Chapter 29 Flashcards
Heredity
Define: autosome
Chromosomes 1-22, not including the sex chromosome
XX and XY chromosomes that determine gender
sex chromosome
Genes that occur at same locus (location) on homologous chromosomes
Alleles
What is the difference between homozygous and heterozygous?
Homozygous: alleles are same for single trait
Heterozygous: alleles are different for single trait
Define: genotype vs phenotype
genotype: genetic makeup
phenotype: physical appearance
Huntington’s disease is caused by:
Degeneration of the white brain matter and cerebral cortex
Explain the events of crossing over
Chromosomes can break and precisely exchange gene segments with their homologous counterparts
Explain the events of random fertilization
Extreme variation due to a combination of crossing over and independent assortment
Explain the events of independent assortment
Alleles on different pairs of homologous chromosomes are distributed independently of each other.
Traits dictated by dominant alleles include widow’s peaks, ____, and dimples, double-jointed ____, or taste phenylthiocarbamide (PTC) to name a few
freckles; thumbs
Heterozygotes are carriers of ____ trait, meaning they do not express trait but can
pass it on to ____
recessive; offspring
Most genetic disorders are inherited as simple ____ traits
recessive
Define: incomplete dominance
Alleles overlapping instead of one being completely masked, resulting in a phenotype in the heterozygote that is a combination of both traits.
What causes sickle-cell anemia?
Abnormal cell shape caused by low iron resulting in low oxygen levels
More than 2 alleles on a single gene describes what type of inheritance?
Multiple-Allele Inheritance
Codominance is a result of 2 alleles expressed ____
equally
Traits determined by genes on the sex chromosomes describes ____ inheritance, and (males/females) have more proteins on their chromosome to help brain function.
sex-linked; females
Which type of inheritance results in continuous, or quantitative, phenotypic variation between two extremes and explains many human characteristics?
Polygenic inheritence
Examples of polygene traits in humans include:
Skin color, height, metabolic rate, and intelligence.
Describe the influence of small RNA on inheritance:
2nd control layer that forms the parallel regulatory system which reduce the expression of particular genes by destruction, inhibition, or silencing of the mRNA
Describe the influence of epigenetics on inheritance:
Epigenetic marks determine if translation is possible or silenced, inactivates the X in female embryos, and has a potential disposition to turn cells cancerous
Mitchondrial genes are inherited by the ____ because almost the entire ____ is donated to the fertilized egg. Errors in these genes create what type of disorders?
mother; cytoplasm; degenerative muscle or neurological disorders
What tool is used to trace a genetic trait through several generations and help predict the future using phenotypic information
Pedigree
Blood tests are used to test the ____ gene and can detect unexpressed ____ genes
sickling; recessive
What is the most common type of fetal testing, where a wide-bore needle is inserted into the amniotic sac through the mother’s abdominal wall
amniocentesis
Describe the procedure: Chorionic villus sampling (CVS)
Suctions off bits of the chorionic villi from the placenta for examination
Excessively thick mucus production, impairing the lung and pancreatic functioning
Cystic fibrosis
Hemophilia and Duchenne muscular dystrophy are recessive disorders developed through what type of inheritance
sex-linked
