mitosis free radicals cancer causes, types, and treatments embry riddle ret program module 1 embry...

MITOSISFREE RADICALS

CANCERCAUSES, TYPES, AND TREATMENTS

Embry Riddle RET ProgramModule 1

Embry Riddle RET program: Martin Hillier 2011

Cell Mitosis

Mitosis is the division of a cell into 2 identical daughter cells Takes 30-90 minutes

Depends on the type of cell Vital to the growth process and replacement of damaged or

dying cells Occurs most frequently in epithelial tissue (skin,

membranes, glands) Rarely occurs in brain and nerve cells after 6 months of age 6 phases

Prophase Metaphase Anaphase Telophase Cytokinesis

Chromosomes are replicated during the S portion of interphase, which is not part of mitosis


Interphase

The portion of the cell cycle in which the cell is not dividing

There are 3 divisions called G1, S, and G2. G1- cells perform the physiological

functions required by the tissue they are part of.

S- DNA is replicated in preparation for cell division Detail on the next slide

G2- Chromatin (contains DNA) condenses to form the familiar rodlike chromosome structure


DNA Replication

DNA Determines inherited characteristics Directs protein synthesis Controls enzyme production Controls metabolism

Transcription: copies instructions from DNA to mRNA (in nucleus)

Translation: ribosome reads code from mRNA (in cytoplasm) assembles amino acids into polypeptide chain

Animation Think of how many things can go wrong, but usually don’t. Pretty

amazing!Embry Riddle RET program: Martin Hillier 2011

Mitosis- Prophase

Chromatin (genetic material) condenses into pairs of chromosomes

Chromosomes have 2 sister chromatids connected by a centromere

Centrioles coordinate the action of microtubules which will eventually separate the sister chromatids

Features of prophase Nucleoli disappear

Nucleoli produce ribosomes which are necessary for protein synthesis

Centriole pairs move to cell poles Microtubules (spindle fibers) extend

between centriole pairs Nuclear envelope disappearsEmbry Riddle RET program: Martin Hillier

2011

Mitosis- Metaphase

Chromosomes align in a central plane called the metaphase plate


Mitosis- Anaphase

Microtubules pull chromosomes apart Daughter chromosomes group near centrioles


Mitosis- Telophase

Nuclear membranes reform, nucleolus reappears

Chromosomes uncoilCell has 2 complete nuclei


Mitosis- Cytokinesis

The cell splits and becomes 2 identical daughter cells

Mitosis animationEmbry Riddle RET program: Martin Hillier 2011

Key Concept- Cell Organization

The nucleus contains chromosomesChromosomes contain DNADNA stores genetic instructions for proteinsProteins determine cell structure and

function


Mutations

A mutation is a change in the nucleotide sequence of a gene: can change gene function

Causes: exposure to chemicals exposure to ionizing radiation

Radiation that liberates an electron and creates an ion This ion is known as a free radical

mistakes during DNA replication

Free radicals are of major importance 4 slides later


Growth and Suppressor Genes

There are genes that promote growth and replication of cells Overactivity of these cells can cause

uncontrolled cell division

The cell also has protective mechanisms that will create programmed cell death, or apoptosis, when the cell is damaged. Tumor suppressor genes, DNA repair genes,

and telomeres among others Telomeres are the internal cellular clocks that shorten

with each division. Eventually, the cell dies naturally. More than 50% of all cancer cases have an

abnormality in the p53 tumor suppressor gene If any of these operate incorrectly, a damaged cell

may be able to replicate and proliferate.Embry Riddle RET program: Martin Hillier 2011

The Immortal Henrietta Lacks HeLa

There is a line of cervical cancer cells that are remarkably resilient and seemingly immortal. Used for research since 1951 when they were extracted

from Henrietta Lacks. They can divide an unlimited number of times in culture. It has been estimated that the total number of HeLa

cells far exceeds the number of cells in Ms Lack’s body. The telomerase on these cells is remarkably active which

prevents the shortening of the telomeres that seems to lead to normal aging and cell death. Telomerase- enzyme that replenishes non-coding DNA

sequences lost during replication


Proliferation of Cancer

Normal cell division and apoptosis vs. Cancer cell division


Free Radical Production in the Mitochondria

Free radicals are atoms or groups of atoms that have odd numbers of electrons (unpaired electrons) This makes them unstable and highly reactive and can

disrupt important structures like DNA. Because the free radical wants another electron, they

attack and damage other molecules. A chain reaction is created and the body undergoes “oxidative stress”. Oxidation is giving or losing an electron Similar to an apple turning brown or metal rusting

However, free radicals are not always harmful. They can be used to fight disease carrying pathogens.

Mitochondria are organelles inside all cells that generate ATP in a process called aerobic metabolism. Aerobic metabolism involves oxygen and generates free radicals. Mitochondria also play a major role in signaling, cellular

differentiation, cell death, and regulating the cell cycleEmbry Riddle RET program: Martin Hillier 2011

Other Sources of Free Radical Production

Radiation exposure Most radiation exposure is unavoidable and our bodies are

able to withstand the low dose by repairing or replacing damaged cells.

Cigarette smoking Radioactive lead-210 and polonium-210 are inhaled into the

lungs, where the concentration increases over time

Air pollutants Industrial chemicalsExercise

Increased cellular aerobic metabolism

Free radical animation (pause at 2:12)Embry Riddle RET program: Martin Hillier 2011

Fighting Free Radicals

Natural defense system A group of enzymes use dietary minerals like selenium,

copper, manganese, and zinc to fight free radicals

Antioxidants (continue previous animation from 2:12) Molecules that are stable enough to give an electron and

still remain stable Antioxidants literally means “against oxidation”

Thus, they give their electron to prevent the more fragile molecules from being oxidized.

The most well known dietary antioxidants are: Vitamin E Vitamin C CarotenoidsEmbry Riddle RET program: Martin Hillier

2011

Sources of Radiation

Natural sources and manmade sources each account for 50% of all radiation exposure, on average Smoking a pack of cigarettes per day adds 36 mrem / year

Total average dose is 620 mrem or 6.2 mSv / yearPerspective

Chernobyl victims absorbed 80,000 – 1,600,000 mrem in one dose. 28 of 134 died within 3 months.


What is Cancer?

Cancer is an uncontrolled growth of abnormal cells in the body These cells are called malignant cells

Stages of cancer (picture on next slide) 0 – abnormal cells are isolated to the layer of cells in which they

developed 1 – cancer cells are localized to one organ and create a primary tumor 2 & 3 – cancer cells are still local, but the cancer is advanced and may

have spread to nearby lymph nodes and adjacent organs 4- cancer has spread (metastasis) to other parts of the body and

secondary tumor(s) are created

Oncology is the study of cancerA carcinogen is anything that is known or suspected to

increase the risk of cancer


Stages of Cancer


Metastasis of Cancer

Metastasis is the spreading of cancer cells to other parts of the body

Metastasis animation


Characteristics of Normal Cells & Cancer Cells

Normal Cells Grow, divide, and die In the years before adulthood, cell division occurs at a

rapid rate to allow for growth. During adulthood, cells only divide to replace dead or

damaged cells.

Cancer Cells Contain damaged DNA Do not die and continue to replicate Have the ability to invade other tissues


Cancer Statistics

1/2 of all men and 1/3 of all women will develop cancer in their lifetime.

2010 US statistics Male- 790,000 new cases ; 300,000 deaths

The most common form of cancer in men is prostate cancer, followed by lung cancer and colorectal cancer.

Female- 740,000 new cases; 270,000 deaths The most common form of cancer in women is breast

cancer, followed by lung, colorectal, and uterine.


Causes of Cancer (1)

Lifestyle Smoking

Smoking is responsible for almost 20% of all deaths in the US More than car accidents, alcohol, suicide, AIDS, homicide, and illegal drugs

combined In 2009, 20% of high school students and 5% of middle school students

smoked cigarettes Smoking is responsible for 30% of all cancer deaths Lifelong smokers lose 6.5-14 years of life expectancy

Poor diet and physical inactivity 1/3 of all cancer deaths are attributed to obesity, physical inactivity, or

poor diet Obesity causes the body to produce more growth hormones and insulin

This can stimulate cancer growth Body mass index can give a general idea of weight classification

• BMI = mass (kg) / height2 (m)• However, body fat % calculations are more reliable because BMI does not

take into account muscle mass and body fat contributionsEmbry Riddle RET program: Martin Hillier 2011


Genetics 5-10% of all cancer is inherited (hereditary mutation)

Radiation exposure Radon (map to the right) Geographic location

Elevation Cosmic exposure roughly doubles for every 2,000 m (1.24 miles)

increase in elevation

Latitude 70 degrees N or S receives about 4 times the cosmic dose when

compared to 25 degree N or S

Occupation Airline, power plant, manufacturing, medical imaging

Medical Imaging



Certain infections Infections can cause inflammation which induce

cell proliferation (division) and the production of free radicals

22% of cases in the developing world and 6% in the industrialized world

H. Pylori- stomach cancer Hepatitis B and C- 80% of liver cancer cases Papillomavirus- cervical cancer

Chemical exposure


Things you can do to prevent cancer

Although there is no way to prevent cancer, there are lifestyle habits that can help reduce the risk. Healthy diet

Antioxidants Limiting sun exposure or taking protective steps Increase physical activity Don’t smoke


Cancer Treatments (1)

Surgery Used for non-metastasized tumors that are accessible Mastectomy and prostatectomy are 2 examples

The suffix –tomy literally means “to cut out”

Radiation therapy Targeted ionizing radiation is used to damage DNA

and prevent cancer cells from replicating Proton therapy is a fairly new method Dose depends on radiosensitivity of the tissue Healthy cells are also affected, but can usually

recover



Chemotherapy Drug therapy that targets the DNA replication process Affects all cells, thus healthy cells can be damaged

Rapidly dividing cells, like epithelial cells, are most affected

Targeted therapy Huge area of new research Uses drugs that target specific molecules related to

the cancer cell replication process Growth receptor inhibitors are the most common

Much less damage to healthy tissue when compared to chemotherapy



Hormonal therapy Drugs that reduce the production or testosterone or estrogen

Reduction in these growth hormones decreases rate of cell division

Immunotherapy Immune system response is triggered by the injection of

antibodies

Angiogenesis (creating new blood vessels) inhibitors Just like any other tissue, tumors need blood supply If you can cut off the blood supply, the tumor dies

It is important to note that more than 1 treatment method and more than one drug per method may be used concurrently.


Next Generation Sunshine State Standards

Life Science SC.912.L.14.6 SC.912.L.16.3 SC.912.L.16.5 SC.912.L.16.8 SC.912.L.16.14


mitosis free radicals cancer causes, types, and treatments embry riddle ret program module 1 embry...

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