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Bio Exam - Chapter 9
Chapter 9 Vocab/Essay Questions
16
Biology
Undergraduate 2
03/31/2010

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Term
Genetics
Definition
science of heredity
Term
Phenotype vs. Genotype
Definition
Phenotype is the organism's expressed or physical traits, while Genotype is genetic makeup.
Term
co dominant
Definition
Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles
Term
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Definition
A technigque for diagnosing genetic defects while a fetus is in the uterus. A ample of amniotic fluid, obtained by a needle inserted into the amnion, is analyzed for telltatle chemicals and defective fetal cells.
Term
<!-- /* Font Definitions */ @font-face {font-family:Calibri; mso-font-alt:"Century Gothic"; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin-top:0in; margin-right:0in; margin-bottom:10.0pt; margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-fareast-font-family:Calibri; mso-bidi-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> Chorionic villi sampling
Definition
A techniguqe for diagnosing genetic defects while the fetus is in an early development stage within the uterus. A small sample of the fetal portion of the placenta is removed and analyzed.
Term
Karyotype
Definition
A display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere position.
Term
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Definition
An accient of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase.
Term
Autosome
Definition
A chromosome not directly involved in determining the sex of an organisml any chromosome other than X or Y.
Term
Sex-linked trait
Definition
A trait located on a sex chromosome. In humans, the vast majority of sex-linked genes are located on the Y chromosome.
Term
Pleiotropy
Definition
The control of more than one phenotypic characteristic by a single gene.
Term

 

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Definition
The additive effect of two or more gene loci on a single phenotypic characteristic.
Term
Incomplete dominance
Definition
A type of inheritance in which the phenotype of a heterozygote (Aa) is intermediate b/w the phenotypes of the two types of homozygotes (AA and aa)
Term
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Definition

Nondisjunction is an accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase. Sometimes, even though the rest of meiosis occurs normally, all the resulting gameted end up with abnormal numbers of chromosomes, which may result in some abnormal gametes. If an abnormal gamete produced by nondisjunction unites with a normal gamete in fertilization, the result is a zygote with an abnormal number of chromosomes.

 

In amniocentesis, a physician punctures the sac in an area away from the fetus and extracts approximately 20 ml of amniotic fluid. After the amniotic fluid is extracted, the fetal cells are separated from the sample to detect for abnormalties.

Term
Explain how an individual obtains a heterozygous set of alleles and the different ways it can be expressed. Use examples for each.
Definition
An organism that has two different alleles for a gene is homozygous.
Term

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Explain why genes that are located closely on the same chromosome are often inherited together; and under what circumstance would they not be? Create an example.

Definition
Genetic loci on the same chromosome are physically close to one another and tend to stay together during meiosis, and are thus genetically linked. Crossing over of DNA can cause alleles perviously on the same chromosome to be separated and end up in different daughter cells. The further the two alleles are apart, the greater the chance that a cross-over event may occur between them, possibly separating the alleles.
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