Genetics in Health and Disease

Initiator proteins bind to DNA to signal helicase to unzip the DNA strand.

DNA primase creates primers for DNA polymerase to attach to, facilitating the start of DNA synthesis.

DNA is replicated in the 5’ to 3’ direction, resulting in leading and lagging strands.

<p>DNA must be unwound from its histone proteins to become accessible for replication.</p> Signup and view all the answers

<p>Helicase is responsible for unwinding and unzipping the DNA strands during replication.</p> Signup and view all the answers

<p>Understanding genetics helps us predict disease risk and understand phenotypic variations among individuals.</p> Signup and view all the answers

<p>A nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group.</p> Signup and view all the answers

<p>The human genome contains approximately 3 billion base pairs.</p> Signup and view all the answers

<p>The two categories are purines (adenine and guanine) and pyrimidines (cytosine and thymine).</p> Signup and view all the answers

<p>A double helix refers to the two strands of DNA that twist around each other.</p> Signup and view all the answers

<p>Genes control phenotypes by determining the traits expressed in an individual.</p> Signup and view all the answers

<p>Genetic variation is important as it contributes to the diversity of traits and is crucial for evolution and adaptation.</p> Signup and view all the answers

<p>Mutations in DNA can lead to changes in protein sequences that may result in diseases.</p> Signup and view all the answers

<p>The sugar and phosphate of the nucleotides form the backbone.</p> Signup and view all the answers

<p>A pairs with T and C pairs with G.</p> Signup and view all the answers

<p>Hydrogen bonds hold the strands of DNA together.</p> Signup and view all the answers

<p>Proteins perform crucial functions such as enzymes, hormones, and nutrient transport.</p> Signup and view all the answers

<p>The central dogma describes how DNA is transcribed into mRNA, which is then translated into proteins.</p> Signup and view all the answers

<p>The genetic code is degenerate because multiple codons can encode the same amino acid.</p> Signup and view all the answers

<p>Reading frames determine the correct interpretation of codons for protein synthesis.</p> Signup and view all the answers

<p>Insertions of 1 or 2 nucleotides disrupt the protein code.</p> Signup and view all the answers

<p>DNA polymerase is responsible for correcting mistakes by cutting phosphodiester bonds to release the wrong nucleotide and replacing it with the correct one.</p> Signup and view all the answers

<p>Ligase seals the gaps in the DNA strand after the incorrect nucleotide has been replaced during the repair process.</p> Signup and view all the answers

<p>Nucleotide excision repair removes damaged bases, while DNA polymerase primarily corrects incorrect bases incorporated during synthesis.</p> Signup and view all the answers

<p>A pyrimidine dimer is a type of DNA lesion caused by UV damage, repaired through nucleotide excision where nucleases cut the strand and DNA polymerase fills in the gap.</p> Signup and view all the answers

<p>When a wrong nucleotide is incorporated, it results in a mutation, but DNA polymerase can recognize and correct this mistake through its 3' endonuclease activity.</p> Signup and view all the answers

<p>Xeroderma pigmentosa is a DNA repair disorder that makes skin highly sensitive to UV rays due to the lack of repair mechanisms to fix DNA damage.</p> Signup and view all the answers

<p>Mutations can be caused by external factors, such as UV light and chemicals, or by internal factors, such as errors in DNA repair or replication.</p> Signup and view all the answers

<p>Point mutations affect a single base pair and can be classified as silent, missense, or nonsense, which can lead to varying effects on protein synthesis.</p> Signup and view all the answers

<p>BRCA1 and BRCA2 are DNA repair genes responsible for repairing breaks caused by radiation and errors during cell division, thus maintaining genome stability.</p> Signup and view all the answers

<p>Mutations in DNA repair genes are associated with pancreatic, colon, and colorectal cancer.</p> Signup and view all the answers

<p>Pyrimidine dimers distort the DNA double helix, impairing DNA replication and increasing the risk of skin cancer.</p> Signup and view all the answers

<p>Insertions and deletions can disrupt the reading frame of a gene, leading to dysfunctional proteins and various genetic disorders.</p> Signup and view all the answers

<p>Environmental factors such as UV light and radiation contribute to DNA mutations by damaging the genetic material.</p> Signup and view all the answers

<p>Germ cell mutations occur in reproductive cells and can be inherited, while somatic cell mutations occur in non-reproductive cells and are not passed to offspring.</p> Signup and view all the answers

<p>DNA repair mechanisms can fail due to mutations in repair genes, which may prevent the correction of DNA damage, leading to uncontrolled cell growth and cancer.</p> Signup and view all the answers

<p>Crossing over introduces genetic variation by allowing homologous chromosomes to exchange genetic information.</p> Signup and view all the answers

<p>Random assortment determines the combination of maternal and paternal genes in gametes, leading to unique genetic compositions.</p> Signup and view all the answers

<p>Karyotypes visualize and help identify chromosomes, allowing study of chromosomal abnormalities.</p> Signup and view all the answers

<p>Aneuploidy is an error in chromosome number, typically caused by nondisjunction during meiosis.</p> Signup and view all the answers

<p>Extra copies of sex chromosomes can lead to conditions like intellectual disability and sterility.</p> Signup and view all the answers

<p>Down syndrome is a viable trisomy (trisomy 21) that causes developmental and health challenges.</p> Signup and view all the answers

<p>X inactivation is the process where one X chromosome is inactivated to balance gene dosage in females.</p> Signup and view all the answers

<p>Chromosomal inversions may disrupt gene sequences and alter gene expression by relocating regulatory elements away from their target genes.</p> Signup and view all the answers

<p>The risk of chromosome number disorders increases with parental age due to factors affecting meiotic stability.</p> Signup and view all the answers

<p>A translocation is the switching of chromosome segments that can contribute to cancer when it involves the rearrangement of oncogenes.</p> Signup and view all the answers

<p>Williams-Beuren syndrome is characterized by distinctive facial features, intellectual disability, and a friendly demeanor, resulting from a specific chromosomal translocation.</p> Signup and view all the answers

<p>Monosomy, the loss of one chromosome, is usually fatal, leading to severe developmental issues.</p> Signup and view all the answers

<p>The clinical significance of chromosome 9 inversion disorder is unclear but it may be associated with various congenital abnormalities and psychiatric conditions.</p> Signup and view all the answers

<p>Meiosis reduces the chromosome number to form haploid gametes, which ensures that the resulting zygote has the correct diploid number of chromosomes.</p> Signup and view all the answers

<p>Genetic variation arises from processes like crossing over and independent assortment, as homologous chromosomes and their alleles are shuffled.</p> Signup and view all the answers

<p>Non-disjunction is the failure of homologous chromosomes or sister chromatids to separate properly during meiosis, leading to gametes with an abnormal number of chromosomes.</p> Signup and view all the answers

<p>Turner syndrome is caused by the absence of one X chromosome (45,X), while Klinefelter syndrome results from the presence of an extra X chromosome in males (47, XXY).</p> Signup and view all the answers

<p>Inversions occur when a segment of a chromosome is reversed end-to-end, while translocations involve segments of chromosomes swapping places.</p> Signup and view all the answers

<p>Haploid cells are essential for sexual reproduction as they combine to form a diploid zygote, maintaining genetic continuity across generations.</p> Signup and view all the answers

<p>Understanding meiosis and chromosomal diseases is crucial for diagnosing and managing genetic disorders, as well as for providing insights into human genetics.</p> Signup and view all the answers

<p>Homologous chromosomes line up and exchange genetic material during meiosis, fostering genetic diversity through recombination.</p> Signup and view all the answers

<p>Alleles are different versions of the same gene that determine specific traits or characteristics in an organism.</p> Signup and view all the answers

<p>Pedigrees help track the inheritance of traits over generations and identify carriers of genetic disorders.</p> Signup and view all the answers

<p>A genotype refers to the genetic makeup of an organism, while a phenotype is the observable expression of specific traits.</p> Signup and view all the answers

<p>Dominant alleles are expressed in the phenotype even if only one copy is present, while recessive alleles require two copies to manifest.</p> Signup and view all the answers

<p>X-chromosome inheritance refers to genes located on the X chromosome, which can lead to sex-linked disorders primarily affecting males.</p> Signup and view all the answers

<p>Males are hemizygous for X-linked traits, having only one X chromosome, so a single recessive allele will manifest as the trait, while females require two copies to express the disorder.</p> Signup and view all the answers

<p>Dominant lethal inheritance occurs when a single copy of a dominant allele leads to death, often resulting in no offspring carrying the allele.</p> Signup and view all the answers

<p>'Recessive lethal alleles' can lead to death if an individual is homozygous recessive, but they can persist in the population because heterozygous individuals survive and carry one functional allele.</p> Signup and view all the answers

<p>Dominant lethal alleles can be transmitted if their lethal effects do not manifest until after reproductive age, allowing carriers to pass the allele to their offspring.</p> Signup and view all the answers

<p>Multiple alleles can interact to produce varying phenotypes, as seen in albinism, which is influenced by different genes like the TYR gene.</p> Signup and view all the answers

<p>Carrier females can pass the recessive X-linked alleles to their male offspring, who will express the trait, while their daughters can become carriers themselves.</p> Signup and view all the answers

<p>Homologous chromosomes contain the same genes from both parents and are crucial for genetic diversity during reproduction.</p> Signup and view all the answers

<p>If a recessive lethal allele is essential for life, about 25% of offspring from two heterozygous parents may inherit it and die, impacting population genetics over time.</p> Signup and view all the answers

<p>Driver mutations lead to cancer progression, while passenger mutations do not affect the growth of cancer cells.</p> Signup and view all the answers

<p>Gain of function mutations result in a gene taking on a new function, often due to failure in gene regulation.</p> Signup and view all the answers

<p>Proto-oncogenes are positive regulators of the cell cycle, and when mutated, they become oncogenes that can promote cancer.</p> Signup and view all the answers

<p>Complete gene deletion can result in the absence of protein products, leading to a total loss of gene function.</p> Signup and view all the answers

<p>Mutations in oncogenes can increase the rate of cell cycle progression, leading to rapid cell division and tumor growth.</p> Signup and view all the answers

<p>Chaperone proteins recognize misfolded proteins and assist them in refolding to achieve the correct shape.</p> Signup and view all the answers

<p>Tumor heterogeneity means that cancer cells in a tumor can differ, making treatment challenges more complex due to varied responses to therapy.</p> Signup and view all the answers

<p>Subsequent mutations in cancer cells can lead to further enhanced proliferation and additional resistance to treatment.</p> Signup and view all the answers

<p>Misfolded proteins can form aggregates, such as amyloid plaques, which are associated with neurodegenerative diseases.</p> Signup and view all the answers

<p>Healthy individuals can carry variants that ablate gene function without being pathogenic, meaning they may not cause disease.</p> Signup and view all the answers

<p>Oncogenes increase the rate of cell cycle progression, facilitating uncontrolled cell division.</p> Signup and view all the answers

<p>Loss of function can result from gene deletion, disruption of the promoter, or alterations in the coding sequences.</p> Signup and view all the answers

<p>Identifying driver mutations can lead to the development of targeted therapies that specifically inhibit these mutations.</p> Signup and view all the answers

<p>A mutation that enhances proto-oncogene activity can lead to uncontrolled cell growth and cancer development.</p> Signup and view all the answers

<p>Deletion of an internal exon may lead to a frameshift mutation, stopping functional protein production or altering its 3D structure.</p> Signup and view all the answers

<p>Stable proteins require hydrophobic residues to be sequestered inside to maintain their proper shape and stability.</p> Signup and view all the answers

<p>Molecular pathology is the study and diagnosis of disease at the molecular level, focusing on how genetics influence human phenotypes. Its significance lies in linking genetic variations to specific diseases, facilitating targeted treatments.</p> Signup and view all the answers

<p>Loss of function mutations result in a gene losing its normal function or product, while gain of function mutations enable a gene to acquire a new or abnormal function. Both types of mutations can significantly impact phenotypes.</p> Signup and view all the answers

<p>Genomic aberrations that can cause LOF include gene deletion, chromosomal rearrangements, and promoter deletion. Examples of diseases caused by LOF mutations include cystic fibrosis and muscular dystrophy.</p> Signup and view all the answers

<p>Gain of function can be caused by chromosomal rearrangements, missense mutations, and the production of toxic RNA/protein products. Diseases like certain cancers and Huntington's disease are associated with GOF mutations.</p> Signup and view all the answers

<p>Protein structure is crucial for its function; any disruption can lead to loss of activity or abnormal interactions within biochemical pathways. This can result in diseases if essential proteins become dysfunctional or gain abnormal properties.</p> Signup and view all the answers

<p>Whole exome sequencing identifies all variants in protein-coding regions of the genome, facilitating the discovery of mutations linked to diseases. It allows for a more comprehensive and efficient approach to diagnosing genetic disorders.</p> Signup and view all the answers

<p>A total loss of function mutation results in no gene product being produced, which can severely disrupt normal biological processes and lead to diseases. This can manifest as a complete lack of function in critical metabolic or regulatory pathways.</p> Signup and view all the answers

<p>A gain of function mutation in the gene encoding a growth factor receptor may lead to uncontrolled cell division, contributing to the development of cancer. This abnormal signaling exploits normal cellular pathways inappropriately.</p> Signup and view all the answers

<p>LOF mutations result in a complete or partial loss of gene function, while GOF mutations lead to enhanced or novel functions of the gene product.</p> Signup and view all the answers

<p>Chromosomal rearrangements can activate oncogenes or create chimeric genes, which can lead to uncontrolled cell growth.</p> Signup and view all the answers

<p>Proto-oncogenes can mutate into oncogenes through various mechanisms, such as point mutations or amplification, leading to deregulated cell growth.</p> Signup and view all the answers

<p>Tumor suppressor genes help to regulate the cell cycle and prevent excessive cell growth by inhibiting progression through checkpoints.</p> Signup and view all the answers

<p>The three checkpoints are the G1/S checkpoint, the G2/M checkpoint, and the metaphase checkpoint.</p> Signup and view all the answers

<p>Missense mutations result in the substitution of one amino acid for another in a protein, potentially altering its function and stability.</p> Signup and view all the answers

<p>Uncontrolled cell growth refers to the abnormal proliferation of cells that bypass normal regulatory mechanisms, leading to tumor formation.</p> Signup and view all the answers

<p>DNA repair mechanisms correct errors in DNA structure to prevent mutations from accumulating, thereby maintaining genomic stability.</p> Signup and view all the answers

<p>They become oncogenes, which increase cell cycle progression.</p> Signup and view all the answers

<p>Mutations can activate protooncogenes, leading to increased cell division and tumor formation.</p> Signup and view all the answers

<p>Amplification, such as multiple copies of the ERBB2 (HER2) gene.</p> Signup and view all the answers

<p>They act as negative regulators that inhibit cell cycle progression.</p> Signup and view all the answers

<p>p53 is a critical tumor suppressor that helps detect DNA errors and trigger repair or apoptosis.</p> Signup and view all the answers

<p>They can create chimeric genes that disrupt normal gene function, promoting malignancy.</p> Signup and view all the answers

<p>Such mutations result in cells that grow uncontrollably, leading to tumor growth.</p> Signup and view all the answers

<p>Cells lose the ability to halt the cell cycle, leading to unchecked proliferation.</p> Signup and view all the answers

<p>Mutations or deletions such as those found in the EGFR gene in non-small cell lung cancer.</p> Signup and view all the answers

<p>These mutations can lead to the accumulation of more mutations, increasing cancer risk.</p> Signup and view all the answers

<p>Molecular pathology is the study and diagnosis of diseases at the molecular level, connecting genetic variations with human phenotypes. It is significant because it helps identify genetic factors that contribute to various diseases.</p> Signup and view all the answers

<p>LOF mutations result in the gene losing its normal function, often producing no gene product, while GOF mutations lead to a gene acquiring new functions or responding inappropriately to signals.</p> Signup and view all the answers

<p>Genomic aberrations causing LOF phenotypes include gene deletion, chromosomal rearrangement, and promoter deletion.</p> Signup and view all the answers

<p>An example of a disease caused by a gain of function mutation is Huntington's disease, where a mutation causes the protein to misfold and aggregate.</p> Signup and view all the answers

<p>Protein structure is crucial because disruptions can lead to loss of function or abnormal functions that may contribute to the development of diseases.</p> Signup and view all the answers

<p>The approach has shifted from labor-intensive searches for candidate genes to whole exome sequencing, which can identify all variants in protein-coding regions.</p> Signup and view all the answers

<p>Gain of function mutations can cause genes to respond to incorrect signals or activate pathways inappropriately, leading to abnormal cell behavior.</p> Signup and view all the answers

<p>The presence of numerous variants can make it challenging to identify which specific variant is causative of a particular disease phenotype.</p> Signup and view all the answers

<p>The main types of mutations are loss of function (LOF) and gain of function (GOF). LOF mutations typically hinder protein function, while GOF mutations enhance or alter it.</p> Signup and view all the answers

<p>Chromosomal rearrangements can create novel chimeric genes or reposition oncogenes under enhancer control, increasing their expression. This disrupts normal cell regulation and can lead to uncontrolled cell growth, a hallmark of cancer.</p> Signup and view all the answers

<p>Tumor suppressor genes regulate the cell cycle and prevent uncontrolled cell growth. Mutations in these genes can impair their function, leading to unregulated proliferation and cancer development.</p> Signup and view all the answers

<p>Proto-oncogenes become oncogenes through mutations that increase their activity or expression. This can lead to excessive stimulation of cell division and contribute to cancer progression.</p> Signup and view all the answers

<p>Internal control checkpoints are crucial for ensuring that cells do not progress to the next phase of the cell cycle until certain conditions are met. These checkpoints help prevent genomic instability and carcinogenesis.</p> Signup and view all the answers

<p>Missense mutations result in a single amino acid change in a protein, which can alter its structure and potentially enhance its activity or create a toxic gain of function. This change can lead to various diseases, including some cancers.</p> Signup and view all the answers

<p>Toxic proteins and aggregates can disrupt cellular function by interfering with normal protein activities and cellular homeostasis. They can lead to cell death or malfunction, commonly seen in neurodegenerative diseases.</p> Signup and view all the answers

<p>DNA repair mechanisms are essential for correcting mutations and maintaining genomic integrity. When these mechanisms fail, mutations accumulate, increasing the risk of cancer development.</p> Signup and view all the answers

<p>Uncontrolled cell growth is a hallmark of cancer as cancer cells proliferate beyond normal limits, forming tumors and can invade surrounding tissues. This behavior is a direct result of genetic mutations affecting cellular regulation.</p> Signup and view all the answers

<p>The G1 phase involves accumulating resources for DNA synthesis, the S phase is where DNA replication occurs, and the G2 phase prepares the cell for mitosis. Each phase is critical for ensuring accurate and efficient cell division.</p> Signup and view all the answers

<p>P53 acts as a transcription factor that initiates DNA repair and regulates the cell cycle.</p> Signup and view all the answers

<p>P53 regulates the cell cycle by transcribing the P21 gene, which inhibits cell cycling to allow for DNA repair.</p> Signup and view all the answers

<p>PUMA and NOXA are pro-apoptotic proteins that stimulate apoptosis if DNA damage cannot be repaired.</p> Signup and view all the answers

<p>Upon phosphorylation, p53 is activated which allows it to transcribe genes involved in DNA repair and apoptosis.</p> Signup and view all the answers

<p>P53 is termed 'the guardian of the genome' because it plays a critical role in monitoring DNA integrity and initiating repair mechanisms.</p> Signup and view all the answers

<p>Driver mutations</p> Signup and view all the answers

<p>Driver mutations increase the growth rate of cancer cells, whereas passenger mutations do not significantly affect cell behavior.</p> Signup and view all the answers

<p>Protooncogenes are positive regulators of the cell cycle, and when mutated, they become oncogenes that promote excessive cell growth.</p> Signup and view all the answers

<p>Oncogenes drive the accumulation of further mutations in subsequent cell generations, resulting in diverse cancer cell populations.</p> Signup and view all the answers

<p>Normal mutations typically lead to non-functional proteins, which likely result in cell death.</p> Signup and view all the answers

<p>They are essential because they regulate cell cycle progression; mutations that activate them can lead to uncontrolled cell proliferation.</p> Signup and view all the answers

<p>Passenger mutations are background mutations that occur in cancer cells but do not contribute to cancer growth or progression.</p> Signup and view all the answers

<p>If a positive cell cycle regulator is mutated to increase its activity, it can accelerate cell division and promote tumor formation.</p> Signup and view all the answers

<p>Identifying driver mutations allows for targeted therapies that can effectively inhibit tumor growth.</p> Signup and view all the answers

<p>Tumor progression is a multi-stage process where cells acquire additional mutations, leading to increased heterogeneity and aggressiveness.</p> Signup and view all the answers

<p>They undergo multiple mutations that disable these control mechanisms.</p> Signup and view all the answers

<p>They inherit a growth advantage that brings them closer to becoming cancerous.</p> Signup and view all the answers

<p>It increases the mutation rate and leads to structural abnormalities in the genome.</p> Signup and view all the answers

<p>'Driver' mutations contribute to cancer progression, while 'passenger' mutations are incidental changes with no direct effect on growth.</p> Signup and view all the answers

<p>They contain a diverse population of cancer cells, each with different genetic mutations.</p> Signup and view all the answers

<p>Mutations increase the growth rate by enhancing cell proliferation and survival mechanisms.</p> Signup and view all the answers

<p>Identifying the first mutation helps target key processes in cancer therapy.</p> Signup and view all the answers

<p>Cancer evolves through multiple stages characterized by additional mutations and increased growth advantage.</p> Signup and view all the answers

<p>They contribute to further genetic instability, increasing the likelihood of additional mutations.</p> Signup and view all the answers

<p>They enable cancer cells to survive and proliferate more effectively than normal cells.</p> Signup and view all the answers