Module 3 Genetics Study Guide
Module 3 Genetics Study Guide BIOSC 0150
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This 5 page Study Guide was uploaded by Tarina Usher on Monday March 23, 2015. The Study Guide belongs to BIOSC 0150 at University of Pittsburgh taught by McGreevy in Spring2015. Since its upload, it has received 397 views.
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Date Created: 03/23/15
BIOSC 0150 Module 3 Genetics Study Guide Basic Terminology and Content Genetics is the study of inheritance traits which are the transmission of traits characteristics such as height eye color protein structures etc from parent to offspring heredity Body cells referred to as somatic cells contain two full sets of all genetic information diploid cell one inherited from each parent via haploid cells gametes o The haploid gametes created via meiosis join together to create a diploid cell undergoes mitosis to grow DNA is the inheritance molecule 0 DNA arrangement of G C A T 9 RNA transcription mRNA translation 9 Protein amino acids 9 Expression of gene phenotype I Three nucleotides in the proteincoding region of a gene is a codon o Mutations in DNA form new alleles A gene is a heredity factor that in uences a particular trait Alleles are the avors forms of genes which can be homozygous two of the same allele HH or hh or heterozygous two different alleles Hh The genotype is a listing of alleles in an individual eg HH is the genotype and the phenotype is the observable trait in an individual e g height is the phenotype Gregor Mendel studies pea plants and is considered the father of basic genetics He studies simple traits controlled by one gene with two alleles and little environmental in uence Most phenotypes on the other hand are complex phenotypes in uenced by many genes as well as the environment and example is skin color A dominant gene describes the trait that is expressed in a heterozygote phenotype and a recessive gene is the trait that is not expressed in the heterozygote e g Hh the H is the dominant phenotype and will be expressed as tall 0 Punnett Square shows the possible combinations of two haploid gametes when forming a diploid offspring Maltquot qa mm v i rib l I 1 l BIOSC 0150 Module 3 Genetics Study Guide 0 Pedigree shows the inheritance pattern of a particular trait y m r 3 L HEELQEEEL he mema WNQMS quotvou r malt itwwdr Law of Segregation of Alleles Each gamete carries only one allele for a trait eg seed shape because the alleles have segregates during meiosis See g 14 7 Law of Independent Assortment Genes for a particular traits e g seed shape and seed color assort independently because they are located on different chromosomes See g 148 Chromosomes are tightly wound DNA strands wrapped around a protein Humans have 23 chromosomes the first 22 sets of chromosomes are autosomal nonseX chromosomes where the 23rd is the X and Y chromosome which are seX chromosomes XX for female XY for male these chromosomes determine seX of a human Genes can have sexlinked inheritance meaning the inheritance pattern is observed on the genes carried on seX chromosomes Xlinked and Y linked inheritance includes things like malepattem baldness blindness placement of sweat glands etc Sex linked inheritance occurs because sometimes one allele is not enough e g since males have only one X chromosome they are more prone to things like baldness o Naming a chromosome example l7q253 the 17 is the chromosome the q is the longer arm as opposed to the p short arm and the 253 is the stained band number Codominance is when both phenotypes are shown See g 1415 Incomplete dominance is when an in between of the parent phenotypes are shown in the offspring See g 1416 Pleiotropy is a single gene that affects many traits multiple allelism is when more than two alleles are present at a locus in a population and polymorphism is when more than two phenotypes associated with a single gene are present Quantitative traits are traits with continuously variation that don t fall into a discrete category and create a bellshaped curve when quanti ed See g 1 42 Meiosis is a twostage cell division where a diploid 2n parent cell produces haploid 11 cells gametes sperm in male testes or eggs in female ovaries See g I 3 7 o Interphase where chromosomes are replicated BEFORE meiosis o Meiosis 1 Early Prophase l homologues chromosomes that are samesimilar in size shape and gene content pair 0 Late Prophase l chiasmata crossing over points aka recombination takes place BIOSC 0150 Module 3 Genetics Study Guide I Genes linked on the same chromosome do not assort independently and are inherited together unless recombination between them takes place 0 Metaphase l chromosomes align at equator of cell random for any homologous pair where it is located and is very rare if same alignment 0 Anaphase l Homologs separate and begin and move to opposite poles of cell via spindle apparatus microtubules polymerized that help pull cell apart Separation of homologs but sister chromatids two identical chromatid copies in a replicated chromosome stay together 0 Telophase l amp Cytokinesis chromosomes move to opposite poles cell splits into two which sister chromatids still together 0 Meiosis 2 Prophase 2 new spindle apparatus form 0 Metaphase 2 chromosomes line up at the middle of the spindle apparatus 0 Anaphase 2 Sister chromatids separate amp begin moving to opposite poles of the apparatus 0 Telophase 2 and Cytokinesis chromosomes move to opposite poles of the spindle Four haploid cells form Mistakes in meiosis such as nondisjunction can cause aneuploidy where all gametes have too many or too few chromosomes An example is Down syndrome where there are three chromosomes trisomy of chromosome 21 In a majority of cases aside from this one things of this nature are lethal When genes are located on the same chromosome recombination is more frequent when the genes are farther apart 0 Measured in Centimorgans cM or map units To calculate distance between genes if there s 196 recombinant offspring that translates to 196 map units or cM between the two genes Genetic carriers are people who carry a disease causing allele but do not display said disease because they have a normal allele which is enough to function properly Let s Get Down to Business with Diseases Pompe Disease See lectures 3132 o Lysosomal storage glycogen storage disease where muscles become progressively weaker An infant will start out normal but eventually muscles weaken because glycogen in lysosomes in the muscles is not being broken down causing problems in the lysosome leading to bursting I Linked to alphaacidglucosidase GAA which is a hydrolase that breaks down glucose in the lysosome I Autosomal recessive since one allele for functional GAA is good enough I Found on chromosome 17 and there are many different mutations of the GAA that can cause Pompe I Some Pompe is worse than others BIOSC 0150 Module 3 Genetics Study Guide Achondroplasia From recitation problemset 32 3 o A type of short limbed dwarf1sm that is caused by a decrease in bone growth 0 The gene responsible is Fibroblast Growth Factor Receptor 3 FGFR3 which signals cells during bone growth FGFR3 typically limits bone growth but when it is overactive bone growth stops causing short bones and limbs 0 Dominant recessive pattern heterozygotes have achondroplasia whereas the dominant homozygous allele combination is lethal and the recessive homozygous allele combination produces a normal offspring Hypertrophic Cardiomyopathy HCM See lectures 353 6 o The thickening of a heart from increased amounts of muscle tissue typically wall of left ventricle The heart is made up of cardiac muscle cells that consist of repeating units of actin and myosin bundle these bundles are called sarcomeres lengthen and shorten when muscles contract There is a cycle of myosin binding and releasing from acting since myosin is an ATPase An electrical signal is pulsed to the heart to allow it to contract and relax and HCM is caused by confusion in the signal Sudden death can occur from this confusion o Mutations in genes coding for sarcomere proteins can cause HCM o Autosomal dominant inheritance pattern some HCM worse than others Breast Cancer See lecture 38 0 Tumor growing in the breast from cells uncontrollably dividing via mitosis cell splitting to create two diploid cells 0 Gene associated with this type of cancer is BRCAl but certain alleles of a number of other genes polygenic can increase cancer risk as well as environmental in uences BRCAl is a protein that works with BRCA2 to repair DNA mistakes and damage but if there is a problem with one of BRCA genes repair becomes harder and additional mistakes from are more likely to accumulate o Autosomal dominant inheritance pattern since you only need one copy of BRCA1 for a risk of cancer Single Nucleotide Polymorphism SNP See lecture 3 7 0 DNA sequence variation which occurs commonly within a population in which single nucleotides vary in sequence 0 One of the cheapest form of genomics BIOSC 0150 Module 3 Genetics Study Guide Discussion Questions 1 What are possible ways to test complex phenotypes genetics vs environment See lecture 34 2 Describe the differences and similarities in meiosis and mitosis See lecture 38 or table 132 orfigure 138 3 How does a change in DNA change the overall phenotype Think about DNA 9 Protein 4 Are all mutations bad Refer back to chapter 164 5 What might be defective in Pompe patients Refer back to lectures 31 amp 32 for help 6 Draw meiosis and predict possible genotypes for a person who is heterozygous GAAGAA39 where GAA is the allele for functional GAA gene and GAA39 is the allele for a nonfunctional GAA gene for Pompe Refer back to lectures 31 amp 32 7 Are most traits determined by a single gene or multiple genes Consider complex phenotypes and refer back to lecture 34 8 Why do seX linkages occur Refer back to lecture 33 I would like to note this is just a study guide you should read over notes you took in class actively study and apply your knowledge take the practice exam review recitation problem sets and go to the review sessions This is just a supplement to what we have been doing and is an overview Good luck BIOSC 0150 students
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