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level: apoptosis, necrosis, chemotherapy, and chromosomal abnormalities

Questions and Answers List

level questions: apoptosis, necrosis, chemotherapy, and chromosomal abnormalities

QuestionAnswer
what is apoptosisApoptosis or programmed cell death is the deliberate death of healthy cells → natural feature of healthy tissue and cells are preprogramed to die
what happens when cell reproduction and cell death is unbalancedCell reproduction and death is usually balanced – if there is too much reproduction it can lead to tumours and if there is too much it can lead to neurodegenerative diseases
what is the function of apoptosisApoptosis is a form of self-defence as well as it killed cells with viruses, old cells, cells with DNA damage, cells of the immune system, and cancerous cells
what are three reasons otherwise healthy cells die via apoptosis→ not fully developed cells are killed – in the embryonic brain cells that are not incorporated into the brain network are killed via apoptosis → there are more than needed – it takes energy to keep extra cells alive so excess cells die via apoptosis → they have outlived their usefulness – foetuses have webbed toes and fingers and when this feature is no longer needed the cells connecting these extremities die via apoptosis – also when you recover from an illness any leftover immune cells that are not needed anymore die via apoptosis
what is syndactylyIncomplete differentiation of toes or fingers is called syndactyly and is a result of a lack of apoptosis
what are the two signals to activate apoptosisthe mitochondrial pathway and the death receptor pathway
for what reason is the mitochondrial pathway activatedThe mitochondrial pathway is a signal from inside the cell to activate apoptosis and begins when there is serious damage inside the cell (damaged DNA)
what are the four steps of cell death via the mitochondrial pathway→ first proteins on the outside of the mitochondria are activated breaking down the mitochondrial membrane → this causes an enzyme known as caspase to enter the nucleus and destroy the DNA → organelles other than the nucleus and mitochondria are preserved as the cell is broken down into small fragments which are enclosed by a membrane → fragments bind to phagocytes which engulf them
what is the death receptor pathwayThe death receptor pathway is a signal from outside the cell to activate apoptosis – cells have death receptors on their membrane that receive the message to begin apoptosis – process occurs in 5 steps
what are the five steps of the death receptor pathway→ message is received, caspases are activated, contact to neighbouring cells is lost, and messages are sent to phagocytes → cells shrink and blebs (bumps) form of the outside of the cell → caspase enters the nucleus destroying all DNA → organelles other than the nucleus and mitochondria are preserved as the cell is broken down into small fragments which are enclosed by a membrane → fragments bind to phagocytes which engulf them
what are blebsthey are bumps on the outside of the cell which are caused by the onset of apoptosis via the death receptor pathway
what is caspasecaspase is an enzyme that destroys DNA and it is used in apoptosis
what can too much apoptosis lead toToo much apoptosis can lead to neurodegenerative diseases such as AD and PD
what can too little apoptosis lead toToo little apoptosis can lead to the formation of cancer and can lead to autoimmune diseases
what is necrosisIs a type of cell death that occurs when cells are damaged by chemical or mechanical trauma
what are the main two steps of necrosis→ first the plasma membrane is damaged so it can’t control what enters and exits the cell, chromatin clumps, organelles swell, and the mitochondria has a loosely clumped texture almost resembling tufts of wool → cell swells and bursts, spreading intracellular contents over nearby cells causing inflammation
what causes necrosischemical or mechanical trauma
what is chemotherapyChemicals that inhibit mitosis and causes apoptosis – also blocks growth promoting signals
what are some side effects of chemotherapySide effects – also effects cells that divide fast such as hair follicles and cells in the digestive tract
what are the two types of chromosomal abnormalities or mutationsnumerical or structural
define aneuploidyit is when there is an abnormal number of chromosomes
what are the two main types of aneuploidymonosomy and trisomy
what is trisomywhen there is an additional chromosome
what is monosomywhen there’s one chromosome missing – usually fatal (turners’ syndrome is one of the only survivable monosomy syndrome)
what is mosaicism and how does it usually present physicallywhen someone has two or more sets of cells that vary genetically – can affect any cell – begins as one or a small group of cells which are affected but then it spreads – can be present in some tissues and now others causing an unsymmetrical appearance
what is the difference between chimaerism and mosaicismthey are essentially the same (more then one set of cells - additional cell lines in some cells) however chimaeras involves a larger input of genetically different cells whereas chimaerism usually only starts off with one or two abnormal cells
what are the two types of structural abnormalities relating to centromeresdicentric and acentric
what is dicentricwhen a chromosome has 2 centromeres
what is acentricwhen a chromosome doesn't have a centromere
what are the four structural changes that can occur as a result of faulty meiosisdeletion, duplication, inversion, and translocation
what is a duplication abnormalityduplication is when a segment is repeated
what is a deletion abnormalitydeletion is the removal of part of a chromosome
what is an inversion abnormalityinversion is when a segment of the chromosome is reversed
what is a translocation abnormalitytranslocation is the movement of a segment from one chromosome to a non-homologous one
what is Down syndrome and what type of disorder is itdown syndrome is when a person has an extra copy of chromosome 21 – this is a trisomy disorder (trisomy 21)
what are the three trisomy syndromes that are compatible with lifedown syndrome (trisomy 21), Edwards syndrome (trisomy 18), and patau syndrome (trisomy 13)
what is non-disjunctionOccurs when chromosomes don’t separate in meiosis – either meiosis 1 or 2 Causes one gamete has an extra copy of a chromosome and one to have one less chromosome – leads to aneuploidy disorder
what is non-disjunction in sex chromosomeswhen there is either an extra or a missing sex chromosome
what are the 4 syndromes related to the non-disjunction of allosomesturners syndrome (XO), Klinefelter's syndrome (XXY), trisomy X (XXX) and trisomy Y (XYY)
what is turners syndrometurner’s syndrome is when a person is missing an X chromosome meaning there’s only 45 chromosomes rather than 46 – occurs only in females – most foetuses with turners’ syndrome are spontaneously aborted it if they survive past infancy their prognosis is usually good (will have certain health issues but they can usually be fixed)
what is Klinefelter's syndromeKlinefelter’s syndrome is when males have an additional X chromosome – usually leads to infertility
what is Trisomy XTrisomy X or super female syndrome occurs when there is an extra X chromosome – effects 1 in 1000 females (most feel no side effects – usually some psychological effects)
what is trisomy XYYTrisomy Y or XYY syndrome is when a male displays an addition Y chromosome – very common and very few side effects
what is the only form of genetic variation in asexual reproductionErrors that occur during S phase in regard to DNA replication are passed on to daughter cells – mutations like these are the only form of genetic variation in asexual reproduction
what is one cause of mutations during mitosismutagens increase the rate that DNA changes and can negatively affect proto-oncogenes and tumour suppressor genes (genes that control cell cycle) - the presence of mutagens is one of the main causes of mutations in offspring produced asexually
what are mutagensMutagens are substances or agents, such as radiation or a virus, that increase the rate that DNA changes - can negatively affect proto-oncogenes and tumour suppressor genes