1C: Transmission of heritable information from generation to generation & the processes that increase genetic diversity Flashcards Preview

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Flashcards in 1C: Transmission of heritable information from generation to generation & the processes that increase genetic diversity Deck (121):
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Phenotype

Physical manifestation of genes; observable; non-inheritable; e.g. Hair color, eye color

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Genotype

Genetic makeup; information in two alleles in the cell; inheritable; contains all heritable information, expressed and not expressed

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Genes

Very long strands of DNA that code for a particular trait; genes are found in chromosomes; codes for protein

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Genes

Very long strands of DNA that code for a particular trait; genes are found in chromosomes; codes for protein

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Locus

Location of a gene on a chromosome; two homologous chromosomes have genes located at the same location on the DNA strand

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Homologous Chromosomes

Two different alleles at their respective loci

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Gene Mapping

Determines the particular biological trait that a locus is responsible for

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Gene Mapping

Determines the particular biological trait that a locus is responsible for

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Allele

Form of a gene located at a locus of a particular chromosome; there can be single or multiple alleles at each locus

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Dominant Allele

Expressed and codes for a functional protein

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Recessive Allele

Does not get expressed unless there are two present

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Homozygous

Two alleles are the same

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Heterozygous

Two alleles are different

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Homozygous

Two alleles are the same
[AA]

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Heterozygous

Two alleles are different
[Aa]

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Homozygous

Two alleles are the same for a given trait
[AA]
[aa]

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Heterozygous

Two alleles are different for a given trait
[Aa]
-recessive trait is not expressed but can be inherited

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Heterozygous

Two alleles are different for a given trait
[Aa]
-recessive trait is not expressed but can be inherited

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Wild Type

The typical phenotype that an organism has, non-mutant phenotype

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Recessiveness

Viewed as the weaker of two alleles when it comes to determining one's phenotype

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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

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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

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Complete Dominance

Recessive allele is completely ignored phenotypically; always defined with respect to the phenotype of the Heterozygote

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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

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Incomplete Dominance

A new allele is expressed that is a blend of traits between the crossed alleles; RR x rr = Rr

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Genetic Leakage

When genes are moved from one species to another

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Penetrance

The percentage change that an organism will express the traits of a given gene

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Penetrance

The percentage change that an organism will express the traits of a given gene

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Expressivity

Determines how well genes are expressed

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Expressivity

Determines how well genes are expressed

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Hybridization

The process of two complementary, ssDNA or RNA combined together producing dsDNA through base pairing

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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

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Large Gene Pool

This gives high genetic diversity and greater biological fitness

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Small Gene Pool

This gives low genetic diversity and reduced biological fitness = increased chance of extinction

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Significance of Meiosis

Introduces genetic variability by genetic recombination which is a product of independent assortment & crossing-over

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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

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Law of Independent Assortment

Generates genetic variation;

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Law of Independent Assortment

Generates genetic variation; each genes inheritance is independent of the inheritance of other genes

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Genetic Linkage

Genes located near each other on a chromosome are likely to be inherited together during meiosis

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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

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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

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Synaptonemal Complex

A protein complex between homologue chromosomes

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Tetrads

Produced during meiosis through the process of synapsis

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Chiasma

Joining between a pair of homologous chromosomes resulting in the formation of four chromatids

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Chiasma

Joining between a pair of homologous chromosomes resulting in the formation of four chromatids

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Sex-Linked Characteristics

Carried on the X chromosome - can affect both females and males; Y genes only affect males

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X-linked recessive traits

Trait always expressed in men; women considered carriers

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X-linked dominant traits

50% chance of inheriting from mother; 100% chance of inheriting from father

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Genes of Y Chromosome

Sex-determining chromosome responsible for initiation of male sex determination; very few genes

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Sex Determination

XX = female
XY = male

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Cytoplasmic Inheritance

Inheritance of things other than genomic DNA; cellular organelles (mitochondria) inherited from the mother

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Mutation

Change in DNA sequences by means other than recombination

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Types of Mutations

Random
Translation Error
Transcription Error
Base Substitution
Inversion
Addition
Deletion
Translocation
Mispairing

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Random Mutation

Random changes in DNA sequence due to radiation, chemicals, replication errors

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Translation Error

Errors during translation that cause expression of a mutant phenotype

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Transcription Error

Errors during transcription can cause expression of a mutant phenotype

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Base Substituion

Mutation involving a base [ATGC] changing to a different base

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Inversion

A stretch of DNA breaks off and reattaches in the opposite orientation

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Addition (Insertion)

An extra base is added/inserted into the DNA sequence

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Addition (Insertion)

An extra base is added/inserted into the DNA sequence

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Deletion

A base is taken out of the DNA sequence

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Single Addition/Insertion & Deletion Mutations

Result in Frameshift Mutation

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Translocation

A stretch of DNA breaks off and then reattaches somewhere else

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Mispairing

A not pairing with T or G not pairing with C

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Mispairing

A not pairing with T or G not pairing with C

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Advantageous Mutation

Results in a benefit to the fitness of the organism

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Deleterious Mutation

Results in harmful effect to the fitness of the organism

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Inborn Errors of Metabolism

Genetic diseases that result in faulty metabolism; example Phenylketonuria

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Phenylketonuria

People can't metabolize phenylalanine

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Mutagen

Something that causes mutation

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Carcinogen

Something that causes a mutation that causes cancer

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Relationship between mutagens and carcinogens

Carcinogens are almost always mutagens, not all mutagens are carcinogens

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Mitogen

Something that increases the rate of mitosis

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Mitogen

Something that increases the rate of mitosis

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Genetic Drift

Random sampling that causes changes in gene frequency in a population; a mechanism of evolution; increased by synapsis and crossing over

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Synapsis

A mechanism that occurs during Prophase I of Meiosis; occurs before crossing over

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Crossing Over

Exchanging of a section of chromosomes which results in daughter cells containing genes from both parents

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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

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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

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Hardy-Weinberg Equations

p + q = 1
p^2 + 2pq + q^2 = 1

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p

Frequency of allele A

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q

Frequency of allele a

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p^2

Frequency of genotype AA

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q^2

Frequency of genotype aa

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2pq

Frequency of genotype Aa

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2pq

Frequency of genotype Aa

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Five Assumptions of Hardy-Weinberg

1. No Genetic Drift (infinitely large population)
2. No Mutation
3. No Migration
4. No Sexual Selection (Random mating)
5. No Natural Selection

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Back Cross

Mating between offspring and parent

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Back Cross

Mating between offspring and parent

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Multiplication Rule

Independent events in sequence; questions with and

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Addition Rule

Mutually exclusive events; questions with or

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Addition Rule

Mutually exclusive events; questions with or

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Natural Selection

Survival and reproduction of the fittest

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Fitness Concept

The ability to pass on genes or reproductive success

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Selection by Differential Reproduction

Individuals who reproduce more viable offspring are selected for; less viable offspring are selected against

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Directional Selection

Selects for a trait on one extreme; away from the average

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Divergent (Disruptive) Selection

Selection in both directions away from the average

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Stabilizing Selection

Selection for the average, against the extremes

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Group Selection

The idea that natural selections can affect the group/population and not just the individual

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Speciation

Formation of a new species which can occur due to barriers to successful interbreeding within an initial species

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3 conditions of biological species

1. Ability to interbreed
2. Ability to produce fertile viable offspring
3. Does all of this naturally

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Polymorphism

Different phenotypes within a population of species; different forms of alleles/traits

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Polymorphism

Different phenotypes within a population of species; different forms of alleles/traits

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Adaptation

A change in the species over generations in order to better survive in the environment; genetic change caused by natural selection

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Specialization

Certain traits or characteristics are adapted to increase the species' survival

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Specialization

Certain traits or characteristics are adapted to increase the species' survival

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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

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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

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Outbreeding

Mating of unrelated members of a species; increases frequency of heterozygosity and genetic diversity; less subjection to diseases and genetic deformities

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Bottlenecks

The loss of most of the population usually following a disaster, increases the effect of genetic drift

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Bottlenecks

The loss of most of the population usually following a disaster, increases the effect of genetic drift

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Divergent Evolution

Same lineage, evolving apart to be more different; produces homologous structures

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Parallel Evolution

Same lineage, evolving closer together to be similar, using similar mechanisms

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Convergent Evolution

Different lineage, evolving closer together to be similar, using different mechanisms; produces analogous structures

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Convergent Evolution

Different lineage, evolving closer together to be similar, using different mechanisms; produces analogous structures

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Coevolution

Two species evolve in response to each other; predator/prey or host/parasite species

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Symbiotic Relationships

Parasitism, Commensalism, Mutualism

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Parastism

Relationship where

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Parastism

Relationship where one benefits and the other is harmed

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Commensalism

Relationship where one benefits and the other is not affected

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Mutualism

Relationship where both species benefit