1 Intro to Genetics

particular copy of a gene on a chromosome

arrangement of the chromosomes or the description of the karyotype

a change present at birth, in all or some cells

a change present at birth, often before birth (usually genetic)

genetic alteration causing disease

occurring in the body, but not in the gametes; therefore can't be passed on to offspring

subpopulations of cells that occur at places in the body but not in the gametes

• • occurring in the testis or ovary
• • can be passed on to offspring
• • everywhere else is normal, but testes or ovaries have a mix of cells

the parent of a child with a recessive condition

two or more cell lines in one person

mix of cells from two individuals (eg. females that get male marrow after a bone marrow transplant = chimera)

a change that happens after birth, usually associated with cancer

• • male: square
• • female: circle
• • sex unspecified: diamond
• • proband: lower left arrow
• • deceased: line slashed
• • affected with trait: symbol filled in
• • carrier: dot
• • asymptomatic carrier (AD): vertical line
• • adopted: brackets
• • consanguinity: double joining line
• • pregnancy: P
• • miscarriage: triangle
• • preg termination: slash through a triangle
• • stillbirth: deceased slash with SB underneath
• 

boy & a girl

same sex twins

cousins, but displaced by a generation

• individuals descended from a common ancestor

• 2nd cousin or closer in genetics

• 20% of world in a consanguineous marriage

• each gene occupies a specific place (locus) on a chromosome
• in most cell in the body there are two alleles at each locus - one maternal, one paternal
• during meiosis one chromosome from each pair goes to the germ cell
• genes close together on a chromosome tend to be inherited as a block
• genes on different chromosome sort independently