MI - Friday Quiz unit 3

G₀

Dormant cell phase

• cells is still metabolically active

• Temporary or permanent

• Caused by

  • DNA repair

  • Little/no growth signals

  • Maturity (I.E. Neurons)

Proto-oncogene

Healthy gene that regulates cell growth, division, and apoptosis

Oncogene

Mutated proto-oncogene that is overactive

• causes uncontained cell division and tumor formation

Tumor suppressor genes

produce proteins that inhibit cell growth/division

• Control division

• Identify and repair mutated DNA

• Apoptosis

Risk factor: Genetic

Genetic predisposition

• specific gene

• hereditary

Risk factor: Biological

Sex, Age, Race, etc

Risk factor: Environmental:

Diet, Exercise, Habits, etc

Healthy vs cancer cell morphology

Healthy

• uniform

• Higher cytosol volume

Cancer

• unorganized

• irregularly shaped nucleus/multiple nuclei

• lower cytosol volume

How does p53 regulate cell division

Activates genes to slow/inhibit cell growth or trigger apoptosis when the cell is stressed

• low oxygen

• DNA damage

• etc

Its protein can also activate repair factors

Structure of tp53

Transactivation Domain: allows tp53 to activate other genes after binding to their regulatory regions. Recruits enzymes that transcribe RNA.

DNA Binding Domain: responsible for tp53’s ability to bind to genes regulatory sequences. Checks for mutations. Most tp53 mutations are found here

Complexing Domain: Brings 4 tp53 molecules together so they become active

What happens when tp53 is mutated?

It cannot bind to DNA or halt cell division

Why might apoptosis occur?

• Cell damage

• Maintaining cell balance

• Growth

Internal apoptosis pathway

Happens within mitochondria

When stimulus occurs the antiapoptotic BCL class is inhibited

• results in increased membrane permeability

Cytochrome C is then released into the cytosol and forms a DISC (Death Inducing Signaling Complex)

External apoptosis pathway

Regulated by immune cells binding to a TNF receptor. The binding causes a capase cascade that kills the cell.

What do microarrays measure

mRNA expression

What are microarrays used for

determining which genes aren’t being expressed properly

Why are microarrays used with pearson correlation coefficient

determine how similar the genetic expression is in two or more individuals.

Human carcinoembryonic antigen (CEACAM6)

• codes for a protein located in the extracellular matrix

• cell cycle regulation, particularly with adhesion between cells

• When over-expressed, it becomes an oncogene, because it leads to unregulated cell division and inhibits cellular death.

Cytochrome P450 (CYP1A1)

• codes for a protein that is located in the endoplasmic reticulum

• protein catalyzes reactions involved in drug metabolism and synthesizes cholesterol, steroids, and other lipids

• expression of this protein is induced by some polycyclic aromatic hydrocarbons (PAHs), some of which are found in cigarette smoke

Sufactant protein B (SFTPB)

• codes for proteins that assist breathing and is not involved in the regulation of the cell cycle. 

SRY

• codes for a protein located in the nucleus

• protein is testis-determining factor (TDF), which initiates male sex determination

X-ray

• noninvasive

• electromagnetic radiation

• dense structures and dyes appear white

• structures like fat, muscle, and fluid appear black

• examines bones, teeth, lungs, breasts, heart, blood vessels, and the digestive tract

• uses ionizing radiation which can increase risk of developing cancer

X-ray: Pros and Cons

Pros

• noninvasive

• inexpensive

Cons

• ionizing radiation

• contrast material can cause allergic reaction

Computerized Axial Tomography (CAT Scan)

• Noninvasive

• series of X-ray views taken from many different angles are combined to produce cross-sectional images of the bones and soft tissues

• examines the chest, abdomen, pelvis, spine, and other skeletal structures

• ionizing radiation

Computerized Axial Tomography (CAT Scan): Pros and Cons

Pros

• noninvasive

• image bone, soft tissue, and blood vessels all at the same time

• able to be performed with implants

Cons

• ionizing radiation

• contrast material reaction

Magnetic Resonance Imaging (MRI)

• noninvasive

• uses magnets and radio waves instead of radiation

• images of soft tissue

• cross sectional images

• examine the brain, spine, joint, abdomen, blood vessels, and pelvis

Magnetic Resonance Imaging (MRI): Pros and Cons

Pros

• noninvasive with almost no risk

• no exposure to ionizing radiation

• images of the soft tissue structures of the body are more likely to identify and accurately characterize diseases than other imaging methods

• contrast materials are less likely to cause reactions

Cons

• implants may pose a risk

• confined space →claustrophobia

Bone scan

• noninvasive

• nuclear image testing

• examine the skeleton to detect abnormalities

• uses tiny amounts of radioactive materials called tracers (radionuclides)

Bone scan: Pros and Cons

Pros

• noninvasive

• extremely sensitive to abnormalities and variations in bone metabolism

• can scan the entire skeleton

Cons

• cannot determine cause of bone metabolism abnormalities

• tracers used produce a small amount of radiation exposure