New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here


by: Marjolaine Smitham


Marjolaine Smitham
GPA 3.68

G. Hay

Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

G. Hay
Class Notes
25 ?




Popular in Course

Popular in Animal Science

This 10 page Class Notes was uploaded by Marjolaine Smitham on Tuesday October 13, 2015. The Class Notes belongs to ANSC 2072 at Louisiana State University taught by G. Hay in Fall. Since its upload, it has received 44 views. For similar materials see /class/222510/ansc-2072-louisiana-state-university in Animal Science at Louisiana State University.

Similar to ANSC 2072 at LSU

Popular in Animal Science




Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 10/13/15
GENETICS TEST1 STUDY GUIDE Lecture 1 Introduction to Agriculture I Ancient Greece 500300 BC Hippocrates and Aristotle o traits were carried in the male seed and produced offspring with similar characteristics I Ancient Rome 300 B 500AD 0 Plant Grafting and Animal Breeding Rome 0 Improved plant varieties and animal breeds I Middle Age 3ooBC16ooAD Theoretical understanding of genetics was not extended by new or significant ideas 0 Naturalists aware of the impact of heredity on studied organisms I Epigenesis states that structures such as body organs are not initially present in the early embryo but are formed during embryonic development I Preformation states that each male sex cell contains a complete miniature adult homunculus which contains all the organs and body parts of a mature adult in miniature form after being placed in the female during intercourse it simply grows larger until birth I Celthheory states that all living organisms are composed of basic visible units called cells which are formed from similar preexisting cells I Spontaneous Generation the creation of living organisms from nonliving organisms was widely believed I Fixity of Species states that all animal and plant species have remained unchanged since the creation of the earth 0 Influenced by religious beliefswidely promoted o Akin with creationism or creation science I Charles Darwin and the Origin of Species 0 English naturalist 0 Published On the Origin of Species in 1859 In 1859 an English naturalist Charles Darwin published On the Origin of Species based on geological geographical and biological observations made during his voyage the southern tip of South America and throughout the Pacific 0 Theory of Natural Selection based on the observation that natural populations tend to produce more offspring than the local environment can support leading to a struggle for survival among members of a population survival of the fittest 0 Living species CAN and DO evolve or change genetically and physically over time I Gregor Johann Mendel o Austrian monk and naturalist o Conducted experiments from 18561865 using peas in which he discovered statistical patterns that demonstrated the fundamental laws of inheritance o Mendel s work and the discovery of chromosomes 1900 made it clear that hereditydevelopment are dependent on the information carried in chromosomes and that this information was distributed to the offspring through the gametes or sex cells I QuickTimeline 1920 s use of math tm in nix to explain ieiences among animals for specific traits Dr Jay Lush developed statistical techniques to measure variationpredict how complex traits were passed to offspring 0 1940 s perfection of artificial insemination in cattle allowed for more accurate predictions of how traits are passed from one generation to the next Watson and Crick hypothesized the molecular structure of DNA as a double helix I 41 0 1970 s Norman Bourlag produced hybrid corn that adapted to specific climates and were more prolific Green Revolution development of recombinant DNA technology 1980 s Dr Kary Mullis developed the polymerase chain reaction PCR technique to produce unlimited quantities of DNA pieces for molecular studies embryo harvesting and freezing techniques 0 1990 s in vitro fertilization split embryos and cloning super computers analyzesequence long sections of DNA 0 2000 s gene sequencing genomics the birth of biotechnology 0 Lecture 2 Basic Units of Inheritance I Deoxyribonucleic Acid DNA large complex molecules that makes up the genetic material of all living organisms consists of a long chain of molecules called nucleic acids or nucleotides joined together that form linear chains normally exists in cells in a long threadlike structure called chromatin during cell division chromatin thickens and condenses into visible chromosomes o Is made through a process called transcription 0 RNA travels from the cell nucleus to the ribosomes in the cell cytoplasm where it is used to produce proteins used as cellular building blocks and to control most cellular functions in a process known as translation 0 Nucleotides consists of 3 compounds A nitrogen containing base compound A 5 carbon sugar called a pentose sugar A phosphate molecule I DNA consists of 2 polynucleotide chains joined together by weak Hbonds between complimentary nucleotides on each chain Adenine Guanine Cytosine Thymine Uracil AT and CG I Chromatin is a long threadlike structure dispersed throughout the nucleus and is not visible through most of the cell s life it is made up of a complex of DNA and protein molecules 0 All cells in an individual plant or animal have the same number of chromosomes 0 All individuals of the same species have the same number of chromosomes I Chromosomes have 2 distinct features 0 Centromere a condensed or constricted area occurring in a specific location on a chromosome Chromosomes can be classified by the position of their centromere 0 Length the same chromosome in 2 cells in an individual are the same length I Each visible chromosome actually contains the original DNA and a replicated copy of the DNA The original DNA each replicated copy contains a kinetochore located in the area of the centromere the original DNA and the replicated copy are located on the same side of the centromere sister chromatids 0 Sister chromatids are exact copies of the same DNA strand 0 Telomeres are the ends of the DNA strands I Homologous chromosomes 0 Pairs of chromosomes in each cell that are identical with respect to length and centromere location 0 Each cell in an individual has the same pairs of homologous chromosomes 0 All individuals in the same species have the same pairs of homologous chromosomes I All somatic body cells derived from the same members of a species have a diploid 2n number of chromosomes 0 Diploid 2n represents the total number of chromosomes in a somatic cell 0 Haploid n represents the total number of pairs of homologous chromosomes in a cell I In humans and many higher animals the larger chromosome is called the X chromosome and the smaller chromosome in this pair is called the Y chromosome o In mammals the combination of 2 X chromosomes XX is a female while the combination of an Xand a Y chromosome XY is a male o In many species of fowl the combination of an Wand a Z chromosome ZW is a female while the combination of 2 Z chromosomes 22 is a male I Chromosomes have 3 main functions 0 Storage of genetic information within the cell 0 Transmission of genetic information from cell to cell and across generations 0 Expression of the genetic information to control cellularfunctions A specific location on a pair of homologous chromosomes is called a locus each specific locus is called a gene specific loci produce specific strands of mRNA which then produce specific proteins which finally produce specific metabolic functions A gene is defined by its subsequent protein function a gene is identified as a specific DNA sequence at a specific location or locus on a pair of homologous chromosomes a gene is made up of a sequence of nucleotide base pairs on a DNA molecule All the genetic material contained in all of the pairs of homologous chromosomes is called an individual s genotype o In diploid organisms the genotype contains two alleles of each gene 0 All the genetic material contained in the set of one chromosome from each of the pairs of homologous chromosomes is called a species genome Triplet codon a linear sequence of 3 nucleotides in a DNA molecule 0 Transcribed into a linear sequence of 3 nucleotides in a mRNA molecule which is then translated into a linear sequence of 3 nucleotides in a protein molecule aka amino acid or polypeptide o This sequence of 3 nucleotides is called the triplet code of genetics Polypeptides make up proteins which are the end product of genetic expression proteins are the molecules that impart the properties attributed to the process called life enzymes are the most common type of proteins Enzymes serve as the biological catalysts that control the rate at which all biochemical reactions occur within a cell they also control both the synthesis anabolism and breakdown catabolism of all organic molecules carbohydrates lipids nucleic acids and other proteins in a cell Lecture 3 Cell Division and the Cell Cycle I Prokaryotic Organisms species without a distinct cellular nucleus bacteria viruses some protozoans and some plant species Eukaryotic Organisms species that DO have a distinct cellular nucleus higher plants and animals The Cell Cycle is the series of events that occur from the completion of one cell division to the completion of the next cell division the Cell Cycle is made up of two distinct parts 0 Interphase Gap 1 G1 5 and Gap 2 G2 0 Cell Division M I DNA replication occurs during the S phase of Interphase the beginning of the G1 phase is the start of the cell cycle intense metabolic activity cell growth and differentiation of intracellular organelles occurs during the G1 5 and G2 phases by the end of G2 the cell has roughly doubled in size human cells take about 16 hours to complete 1 cell cycle Disruption of this genetic control or regulation can lead to uncontrolled cell division and growth characterized by malignancies Changes in the nucleotide sequence of DNA are called mutations Mutations can occur naturally or spontaneously or can be caused by outside influences Mutations in the genes that regulate the cell cycle can cause uncontrolled cell division and growth and are called cdc cell division control mutations There are 3 checkpoints during the cell cycle which can delay or stop cellular development if the replicated DNA is damaged or cell growth is not adequate These checkpoints are controlled by enzymes called kinases that are produced by specific genes in the DNA The key feature of mitosis is that the daughter cells produced have the same number of chromosomes 2n and therefore the same amount of DNA as the parent cell Mitotic cell division consists of 2 interrelated processes karyokinesis and cytokinesis the division of cytoplasm Karyokinesis is defined as division of the nucleus Mitotic cell division consists of 5 sequential phases 0 Interphase G1 S and G2 the portion of cell division where cellular growth and DNA replication occurs chromosomes are not visible 0 Prophase karyokinesis portion 0 Metaphase karyokinesis portion 0 Anaphase karyokinesis portion Two centrioles appear in the centrosome a microtubule forming organelle of the cell the centrosome begins to divide and centrioles begin to migrate towards opposite poles of the cell the microtubule allta spindle fibers begin to develop and radiate out from the centrioles in a structure called an aster the chromosomes begin to condense and become visible the spindle fibers from different centrioles begin to attach to the kinetochores in the centromere of a replicated chromosome each of the two sister chromatids becomes attached to a different pole of the cell then the nuclear membrane begins to disintegrate Mitosis Metaphase o Condensed visible chromosomes line up on the equatorial plate of the cell 0 Arms of sister chromatids extend from the centromere toward the different poles of the cell 0 Sister chromatids are held together at the centromere until the next phase Mitosis Anaphase o Begins when the centromeres of the chromosome separate and the sister chromatids of each chromosome move toward opposite poles of the cell 0 The process of sister chromatid separation is called disjunction failure to disjoin is called nondisjunction 0 When anaphase is complete each chromatid has its own centromere and is considered a chromosome 0 Anaphase chromosomes begin to elongate and move towards opposite poles Mitosis Telophase Chromosomes are located at opposite poles of the cell they then begin to uncoil and elongate Spindle fibers and centromeres disappear The nuclear membranes begin to reappear The cytoplasm begins to elongate and creases appear along the equatorial plane There are 2 complete diploid 2n sets of chromosomes in the cell O 0000 Meiosis produces haploid n cells that contain V2 the genetic material of the original cell these haploid cells are called germ cellsgametes o Gametes produced by plants are called spores 0 Each gametespore contains a copy of one of each pair of homologous chromosomes During sexual reproduction gametes from each of the parents combine in a process called fertilization to restore the diploid 2n complement of each of the homologous chromosome pairs to the newly formed cell called a zygote 0 Therefore the zygote gets V2 of its DNA from each of its parents 0 While the zygote has the same amount of DNA as each of its parents it is genetically different from both of its parents 0 The processes of meiosis and sexual reproduction ensures genetic variation among members of a species Successful completion of meiosis ensures genetic continuity from one generation to the nextif meiosis is not successful the newly formed gamete can have either too little or too much DNA which causes radical changes in the amount of genetic material in the newly formed zygote that results from sexual reproduction and could seriously disrupt genetic continuity from one generation to the next and lead to rapid destruction of a species Crossing Over an exchange of DNA between members of a pair of homologous chromosomes 0 Occurs during meiosis o Contributes to genetic variation from one generation to the next I DNA replication occurs in the interphase period in meiosis just as it does in mitosis after the interphase period just prior to the beginning of meiosis the cell contains each original chromosome and a replicated copy joined at the centromere during mitosis each chromosome behaves 39 I 39 39 L 39 ct join together in a process called synapsis the synapsed structure is called a bivalent and eventually becomes a tetrad that contains 4 chromatids In order to achieve a haploid n number of chromosomes in the resulting gamete or spore meiosis consists of 2 cell divisions 0 Reduction Division 1St division the tetrad separates into 2 dyads which contains 2 sister chromatids o Equational Division 2 d division each dyad separates into 2 monads each monad has a haploid n chromosome number one copy of one of each of the original homologous chromosome pairs I The alignment of each tetrad on the equatorial plane prior to anaphase1 is random onehalf of each tetrad is then pulled to each pole of the cell the same is true for the dyads during anaphase 2 this random separation of nonhomologous chromosomes during meiosis is called independent assortment Disjunction the separation of the tetrad into a dyad a pair of sister chromatids during meiosis o Nondisjunction happens if this process fails to occur it can lead to abnormal numbers of chromosomes in the gamete and therefore in the fertilized zygote 0 Chromosomal Aberrations abnormalities casued by nondisjunction Oogenesis the process of gamete formation in females and results in female gametes called ova egg cells begins at the onset of puberty when waves of diploid 2n oogonia undergo meiosis to produce haploid n immature ova in most animal species these ova do not reach complete maturity One of these immature ova matures during a specific time period or reproductive cycle of the female s life each diploid 2n oogonium produces 1 viable ova and 3 nonviable polar bodies 0 Menstrual Cycle the female reproductive cycle in primates o Estrus Cycle the female reproductive cycle in other mammalian species 0 The female reproductive cycle varies in length and frequency of occurrence in different species I Spermatogenesis the process of gamete formation in males and results in male gametes called spermatozoa sperm cells begins at the onset of puberty and occurs continuously throughout adulthood waves of diploid 2n spermatogonia undergo meiosis and maturation to produce haploid n spermatozoa each diploid 2n spermatogonium produces 4 haploid n spermatozoa Lecture 4 Mendelian Genetics I Mendel showed remarkable insight into the methodology of scientific experimentation 1 Formulate a hypothesis 0 2 Experiment and collect data 0 3 Interpret the data 0 4 Prove or disprove the hypothesis based on the results of the data I Pisum sativum the common garden pea selffertilizing in nature meaning that true breeding strainsvarieties of the plant are readily available relatively easy to grow and artificially hybridizecrossbreed very prolific and grows to sexual maturity in a relatively short period of time one growing season I Pisum sativum traits 0 Stem height tall or dwarf 0 Seed shape round or wrinkled Seed color green or yellow Pod shape full or constricted Pod color green or yellow Pod placement axial or terminal 0 Flower color violet or white I Mendel s Process Mendel planted seeds and grew the plants into sexual maturity creating the parental generation P1 he harvested pollen from the male plants of one strain and used it to fertilize ova of female plants from the opposite strain then took seeds from the resulting cross bred generation or filial generation F1 and grew these seeds into sexually mature plants he allowed the F1 plants to naturally selffertilize and produce seeds finally he grew these seeds from the 2nd filial generation F2 to maturity o Reciprocal Crossing no matter how the plants were crossbred ex using pollen from tall plants to fertilize dwarf plants or vice versa the same ratios result I Mendel s Postulates 0 Individuals carry pairs of unit factors or genes 0 One of these genes is dominant to the other in an individual 0 These genes segregate or separate during the formation of gametes so that only one of the unit factors from each pair is passed to the next generation 0 Genes separate independently of each other independent assortment I Homozygous when an individual has two alleles fora gene that are identical dominant homozygous DD or recessive homozygous dd I Heterozygous when an individual has two different alleles for the same gene Dd I Monohybrid crosses crosses which examine only one trait at a time Dihybrid crosses crosses which examine two traits at a time I Genotypic Ratio the ratio of DD to Dd and dd plants is called the genotypic ratio 0000 Lecture 5 Laws of Probability ChiSquare Analysis and Pedigree Analysis I Additive Law the sum of the probabilities of all possible outcomes of a given event is 10 I Multiplicative Law the probability of 2 independent events occurring simultaneously is the product of their individual probabilities I If you flip a coin two times outcome of second flip is independent of the outcome of the first flip 0 Each toss is an independent event and the outcome occurs randomly o The chances of getting exact results are low especially with a small number of tosses o This is called chance or random deviation I Chromosomal Theory of Inheritance the theory that chromosomes are linear sequences of genes The unifying theory stating that inheritance patterns may be generally explained by assuming that genes are located in specific sites on chromosomes I Chisquare Analysis calculates a statistic x2 that allows observed values to be compared to expected values predicted from probabilities I Pedigrees diagrams that show the relationships among related individuals or members of a family 0 Pedigree analysis used extensively in many species especially animals to trace the relationship from an existing individual or some future individual to a specific ancestor I Pedigreespedigree analysis are useful for several reasons 0 They can be used to predict the genotypic and phenotypic outcome of some future mating They can be used in species where artificial selection and mating is not possible They can be used to predict the phenotypes of individuals before the phenotypes are expressed 00 Lecture 6 Modifications of Mendelian Ratios Allelic Variation genes can exist in more than two allelic states and each allele can have a different impact on the phenotype IncompletePartial Dominance for some traits heterozygous individuals have phenotypes that are different from either of their associated L Iiowei color in r 39 W red flowers 0 ww white flowers Ww pinkflowers I Codominance implies that each allele functions independently of the other and neither is completely or even partially dominant to the other coat color in Shorthorn cattle 0 WW red hair coat 0 ww white hair coat 0 Ww Roan hair coat red and white mixed I SexLinked Genes genes that are located on the sex chromosomes especially the X chromosome 0 If a gene located on the Xchromosome has two alleles then the genotypic and phenotypic ratios for the gene and the trait affected by the gene can be different in males and females 0 Hemophilia a rare blood disorder that occurs when a clotting protein is missing Phenotypic expression minor cuts and bruises cause extreme blood loss excruciating joint pain due to internal bleeding It is caused by a sexlinked recessive mutation Even though Hemophilia can occur in females it is much more prevalent in males I Sexlimited vs Sex Influenced Traits o Sexlimited and sexinfluenced traits are traits which are affected by genes located on the autosomes o Sexlimited traits traits that only occur in one sex or the other ex milk production in females gamete production in males and females 0 Sexinfluenced traits traits that can be expressed in both genders but their expression varies between genders ex pattern baldness secondary sex characteristics is another I Wild Type the most common allele found in a population the symbol is used to identify the wild type allele fora gene ex C Amorphic alleles nonfunctional alleles Hypomorphic alleles partially functional alleles Drosophila Melanogaster the common fruit fly one of the most genetically studied species eye color is controlled by a single locus with over 100 known alleles Lecture 7 Modifications of Mendelian Ratios I Population refers to all or part of the members of a species 0 A specie population can contain many different mutant alleles for a given gene 0 Each of these different alleles can have different phenotypic effects on individuals in the population I Mutation the process that occurs when a nucleotide sequence in the DNA that constitutes the allele is changed 0 Mutations always involve a change in the physical composition of an allele 0 Mutations do not however always produce phenotypic changes 0 In nature mutations provide the raw material for evolution to occur I Visible Mutations mutations that effect the morphology the form nor function of an organism of the individual Sterile Mutations mutations that impair or inhibit reproduction o If a sterile mutation is dominant and completely inhibits reproduction it will not survive in a population I Lethal Mutations mutations that interfere with necessary body functions and cause death in an individual many genes are capable of mutating to lethals Dominant lethal alleles that act early in life only last one generation in a population 0 Dominant lethal alleles that act later in life after reproduction can be passed on to the next generation 0 Recessive lethal alleles can last many generations in a population sometimes forever because they can be masked by wildtype alleles I Polypeptides large macromolecules composed of linear chains of amino acids that are created from the sequences of nucleotides in a specific portion of a DNA molecule 0 Two or more linear polypeptides combine to form 3dimensional proteins 0 Some proteins called enzymes function as catalysts in biochemical reactions while other proteins form the structural components of cells or function as transport molecules for transporting other molecules within and between cells I LossofFunction Recessive Mutation recessive mutations often cause a loss of gene function by altering the polypeptide product so that it is either underfunctional or nonfunctional 0 Usually have little or no phenotypic effect in heterozygotes because the other allele usually a wildtype allele in the individual is dominant to the mutant allele I GainofFunction Dominant Mutation creates new polypeptides that enhances the biochemical function of the subsequent protein I DominantNegative Mutations other dominant mutations may interfere with the function of the wildtype allele by creating a polypeptide that inhibits the function of the polypeptide created by the wildtype allele I Gene Interaction genes do not act in isolation frequently they act in concert with other genes 0 Genes frequently have effects on more than one trait or phenotype 0 Genes also interact with environmental events or effect a gene can have different effects under different environmental conditions I Penetrance the degree in which a trait is exhibited in an individual sometimes individuals may possess the correct genotype to produce a certain phenotype but that phenotype is not completely expressed in the individual I Expressivity some genotypes are not expressed uniformly across individuals in a population I Epistasis when two or more genes affect a trait an allele of one gene may affect the expression of the other gene I Pleiotrophy when a gene has an effect on the phenotypes for several traits or when a single gene may affect a single trait in several ways I Genetic Anticipation when a genetic disorderdisease exhibits a progressively earlier age of onset and increased severity in successive generations ex many metabolic disorders I Extranuclear inheritance in addition to the DNA found in a cell s nucleus DNA is also located in the mitochondria many times this extranuclear DNA is replicated and expressed independently of the nuclear DNA and can have dramatic effects on phenotypic expression for particular traits an important source of phenotypic variation 0 Maternal Effects these genetic effects occur much more frequently in the ova Lecture 8 Sex Determination and Sex Chromosomes I Sexual Reproduction when two haploid gametes usually from two different individuals unite to form a new diploid individual implies successful mating between two individuals relies on differentiation of primary sex organs in each individual organism o This differentiation occurs in species considered low on the evolutionary scale such as bacteria and singlecelled algae as well as in higher eukaryotes o In more highly differentiated eukaryotes this differentiation is evident as morphological or phenotypic differences Asexual Reproduction mitotic division of either haploid or diploid cells within a single individual Heteromorphic in some species such as mammals individuals express male gender as X Y and female gender as X X o Homomorphic in other species such as some fowl reptiles and amphibians individuals express male gender as 22 and female gender as ZW Unisexualdioeciousgonochoric refers to plants and animal individuals that contain only one type of reproductive organ Bisexualmonoecioushermaphroditic refers to plant and animal individuals that contain both sets of primary reproductive organs these individuals are often capable of producing both types of fertile gametes Intersex refers to plant and animal individuals that have partially developed primary reproductive organs and are usually infertile Chlamydomonas a bluegreen algae that spends most of its life in a haploid form and reproduces asexually through mitotic division of its haploid cells during periods of stress some of the haploid cells function as gametes and undergo fertilization to produce diploid zygotes which can withstand difficult environmental conditions these diploid zygotes will undergo meiosis and again become haploid once the environmental stress is removed these gametes called isogametes are morphologically indistinguishable but have been shown to have two chemically different phenotypes only the isogametes that are chemically different will unite to form a zygote Caenorhabditis elegans ia roundworm that has become widely studied for its unique form of reproduction the worms have two distinct sexual phenotypes males which have only testes and hermaphrodites which have both male and female primary sexual organs the hermaphrodites make up over 99 of the adult population and produce both male and female gametes which can unite in selffertilization the males mate with and provide male gametes to the hermaphrodites Zea mays maize corn plants have a unique life cycle and genetic differentiation corn alternates between a haploid gametophyte stage and a diploid sporophyte stage during its normal life cycle mature corn plants are sporophytes corn is a monoecious species where the sporophyte stage and its associated morphological structures represent the predominate stage of its life cycle Humans normally have 23 pairs of homologous chromosomes one pair of which are different in size and overall length sex chromosomes while the other 22 pairs are called autosomes o Heteromorphic individuals with respect to the sex chromosomes XY differentiate into males 0 Homomorphic individuals with respect to the sex chromosomes XX develop into females Possible explanations for sex determination in humans 0 The presence of the Y chromosome determines males 0 The presence of two X chromosomes determines females 0 The presence of only one X chromosome determines males Klinefelter s Syndrome a condition where individuals are characterized by small rudimentary testes and internal male ducts that do not produce sperm these individual also have small underdeveloped male external genitalia but also have many feminine secondary sex characteristics such as enlarged breasts and rounded hips o Chacterized by having an additional Xchromosome as well as a Y chromosome Most of the time they have an XXY chromosome compliment as well as 44 normal autosomes 0 They are designated 47 XXY o This condition is called a trisomy in terms of chromosome number Anothertype of trisomy is characterized by a 47 XYY chromosome number Individuals with this trisomy are usually morphologically normal males Turner s Syndrome sndividuals with Turner s syndrome are phenotypically females however they are usually characterized by distinct phenotypic traits such as short stature webbed necks hearing deficiencies significant cardiovasculardeficiencies and rudimentary sexual organs that are sterile a condition that is characterized by a chromosomal abnormality called a monosomy 0 Individuals with Tumer s syndrome have only one Xchromosome and have a 45 X chromosome number Testes Determining Factor TDF it has been shown that the presence of TDF is responsible for differentiation of embryonic structures into testes it is produced by genes in what is called the sex determining region of the Y chromosome SRY region located on the short arm of the Y chromosome the SRY region has no comparable region on the X chromosome Xlinked Genes in Humans o Hemophilia an Xlinked blood clotting disorder 0 Xlinked color blindness o Fragile Xsyndrome an Xlinked chromosome anomaly that causes various degrees of mental retardation in humans caused by a constriction near the tip of the long arm of the Xchromosome Pseudoautosomal Region a region of the Y chromosome that has been shown to have a comparable region on the X chromosome the comparable regions synapse during meiosis and crossing over can occur between them Ylinked genes have been discovered in this region Dosage Compensation the amount of gene product produced by these Xlinked genes has been shown to be similar in males and females very important to the viability of species can be the result ofA hyperactivity mechanism of the Xlinked genes in males the Xlinked genes in males work harder and produce more gene product than the Xlinked genes in females Lyon hypothesis Presence of inactivated X chromosomes Barr bodies are present in the nucleus of many different types of body cells o In mammalian females one X chromosome comes from the individual s mother and one comes from the father the inactivation of one of the Xchromosomes occurs randomly at a point early in embryonic development 0 Once this inactivation occurs in a particular cell all subsequent daughter cells of this cell will have the same Xchromosome inactivation


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Janice Dongeun University of Washington

"I used the money I made selling my notes & study guides to pay for spring break in Olympia, Washington...which was Sweet!"

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.