Chapter 22 GENETICS AND GENETICALLY LINKED DISEASES Copyright
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Chapter 22 GENETICS AND GENETICALLY LINKED DISEASES ©© Copyright 2004 Delmar Learning, a division of Thomson Learning, Inc.
GENETICS • Genetics is the branch of biology that studies how genes are transmitted from parent to offspring © Copyright 2004 Delmar Learning, a division of Thomson Learning, Inc. 2
TYPES OF MUTATIONS • There are two types of mutations – Gene mutation - a new or altered gene is produced to replace a normal, preexisting gene – Chromosomal mutation - involves a change in the number of chromosomes in the nucleus or a change in the structure of a whole chromosome © Copyright 2004 Delmar Learning, a division of Thomson Learning, Inc. 3
TYPES OF MUTATIONS • Somatic cell mutation - mutations that occur in individual body (somatic) cells will not be transmitted to the offspring • Gametic cell mutation - mutations that occur in the gametes that will be passed on to the next generation © Copyright 2004 Delmar Learning, a division of Thomson Learning, Inc. 4
LETHAL GENES • Lethal genes are those genes that usually end in death • Each person carries two or three recessive lethal genes • Two similar recessive genes must be present for the lethal gene to be expressed © Copyright 2004 Delmar Learning, a division of Thomson Learning, Inc. 5
HUMAN GENETIC DISORDERS • • Phenylketonuria Sickle cell anemia Tay-sachs disease Duchenne’s muscular dystrophy Huntington’s disease Cystic Fibrosis Thalassemia © Copyright 2004 Delmar Learning, a division of Thomson Learning, Inc. 6
HUMAN GENETIC DISORDERS • Hemophilia • Chromosomal Aberrations • Mutagenic Agents © Copyright 2004 Delmar Learning, a division of Thomson Learning, Inc. 7
GENETIC COUNSELING • Genetic counseling involves screening for potential genetic disorders by talking with prospective parents about the possibility of genetic disorders © Copyright 2004 Delmar Learning, a division of Thomson Learning, Inc. 8