Genetics Final Exam Study Guide
Genetics Final Exam Study Guide BSCI - 30156 - 002
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BSCI - 30156 - 002
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This 6 page Study Guide was uploaded by Jessica Brown on Monday May 9, 2016. The Study Guide belongs to BSCI - 30156 - 002 at Kent State University taught by Chi-hua Groff (P) in Fall 2015. Since its upload, it has received 42 views. For similar materials see ELEMENTS OF GENETICS in Biological Sciences at Kent State University.
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Date Created: 05/09/16
Genetics Final Exam Study Guide Highlight: definitions Highlight: important information Be able to define ALL mutations we have covered this semester Stem Cells: cells that are continuously divide and are able to differentiate into different cell types 1. Totipotent: The most potent and can differentiate into everything needed to make a new individual. These cells are harvested the earliest. 2. Pluripotent: Can give rise to many different cell types but not as many as a totipotent cell can. 3. Multipotent: cells are already differentiated but can give rise several different tissue types. It differentiates into the least amount of different cells out of the three. These are harvested the latest. Stem cells are typically used to clone Induced Pluripotent Stem Cells (iPS): cells induced to become pluripotent by activating four genes. This process dedifferentiates the cell. Is less controversial since you can use a normal cell from an adult. Know the four genes that must be turned back on to induce the cells 1. OCT4 2. SOX2 3. NANOG 4. Lin28 Gene Therapy: the introduction of cloned genes into living cells in an attempt to cure a disease Has to be a single locus single trait disease Gene therapy isn’t straightforward, you can’t control where the new material is going to go o It could integrate into heterochromatin Recall: Heterochromatin is not expressed therefore, nothing would happen if the new material integrated here There are two ways for DNA to be integrated 1. Non-viral Gene Transfer a. Utilizes liposomes i. Liposomes do not activate the immune system 2. Viral Gene Transfer a. Modify the viral genome to contain the human gene of interest i. The virus is engineered so that it can’t replicate in target cells 1. This keeps from overexpression of target gene Microarrays: Identifies genes that are transcribed in the transcriptome. Often used to compare gene expression in wildtype vs knockout Monitors mRNA expression of thousands of genes simultaneously Have a wide variety of applications o Can be used to identify DNA-protein binding at the genome level Chromatin Immunoprecipitation (chIP): uses crosslinking agent to covalently link proteins to their associated DNA o Helps find regulatory switches when you don’t know the specific sequence o To identify all genomic binding targets of a protein, the precipitated DNA fragments are amplified. All amplified DNA is fluorescently labeled and associated with a microarray for identification This is known as chIP on chip assay Proteomics: used to study the proteins in an organism Can separate proteins by size and charge Cancer Genetics *a good amount of questions will come from this* *Be familiar with the cell cycle to have a good understanding of cancer* Cancer: uncontrolled cell division. Colonal in origin o Meaning it starts in a single cell Know the stages of cancer o Benign: non invasive o Malignant: invades into surrounding tissue o Metastatic: moves into different site of the body Carcinogen: environmental factor that causes cancer Oncogene: an abnormally active gene that promotes cancer Many oncogenes code for proteins that function in cell growth signaling pathways o They may keep the cell growth signaling pathway in a permanent on position This could be due to overexpression of the oncogene or the production of a functionally aberrant protein Oncogene example: Ras protein o Ras is normally a proto-oncogene but can become an oncogene if it ends up with a mutation that prevents its GTP hydrolysis function Proto-oncogene: a normal cellular gene with the potential to incur a mutation that causes it to become an oncogene. Things that can happen to cause it to become an oncogene The amount of proto-oncogene protein is increased The protein structure is changed and the protein becomes overactive The protein is expressed in an abnormal place/cell/time There are four major changes that cause proto-oncogenes to convert to oncogenes 1. Missense mutations a. A missense mutation in the ras H gene that change a glycine to a valine is responsible for the conversion of ras H into an oncogene 2. Gene Amplification a. Caused by an abnormal increase in the copy number of a proto- oncogene i. Ex.) c-myc 3. Chromosomal Translocation a. A translocation that fuses the genes BCR and ABL is oncogenic. i. Causes Leukemia 4. Viral Integration a. Retroviruses integrate their genomes into the host chromosomal DNA next to a proto-oncogene causing it to be over expressed Tumor Suppressor Genes: prevent cancerous growth They can play a role in genome maintenance o Accomplished by both checkpoint proteins and DNA repair proteins o Checkpoint proteins prevent cell division when damaged DNA is detected o Checkpoint proteins can prevent the accumulation of cyclin-CdK complexes that promote cell division o DNA repair enzymes are often inactivated in cancer cells If they’re inactivated the chances of cancer occurring increase greatly First experiment to discover TSG involved studies of retinoblastoma o “two hit model” is proposed In order to be affected both alleles have to be “hit” or mutated This means that people with inherited forms already have one mutation and only need one more mutation in the gene to develop the disease o These people get cancer at a much younger age People with non-inherited forms must have two mutations occur in the same cell to cause the disease o These people get cancer at an older age since it takes longer to end up with both of the forms mutated Tumor Suppressor genes can be silenced in multiple ways 1. Gene mutation 2. Aberrant CpG methylation 3. Aneuploidy—that leads to the loss of a tumor suppressor gene Cancer cells begin with a benign genetic alteration, but as multiple mutations occur, it may end up progressing to become malignant or metastatic. Over 300 genes may play a role in causing and preventing cancer Karyotyping cancer cells often shows aberrant copy numbers for several chromosomes and multiple chromosomal translocations P53 Gene: a master tumor suppressor gene that senses DNA damage The primary role is to determine if a cell has incurred DNA damage. Promotes three types of cellular pathways that are aimed at stopping the proliferation of cells with damaged DNA 1. Repair of DNA 2. Arresting the cell cycle 3. Initiating apoptosis a. Apoptosis: programmed cell death Molecular Profiling: enables researchers to understand the molecular changes that occur in diseases such as cancer Used to classify tumors DNA microarrays—allow unique expression profiles to be examined o Helps distinguish what type of cancer it is o Can provide information of the outcome of the specific cancer Molecular profiling is useful for o Distinguishing between tumors that look very similar in the microscope o Gaining a better understanding of molecular changes related to cancer o Affecting treatment options and patient outcomes (personalized medicine) Inherited Cancers 5-10% of cancers involve inherited (germ-line) mutations. o These people will have a predisposition to develop cancer Many develop a defect in a tumor suppressor gene Some are due to the activation of an oncogene A predisposition for developing caner is inherited in a dominant fashion because the heterozygote exhibits this predisposition Many times the actual development of cancer is recessive due to loss of heterozygosity o Loss of heterozygosity: formal way to say “two hit”. Cell has zero function in the target locus. Human Ancestry Mirochondrial DNA (mtDNA): an energy producing organelle located in the nucleus of a cell. Our body contains hundreds of mitochondria Mitochrondria contains its own genome o It is a small, double stranded, circular genome About 16.5kilobases long Scientists can easily isolate mtDNA because of its small genome o This is useful in forensics o Also can be pulled from fossil making it important for evolutionary scientists mtDNA is inherited maternally Sub-Saharan African populations are more genetically diverse than other populations o This could be for two reasons Populations have been in existence longer and therefore, have more genetic mutations which means more diversity Large population sizes influence genetic diversity—large populations tend to have more diversity than smaller o Time of most recent common ancestor (TMRCA) is 171,000 years ago. Scientists have referred to this as African Eve—mother of all humanity When saying African eve it is not talking about a single person. o Neandertal mtDNA (found from fossils) and living human mtDNA are distinct and show no evidence that interbreeding occurred between them. Y-Chromosome DNA Inherited Paternally Haplotypes indicate a recent origin from Africa Nuclear DNA Markers DNA markers support o That recent origin of modern day humans is from Africa o Highest amount of genetic variation in Africa Scientists found many SNP’s never discovered in other populations previously Epigenetics Newest field of study in genetics o Encompasses two areas of research Mechanistic basis for how chromatin remodeling relates to genome function Inheritance of modifications over generations Epigenome: encompasses modifications to DNA that do not change the sequence of DNA but they do change genome function o Usually methylation leads to decrease in gene expression Recall methylation silences Methylation is not present in all eukaryotes In mammals 2-7% of DNA is methylated Hemimethylation: one strand of DNA gets methylated while the other remains unmethylated Fully methylated has both strands methylated CpG islands are sites of methylation and gene regulation In housekeeping genes the CpG islands are unmethylated. These genes are not inhibited and therefore are expressed in most cells In tissue specific genes the CpG islands are methylated meaning these genes are turned off and not expressed Methylation can inhibit transcription Methylation of CpG islands can inhibit binding of transcription factors Methylation can cause the chromatin to go from open to closed reading frame o Acetylation of histones leads to an increase in gene expression o Imprinted genes are the product of allele-specific methylation marks on DNA o Most of the epigenome is deleted at the formation of the zygote. This is necessary for cells to be able to take on different functions
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