Please enable JavaScript.
Coggle requires JavaScript to display documents.
Ch 14 & 15, Sources: Urry, L. A., Cain, M. L., Wasserman, S. A.,…
Ch 14 & 15
Ch 15 - The Chromosomal Basis of Inheritance
Medelian Inheritance
Chromosome Theory of Inheritance:
basic principle stating that the genes are located at specific positions on chromosomes and that the behavior of chromosomes during meiosis account for inheritance patters
Sex-Linked Genes
Sex-Linked Gene:
gene located on either sex chromosome; X chromosome show distinctive patterns of inheritance, few genes on the Y chromosome,
ex: color blindness
X-Linked Genes:
gene located on the X-chromosome; genes show a distinctive patters of inheritance
Duchenne Muscular Dystrophy:
human genetic disease caused by sex-linked recessive allele; progressive weakening and loss of muscle tissue
Hemophilia:
human genetic disease caused by a sex-linked recessive allele resulting in the absence of 1 or more blood-clotting proteins
Linked Genes
Linked Genes:
genes located close enough together on a chromosome that they tend to be inherited together,
ex: freckles and red hair
Genetic Recombination:
production of offspring with combinations of traits that differ from those found in either parent
Parental Type:
offspring with a phenotype that matches 1 of the true-breeding parental phenotypes
Crossing Over:
reciprocal exchange of genetic material between non sister chromatids during prophase 1 of meiosis
Genetic Map:
ordered list of genetic loci along a chromosome
Linkage Map:
genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes
Alterations of Chromosome Number or Structure
Aneuploidy:
chromosomal aberration in which 1 or more chromosomes are present in extra copies or are deficient in number
Monosomic:
diploid cell that has only 1 copy of a particular chromosome instead of the normal 2,
ex: turner syndrome
Trisomic:
diploid cell that has 3 copies of a particular chromosome instead of the normal 2,
ex: trisomy 21 - down syndrome
Polyploidy:
chromosomal alteration in which the organism possesses more than 2 complete chromosome sets,
ex: strawberries
Deletion:
deficiency in a chromosome resulting from the loss of a fragment through breakage or mutational loss of 1 or more nucleotide pairs from a gene
Duplication:
fusion with a fragment from a homologous chromosome, that portion is duplicated
Inversion:
aberation resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated
Translocation:
aberration resulting from attachment of a chromosomal fragment to a non homologous chromosome
Exceptions of Inheritance Patterns
Genomic Imprinting:
expression of an allele in offspring depends on whether the allele is inherited from the male or female present
Ch 14 - Mendel and the Gene Idea
Two Laws of Inheritance
Character:
observable heritable feature that may vary among individuals,
ex: eye color
Trait:
1 of 2 or more detectable variants in a genetic character,
ex: purple or white color for flowers
True-Breeding:
organisms that produce offspring of the same variety over generations of self-pollination,
ex: Mendel's pea plants
Hybridization:
the mating or crossing of 2 true-breeding varieties
P Generation:
true-breeding (homozygous) parent individuals from which F1 hybrid offspring are derived in studies of inheritance
F1 Generation:
hybrid (heterozygous) offspring from a parental (P generation) cross
F2 Generation:
offspring resulting from interbreeding of the hybrid F1 generation
Alleles:
any of the alternative versions of a gene that may produce distinguishable phenotypic effects,
ex: alleles for brown, blue, and green eyes
Dominant Allele:
allele that is fully expressed in the phenotype of a heterozygote,
ex: B for brown eyes
Recessive Allele:
allele whose phenotypic effect is not observed in a heterozygote,
ex: b for blue eyes
Law of Segregation:
Mendel's first law; 2 alleles in a pair segregate into different gametes during gamete formation
Law of Independent Assortment:
Mendel's 2nd law; each pair of alleles segregates independently of each other pair during gamete formation
Punnett square:
diagram used to stufdy inheritance and to show the predicted genotypic results of random fertilization in genetic crosses between individuals of known genotype
Homozygote:
organism that has a pair of identical alleles for a gene
Homozygous:
having 2 identical alleles for a given gene
Heterozygote:
organism that has 2 different alleles for a gene
Heterozygote:
having 2 different alleles for a given gene
Phenotype:
observable physical and physiological traits of an organism which are determined by its genetic makeup,
ex: shade of flower color, pale/vibrant
Genotype:
genetic makeup or set of alleles of an organism,
ex: genotype for flower color
Testcross:
breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype
Monohybrid:
organism that is heterozygous with respect to a single gene of interest
Monohybrid Cross:
cross between 2 organisms that are heterozygous for the chanacter being followed
Dihybrid:
organism that is heterozygous with respect to 2 genes of interest
Dihybrid Cross:
cross between 2 organisms that are each heterozygous for both of the characters being followed
Inheritance Patterns
Complete Dominance:
situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable,
ex: PP or Pp masks pp
Incomplete Dominance:
phenotype of heterozygote is intermediate between the phenotypes of individuals homozygous for either allele,
ex: cross between red and white snapdragon produces pink snapdragon
Codominance:
phenotypes ob both alleles are shows in the heterozygote because both alleles affect the phenotype in separate ways,
ex: human blood type AB
Tay-Sachs Disease:
genetic disease caused by recessive allele for a dysfunctional enzyme; leads to accumulation of lipids in the brain
Pleiotropy:
ability of a single gene to have multiple effects
Epistasis:
type of gene interaction which the phenotype expression of 1 gene alters that of another independently inherited gene,
ex: color coat in Labs
Quantitative Characters:
heritable feature that varies continuously over a range rather,
ex: height, weight, blood pressure
Sickle-Cell Disease:
inherited human blood disorder which a single nucleotide change in the a-globin gene causes hemoglobin to aggregate, changed blood cell shape
Huntington's Disease:
genetic disease cause by a dominant allele; uncontrollable body movements and degeneration of the nervous system
Amniocentesis:
technique in which amniotic fluid is obtained from a needle inserted into the uterus
Chorionic Villus Sampling:
technique with prenatal diagnosis which a small sample of the fetal portion of the placenta is removed for analysis to detect genetic defects
Human Traits
Pedigree:
diagram of a family tree with symbols; shows the occurrence of heritable characters in parents and offspring over generations
Cystic Fibrosis:
human genetic disorder caused by recessive allele for a chloride channel protein; excessive secretion of mucus and vulnerable to infection
Carriers:
individual who is heterozygous at a given genetic locus for a recessively inherited disorder; can pass on the recessive allele to offspring
Sources: Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Reece, J. B. (2017). Campbell Biology (12th ed.). Pearson.