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Unit 5: Genetics Learning Goal 5: Examine problems that arise from miscoded DNA and chromosome conditions.

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Presentation on theme: "Unit 5: Genetics Learning Goal 5: Examine problems that arise from miscoded DNA and chromosome conditions."— Presentation transcript:

1 Unit 5: Genetics Learning Goal 5: Examine problems that arise from miscoded DNA and chromosome conditions.

2 Mutation A Mutation occurs when a DNA gene is damaged
or changed in such a way as to alter the genetic message carried by that gene. A Mutagen is an agent of substance that can bring about a permanent alteration to the physical composition of a DNA gene such that the genetic message is changed.

3 Types of Mutations

4 Types of Mutations Point Mutation: Gene mutations involving changes in one or a few nucleotides. Substitution: One base is changed to another. This only affects one amino acid. Frameshift Mutations: Changes that shift the “reading frame” of the genetic message. This may change every amino acid after that point. This occurs if a nucleotide is added or deleted.

5 Types of Mutations

6 Types of Mutations Types of Mutations

7 Chromosomal Mutations
Changes in the number or structure of chromosomes.


9 Chromosomal Mutations
Deletion: Involves the loss of all or part of the chromosome. Duplication: produce extra copies of parts of the chromosomes. Inversion: Reverse the direction of parts of the chromosomes. Translocation: Occurs when part of one chromosome breaks off and attaches to another.


11 Significance of Mutations
Most mutations are neutral. Meaning that they have little or no effect on the expression of genes or the function of the proteins for which they code. Mutations that cause dramatic change in the protein structure are usually harmful. Some are beneficial. They lead to variations in populations

12 Karyotype A picture of chromosomes grouped in order of pairs.

13 Cystic Fibrosis Cystic fibrosis is a genetic disorder that affects the respiratory and digestive systems.

14 Sickle Cell Disease Sickle cell disease is a disorder that affects the red blood cells, which use a protein called hemoglobin to transport oxygen from the lungs to the rest of the body.

15 Huntington’s Disease Huntington's Disease (HD) is a brain disorder that affects a person's ability to think, talk, and move.

16 Alzheimer’s Disease Alzheimer's is a disease that causes dementia, or loss of brain function. It affects the parts of the brain that deal with memory, thought, and language.

17 What Are BRCA1 And BRCA2 Genes?
In the 1990s, mutations in two genes, BRCA1 (BReast CAncer 1) and BRCA2 (BReast CAncer 2), were shown to be involved in inherited breast cancer. It is estimated that 40 percent to 90 percent of families with an inherited form of breast cancer have a defective copy of the BRCA1 or BRCA2 gene. BRCA1 and BRCA2 are called "tumor suppressor genes" because they make proteins that help prevent the cells from forming tumors. If one of these genes is changed through a mutation, the protein may not do its job, making it easier for a tumor to develop. Women who inherit a mutated copy of either the BRCA1 or BRCA2 gene have an increased chance of developing breast cancer. In addition, there may be an increased risk for other cancers.

18 Hemophilia Hemophilia is an inherited bleeding, or coagulation, disorder. Persons with hemophilia lack the ability to stop bleeding because of the low levels, or complete absence, of specific proteins, called “factors,” in their blood that are necessary for clotting.

19 Hemophilia

20 Turner Syndrome Turner syndrome is caused by a missing or
incomplete X chromosome. People who have Turner syndrome develop as females. The genes affected are involved in growth and sexual development. sex organs don't mature at adolescence sterility short stature

21 Down Syndrome Down syndrome is a developmental disorder caused by an extra copy of chromosome 21 (which is why the disorder is also called "trisomy 21"). Having an extra copy of this chromosome means that each gene may be producing more protein product than normal. Children with Down Syndrome develop slower, may have heart and stomach illnesses and vary greatly in their degree of intelligence

22 Klinefelter Syndrome Klinefelter syndrome is a
disorder that affects only males. Males normally have an X chromosome and a Y chromosome (XY). Males who have Klinefelter syndrome have an extra X chromosome XXY, XXYY, XXXY Sterility Breast enlargement

23 XYY Syndrome “super male”
This condition occurs in about 1 in 1,000 newborn boys. Five to 10 boys with 47,XYY syndrome are born in the United States each day. Most males with 47,XYY syndrome have normal sexual development and are able to father children. 47,XYY syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Delayed development of motor skills (such as sitting and walking), weak muscle tone (hypotonia), hand tremors or other involuntary movements (motor tics), and behavioral and emotional difficulties are also possible. These characteristics vary widely among affected boys and men.

24 XYY Syndrome “super male”
Normal male traits Often tall and thin Associated with antisocial and behavioral problems

25 Triple X syndrome also called trisomy X or 47,XXX,
characterized by the presence of an additional X chromosome in each of a female's cells. This condition occurs in about 1 in 1,000 newborn girls. Five to 10 girls with triple X syndrome are born in the United States each day.

26 Triple X syndrome Physical Symptoms -Taller than average
Developmental Symptoms: -Learning disabilities -Speech & language delays -Poor coordination -Awkwardness -Clumsiness Physical Symptoms -Taller than average -Increased width between eyes -Skin fold at inner eyelid -Smaller head size -Porportionatly tinier chin

27 Trisomy 18 Edwards Syndrome
Caused by extra chromosome at chromosome 18. It is three times more common in girls than boys. Fifty percent of infants with this condition do not survive beyond the first week of life. Some children have survived to the teenage years, but with serious medical and developmental problems.

28 Trisomy 18 Edwards Syndrome
Symptoms Clenched hands Crossed legs (preferred position) Feet with a rounded bottom (rocker-bottom feet) Low birth weight Low-set ears Mental deficiency Small head Small jaw Underdeveloped fingernails Undescended testicles Unusual shaped chest

29 Trisomy 13 Patau Syndrome
Trisomy 13 occurs when extra DNA from chromosome 13 appears in some or all of the body's cells. The extra material interferes with normal development. Trisomy 13 occurs in about 1 out of every 10,000 newborns. Most cases are not passed down through families (inherited). Instead, the events that lead to Trisomy 13 occur in either the sperm or the egg that forms the fetus. The syndrome involves multiple abnormalities, many of which are not compatible with life. More than 80% of children with trisomy 13 die in the first month.

30 Trisomy 13 Patau Syndrome Symptoms
Cleft lip or palate Clenched hands (with outer fingers on top of the inner fingers) Close-set eyes -- eyes may actually fuse together into one Decreased muscle tone Extra fingers or toes Hole, split, or cleft in the iris Low-set ears Mental Retardation,severe Scalp defects (missing skin) Small eyes Small head Small lower jaw

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