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Cancer. By: Aujan M., Zach J., Aditya P. 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.

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cancer

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
overview1

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.
Overview
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
genetic basis1

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.
Genetic Basis
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.
Causes of Cancer
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:Point Mutations
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.
Types of Mutations:Substitutions
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.
Types of Mutations:Insertions/Deletions
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:Benign
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.
Types of Neoplasms:Malignant
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
How do cells avoid death?
tumor suppressor genes

Inhibit cell division

  • Contains p53 gene which binds DNA and stops it from allowing damaged DNA to divide
Tumor Suppressor Genes
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
Proto-Oncogene
why do cancer cells grow uncontrollably

Divisions determined by telomeres

  • Cancer cells turn on telomerase
  • Cancer cells now divide without any limits
Why do cancer cells grow uncontrollably?
processing nutrients

Cancer cells need nutrients

  • Blood vessels nourish the tumor
  • angiogenesis
Processing Nutrients
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
Treatments
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