Chapter 5: Population Genetics Flashcards
- the study of evolution from a genetic point of view
Population Genetics
- a field of biology that studies the genetic composition of biological populations, and the changes in genetic composition that result from the operation of various factors, including natural selection
Population Genetics
population genetics it is the study of the allele frequency distribution and change under the influence of the four evolutionary processes: ______________________. It also involves the concepts of migration and isolation.
a. natural selection
b. genetic drift
c. mutation
d. gene flow
- the percentage of alleles of a given type in a population
allele/gene frequency
- a term of population genetics that is used in characterizing the genetic diversity of a species population, or equivalently the richness of its gene pool
allele/gene frequency
Levels of Biodiversity:
Ecosystem
Species
Genes
The amount of diversity at the genetic level is important because it represents the raw material for ________ and __________.
evolution and adaptation
More genetic diversity in a species or population means a greater ability for some of the individuals in it to_________________ in the environment.
adapt to changes
- a change of the genetic structure of a population, and are brought by evolutionary factors
Evolution
Evolution type:
a. Microevolution
b. Macroevolution
- changes in allele frequency of a population over time (genetic diversity)
Microevolution
- large scale evolution of groups of species (speciation)
Macroevolution
Evolutionary Factors:
a. Natural Selection
b. Mutation
c. Genetic Drift
d. Gene Flow
- is a mechanism of evolution
Natural Selection
- organism that are more adapted to their environment are more likely to survive and pass on the genes that aided their success. This process causes species to change and diverge over time
Natural Selection
- random changes of genetic information
Mutation
- errors in DNA replication during cell division, exposure to mutagens or a viral infection
Mutation
Mutation is the ultimate source of ________
variation
Mutation often _______
lethal/detrimental
Type of Mutation:
a. Chromosomal Mutation
b. Gene Mutation
- changes in structure as well as in number of chromosomes
Chromosomal Mutation
Chromosomal Types:
a. Euploidy
b. Aneuploidy
c. Chromosomal Aberrations
- variation in complete sets of chromosome
- refers to the changes involving the whole genome or entire set of chromosome
Euploidy
Euploidy Types:
a. Monoploidy
b. Diploidy
c. Polyploidy
- the number of sets of chromosome in a cell or an organism
Ploidy
- contains one half the normal number of chromosomes and is exhibited by monoploids (individuals having one set of chromosome)
Monoploidy (n)
- have two sets of chromosomes
Diploidy (2n)
- have 3 or more sets of chromosomes
Polyploidy (>2n)
- are organism with the cells containing 3 or more sets of chromosome or genomes (organisms with more than two genome0
Polyploids
- (3 sets or 3n;3x)
- banana, apple, ginger, watermelon, citrus
Triploidy
- (4 sets or 4n;4x)
- maize, cotton, potato, cabbage, tobacco, peanut
Tetraploidy
- (6 sets or 6n;6x)
- wheat, kiwi, chrysanthemum
Hexaploidy
- variation in parts of chromosome sets
- occurs when one or more chromosome of a normal set are lacking (hypoploidy) or present in excess (hyperploidy). This mostly causes abnormalities in human.
Aneuploidy
Aneuploidy Types:
a. Monosomy
b. Trisomy
c. Tetrasomy
- (2n - 1)
- the monosomics have only one chromosome instead of the 2 normal sets
Monosomy
- (2n +1)
- the trisomics have one chromosome more than the normal 2 sets
Trisomy
- (2n + 2)
- the tetrasomics have one chromosome represented 4 times
Tetrasomy
- the presence of more than two homologous chromosome sets
- rare in humans
Polyploidy
- the presence of an abnormal number of chromosome
- more common in humans
Aneuploidy
- changes in chromosome structure or structural changes involving parts of one or more chromosomes
Chromosomal Aberrations
Chromosomal Aberrations are caused by ___________________ or chromatids
breaks in the chromosomes
Kinds of Chromosomal Aberrations:
- Deletion or Deficiencies
- Duplication or Repeats
- Inversion
- Translocation or Interchange
- represent a loss of a segment or part of a chromosome. This may result to lethality or production of unique phenotypic effects on organism
- e.g. Philadelphia 22 and Cri-du-chat syndrome
Deletion or Deficiencies
- occur when a section of chromosome is in excess of normal amount or there are extra copies of a part of a chromosome. This may result in the production of wild type of phenotypes
- e.g. duplications of recessive alleles
Duplication or Repeats
- rotation of a chromosome segments to a full 180 degree
- may result to partial or complete sterility of the organism
- reverse the direction of a part of a chromosome
Inversion
Inversion types:
a. Paracentric Inversion
b. Pericentric Inversion
- occurs when the centromere is not included in the inverted segment
Paracentric Inversion
- occurs when the inverted segment includes the centromere
Pericentric Inversion
- occurs when a single breaks in two non-homologous chromosome produce an exchange of chromosome sections between them
- occurs when part of a chromosome breaks off and attaches to another chromosome
- may result to partial sterility or lethality in organism
Translocation or Interchange
- results from changes in an organism’s genotype or a change in the stored chemical information in DNA
- changes to your DNA sequence that happen during cell division when your cells make copies of themselves
Gene Mutation
Gene Mutation Types:
a. Point Mutation
b. Frameshift Mutation
- a genetic mutation where a single nucleotide base is changed, inserted, or deleted from a sequence of DNA or RNA
Point Mutation
- an insertion or deletion of a single base that change the reading frame of the entire subsequent sequence
Frameshift Mutation
- random fluctuation in the numbers of gene variations in a population
- a change in the gene pool of a small population that takes place strictly by chance
Genetic Drift
- genes and other genetic elements of the next generation will be those of the lucky individuals, not necessarily the healthier or better individuals
- most often observed in small population
Genetic Drift
- the transfer of alleles from the gene pool of one population to the gene pool of another population
Gene Flow/ Migration
Main Factors Affecting Gene Flow/ Migration in Crop Species
- Pollinators
- Seed Dispersal
- Breeding System
Pollination (Biotic and Abiotic Agents)
(Zoophily):
- Hydrophily
- Anemophily
- Myrmecophily
- Ornithophily
- Malacophily
- Chiropterophily
