Genetics Exam 2 Study Guide
Genetics Exam 2 Study Guide GEN 3000
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This 0 page Study Guide was uploaded by Jomary Arias on Friday February 12, 2016. The Study Guide belongs to GEN 3000 at Clemson University taught by Dr. Kate Tsai in Spring 2016. Since its upload, it has received 248 views. For similar materials see Genetics in Biomedical Sciences at Clemson University.
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Date Created: 02/12/16
GEN 3000 Genetics Dr Kate Tsai Study Guide Exam 2 Cha ter 5 Key Terms formation of offspring that are genetically different from the parent Offspring must have 2 different types of gametes male and female defined by the PHENOTYPE of an individual not their genotype genes are located on chromosomes and chromosomes are substrates for gene segregation the sex that produces IDENTICAL gametes All gametes end up the same as far as the number of chromosomes the sex that produces two DIFFERENT gametes All gametes end up With different number of chromosomes have 1 set of chromosomes have 2 sets of chromosomes 0 When chromosomes or chromatids pull apart and divide during Anaphase o When chromosomes fail to seperate 0 discovered that Male insects has a strange chromosomal X body in the nuclei 0 discovered that Female grasshopper cells had 1 more chromosome than males 0 discovered that Female grasshoppers have 2 X chromosomes Also that the X chromosome in males was paired With a smaller Y chromosome These X and Y chromosomes separate into different sperm cells While egg cells all get a single X chromosome 2 Types of Organisms ONE house has BOTH female and male reproductive structures Ex Plants because they can selffertilize TWO house Individual has EITHER female or male reproductive structures Ex Mammalians GEN 3000 Genetics Dr Kate Tsai Study Guide Exam 2 1 Chromosomal Sex Determining System 2 Genetic Sex Determining System 3 Environmental Sex Determining System Chromosomal and Environmental Sex Determining systems trigger differences between sex males and females Genetic Sex Determining system over laps with the other mechanisms 1 Chromosomal Sex Determining System 0 some plants insects reptiles and mammals Female XX Homogametic Male XY Heterogametic 1mm is a more simple system At meiosis half of the sperm receive an X chromosome and the other half get no sex chromosome Female XX Homogametic Male X0 O place holder 0 1 In this system the Female produces 2 Different games so the offspring will receive half Z and the other half W Female ZW Heterogametic Male 22 Homogametic Ex Birds moths some fish 2 Genetic Sex Determining System No obvious difference in chromosomes because there is no sex chromosome Genes determine the sex of an individual Similar to chromosomal sexdetermining 3 Environmental Sex Determining System Environmental factors such as temperature determine the sex of the organism Alligator Warm temperature during embryonic development produces males while cool temperatures produce females studied 1237 ies the F1 generation produces all but 3 of the ies had red eyes The 3 ies were males with white eyes Why was this Nondisjunction and not a random mutation This phenotype occurred too frequently therefore it was hypothesized that the cause for the mutation is that the X chromosome fails to separate in Anaphase I of Meiosis GEN 3000 Genetics Dr Kate Tsai Study Guide Exam 2 Nondisjunction I 2 copies of the X chromosome going to some eggs while other get none Can occur in any stage of Anaphase during meiosis or mitosis Flies With just a Y chromosome or XXX extra X chromosome is lethal In Drosophila ies Sex is not determined by the presence of absence of the Y chromosome instead sex is based on a ratio 0 X0 females receive only 1 X 0 XXXY XXXXY or XXYY Males chromosome so they have 45 instead have one or more Y chromosomes of the normal 46 chromosomes and multiple X chromosomes 0 Do not undergo puberty 39 47 Chromosomes 0 Low hairline extra folds of skin on 39 M3163 haVe small teSteSa 611131quotng neck breast and reduced facial hair 0 normal female anatomy fertility and intelligence May have some cognitive impairment severity and phenotypic differences increase With increasing number of X chromosomes 1 X contains genetic information that is essential for BOTH sexes at least 1 X chromosome is required 2 Maledetermining gene is located on the Y chromosomes Klinefelter Syndrome 3 The absence of Y chromosome I defaults to female development 4 Genes required for fertility are on BOTH X and Y chromosomes Females need at least 2 X chromosomes to be fertile Turner Syndrome 5 Addition X chromosomes are detrimental sometimes lethal All humans have neutral undifferentiated gonads early in development Males have a which triggers teste development they then secrete testosterone expressing the male characteristics GEN 3000 Genetics Dr Kate Tsai Study Guide Exam 2 In male with XX chromosomes they lack the Y chromosome and therefore do not have the SRY gene During meiosis homologous chromosomes line up at pseudoautosomal regions when crossing over takes place the SRY could accidentally be transferred to an X chromosome Women with Androgen insensitivity syndrome These women have a functional SRY gene triggers teste developments but they lack the receptors DOSAGE COMPENSATION since females have 2 copies of every Xlinked gene they should produce twice the amount of the gene produce as males inactive X chromosomes heterozygous females at the X loci will express only 1 allele or the other in a given cell Females are mosaic for expression of a Xlinked gene Chapter 6 Key Terms display of a complete set of chromosomes of chromosomes is altered addition deletion one or more complete sets of chromosomes are added getting 2 copies of a chromosome from one parent sites prone to breaking most common form of inherited mental impairment number of repeats increases in future generations causing symptoms to be worse 3 Types of Chromosomal mutations 1 Chromosomal Arrangements 2 Aneuploids 3 Polyploids 1 Chromosomal Arrangements Arrangements can occur in the 4 ways 1 extra chromosomes gain of genetic material Duplication is characterized by a loop formed during meiosis Tanden Duplication Displaced Duplication GEN 3000 Genetics Dr Kate Tsai Study Guide Exam 2 Duplicated region is immediately adjacent Duplication is located on a different or located some distance away chromosome Why does duplication alter phenotype Genes are normal but phenotypic changes are due to gene dosage 2 missing chromosomes loss of genetic material 0 Deletion of a centromere I results in loss of the entire chromosome 0 In Homozygous individuals loss of essential genes is lethal 0 In Heterzygous individuals deletions result in Gene products being imbalanced Allows recessive alleles on undeleted chromosomes to be expressed known as Pseudo dominance Some genes have to be present in 2 copies to produce enough gene produce known as Haploinsufficent Also leads to problems during gene pairing 3 rearrangement of gene order in the original chromosome can break a gene in two Inversions also characterized by a loop in meiosis Paracentric Paricentric Inversions that DO NOT include the Inversions that DO include the centromere we centromere don t get dysenteric bridges 4 addition of genetic material from another chromosome order is changed Movement between NONhomologous chromosomes this is not crossing over instead it is just switching up the alleles NON reciprocal Translocation Reciprocal Translocation Movement 1 way from one chromosome to Movement 2 ways both chromosomes break another without equal exchange One and switch genetic material chromosome breaks and gets attached to another chromosome GEN 3000 Genetics Dr Kate Tsai Study Guide Exam 2 Robertsonian Translocation is a translocation combined with a deletion cause some forms of Down Syndrome 2 Aneuploidy These are changes in the number of individual chromosomes In Humans sex chromosome aneuploidies are best tolerated because of dosage compensation EX Tumer Klinefelter Syndrome In Humans autosomal aneuploidy are more common 75 result from nondisjunction in the mother Why does aneuploidy occur These changes occur because of a loss of a chromosome which has lost its centromere a Robertsonian translocation or Nondisjunction most common There are 4 types of Aneuploidy loss of BOTH members of homologous pairs loss of 1 single chromosome gain of 1 single chromosome gain of 2 homologous chromosomes an organism with an extra PPP copy of two different chromosomes is NOT tetrasomyit is double trisomic 3 Polyploidy Why does Polyploidy occur These occur because of errors in meiosis events at fertilization or errors in mitosis following fertilization EX Dispermy is an at fertilization error which results in simultaneous fertilization of egg with two sperm Usually results in sterility Auto Polyploidy Allo polyplody All chromosome sets are from SAME Chromosome sets are from DIFFERENT species species Occurs as a result of hybridization followed by chromosome doubling Cha ter 7 GEN 3000 Genetics Dr Kate Tsai Study Guide Exam 2 Key Terms 0 each diploid individual possesses two alleles that separated in meiosis one allele to each gamete o 2 alleles separated independently of alleles at other loci genes are found on Chromosomes 0 created by Alfred H Stutton proposed that frequency of recombination could be used to determine the physical distance separating two genes on a chromosome 0 testcross between 2 genes 0 use recombination frequencies to make chromosome maps and distances are written in terms of units of centimorgans cM 0 can establish order of genes in a single cross and double crossovers can be easily detected 0 happens when 1 crossing over starts and prevents a 2nd crossing over from occurring in the same location 0 difference distances but same gene order Recombination Frequency Can be determined using the following formula Recombination Freq of recomb Progeny Total of Progeny Interference and Coefficient of Coincidence Can be determined using the following formula COC of observed double crossovers of expected double crossovers Inference 1 COC Coupling Cis Repulsion Trans Wild type alleles on one chromosomemutant Each chromosome has one wild type and one on the other mutant Genes may be on 1 Different Chromosomes 2 Complete Linkage genes on same chromosome RARE GEN 3000 Genetics Dr Kate Tsai Study Guide Exam 2 3 Incomplete Linkage genes on same chromosome but some distance allows some recomb Inter chromosomal Recombination Intra chromosomal Recombination Occurs between genes on DIFFERENT Occurs between genes on the SAME chromosomes arises from independent chromosome crossing over in Prophase I in assortment in Anaphase I of meiosis meiosis Chapter 8 Key Terms 0 identifies the prototroph from the auxotroph based on the selected media 0 wild type bacteria that can synthesize all compounds needed for growth from simple ingredients mutant strain that lacks one or more enzymes required for metabolizing nutrients will grow on supplemented media 0 fails in between minimum and complete media 0 contains 2 present living cells which switch genetic information using one of the three mechanisms 0 contain origin of replication genes involved in conjugation plasmid that are capable of integration into the chromosome arise from episome cells 3 Gene Transfer Mechanisms Conjugation Transformation Transduction DIRECT transfer of DNA DNA taken up from a medium Bacterial viruses phages from one bacterium to carry DNA from one another donor I recipient bacterium t0 anOthef only
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