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Mutations and other genetic issues

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1 Mutations and other genetic issues
Genetics Unit

2 Mutations Changes in the genetic material.
Any deviation from the normal chromosomal compliment Two types: Spontaneous mutations-occur randomly; no cause can be determined Induced mutations are caused by some traceable artificial factor: exposure to chemicals, alcohol, drugs, radiation

3 Mutations Mutations that produce changes in a single gene are gene mutations. Mutations that produce changes in a whole chromosome are chromosomal mutations.

4 Gene Mutations Point mutation-change in one or just a few nucleotides. So named because it occurs at a single point. Substitutions Deletions Insertions

5 Gene Mutations Frameshift mutation—shift the reading frame of the genetic code Can alter a protein so much that it can’t perform its job.

6 Chromosomal Mutations
Involve a change in the number or structure of the chromosome Some change the location of some genes on the chromosome Some may change the number of copies of some genes.

7 Chromosomal Mutations
Four main types of mutations: Deletion Duplication Inversion translocation

8 Deletion The permanent loss of a segment of chromosome
Can be found anywhere on the chromosome Can be caused by heat, radiation, viruses, chemicals, errors

9 Deletion

10 Duplication Doubles a segment of chromosome Can be fatal
Can be caused by uneven crossing over during meiosis or replication error before meiosis

11 Duplication

12 Causes of abnormalities
Nondisjunction The failure of the chromosome pairs to separate during Meiosis I or Meiosis II Result will be a zygote with too many or too few chromosomes Two types: Primary and secondary nondisjunction

13 Primary Nondisjunction

14 Secondary Nondisjunction

15 Types of Genetics Tests
When trying to determine a genetic problem, we can use non-invasive tests such as Pedigrees Karyotypes

16 Pedigrees A pedigree follows a specific trait through several generations Resembling a type of map, the pedigree uses symbols to represent certain elements

17 Pedigree key

18 Pedigree

19 Karyotypes A photographic inventory of an individual’s chromosomes
Can show the individual’s gender and any abnormalities in chromosome number or structure

20 Karyotypes

21 Karyotypes

22 Amniocentesis An invasive test that obtains amniotic fluid surrounding the fetus using a needle

23 Amniocentesis Pros and Cons
Able to determine fetus’ gender and/or any abnormalities Can’t be done before 16th week of pregnancy Can cause infection to mother and/or fetus Can cause premature delivery and birth

24 Chorionic Villus Sampling (CVS)

25 CVS Pros and Cons Can determine fetus gender and any genetic abnormalities Can be done after 10 weeks Can cause leakage of amniotic fluid Can cause premature labor and delivery

26 Recessive Disorders Must be inherited from BOTH parents
Autosomal recessive disorders (non-sex cells) Tay-Sachs PKU Cystic fibrosis

27 Recessive Disorders Tay-Sachs—lipid accumulation in the brain; mental deficiency; blindness, death in early childhood PKU-phenylketonuria—accumulation of phenylalanine in tissues; lack of normal skin pigment; mental retardation Cystic fibrosis—excess mucus in lungs, digestive tract, liver; increased susceptibility to infections; often die young

28 Dominant Disorders Can get the disorder by inheriting only one dominant allele Huntington’s disease Achondroplasia

29 Dominant Disorders Huntington’s Disease Achondroplasia
Mental deterioration and uncontrollable movements Doesn’t appear until middle age Achondroplasia One form of dwarfism

30 Sex Linked Disorders Is there a pattern of inheritance for genes located on the X or Y chromosome? YES especially on the X Many times it is male children that inherit these disorders from their mothers because They inherit their X from their mom’s Many sex linked genes are on the X Colorblindness Hemophilia Duchenne Muscular Dystrophy

31 Sex Linked Disorders Colorblindness Most often found in males
Females have to inherit from both parents 1 in 100 females Most common is red-green colorblindness

32 Sex Linked Disorders Hemophilia
Two genes on the X chromosome control blood clotting Many times it is male children that inherit this from their mom’s X chromosome 1 in 10,000 males A bleeding disorder; can cause death in severe cases

33 Sex Linked Disorders Duchenne Muscular Dystrophy 1 in 3000 males
Progressive weakening and loss of skeletal muscle Caused by defective version of gene that codes for a muscle protein

34 Genetic Disorders Trisomy Downs Syndrome (extra chromosome 21)
Edwards Syndrome (extra chromosome 18) Patau Syndrome(extra chromosome 13)

35 Downs Syndrome (Trisomy 21)

36 Edwards Syndrome (Trisomy 18)

37 Patau Syndrome (Trisomy 13)

38 Turner’s Syndrome

39 Turner’s Karyotype

40 Klinefelter’s Syndrome

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