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What is a mutation?
A change in the DNA sequence
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What happens in chromosomal mutation?
Part of a chromosome may be lost, added, or moved to another chromosome. It is usually not passed on because zygote dies.
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Explain crossing over
occurs when chromosomes exchange genes. When two chromosomes overlap. Some genes cross over and switch places.
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What does nondisjunction fail to do?
Properly seperate a chromosome pair.
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What are the two types of nondisjunctions and what happens with each type? Give an example of each.
Monosomy: When one gamete has one less chromosome the it should. When it joins with another gamete the zygote would have only 45 chromosomes.
Trisomy: When gamete has one more chromosome than it should. When it joins with another gamete the zygote would have 47 chromosomes.
- example of Monosomy: Turner syndrome
- example of Trisomy: Down syndrome
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What is a pedigree?
A graphic representation of a family tree
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What is a test cross?
A test cross is a way of determining genotype by crossing an individual of unknown genotype with homozygous recessive.
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When are test crosses used?
breeding plants and animals if a certain offspring is needed
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What is used in ultrasound's and what is it used to detecet?
- Sound waves; Used to detect abnormalities of limbs,organs, etc.
- Another name for ultrasound is sonogram
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How is an amniocentesis performed? What happens to the collected cells?
Fluid surrounding the fetus is drowned our by a needle; fetal cells are collected and grown in a lab
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How is a chorion villi sampling performed?
A sample of the chorion (membrane surrounding the fetus) is taken, chemical tests and karyotyping are prepared.
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What happens in a point mutation?
One nucleotide is subsituted for another.
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What happens in a frameshift mutation?
Shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide.
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Describe Down Syndrome
- Also called Trisomy 21 due to presence of extra #21 chromosome
- Mental retardation,distinct phenotype, upward slant to eyes
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Describe Klinefelters
- Has 47 chromosomes, XXY- affects males only
- Mild learning disability, abnormally tall, development of breasts, infertile
- Treated with testosterone injections
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Describe Turners syndrome
- Has 45 chromosomes, X-affects females only
- normal phenotype, normal intelligence, infertile, short stature
- treated with estrogen injections
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Describe Hemophilia
- Sex linked disorder, rare in females
- failure of blood to clot
- injections of clotting factors to stop bleeding disorders
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Describe Sickle Cell Anemia
- Mutation in blood causing "sickled" shape to red blood cells
- most common in African Americans
- pain associated with blocked vessels
- common where mosquito-borne malaria is present
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Describe Phenylketonuria (PKU)
- Mutation disrupts functions of enzyme leading to high phenylalanine levels in brain
- metal retardation, epilepsy, look normal
- common in Caucasian
- need low protien diet
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Describe Huntingtons disease
- progressive loss of muscle control
- loss of mental function around one's late 30's
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What is Huntingtons disease?
(sex-linked genetic, dominant autosomal, recessive autosomal, chromosomal nondisjunction)
Dominant Autosomal
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What is Turner's Syndrome?
(sex-linked genetic, dominant autosomal, recessive autosomal, chromosomal nondisjunction?)
Chromosomal Nondisjunction
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What is Colorblindness?
(sex-linked genetic, dominant autosomal, recessive autosomal, chromosomal nondisjunction?)
Sex-linked
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What is PKU?
(sex-linked genetic, dominant autosomal, recessive autosomal, chromosomal nondisjunction?)
Recessive autosomal
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What is hemophilia?
(sex-linked genetic, dominant autosomal, recessive autosomal, chromosomal nondisjunction?)
Sex linked
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What is Klinefelters syndrome?
(sex-linked genetic, dominant autosomal, recessive autosomal, chromosomal nondisjunction?)
Chromosomal nondisjunction
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What is Down syndrome?
(sex-linked genetic, dominant autosomal, recessive autosomal, chromosomal nondisjunction?)
Chromosomal Nondisjunction
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