Chapter 11.1: The Direct Detection Of Genotype Distinguishes Individual Genomes

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in vitro fertilisation (IVF)

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process by which egg cells are fertilised by sperm outside the body, in vitro.

IVF is a major treatment in infertility when other methods of assisted reproductive technology have failed.

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obstetrician

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obstetrics is the surgical specialty dealing with the care of women and their children during pregnancy (prenatal period), childbirth and the postnatal period.

Midwifery is the non-surgical equivalent.

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locus

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a designated location anywhere on a chromosome

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gene

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a coding locus

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allele

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one of two or more alternative DNA sequences found at a locus--either coding or noncoding--in different homologs of the same chromosome, in a single heterozyous individual, or in different individuals

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polymorphic

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a locus with two or more distinct alleles in a population

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DNA polymorphisms

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two or more alleles at a locus detected with any method that directly distinguishes differences in DNA sequences.

The sequence variation of a DNA polymorphism can occur at any position on a chromosome and may, or may not, have an affect on phenotype.

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DNA marker

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an identifiable physical location on a chromosome, whose inheritance can be monitored. Markers can be expressed regions of DNA (genes) or any segment of DNA with variant forms that can be followed

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anonymous locus

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a designated position on a chromosome with no known function

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single nucleotide polymorphisms (SNP)

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a single nucleotide locus with two naturally existing alleles defined by a single base pair substitution. SNP loci are useful as DNA-based markers for formal genetic analysis.

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microsatellite

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DNA element composed of 15-100 tandem repeats of one, two-, or three-base-pair sequences.

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minisatellite

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DNA composed of 10-40 bp tandem repeating units of identical sequence.

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indels

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deletion, duplication, and insertion at non-repeat loci

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preimplantation genetic diagnosis PGD

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rocedures that are performed on embryos prior to implantation, sometimes even on oocytes prior to fertilization. PGD is considered another way to prenatal diagnosis. Its main advantage is that it avoids selective pregnancy termination as the method makes it highly likely that the baby will be free of the disease under consideration.

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Does most DNA code for proteins?

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No.

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What happens when mutations occur in coding or regulatory sequences?

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They are not passed on to future generations because their affect on gene function is almost always negative.

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When two or more alleles exist at a DNA locus, the locus is considered:

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polymorphic

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biallelic

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have only two alleles

e.g., most SNPs are biallelic

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SSRs (simple sequence repeats) is another name for:

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microsatellite

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small deletions and duplications most often arise from:

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unequal crossing-over between nonhomologus sites