cancer by: aujan m., zach j., aditya p.. * genetic disease that results in uncontrolled growth. *...
TRANSCRIPT
Cancer
By: Aujan M., Zach J., Aditya P.
*Overview
*Genetic disease that results in uncontrolled growth.
*Mutation in genetic code results in failure of cell division control.
*~90% of time, cancer mutation due to external environmental factors. Cancer due to inherited mutations ~10% of time.
*Overview
*Deletion or duplication of nucleotides in genetic sequence can lead to mutation.
*Once cell’s life cycle is disrupted, cancerous cells begin to grow at rapid rate, forming a neoplasm.
*Genetic Basis
*Cell undergoes cell division before cell is fully mature. Since they divide at a rapid rate, successive cancer cells will be immature and dysfunctional.
*Mutations occur after birth, not a hereditary disease.
*Genetic Basis
*Genes that inhibit cell division are proto-oncogenes. These can mutate and become oncogenes.
*Oncogenes – mutations causes constant production of proteins/enzymes stimulating unrestrained cytokinesis.
*Causes of Cancer
*Majority of genetic mutations occur during S phase.
* Result of 3 major mechanisms:
*1.) Carcinogens – cancer causing agents that cause mutation to cell’s DNA (anti-oncogenes). i.e.- chemicals and radiation.
*2.) Viruses – viruses insert their fragment of DNA into genetic material of cells they infect. DNA can compromise proto-oncogenes of cell.
*3.) Replicative Mutations – during replication, mutations can affect proto-oncogenes turning them into oncogenes.
*Types of Mutations:
Point Mutations
*Changes to a specific portion of a gene.
*May be transmitted to offspring, allowing it to be found in successive generations.
*Types of Mutations:
Substitutions
*Base Pair Substitution – replacement of one nucleotide and complimentary base with another complimentary pair.
*Missense Mutation – altered codon still codes for amino acid, but amino acid doesn’t make sense with function of protein.
*Nonsense Mutation – causes production of stop codon.
*Substitution
*Types of Mutations:
Insertions/Deletions
*Adding/Losing Nucleotide Pairs – more harmful than substitutions because mRNA coded in series of triplets. Loss/gain causes entire sequence to shift over, resulting in shift in reading frame.
*Frameshift Mutation – nucleotides inserted/deleted don’t come in multiple of three. Alters reading frame. Produces useless protein.
*Insertion/Deletion
*Types of Neoplasms:
Benign
*Benign Neoplasm – mass of cells whose cellular compositions is same as cells of surrounding tissues.
*Surrounded by connective tissue, so metastasis doesn’t occur.
*Nuclear fission similar to that of normal cells.
*Since rate of division slightly higher than that of normal cells, tumor will grow slowly.
*Types of Neoplasms:
Malignant
*Neoplasms whose DNA has mutated. Different from surrounding tissues.
*Resemble immature and undifferentiated cells.
*Growth is greatly accelerated and can become detrimental to surrounding tissue.
*Neoplasm then breaks out of connective tissue capsule and can metastasize.
*Usually contain degraded chromosomes joined incorrectly to another gene.
*Benign (top) and Malignant (bottom)
Tumors
*How do cells avoid death?
*Apoptosis- programmed cell death
*Inhibit the expression of Apaf-1
*Secrete elevated levels of decoy soluble molecule that binds to Fas-L
*Utilization of human proto-oncogene Bcl-2
*Tumor Suppressor Genes
*Inhibit cell division
*Contains p53 gene which binds DNA and stops it from allowing damaged DNA to divide
*Proto-Oncogene
*Stimulates the cell cycle
*Ras is a gene turns on other genes through the signal transduction cascade which tells the cell cycle to go
*Why do cancer cells grow
uncontrollably?
*Divisions determined by telomeres
*Cancer cells turn on telomerase
*Cancer cells now divide without any limits
*Processing Nutrients
*Cancer cells need nutrients
*Blood vessels nourish the tumor
*angiogenesis
*Invading Tissues
*Invading tissues and disrupting functions
*metastasizing
*Treatments
*There are no cures for cancer but treatment options do exist.
*Chemotherapy- poison cancer cells
*Radiation- uses x-rays and radio isotopes to destroy cancer causing cells
*Surgery- removes neoplasm and surrounding tissues