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54 Cards in this Set
- Front
- Back
alleles
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two like genes
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chromosomes
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the structure that weaes genes into strands in the nucleus of all body cells
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dermatoglyphics
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the study of surface markings of the skin
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genes
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basic units of heredity that determine bth the physical and menta characteristics of people
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genetics
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study of hw and why chromosomal disorders occur; the science of heredity
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genome
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compete set of genes present
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genotype
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actual gene composition
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heterozygous
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having two different r unlike genes fr a designated characteristic
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homozygous
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having two like genes for a designated characteristic
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karyotype
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a visual presentation of chromosomes
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meisosis
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type of cell division in which the number of chromosomes inthe cell is reduced to the halid number for reproudtion (23 rather than 46 chromosomes)
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nondisjunction
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uneven cell idivision that leads to abnormal chromosomal divisions
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phenotype
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outward appearance or the expression of the genes
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cytogenetics
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the study of chromosomes by light microscopy and the method by which chromosomal aberrations are identified
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most autosomal dominant disorders cause ...
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structural defects
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Huntington disease
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-autosomal dominant disorder
-a progressive neurologic disorder characterized by loss of motor control and intellectual deterioration -symptoms do not manifest themselves until pepl reach 35 to 45 years of age -no cure |
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Examples of autosomal dominantly inherited disorders
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-facioscapulohumeral muscular dystrophy
-a form of osteogenesis imperfecta -Marfan syndrome -breast/ovarian cancer syndrome |
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facioscapulohumeral muscular dystrophy
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an autosomal dominant disorder that results in muscle weakness
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osteogenesis imperfecta
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a disorder in which bones are exceedingly brittle (one form is autosomal dominant)
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Marfan syndrome
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an automsomal dominant disorder of connective tissue that results in an individual being thinner and taller than usual and perhaps with associated heart disorders
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breast and breast/ovarian cancer syndrome
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an autosomal dominant disorder that accounts for 5 to 10% of breast cancer in women
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def: vertical transmission picture
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in a family genogram one of the parents of a child with a disorder wil have the disorder (occurs with autosomal dominant disorders)
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def: horizontal transmission picture
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in a family genogram the family history for the disrder is negative - no one can identify anyone else who had it (occurs with autosomal recessive disorders)
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most autosomal recessive disorders tend to be...
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biochemical or enzymatic
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examples of autosomal recessive disorders
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-cystic fibrosis
-adrenogenital syndrome -abinism -Tay-Sachs disease -galactosemia -phenylketonuria -limb-girdle muscular dystrophy -Rh-factor incompatibility |
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X-linked inheritance
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one of about 300 known disorders that are located on and therefore transmitted only by the female sex chromsome
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With an x-linked dominant disorder, how are children of an affected man affected?
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all female children are affected and all male children are unaffected
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Example of an X-linked dominant disorder
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Alprt's sydrome
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Alport's syndrome
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-an X-linked dominant disorder
-a progressive kidney failure disorder |
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Exammples of X-linked recessive disorders
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-hemophilia A
-Christmas disease -color blindness -Duchenne muscular dystrophy -fragile X syndrome |
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What features are found on the Y-chromosome?
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height, tooth size
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Phenotypic features associated with having an extra Y chromsome include...
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tall stature and aggressive personality
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HLA stands for...
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human lymphocyte antigen
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multifactorial (polygenic) inheritance
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disorder that appear to occur from multiple gene combinations possibly combined with environmental factors. their incidence is unpredictable
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mitochondrial inheritance
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a number or rare myopathies (muscle diseases) are inherited this way. mitochondria are inherited solely from the cytoplasm of the ovum. therefore female carriers will pass mitochondrials disorders to 100% of their children. affected males will not pass on a mitochondrial disorder
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imprinting
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refers to differential expression of genetic material and allws researchers to identify whether the chromosomal material has come from the male or female parent
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hydatidiform mole
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an embyronic disorder in which two separate sperm fertilized a single ovum
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Prader-Willi syndrome
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a chromome 15 abnormality in which children are severely obese and cognitively challenged. in this case no paterna contribution is present at certain gene points
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FISH
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flourescent in situ hybridization - a method to identify the number of chromsomes and specific parts of chromsomes
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Down's syndrome
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a cytogenic disorder resulting from nondisjunction leading to 3 copies of chromosome 21
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the incidence of Down syndrome increases with....
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advanced maternal age and is highest if the mother is older than 35 years and the father is older than 55 years
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deletion abnormalities definition
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a form of chromosome disorder in whch part of a chromsome breaks during cell division. ex. Cri-du-chat syndrome
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tranlocation abnormalities
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2 to 5% of Down syndrom occurs this way. child inherits an extra chromosome from one of the parents abnormally attached chromosomes
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mosaicism
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an abnormal condition that is present when a nondisjunction disorder occurs AFTER fertilization of the ovum. different cells in the body then have different chromosome counts. this can lead to Down syndrome with near normal intelligence abbreviated 46XX/4XX21+ to show that some cells cntain 46 and some 47 chromosomes.
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isochromosomes
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occurs if a cromosome accidentally divides not by a vertical separation but by a horizontal one, resulting in a new chromosome with mismatched long and short arms
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balanced translocation carrier
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means that a person has 46 chromosomes but one of the chromosomes is abnormally attached to another chromosome. offspring have a great than average chance of having a disorder - unbalanced translocation syndrome
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What disorder do Mediterranean people have a high incidence of?
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thalassemia - a blood disorder
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What disorder do those with a Chinese ancestry have a high incidence of?
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glucose-6-phosphate dehydrogenase (G6PD) deficiency - a blood disorder where destruction of red cells can occur
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What phase are cells in during traditional karyotyping?
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metaphase
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"Why do I have to wait so late in pregnancy for genetic studies by amniocentesis?"
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Genetic analysis is done n skin cells obtained from amniotic fluid. The test cannot be scheduled until enugh amniotic fluid is present for analysis. This analysis now can be done as early as the 12th week of pregnancy.
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If there are no inherited diseases in a couple's famiy, should the coouple have a aryotype done "just to be sure" before they have their first baby?
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A genetic analyss is not routinely recommended unless there is evidence or suspicion of genetic disease in the family.
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What is the chance that a mother, and separately a father, who are balanced translocation carriers of chromosome 21 wil have a child born with Down syndrome.
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For a father, 5%
For a mother, 15% |
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What might decreased levels of maternalserum alpha-fetoprotein indicate?
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Down syndrome in the child
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def. consanguineous
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related to each eachother (refers to couples)
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