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16 Cards in this Set
- Front
- Back
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Discuss the roles of mRNA, rRNA, and tRNA in the processes of transcription and translation.
Pg. 128 |
Transcription is the process by which RNA is synthesized from a DNA template. The result is mRNA. RNA is chemically similar to DNA, but it is single stranded, has ribose sugar molecule, and has uracil rather than thymine as one of its four nitrogenous bases. rRNA is ribosomal RNA and is when translation takes place. RNA directs the synthesis of polypeptides. Takes place in the ribosomes, which consist of proteins and ribosomal RNA. During translation, mRNA interacts with transfer RNA (tRNA), a molecule that has an attachment site for specific amino acid.
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Describe the normal karyotype
Pg. 130 |
Is an ordered display of chromosomes arranged according to length and the location of the centromere.
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Discuss the clinical consequences of the major chromosomal abnormalities.
Pg. 131 |
1 in 150 live births has a maor diagnosable disorder. Leading known cause of mental retardation and miscarriage. See description of diseases in text..
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Autosomal Dominant Inheritance
Pg. 141 |
The abnormal allele is dominant and the normal allele is recessive. Typically in autosomal dominant inheritance, the affected child usually has an affected parent. Also, the person who is affected and mates with a normal person has an equal chance of producing unaffected and affected children. If the child born to the affected parent is not affected, that child's children will also not be affected. Because this is not a x-linked inheritance, male and female children have equal changes of being affected.
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autsomal recessive
Pg. 141 |
Here, the abnormal allele is recessive and the normal allele is dominant giving the genotypes of DD and Dd which will express a normal phenotype. The only person who will express the disorder will be a homozygote (dd). The offspring that is the heterozygote (Dd) has a risk of transmitting the disease (d) and approximately 50% of their gametes will carry the abnormal allele. These people are considered to be heterozygous carriers. In autosomal recessive inheritance, usually the trait appears in the offspring, not in the parents. Again, males and females can be affected. If one child is affected, the risk is one in four for every subsequent birth. The trait is expressed when both parents are heterozygous for the trait and the child receives a recessive allele from both parents. This probability is increased when blood relatives marry (consanguineous marriage). Some autosomal recessive disorders do not express themselves until the person is older (delayed onset). Like autosomal dominant inheritance, some autosomal recessive disorders can also demonstrate incomplete penetrance and different levels of severity of the disease (expressivity) (described on pages 143-145 of your text). Please see the Punnett Square on page 142 of text for an example of autosomal dominant.
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x-linked traits inheritance
Pg. 141 |
X-Linked Dominant Inheritance is rare. With this inheritance, the affected dad has all non-affected sons and all daughters are affected. The affected females are heterozygous for the trait and therefore have a 50% chance of passing the abnormal gene to each daughter or son. The severity of the disorder is more in males than in females.
X-Linked Recessive Inheritance - If a man inherits a recessive disease gene on his X chromosome, because there is no counterpart on his Y chromosome, he will be affected by the disease. If this man mates with a normal female, half of the female children with be carriers. If this man mates with a heterozygous female who carries the trait, half of their children will be affected. (See the Punnett Square on page 146 for example of X-linked recessive). |
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Describe sex-limited and sex-linked traits and give an example of each.
Pg. 141? |
X-linked diseases include Duchenne muscular dystrophy and Hemophilia A and are also discussed in the text.
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Discuss the difference between incidence and prevalence. Pg 157
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Incidence-the number of new cases of a disease reported during a specific period of time (typically 1 year) divided by the number of individuals in the population. The denominator is often expressed as person-years.
Prevalence- is the proportion of the population affected by a disease at a specific point in time. Determined by bith incidence rate and the length of the survival period in affected individuals. |
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Incidence
pg 157 |
Incidence-the number of new cases of a disease reported during a specific period of time (typically 1 year) divided by the number of individuals in the population. The denominator is often expressed as person-years.
Prevalence- is the proportion of the population affected by a diseas at a specific point in time. Determined by bithe incidence rate and the length of the survival period in affected individuals. |
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Prevalence
pg 157 |
Incidence-the number of new cases of a disease reported during a specific period of time (typically 1 year) divided by the number of individuals in the population. The denominator is often expressed as person-years.
Prevalence- is the proportion of the population affected by a diseas at a specific point in time. Determined by bithe incidence rate and the length of the survival period in affected individuals. |
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Identify risk factors associated with disease states. Pg 158
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Relative risk- is a common measure of the effect of a specific risk factor. It is expressed as a ratio of the incidence rate of the disease among individuals exposed to a risk factor divided by the incidence of the disease among individuals not exposed to a risk factor. Many factors can influence the risk of acquiring a disease such as cancer, diabetes, or hypertension. The factors can include age, gender, diet, exercise and family history of the disease
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State the principles involved in multifactorial inheritance pg 158
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State the principles involved in multifactorial inheritance pg 158
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mutifactorial inheritance
pg 165 |
traits in which variation is thought to be caused by the combined effects of multiple genes are polygenic and is used when environmental life style factors also are believed to cause variation in the trait. Many of these traits are quantitative (eg BP) Because these traits are caused by the additive effects of many genetic and environmental-life-style factors, they tend to follow a normal (bell shaped ) distribution in populations. Diseases that don’t follow a bell shaped distribution and are either present or absent. These follow an underlying liability pattern and until the threshold is crossed the disease is not expressed
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Criteria to be multifactorial inheritance
pg 165 |
a) the recurrence risk becomes higher if more than one family member is affected; (b) if the expression of the disease in a proband is more severe, the reoccurrence risk is higher; (c) the reoccurrence risk is higher if the proband is of the less commonly affected gender; (d) the reoccurrence risk for the disease usually decreases rapidly in more remotely related populations and (e) if the prevalence of the disease in a population is f, the risk for offspring and siblings of probands is approximately √f.
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Identify disease states in each body system that shows some family tendency PG 165
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Hypertension, some cancers including colorectal and breast, diabetes, obesity, Alzheimer’s, alcoholism, bipolar, schizophrenia.
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Identify some combined effects and interactions among risk factors that contribute to a specific chronic illness.pg 164
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Most common diseases are not the result of either genetics or environment. Instead, genetics and nongenetic factors usually interact to influence one’s likelihood of developing common disease. In some cases a genetic predisposition may interact with an environmental factor to increase the risk of disease to a much higher level than would wither factor acting alone. A good example of a gen-environmental-life-style interaction is given by α₁-antitrypsin deficiency.
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