BIOL 1107 1st Edition Exam 2 Study Guide Lectures 15 20 Lecture 15 March 5 Mendelian genetics focuses on inheritance traits by preforming reciprocal crosses between the mother and father parental generation to form the offspring F1 generation Mendel proposed that each individual has two versions of each gene these versions being called an allele Different alleles are responsible for the variation in the traits Mendel studied Alleles that are found in an individual are called its genotype which affects an individual s phenotype observable features expression Individuals have two alleles for each gene homozygous two copies of the same allele RR or rr or heterozygous two different alleles Rr Pure line individuals always produce offspring with the same phenotype because they are homozygous there are no other alleles present Independent assortment means that alleles of different genes are transmitted independently of one another and a dihybrid cross is mating between parents that are both heterozygous for two traits The Chromosome Theory of Inheritance states that chromosomes are composed of genes from maternal and paternal sets alleles can be different Lecture 16 March 7 The expression of an allele is completely dependent of its origin There can be an external influence of a gene sex for example on genomic imprinting alleles are imprinted The environment can influence our genetics and DNA the central dogma being that the environment only affects genome after adaptation is in place Both alleles can be transcribed by DNA polymerase and females can only transcribe one X chromosome We don t know what drives the female zygote to determine the maternal or paternal X to shut down Lecture 17 March 10 Crossing over is rare between genes that are close together and more frequent in genes that are far apart Co dominance is when both alleles are expressed and incomplete dominance is when alleles mix to form a combination of both Some genes are pleiotropic meaning they influence many traits Epistasis occurs when one gene influences the expression of other genes and alleles Polygenic inheritance is the transmission of quantitative traits Lecture 18 March 12 If males inherit a mutant X chromosome they will have the phenotype disorder however if females inherit it they are just carriers because they have a second X chromosome to use An X linked recessive trait means that males in every other generation will express the gene and an Xlinked dominant trait means that males and females are equally likely and it does not skip generations In bacteria gene expression can be controlled at three levels transcription translation or posttranslation protein activation Transcriptional control can be negative or positive negative control occurs when a regulatory protein prevents transcription and positive control occurs when a regulatory protein increases the transcription rate If a gene is expressed it has been transcribed Transcriptional control occurs when a cell does not produce mRNA for specific enzymes and post transcriptional control occurs when a cell fails to activate a manufactured protein by chemical modification Lecture 19 March 14 Catabolic repression occurs when one of the product molecules of a reaction represses the production of glucose A catabolic activation protein CAP binds to CAP building site near the lac promoter and triggers transcription The lac promoter is strengthened to increase expression and then regulated by cyclic AMP cAMP binding to it Only when CAP is bound to cAMP can it bind to DNA This process is not going to shut down transcription it will only slow it down The amount concentration of glucose affects the amount of cAMP and the rate of transcription of the lac operon As glucose increases transcription decreases and vice versa Lecture 20 March 24 Another way to manipulate gene protein expression besides splicing is to manipulate the RNA Chaperone proteins can manipulate protein folding by enzymes modifying the proteins by adding carbohydrate groups or clearing off certain amino acids Proteins may be activated or deactivated by phosphorylation Tags are added to cylcin proteins and are recognized by a multimolecular molecule which cuts the protein into short segments To insert genes into plasmids a palindrome recognition site is identified and the same recognition site is attached to the cDNA gene Restriction endonuclease is then added resulting in sticky ends and the gene is inserted into the plasmid A Genomic Library is made up of cloned DNA fragments representing the entire genome A DNA library is a collection of transformed bacterial cells each containing a vector with an inserted gene A cDNA library is a collection of bacterial cells each containing a vector with one cDNA