Chapter 07 - Heredity

• #tags column:4
• Mitosis does not result in genetic variations DATBooster_Biology::07.Heredity
• A gene is genetic material on a chromosome for a trait DATBooster_Biology::07.Heredity
• A locus is location on chromosome where a gene is located DATBooster_Biology::07.Heredity
• An allele is a variant of a gene Ex: different color DATBooster_Biology::07.Heredity
• Homologous chromosomes are a pair of chromosomes, one from each parent DATBooster_Biology::07.Heredity
• The law of segregation occurs during anaphase I, and is the separation of homologous pairs DATBooster_Biology::07.Heredity
• The law of independent assortment states that alleles of different genes separate regardless of one another DATBooster_Biology::07.Heredity
• A test cross is crossing an unknown dominant with homozygous recessive to see whether the parent is hetero- or homozygous dominant For single genes, a monohybrid organism is used, and for two genes, a dihybrid is used. DATBooster_Biology::07.Heredity
• The generations of a test cross are labeled P, F1, F2, etc. DATBooster_Biology::07.Heredity
• Incomplete dominance is best described as blending of phenotypes Ex: A flower with R for red crossed with R’ white, RR’ comes out pink DATBooster_Biology::07.Heredity
• Codominance is when both inherited alleles are completely expressed Ex: blood types A and B or both can show up as AB if expressed DATBooster_Biology::07.Heredity
• Multiple alleles refers to a gene having more than two allele forms Ex: blood groups have 3 possible alleles, the codominant A and B and the O, leading to 4 possible genotypes (phenotypes?): AO (A type), BO (B type), AB (codominant AB type), OO (O type) DATBooster_Biology::07.Heredity
• Epistasis is when one gene affects the phenotypic expression of another gene In pigmentation, for example, one gene could turn on/off the production of pigment, and a second gene could control color or the amount of color. If the first gene codes for no pigment, the second gene has no effect. DATBooster_Biology::07.Heredity
• Polygenic inheritance is when the interaction of many genes affects one phenotype These traits often involve continuous variation, like height, skin color, etc. DATBooster_Biology::07.Heredity
• Linked genes are two or more genes that reside close by on the same chromosomes, and thus are usually inherited together Linked genes exhibit recombination about 18% of the time. DATBooster_Biology::07.Heredity
• "Linked genes example:
• In a cross of BbVv x bbvv, where BV and bv are linked, we only get BV or bv and no Bv or bV. However, if there is recombination, we may get Bv or bV at 18% likelihood" DATBooster_Biology::07.Heredity
• "Linked genes:
• Recombination frequencies >18% indicate farther distance of genes apart on the same chromosome" DATBooster_Biology::07.Heredity
• A sex-linked gene refers to a gene located on a sex chromosome DATBooster_Biology::07.Heredity
• True: When a male (XY) receives an affected X-chromosome from his mother, the phenotype will be expressed regardless of whether it is dominant or recessive DATBooster_Biology::07.Heredity
• Sex-influenced genes refer to genes impacted by the sex of an individual Ex: A heterozygous Bb female is not bald, but a Bb male is, where the gene B or b accounts for baldness DATBooster_Biology::07.Heredity
• Penetrance is the probability that an organism with a specific genotype will express a particular phenotype DATBooster_Biology::07.Heredity
• Expressivity describes the variation of phenotype for a specific genotype DATBooster_Biology::07.Heredity
• X-inactivationIn the embryonic development of female mammals, one X chromosome is a Barr body, which is not expressed DATBooster_Biology::07.Heredity
• X-inactivationHemophilia is an X-linked recessive trait, but carriers can have hemophilia if the dominant trait is inactivated XHXh is the carrier genotype, but XH could be inactivated, leaving Xh to be expressed. DATBooster_Biology::07.Heredity
• Nondisjunction is failure of one or more chromosomes to separate during cell division DATBooster_Biology::07.Heredity
• Mosaicism in cells that undergo nondisjunction in mitosis during embryonic development means that a fraction of body cells have extra or missing chromosomes DATBooster_Biology::07.Heredity
• Polyploidy means having more than two sets of chromosomes This is common in plants DATBooster_Biology::07.Heredity
• A point mutation in DNA is single nucleotide change This includes substitution, insertion, and deletion of ONE nucleotide DATBooster_Biology::07.Heredity
• A transition mutation is a change from purine to purine or pyrimidine to pyrimidine DATBooster_Biology::07.Heredity
• A transversion mutation is a change from purine to pyrimidine or vice versa DATBooster_Biology::07.Heredity
• Aneuploidy describes having extra or missing chromosomes and are often caused by nondisjunction Ex: Down syndrome is trisomy 21, where there are 3 copies of chromosome 21 DATBooster_Biology::07.Heredity
• Turner syndome is missing one X chromosome in females DATBooster_Biology::07.Heredity
• Klinefelter syndrome is a male with XXY instead of XY DATBooster_Biology::07.Heredity
• Chromosomal aberrations are structural changes in DNA DATBooster_Biology::07.Heredity
• "Chromosomal aberration examplesDuplications: chromosome segment is repeated on same chromosome.
• Inversions: chromosome segments are rearranged in reverse orientation.
• Translocation: segment is moved to another chromosome" DATBooster_Biology::07.Heredity