Mutations, Apoptosis, Cancer – Flashcards
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Gene Mutations
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-change in the sequence of bases in DNA -effort can range from none to complete inactivity of the protein
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Germ-Line Mutations
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-occur in sex cells and can be passed to subsequent generations -can lead to inherited cancers
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Somatic Mutations
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-not passed on to the next generation -can lead to cancer development in the individual
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Mutagens
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-environmental influences that can cause mutations --radiation, x-rays, UV radiation, some organic chemicals
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DNA Repair Enzymes
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constantly monitor and repair any irregularities (mutations)
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Transposons
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"jumping genes" -specific DNA sequences that move within and between chromosomes -sometimes alters neighboring gene expressions
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Point Mutations (possible outcomes)
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-involve a change in a single DNA nucleotide -possible outcomes: change in specific amino acids produce abnormal protein produce incomplete protein no effect
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Frameshift Mutations
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-one or more nucleotides are either inserted or deleted from DNA -result can be a completely new sequence of codons and/or a nonfunctional protein
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Nonfunctional Proteins
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can have a dramatic effect on the phenotype because enzymes are often apart of metabolic pathways
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PKV
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phenyl-aline can't be broken down and subsequently builds up, causing mental impairment
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Androgen Insensitivity (testosterone)
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-faulty receptor makes cells insensitive to androgens -ex: testosterone present but cells are unresponsive female external genitals form secondary female characteristics also develop a genetic male looks like a normal female
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Development of Cancer
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involves a series of accumulating mutations that can be different for each type of cancer
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Tumor Suppressor Genes and Proto Oncogenes code for..
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transcription factos or proteins that control transcription factors
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Defects in transcription factor function/structure contribute to cancer development
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front of card
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Major Tumor Suppressor Gene
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-more frequently mutated in human cancers that any other know gene -acts as a transcription factor that controls genes whose products are cell cycle inhibitors -promotes apoptosis when needed
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Retinoblastoma Protein
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-tumor suppressor -controls activity of a transcription facto for cyclin D and other genes whose products promote entry into the "s" stage of the cell cycle
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When tumor suppressor gene p16 mutates ___
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it is unable to control the cell cycle, the RB protein in continuously expressed, resulting in too much cyclin D in the cell
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Most cancers begin as..
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an abnormal cell growth that is benign and not cancerous growth may become malignant meaning cancerous
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Telomeres
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limit the number of cell divisions before they die
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Apoptosis
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-programmed cell death -decreases number of cells -occurs during development to remove unwanted tissue -plays important role in preventing cancer
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Apoptosis Process
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1. Cells round up, nucleus collapses 2. Chromatin condenses and nucleus fragments 3. Plasma membrane blisters and blebs form 4. Cell fragments contain DNA fragments
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Enzyme Responsible for Apoptosis
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caspases
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Characteristics of Cancer Cells
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-genetically unstable -do not correctly regulate the cell cycle -unspecialized due to lack of differentiation -can escape the signals for cell death -do not respond to internal signals to die
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Cancer cells can survive and proliferate elsewhere in the body
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cancer cells disrupt normal adhesive mechanism, move to another place in the body
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Metastasis
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when cancer cells travel through blood or lymphatic vessel and invade new tissues to form new tumors
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Angiogenesis
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provided blood vessels that bring blood and nutrients and oxygen to the tumor, depriving the normal tissue
