Genetics

4. a German surname, meaning "man from Saxony" or "man from Saxon extract"
5. a rare, inherited disease that causes the progressive breakdown (degeneration) of nerve cells in the brain
7. each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome
8. to child
9. The basic unit of heredity passed from parent to child
10. the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment
13. a type of inheritance in which two versions (alleles) of the same gene are expressed separately to yield different traits in an individual
15. having two identical alleles of a particular gene or genes
16. a condition in which a person or animal has more than five fingers or toes on one, or on each, hand or foot
17. the phenomenon whereby, in an individual containing two allelic forms of a gene, one is expressed to the exclusion of the other
18. a hybrid that is heterozygous for alleles of two different genes
19. the study of heredity and the variation of inherited characteristics

1. a congenital absence of pigment in the skin and hair (which are white) and the eyes (which are usually pink
2. characteristic that can be passed from
3. a form of short-limbed dwarfism
6. the production by a single gene of two or more apparently unrelated effects
11. the genetic constitution of an individual organism
12. a hybrid that is heterozygous with respect to a specified gene
14. the smallest unit that can live on its own and that makes up all living organisms and the tissues of the body
16. a register recording a line of ancestors