1C: Transmission of heritable information from generation to generation & the processes that increase genetic diversity Flashcards
Phenotype
Physical manifestation of genes; observable; non-inheritable; e.g. Hair color, eye color
Genotype
Genetic makeup; information in two alleles in the cell; inheritable; contains all heritable information, expressed and not expressed
Genes
Very long strands of DNA that code for a particular trait; genes are found in chromosomes; codes for protein
Genes
Very long strands of DNA that code for a particular trait; genes are found in chromosomes; codes for protein
Locus
Location of a gene on a chromosome; two homologous chromosomes have genes located at the same location on the DNA strand
Homologous Chromosomes
Two different alleles at their respective loci
Gene Mapping
Determines the particular biological trait that a locus is responsible for
Gene Mapping
Determines the particular biological trait that a locus is responsible for
Allele
Form of a gene located at a locus of a particular chromosome; there can be single or multiple alleles at each locus
Dominant Allele
Expressed and codes for a functional protein
Recessive Allele
Does not get expressed unless there are two present
Homozygous
Two alleles are the same
Heterozygous
Two alleles are different
Homozygous
Two alleles are the same
[AA]
Heterozygous
Two alleles are different
[Aa]
Homozygous
Two alleles are the same for a given trait
[AA]
[aa]
Heterozygous
Two alleles are different for a given trait
[Aa]
-recessive trait is not expressed but can be inherited
Heterozygous
Two alleles are different for a given trait
[Aa]
-recessive trait is not expressed but can be inherited
Wild Type
The typical phenotype that an organism has, non-mutant phenotype
Recessiveness
Viewed as the weaker of two alleles when it comes to determining one’s phenotype
Recessiveness
Viewed as the weaker of two alleles when it comes to determining one’s phenotype; phenotype only expressed when both alleles of the recessive variant are present
Recessiveness
Viewed as the weaker of two alleles when it comes to determining one’s phenotype; phenotype only expressed when both alleles of the recessive variant are present
Complete Dominance
Recessive allele is completely ignored phenotypically; always defined with respect to the phenotype of the Heterozygote
Codominance
Occurs when both alleles of a heterozygous allele pair air expressed resulting in phenotypic expression of both the dominant and the recessive phenotype
e.g. Blood Type
Incomplete Dominance
A new allele is expressed that is a blend of traits between the crossed alleles; RR x rr = Rr
Genetic Leakage
When genes are moved from one species to another
Penetrance
The percentage change that an organism will express the traits of a given gene
Penetrance
The percentage change that an organism will express the traits of a given gene
Expressivity
Determines how well genes are expressed
Expressivity
Determines how well genes are expressed
Hybridization
The process of two complementary, ssDNA or RNA combined together producing dsDNA through base pairing
Gene Pool
Sum of all genes (alleles) in a population at a given time; change over time through evolution through mutation, natural selection, genetic drift and other genetic mechanisms
Large Gene Pool
This gives high genetic diversity and greater biological fitness
Small Gene Pool
This gives low genetic diversity and reduced biological fitness = increased chance of extinction
Significance of Meiosis
Introduces genetic variability by genetic recombination which is a product of independent assortment & crossing-over
Differences between Mitosis & Meiosis
Mitosis = asexual, 2n -> 2n, growth and repair, 1 round of division, centromeres split during anaphase
Meiosis = sexual, 2n -> n, genetic diversity, crossing over, homologs pair up, 4 haploid cells, 46 -> 23, centromeres split during anaphase II
Law of Independent Assortment
Generates genetic variation;
Law of Independent Assortment
Generates genetic variation; each genes inheritance is independent of the inheritance of other genes
Genetic Linkage
Genes located near each other on a chromosome are likely to be inherited together during meiosis
Genetic Linkage
Genes located near each other on a chromosome are likely to be inherited together during meiosis; during crossover, genes located near a specific locus are less likely to be separated
Genetic Linkage
Genes located near each other on a chromosome are likely to be inherited together during meiosis; during crossover, genes located near a specific locus are less likely to be separated
Synaptonemal Complex
A protein complex between homologue chromosomes
Tetrads
Produced during meiosis through the process of synapsis
Chiasma
Joining between a pair of homologous chromosomes resulting in the formation of four chromatids
Chiasma
Joining between a pair of homologous chromosomes resulting in the formation of four chromatids
Sex-Linked Characteristics
Carried on the X chromosome - can affect both females and males; Y genes only affect males
X-linked recessive traits
Trait always expressed in men; women considered carriers
X-linked dominant traits
50% chance of inheriting from mother; 100% chance of inheriting from father
Genes of Y Chromosome
Sex-determining chromosome responsible for initiation of male sex determination; very few genes
Sex Determination
XX = female XY = male
Cytoplasmic Inheritance
Inheritance of things other than genomic DNA; cellular organelles (mitochondria) inherited from the mother
Mutation
Change in DNA sequences by means other than recombination
Types of Mutations
Random Translation Error Transcription Error Base Substitution Inversion Addition Deletion Translocation Mispairing
Random Mutation
Random changes in DNA sequence due to radiation, chemicals, replication errors
Translation Error
Errors during translation that cause expression of a mutant phenotype
Transcription Error
Errors during transcription can cause expression of a mutant phenotype
Base Substituion
Mutation involving a base [ATGC] changing to a different base
Inversion
A stretch of DNA breaks off and reattaches in the opposite orientation
Addition (Insertion)
An extra base is added/inserted into the DNA sequence
Addition (Insertion)
An extra base is added/inserted into the DNA sequence
Deletion
A base is taken out of the DNA sequence
Single Addition/Insertion & Deletion Mutations
Result in Frameshift Mutation
Translocation
A stretch of DNA breaks off and then reattaches somewhere else
Mispairing
A not pairing with T or G not pairing with C
Mispairing
A not pairing with T or G not pairing with C
Advantageous Mutation
Results in a benefit to the fitness of the organism
Deleterious Mutation
Results in harmful effect to the fitness of the organism
Inborn Errors of Metabolism
Genetic diseases that result in faulty metabolism; example Phenylketonuria
Phenylketonuria
People can’t metabolize phenylalanine
Mutagen
Something that causes mutation
Carcinogen
Something that causes a mutation that causes cancer
Relationship between mutagens and carcinogens
Carcinogens are almost always mutagens, not all mutagens are carcinogens
Mitogen
Something that increases the rate of mitosis
Mitogen
Something that increases the rate of mitosis
Genetic Drift
Random sampling that causes changes in gene frequency in a population; a mechanism of evolution; increased by synapsis and crossing over
Synapsis
A mechanism that occurs during Prophase I of Meiosis; occurs before crossing over
Crossing Over
Exchanging of a section of chromosomes which results in daughter cells containing genes from both parents
Hardy-Weinberg Principle/Equilibrium
Allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences
Hardy-Weinberg Principle/Equilibrium
Allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences
Hardy-Weinberg Equations
p + q = 1
p^2 + 2pq + q^2 = 1
p
Frequency of allele A
q
Frequency of allele a
p^2
Frequency of genotype AA
q^2
Frequency of genotype aa
2pq
Frequency of genotype Aa
2pq
Frequency of genotype Aa
Five Assumptions of Hardy-Weinberg
- No Genetic Drift (infinitely large population)
- No Mutation
- No Migration
- No Sexual Selection (Random mating)
- No Natural Selection
Back Cross
Mating between offspring and parent
Back Cross
Mating between offspring and parent
Multiplication Rule
Independent events in sequence; questions with and
Addition Rule
Mutually exclusive events; questions with or
Addition Rule
Mutually exclusive events; questions with or
Natural Selection
Survival and reproduction of the fittest
Fitness Concept
The ability to pass on genes or reproductive success
Selection by Differential Reproduction
Individuals who reproduce more viable offspring are selected for; less viable offspring are selected against
Directional Selection
Selects for a trait on one extreme; away from the average
Divergent (Disruptive) Selection
Selection in both directions away from the average
Stabilizing Selection
Selection for the average, against the extremes
Group Selection
The idea that natural selections can affect the group/population and not just the individual
Speciation
Formation of a new species which can occur due to barriers to successful interbreeding within an initial species
3 conditions of biological species
- Ability to interbreed
- Ability to produce fertile viable offspring
- Does all of this naturally
Polymorphism
Different phenotypes within a population of species; different forms of alleles/traits
Polymorphism
Different phenotypes within a population of species; different forms of alleles/traits
Adaptation
A change in the species over generations in order to better survive in the environment; genetic change caused by natural selection
Specialization
Certain traits or characteristics are adapted to increase the species’ survival
Specialization
Certain traits or characteristics are adapted to increase the species’ survival
Inbreeding
Idea of mating between relatives that increases frequency of homozygotes and decreases frequency of heterozygotes and genetic diversity; often due to lack of migration
Inbreeding
Idea of mating between relatives that increases frequency of homozygotes and decreases frequency of heterozygotes and genetic diversity; often due to lack of migration
Outbreeding
Mating of unrelated members of a species; increases frequency of heterozygosity and genetic diversity; less subjection to diseases and genetic deformities
Bottlenecks
The loss of most of the population usually following a disaster, increases the effect of genetic drift
Bottlenecks
The loss of most of the population usually following a disaster, increases the effect of genetic drift
Divergent Evolution
Same lineage, evolving apart to be more different; produces homologous structures
Parallel Evolution
Same lineage, evolving closer together to be similar, using similar mechanisms
Convergent Evolution
Different lineage, evolving closer together to be similar, using different mechanisms; produces analogous structures
Convergent Evolution
Different lineage, evolving closer together to be similar, using different mechanisms; produces analogous structures
Coevolution
Two species evolve in response to each other; predator/prey or host/parasite species
Symbiotic Relationships
Parasitism, Commensalism, Mutualism
Parastism
Relationship where
Parastism
Relationship where one benefits and the other is harmed
Commensalism
Relationship where one benefits and the other is not affected
Mutualism
Relationship where both species benefit
