Human+Genetics

Human Genetics:

Human genetics describes the study of inheritance as it occurs in human beings.


 * Genetic Traits and Disorders
 * Genes that control human traits exhibit several patterns of inheritance[[image:grahamfinal1:Types-of-mutation.png width="258" height="585" align="right" caption="Types-of-mutation.png"]]
 * Gene patterns are the cause of genetic disorders
 * Mutations
 * Can involve an entire chromosome oe a single DNA nucleotide
 * Germ-Cell Mutations
 * Somatic-Cell Mutations
 * Patterns of Inheritance
 * Traits are controlled by a single allele, like...
 * 1) Albinism (Recessive)
 * 2) Sickle-cell anemia (Recessive)
 * Nondisjunction is when chromosomes fail to seperate during cell division, resulting in an extra chromosome
 * One gamete gets an extra chromosome while the other gamete gets nothing
 * Frame Shift Mutation
 * Deletion
 * Insertion
 * Normal Mutation
 * Duplication
 * Translocation
 * X-linked Traits
 * Genes found on the X chromosome include:
 * Hemophilia
 * Muscular Dystrophy (Muscle weakness)
 * Colorblindness
 * Pedigree
 * Shows the rate of how often a gene can be passed down to children
 * Human Genome Project
 * Sequenced Human DNA

Down Syndrome = Extra 21st Chromosome

__Terms to Know: __

//Tetrads:// A group of four closely associated chromatids of a homologous pair formed by synapsis.

//Crossing- Over:// A process occurring during meiosis wherein two chromosomes pair up and exchange segments of their genetic material.

//Homolgous Chromosomes:// chromosome pairs of the same length, centromere position, and staining pattern, with genes for the same characteristics at corresponding loci. One homolgous chromosome is inherited from the organism's mother; the other from the organism's father.

//Diploid:// cell that contains two chromosomes.

//Haploid:// cell that contains one chromosome.

 __Stages of Mitosis:__ __[] __

//Interphase:// DNA has replicated, but has not formed the condensed structure of chromosome. They remain as loosely coiled chromatid.

//Prophase:// The two chromatids remain attached to one another at a region called the centromere, but each contracts into a compact tightly coiled body; the nucleolus and, in most cases, the nuclear envelope break down and disappear. Also during prophase the spindle begins to form.

//Metaphase:// The spindle fibres attach themselves to the centromeres of the chromosomes and align the the chromosomes at the equatorial plate.  //Anaphase:// The spindle fibers shorten and the centromere splits, separated sister chromatids are pulled along behind the centromeres.

<span style="font-family: Georgia,serif;">//Telephase:// The chromosomes reach the poles of their respective spindles. Nuclear envelope reform before the chromosomes uncoil. The spindle fibres disintegrate.