Cancer Unit - Why Biology? (McGraw Hill Connect 2.0)

Cancer

Unregulated cell division

Nucleus

Where the genetic information is

Ribosomes

Where genetic info is used to manufacture proteins

mRNA

messenger RNA

rRNA

ribosomal RNA

tRNA

transfer RNA

Homeostasis

Maintaining internal equilibrium; result of negative feedback mechanisms; 37 C, pH 7.4

DNA

Deoxyribonucleic acid; Sugar: Deoxyribose, Strands: 2, Bases: Thymine, Location: Nucleus

Transcription

1st part of gene expression; Copy of mRNA made from DNA strand

Translation

2nd part of gene expression; mRNA moves to ribosome; tRNA reads codons of mRNA

Start codons

AUG

Codon

Language of gene expression/protein synthesis

Interphase

Majority of cells time in cell cycle; normal functions occur; Consists of G1, S, G2

Mitosis

PMAT

M Phase

Where cell division occurs; consists of mitosis and cytokinesis

Apoptosis

programmed cell death

G0

Retirement/waiting/resting phase; tries to correct or apoptosis

Product of mitosis

2 genetically identical daughter cells

G1

Growth of the cell, duplication of organelles, increasing cytoplasm

S

DNA replication

G2

Additional cell growth and prep for mitosis

Prophase

Chromatids condense, nuclear envelope disappears, spindle fibers assemble from centrioles

Checkpoints function to

1. Regulate the speed at which the cell moves through cell cycle

2. Ensure cell is ready for cell division

Why do cells divide?

For an organism to grow

For an organism to repair itself

Metaphase

Sister chromatids align along cell equator. Centromeres attach to a spindle fiber

Anaphase

Chromatids separate at their centromeres and are pulled to opposite poles. They are now single chromosomes again

Telophase

Spindle fibers disassemble, nuclear membrane reforms, chromosomes return to chromatin.

Where are the checkpoints in the cell cycle?

G1, G2, M

What happens if there are no checkpoints or checkpoints fail?

If checkpoints fail, damaged or mutated DNA will persist in a population of cells

What is a centromere?

Region of chromosomes where sister chromatids attach. This region will be where spindle fibers attach in order to separate during anaphase

RNA

Ribonucleic acid; Sugar: Ribose, Strands: 1, Bases: Uracil, Location: Starts in nucleus - spends most time in cytoplasm

Mutation

any change in the nucleotide sequence of DNA (may or may not impact protein structure)

3 stop codons hit prematurely

incomplete protein

Examples of Tumor Suppressor Genes

p53, BRCA1, BRCA2

Tumor Suppressor Genes

Brakes; Prevent unregulated cell growth by slowing down the progression of the cell through the cell cycle; Most code for proteins that survey DNA for damage during the G1 checkpoint.

Proto-Oncogenes

Accelerator; Speeds up cell cycle; Associated with signaling the pathways: growth hormones interact with target, cell division is promoted; Become oncogenes when mutations cause them to be "stuck" on (only a single mutation is required for this)

Examples of Proto-Oncogenes

ERBB2 (breast cancer; produces HER2)

Cancer cells characteristics

Irregular, immortal (because of telomerase enzymes), lose ability to specialize, dark

Tumors

Masses of unspecialized cells

Benign tumor

Non-cancerous; contained

Malignant tumor

Cancerous (rarely encapsulated)

Angiogenesis

Occurs as growth factors are released and capillaries grow towards the tumor

Metastasis

When cancer moves to other parts of the body

How many stages of cancer

0 or 1-4

Stage 0-1 Cancer

Tumor is limited to very small area (lymph nodes maybe); < 2cm

Stage 2

Tumor has become invasive and grown but is still located entirely within the breast (lymph nodes may be involved); 2-5 cm

Stage 3

Tumor moved out of breast tissue but not spread to distant organs; lymph nodes are involved

Stage 4

Cancer fully metastasized and spread to other organs

How can tumors effect homeostasis?

- Tumors take up space in organs and block blood and lymphatic vessels and ducts, so organs can't function

- Tumors require oxygen and nutrients, depriving nearby tissues

PCR

Polymerase Chain Reaction - By drawing blood and using white blood cells to ? DNA make copies gene of interest for further evaluation

DNA Sequencing

Exact sequence of nucleotides; Fluorescent tags added to nucleotides in DNA molecule and chemical reactions remove 1 nucleotide at a time

Microarrays

Looks at specific mtots? or dffeers? gene expression

CBC

Complete Blood Count - look at basic blood chem

Screening mammogram

X-ray of breast and surrounding tissues; look for abnormalities

Diagnostic mammogram

More angles

CT/CAT Scan (Computerized tomography)

X-ray organs with pictures, multiple angles, 3D images (can involve dye contrast)

PET scan (Positron Emission Tomography)

Uses radioactive tracers to measure the metabolism of cells, cancer cells are more active and stand out.

MRI (Magnetic Resonance Imaging)

Uses radio waves and magnets to generate detailed images of the body.

Treatment of cancer

Surgery, chemotherapy, radiation

Surgery

Excision (can be the treatment); debulking

Chemotherapy

Use of drugs to treat a disease

Chemotherapy (cancer)

Treatment using chemical substances; drugs used systemically to kill rapidly dividing cancer cells;

targets cell cycles - affects al cells

Alkylating agents

Integrate into DNA, causes breaks at different/specific points

Alkalosis

(Naturally produced by some plants) Prevent forming spindle fibers preventing cell division

Taxanes

(Yew tree) Prevent microtubule breakdown

Antimetabolites

Mimic nucleotides, integrate into DNA, interfere with DNA replication

Topoisomerase inhibitors

Disable topoisomerase enzyme preventing DNA replication

Radiation

Beams of intense energy (killing rapidly dividing cells); damages DNA within cell slowing down or stopping cell division; can target specific areas; not good for metastasized cancer

External radiation

Beam; xray or gamma rays

Internal radiation

Brachytherapy; radioactive seeds

Interstitial rad

Seeds direct contact tumor

What are some causes of mutations?

Chemicals, radiation exposure, viruses

Intracavity rad

Seeds in nearby body cavity

Why is it important to keep the filtrate and reagents cold? (Isolating DNA)

Cold temperature stabilizes DNA

What is the purpose of the meat tenderizer? (Isolating DNA)

To digest accosted proteins that bind the DNA

What is the purpose of the ice cold 95% ethanol? (Isolating DNA)

To precipitate the DNA from the filtrate (DNA is not soluble in ethanol but is in water-based filtrate)

What is the correct way to spool the DNA? (Isolating DNA)

Slowly, using a constant motion and pressure to collect the precipitate

Order of Steps to Isolate DNA

1. Place test tube on ice

2. Transfer strawberry filtrate with pipette to test tube

3. In a graduated cylinder, dissolve a spoonful of meat tenderizer into distilled water

4. Add meat tenderizer solution to strawberry filtrate and let it react for 10 minutes

5. Use pipette to add ice cold 95% ethanol along inside of tube to precipitate DNA

6. With the test tube in the rack, spool precipitated DNA onto glass rod

Why is it important to pour slowly and avoid air bubbles? (Gel Electrophoresis)

Such bubbles would interfere with the movement of the sample through the gel, distorting the results.

What is the purpose of installing the comb? (Gel Electrophoresis)

To create a well or pockets in the gel where samples can later be placed.

What would happen if the gel was run for too long? (Gel Electrophoresis)

The sample bands would move too far and leave the bottom of the gel.

TNF 1 (genotype)

Normal

TNF 2 (Genotype)

Disease

What structure is found in plant cells but not in animal cells?

Chloroplast

What structure found in plant cells is an organelle for storing water and metabolites?

Vacuole

What was the purpose of mixing cells with sodium chloride and detergent to form the strawberry filtrate? (Isolating DNA)

Detergent emulsifies cell and nuclear membranes of cells. (The detergent disrupts phospholipid bilayers) Sodium ions neutralize the negative charge of DNA to facilitate precipitation. This helps the DNA come out of solution.

Immunotherapy

Immune system identifies "self" vs "nonself" and targets "nonself"; Convince immune system cancer cells are nonself; Cancer vaccines; Monoclonal antibodies

Cytokinesis

The division of cytoplasm that occurs at the end of mitosis. A cleavage furrow develops to pinch off the cell membrane producing two daughter cells

What is the role of spindle fibers in cell division?

Are microtubules that are critical for alignment of sister chromatids and allow for separation of centromeres. This ensures that a copy of each chromosome reaches each pole of the cell thus giving each daughter cell a copy of each chromosome.

Chromatin

The loose uncondensed form of chromosomes during interphase. Is composed of DNA and histones that are in the form of stringy fibers

Sister chromatids

When two copies of a chromosome are attached by a centromere. Can be condensed or uncondensed (chromatin)

Why is ethidium bromide added at this step? (Gel Electrophoresis)

To see the DNA bands in the gel under UV illumination