms insoluble strands)
Cannon transport oxygen effectively (causing fatigue)
Red blood cells adopt a sickle shape (may form clots)
Sickle cells are destroyed at a higher rate (causes anemia)
