Exam 1 Definitions Flashcards
(23 cards)
Evolution (Pop Gen) Definition
changes in the genetic composition of a population
Evolution (Hist Geol) Definition
The origin of new forms of life by descent from pre-existing forms
Microevolution Definition
Changes in the genetic composition of a population
Macroevolution Definition
The origin of new grades
Grade Definition
a group of organisms with characteristics and abilities that are not found in other groups
Example of Macroevolutoin
The origin of photosynthesis and the origin of mammals
Genotype frequency definition
What fraction of individuals have a specific genotype
Genotype Frequency Formula
Gene\Allele frequency definition
What fraction of the copies of a gene are a specific allele
Gene Definition
A portion of a DNA molecule associated with a specific function
Or
A portion of a DNA molecule that codes for a product
Allele Definition
Alternative form of the same gene
Gene/Allele Frequency Formula 1
Gene/Allele Frequency Formula 2
There must be _____________ in a population in order tohave evolution
genetic variation
Name three ways genetic variation can be added to population
- Mutation (= changes in the hereditary materials [DNA andchromosomes]: for example, allele A → allele a)
- Recombination (formation of new combinations of existingalleles and genotypes: for example, AA x aa → Aa)
- Migration (individuals with new [to the population] alleles or genotypes may migrate into the population)
Gene/point mutations definition
Mutations that involve only a few DNA nucleotides and cannot be detected with light microscopy
Chromosome mutations (chromosome aberrations) definition
Mutations that involve larger segments of DNA and can (often) be detected with light microscopy. Chromosome mutations may change the number of chromosome in a cell, the size of chromosomes, or the order of genes on a chromosome
Name the two main types of gene mutations
Substitutions
Insertions and Deletions
Substitutions Definition
One base replaces another base in the DNA chain
Example: TAC → CAC
Define Insertions and deletions
one or more nucleotides are added to (or deleted from) the DNA chain
Example: TACTACTAC… → TACGTACTAC…
Name two types of substitutions
Transitions
Transversions
Define Transitions
a purine base (adenine or guanine) replaces another purine base or a pyrimidine base (thymine or cytosine) replaces another pyrimidine base
Example: TAC → TGC
Define Transversions
a purine base replaces a pyrimidine base or a pyrimidine base replaces a purine base
Example: TAC → TCC
