Chapter 8: Heredity Flashcards
Allele
On of the several varieties of a gene.
Gene
Represents the genetic material on a chromosome that contains the instructions for creating a particular trait.
Locus
The location on a chromosome where a gene is located.
Mendel’s Law of Segregation
One member of each chromosome pair migrates to an opposite pole so that each gamete contains only one copy of each chromosome and allele.
Test Cross
The mating of an individual whose genotype you are trying to determine with an individual whose genotype is known.
Agglutination
Clumping
Polygenic Inheritance
The interaction of many genes to shape a single phenotype.
Linked Gnes
Genes that reside on the same chromosome and can’t split because they are connected
Linkage Map
A portrayal of the sequence of genes on a chromosome
Cytological Map
A map portraying the true relative positions of the genes
Barr Body
A coiled, dark, compact x-chromosome.
Nondisjunction
The failure of one or more chromosome pairs or chromatids of a single chromosome to properly move to opposite poles during meiosis or mitosis.
Mosaicism
Result of nondisjunction. When a faction of the body cells that are descendent of a cell where nondisjunction occurs have an extra or missing chromosome.
Polyploidy
Occurs if all of the chromosomes undergo meiotic nondisjunction and produce gametes with twice the number of chromosomes.
Point Mutations
Occur when a single nucleotide in the DNA of a gene is incorrect.
Substitution
When a different nucleotide is substituted for the correct one.
Deletion
When the nucleotide base pair is omitted
Insertion
If an extra base-pair is inserted
Sickle-cell disease
Caused by Nucleotide substitution. Results in the production of defective haemoglobin.
Sickle Cell shaped RBC when O2 is limited. Leads to organ damage, bone abnormalities, and impaired mental functioning.
Tay-Sachs Disease
Caused by nucleotide insertion. Results when lysosomes lack the functional enzyme to break down certain fats.
Fats accumulate in nerve cells of the brain, brain cells die.
Aneuploidy
A genome with extra or missing chromosomes.
Often Caused by non-disjunction.
Down Syndrome
Example of Aneuploidy.
Occurs when an egg or sperm with an extra number 21 chromosome fuses with a normal gamete.
Turner Syndrome
Results when there is nondisjunction of the sex chromosomes. Sperm will be either XY or O(No sex chromosomes), and eggs will be either XX or O.
XO= Sterile Female with physical abnormalities.
Missing Y chromosome= Dead, or happily alive male
Klinefelter Syndrome
Occurs when an XY or XX gamete, produced as a result of nondisjunction, combines with a normal X gamete to produce an XXY individual.
XXY individual= Sterile, may experience female secondary sex characteristics.
XXX= Female, often few problems.
Chromosomal Aberrations
Caused when chromosome segments are changed.
Duplications
When a chromosome segment is repeated on the same chromosome.
Huntington’s Disease
Caused by the insertion of multiple repeats of three nucleotides.
The mutant gene codes for a defective enzyme, which results in the death of nerve cells in the brain.
Inversions
When chromosome segments are rearranged in reverse orientation on the same chromosome.
Translocaitons
Occur when a segment of a chromosome is moved to another chromosome.
Maternal Inheritance
Can be used to trace a specific genome from progeny back through multiple generations to its original mother.
