Fichas
BIO 110 Midterm 2
Fichas del conjunto (86)
- 1P1Parental Generation
- 2F1First filial generation
- 3F2Second filial generation
- 4True-breeding (pure-breeding)- homozygous breeding
- children have the same trait as parent - 5Monohybrid cross- follows one trait
- cross between two parents that differ in a single characteristic
- AA and aa breeding
- crossing F1 and F2 yields a 3:1 ratio - 6What monohybrid crosses reveal1. One character is encoded by two genetic factors
2. Two genetic factors (alleles) separate when gametes are formed
3. The concept of dominant and recessive traits
4. Two alleles separate with equal probability into the gametes - 7Mendel's First LawPrinciple of Segregation:
Each individual diploid organism possesses two alleles for any particular characteristic
- These two alleles separate when gametes are formed and one allele goes into each gamete - 8GeneAn inherited factor (region of DNA) that helps determine a characteristic
- 9AlleleOne of two or more alternative forms of a gene
- 10LocusSpecific place on a chromosome occupied by an allele
- 11GenotypeSet of alleles possessed by an individual organism
- 12HeterozygoteAn individual organism possessing two different alleles at a locus
- 13HomozygoteAn individual organism possessing two of the same alleles at a locus
- 14Phenotype or traitThe appearance or manifestation of a characteristic
- 15CharacteristicAn attribute or feature possessed by an organism
- 16Punnett SquareA diagram that is used to predict an outcome of a particular cross or breeding experiment
- 17Test crossCross an individual of unknown genotype with a homozygous recessive individual
- 18Autosomal dominantaffects both sexes and appears in every generation
ex. Huntington's Disease - 19Autosomal recessiveaffects both sexes and can skip generations through carriers
ex. Cystic Fobrosis - 20Mendel's Second LawLaw of Independent Assortment
- Considers two genes on different chromosomes
- The inheritance of one gene does not influence the chance of inheriting the other / Alleles at different loci separate independent of one another - 21Pedigreesymbolic representations of family relationships and the transmission of inherited traits
- 22Lethal allelesCause death at an early stage of development so that some genotypes do not appear among the progeny
- Causes death before the individual can reproduce - 23Multiple allelesFor a given locus, more than 2 alleles are present within in a group of individuals
- only two alleles can be present in a diploid organism
- ex. human blood type - 24Complete dominancePhenotype of the heterozygote is the same as the phenotype of one of the homozygotes
- 25Incomplete dominancePhenotype of the heterozygote is intermediate (falls within the range) between the phenotypes of the two homozygotes
- 26CodominancePhenotype of the heterozygote includes the phenotypes of both homozygotes
- ex. ABO blood types - 27Penetranceall or none expression of a single gene -- the percentage of individuals having a particular genotype that express the expected phenotype
- 28ExpressivitySeverity or extent -- the degree to which a character is expressed
- 29Gene interactionEffects of genes at one locus depend on the presence of genes at other loci
- 30Epistasisone gene masks the effect of another gene -- phenomenon where one gene affects the expression of a second gene
- 31PleiotropyPhenomenon where one gene controls several functions or has more than one effect
- 32Genetic heterogeneityDifferent genes can produce identical phenotypes
Genes may encode enzymes that catalyze the same biochemical pathway, or different proteins that are part of the pathway - 33PhenocopyTrait that appears inherited but is caused by the environment
May have symptoms that resemble an inherited trait or occur within families - 34Features of mitochondrial DNA- no crossing over
- fewer types of DNA repair
- inherited from the mother only
- many copies per mitochondrion and per cell
- high exposure to oxygen free radicals
- no histones
- genes not interupted - 35HeteroplasmyCondition where the mtDNA sequence is not the same in all copies of the genome
- mitochondrion will have different alleles for the same gene
- at each cell division the mitochondrion are distributed at random into daughter cells - 36Heterogametic sexHuman males with different sex chromosomes (XY)
- 37Homogametic sexHuman females with the same sex chromosomes (XX)
- 38SRY gene- sex determining region of the Y chromosome
- stimulates development of male structures
- sends signals to the indifferent gonads to destroy female structures
- Testosterone and dihydrotestosterone are secreted and stimulate male structures - 39X chromosomeContains > 1500 genes
Larger than the Y chromosome
Acts as a homolog to Y in males - 40Y chromosomeContains 231 genes
2 parts: Pseudoautosomal regions and Male specific region - 41Pseudoautosomal regions (Y chromosome)PAR1 and PAR2
5% of the chromosome
Contains genes shared with X chromosome - 42Male specific region (Y chromosome)MSY
95% of the chromosome
Contains majority of genes including SRY and AZF (needed for sperm production) - 43Y-linked traits- Genes on the Y chromosome
- Very rare
- Transmitted from male to male
- Most Y-linked traits involve infertility and are not transmitted - 44X-linked traits- Patterns of expression on the X chromosome differ in males and females
- In females, X inked traits are passed like autosomal traits
- In males, a single copy of an X-linked allele causes expression - 45HemizygousA human male is considered hemizygous for X-linked traits
- 46X linked recessive inheritance- Always expressed in the male
- Expressed in a female homozygote
- Affected male inherits trait from heterozygote or affected moth
- Affected female inherits trait from affected father and heterozygote or affected mother - 47Examples of X-linked recessive traitsColour blindness
Hemophilia
Ichthyosis - 48X-linked dominant inheritance- Expressed in females in one copy
- Much more severe effects in males
- High rates of miscarriage due to early lethality in males
- Passed from male to all daughters but no sons
- Mothers can pass to daughters and sons - 49Examples of X-linked dominant traitsIncontineatia pigmenti
Congenital generalized hypertrichosis - 50Sex Limited TraitsCharacteristic encoded by autosomal genes and expressed in only one sex
- Both males and females carry genes for sex limited traits but the trait has zero penetrance in the other sex
- Ex. beard growth, milk production, preeclampsia in pregnancy - 51Sex Influenced traitsCharacteristic encoded by autosomal genes that is more readily expressed in one sex
- Allele is dominant in one sex but recessive in the other
- Difference in expression can be caused by hormonal differences
- Ex. pattern baldness in humans - 52X inactivationRandom inactivation of one X chromosome in the cells of females
- A female mammal is a mosaic for expression of most genes on the X chromosome
- Balances inequality
- Female mammals are functionally hemizygous at the cellular level for X linked genes
- Occurs early in prenatal development
- Alters the phenotype, not the genotype
- In humans, X inactivation can be used to identify carriers in some X linked disorders - 53Dosage compensation- Equalization in males and females of the amount of protein produced by X-linked genes
- In placental mammals, dosage compensation is achieved by X inactivation - 54Barr bodiesInactivated X chromosome that appears as a condensed darkly staining structure in most cells of female placental mammals
- A result of X inactivation - 55Parent of origin effectParental original influences phenotype
Mechanisms:
- genomic imprinting
- differences between development tables of sperm and oocyte explain some parent of origin effects - 56EpigeneticsThe study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself
- All genetic modifications, excluding changes in the actual DNA sequence - 57Genomic imprinting- An epigenetic process
- A phenomenon in which expression of a gene depends on whether it is inherited from the male or female parent
- Depending on how the genes are 'marked', the offspring expresses either the maternally or the paternally inherited allele (not both)
- Is permanent in somatic cells - 58Stages of Genomic Imprinting1. Establishment of the imprint during gametogenesis
2. Maintenance of the imprint during embryogenesis and in the adult somatic cells
3. Erasure and reestablishment of the imprint in the germ cells
- Imprints are erased during meiosis then reinstituted according to the sex of the individual - 59Genomic imprinting may involve:- A single gene
- A part of a chromosome
- An entire chromosome
- All the chromosomes from one parent - 60The marking process of genomic imprinting- For most gene, methylation results in inhibition of gene expression (methylated either in the oocyte or sperm, not both)
- Imprinting is a process that silences gene expression by preventing transcription
- Methyl (CH3) groups bind a gene or several linked genes and prevent them from being accessed to synthesize protein - 61Prader Willi Syndrom- Defect in genomic imprinting from a small deletion on chromosome 15
- Deletion inherited from the father
- Paternal alleles normally expressed are missing - 62Angelman Syndrom- Defect in genomic imprinting from a small deletion of chromosome 15
- Deletion inherited from mother
- Maternal alleles normally expressed are missing - 63Mendelian traitscaused by a single gene
- discrete or qualitative
- often produce an all or none effect - 64Polygenic traits- Caused by multiple genes
- produce a continuously varying phenotype
- quantitative traits
- influenced by interaction of genes and by the environment
- effect of genes is additive -- input of genes is not necessarily identical
- Frequency of distribution of phenotypes forms a bell shaped curve - 65Behavioural geneticsStudies the relative effects of nature (heredity, genes, and chromosomes) and nurture (environment) on behaviour and mental processes
- Considers nervous system function and variation (includes mood and mind)
- A single gene doesnt determine complex behaviours - 66Major Depressive Disorder- Marked by unexplained lethargy, sadness, and chronic depression
- Affects 6% of the population
- Likely cause is a deficiency of the neurotransmitter, serotonin
- Affects mood, appetite, emotion, sleep
- Many antidepressants are SSRIs (selective serotonin reuptake inhibitors) - 67Schizophrenia- Loss of ability to organize thoughts and perceptions - withdrawal from reality
- 1% affected worldwide
- Typically early adult onset
- Progression: Difficulty in paying attention, memory and learning difficulties, psychosis (delusions and hallucinations)
- Heritability of 0.8
- Dozens of genes may interact with environmental influences to cause this disease - 68Autism Spectrum Disorder (ASD)/AutismTerms for a group of complex disorders of brain development
- Characterized, in varying degrees, by difficulties in social interaction, verbal and non verbal communication, and repetitive behaviours
- Affects 3-6/1000 children
- Boys 4x as likely to be affected
- More than 30 genes have been associated with autism so far
- 2 genes in particular:
Encode the cell adhesion proteins neurexins and neuroligins; Proteins strengthen synaptic connections in neurons associated with learning and memory - 69Population geneticsstudy of the genetics of a population and how the alleles vary with time
- 70PopulationInterbreeding group of the same species in a given geographical area
- 71Gene poolCollection of all alleles in the members of the population
- 72Gene flowMovement of alleles between populations when people migrate and mate
- 73Allele frequency# of particular allele /
total # of alleles in the population
- The percent of an allele in a gene pool
- Count both chromosomes of each individual
- Effect the genotype frequencies
Used to describe the gene pool of a population - 74Phenotypic frequencyFrequency of a trait
- Varies in different populations
- Although phenotype frequency changes from generation to generation, allelic frequency stays the same - 75Genotypic frequencyf(AA) = # AA individuals / N
N = total # of individuals
f = frequency of each genotype
- Used to describe the gene pool of a population - 76Hardy Weinberg Equation- Used algebra to explain how allele frequencies predict genotypic and phenotypic frequencies in a population of diploid, sexually reproducing species
- Disproved the assumption that dominant traits would become more common, while recessive traits would become rarer - 77Hardy Weinberg Law of EquilibriumThe relative frequencies of various kinds of genes in a large and randomly mating population tend to remain constant from generation to generation in the absences of mutation, selection, and gene flow
- Conditions never met in nature - 78Disturbances that effect Hardy Weinberg Equilibrium- Non-random mating
- Mutation
- Selection
- Limited population size
- Random genetic drift
- Gene flow
- Migration - 79Hardy Weinberg Law: AssumptionPopulation is large, randomly mating, not affected by mutation, migration, or natural selection
- 80Hardy Weinberg Law: Prediction 1The allelic frequencies of a population do not change
- 81Hardy Weinberg Law: Prediction 2The genotypic frequencies stabilize
- 82Hardy Weinberg Law: Variablep2 = homozygous dominant allele pair frequency
q2 = homozygous recessive allele pair frequency
2pq = heterozygous allele frequency - 83Hardy Weinberg Equationp + q = 1
p2 + 2pq + q2 = 1
p = allele frequency of dominant allele
q = allele frequency of recessive allele - 845 Conditions that Change Allele Frequencies- Migration
- Mutation
- Genetic Drift
- Natural Selection
- Non Random Mating - 85MicroevolutionSmall genetic changes due to changing allelic frequencies in populations
- 86MacroevolutionFormation of a new species
- Occurs when enough microevolutionary changes have occurred to prevent individuals from one population to successfully produce fertile offspring
Información
- Descripción
- Biology Fichas sobre BIO 110 Midterm 2, creado por Kira Bollen el 06/03/2017.
- Creado por
- Kira Bollen · mar 2017
- Actualizado
- 3 feb 2018
- Visitas
- 0
- Valoración