Human Genome

Chromosomes

threadlike structures made of DNA molecules that contain the genes

Human Karyotype

46 chromosomes, 23 pairs

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape. Shows autosomes, sex chromosomes, and homologous chromosomes.

Autosomes

Any chromosome that is not a sex chromosome

sex chromosomes

X and Y chromosomes.

XX

female sex chromosomes

XY

male sex chromosomes

sex-linked traits

traits controlled by genes located on the X chromosome.

pedigree

A diagram that shows the occurrence of a genetic trait, either dominant or recessive, in several generations of a family.

Circle represents

female

Square represents

male

Half shaded circle or square

carrier

genetic disorder

An abnormal condition that a person inherits through genes or chromosomes caused by mutations in DNA

Huntington's disease

A human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system at 30 to 40 years old.

PKU

A human metabolic disease caused by a mutation in a gene coding for a phenylalanine processing enzyme.

Tay-Sachs disease

A human genetic disease caused by a recessive allele that leads to the accumulation of lipids in the brain.

Allelles

specific versions of a gene

multiple alleles

traits that are controlled by more than two alleles (ex. ABO blood typing = A allele, B allele, & O allele)

dominant allele

represented by a capital letter

recessive allele

represented by a lowercase letter

Sickle-Cell Disease

Genetic disorder in which red blood cells have abnormal hemoglobin molecules and take on an abnormal shape. Caused by a change in one DNA base.

Colorblindness

a recessive x-linked disorder in which an individual cannot distinguish between certain colors. Allele inherited from mother.

Cycstic Fibrosis

human genetic disorder caused by a recessive allele. It causes a single gene to fail to produce a protein that moves ion across the cell membrane. Body produces thick mucus in lungs.

Nondisjunction

Error in meiosis in which homologous chromosomes fail to separate.

Achondroplasia

A form of human dwarfism caused by a single dominant allele

Sex probability of offspring

50% male 50% female

Phenotype

physical characteristics of an organism

Genotype

genetic makeup of an organism

Down Syndrome

a condition of intellectual disability and associated physical disorders caused by an extra copy of chromosome 21.