UA BSC 109 - Genetics (3 pages)

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Genetics



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Genetics

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describes genetics and genetic disorders


Lecture number:
27
Pages:
3
Type:
Lecture Note
School:
University of Alabama
Course:
Bsc 109 - Intro Biology Non Maj II
Edition:
1
Unformatted text preview:

BSC 109 1st Edition Lecture 27 Outline of Last Lecture IX Cancer treatments continued X Common cancers Chapter 19 Genetics and Inheritance I II III IV V Introductory genetics terminology Your genotype is the genetic basis of your phenotype Mendel established the basic principles of genetics Dominant alleles are expressed over recessive alleles Two trait crosses independent assortment of genes for different traits Outline of Current Lecture VI Polygenic inheritance phenotype is influenced by many genes VII Linked alleles may or may not be inherited together VIII Sex linked inheritance x and y chromosomes carry different genes IX chromosomes may be altered in number or structure X deletions and translocations alter chromosome structure XI many inherited genetic disorders involve recessive alleles Current Lecture A B XII XIII Incomplete dominance heterozygotes have an intermediate phenotype Codominance both gene products are equally expressed 1 Sickle cell gene two different alleles of hemoglobin gene 2 Sickle cell anemia must be homozygous for the gene 3 Sickle cell trait heterozygous for the gene Polygenic inheritance phenotype is influenced by many genes A Inheritance of phenotypic traits that depend on many genes B Polygneic traits are usually distributed within a population as a continuous range of values C Both genotype and the environment affect phenotype 1 Phenotype isn t determined by genotype alone 2 Environmental factors can profoundly influence phenotype Linked alleles may or may not be inherited together A Linked alleles physically located on the same chromosome B May be inherited together C May be shuffled during crossing over during meiosis These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute XIV XV XVI XVII Sex linked inheritance x and y chromosomes carry different genes A Sex chromosomes 1 23rd pair of chromosomes 2 not homologous 3 x and y chromosomes carry different genes 4 males have one x and one y chromosome 5 females have 2 x chromosomes 6 male parent determines the gender of offspring B karyotype a composite visual display of all the chromosomes of an individual C shows all 23 pair of chromosomes lined up side by side D sex linked genes are located on sex chromosomes 1 sex linked or x linked inheritance 2 characteristics 3 more males than females express the disease 4 passed to sons by mother 5 father cannot pass the gene to sons but daughters will be carriers E sex influenced traits 1 genes encoding these traits are located on the autosomes not the sex chromosomes 2 expression of the trait is affected by presence of testosterone estrogen chromosomes may be altered in number or structure A nondisjunction during meiosis 1 failure of homologous chromosomes or sister chromatids to separate 2 a gamete may end up with two copies of a chromosome instead of just one B down syndrome 3 copies of chromosome 21 1 distinct physical features 2 developmental disabilities 3 1 1000 lie births in the US 4 increased risk of trisomy with increasing maternal age 5 can be detected by fetal testing C nondisjunction affecting sex chromosomes can produce a variety of combinations deletions and translocations alter chromosome structure A deletions piece of a chromosome breaks off B translocations piece of chromosome breaks off and attaches to a different chromosome many inherited genetic disorders involve recessive alleles A to develop these diseases one recessive allele is inherited from each parent who most often are themselves heterozygous carriers B some human genetic disorders are dominant achondroplasia and Huntington s


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