Rad Bio Exam 1 (3,6,&,7) Condensed

Immature cell characteristics:

-non-specialized (undifferentiated) -undergo rapid cell division

Mature cell characteristics:

-specialized in function (highly differentiated) -divide at a slow rate or not at all

Biology

A science that explores living things and life processes

Deoxyribonucleic Acid (DNA): The Master Chemical

Composed of two long sugar-phosphate chains, which twist around each other in a double-helix configuration and are linked by pairs of nitrogenous organic bases at the sugar molecule of the chain _Hydrogen Bonds_ attach the bases to each other :Contains all the information the cells needs to function. :Carries the genetic information necessary for cell replication Regulates all cellular activity to direct protein synthesis Determines a person's characteristics by regulating the sequence of amino acids in the person's constituent proteins during synthesis of these proteins Sequence of nitrogenous base pairs in a DNA molecule that constitutes the genetic code

Nucleic acids

Comprise about 1% of the cell Are very large, complex macromolecules Are made up by Nucleotides (DNA subunits) Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are two types of Nucleic acids

Lipids

Constitute about 2% of cell content Made up of a molecule of glycerin and three molecules of fatty acid Are organic macromolecules Are the structural parts of cell membranes Present in all body tissue Perform various functions for the body

Deoxyribonucleic Acid (DNA): The Master Chemical

DNA Structure: Double stranded macromolecule that forms a double helix Phosphate + sugar = backbone or side rails 4 nitrogenous bases = rungs Nucleotide: DNA Subunit 1) Nitrogenous base 2)5 Carbon sugar 3)Phosphate group

Low-LET radiation damage

DNA cellular damage can usually be reversed by repair enzymes

Endoplasmic Reticulum (smooth and Rough)

ER- Enables the cell to communicate with the extracellular environment and transfers food from one part to another. Rough ER-Studded with Ribosomes and site of synthesis for glycoproteins and phospholipids Smooth ER- lacks ribosomes site of fatty acid and steroid synthesis.

Proteins

Essential for growth, the construction of new body tissue, and the repair of injured or debilitated tissue Formed when amino acids combine into long, chain-like molecular complexes.> Proteins produced in Ribosomes >Order of arrangement of these amino acids determines the precise Function of each protein molecule > Type of protein macromolecule that any given cell contains determines the Characteristics of that cell

T/F: Cells that are slow to divide are more radiosensitive.

False

T/F: Stochastic (deterministic) effects are biological somatic effects of ionizing radiation that can be directly related to the dose received

False

T/F: It is generally accepted that there are no clinical effects seen from radiation exposure at or below 0.5 rad.

False: 50 rad

T/F: There are 3 ways for cellular injury to occur after ionizing radiation exposure: division delay, reproductive failure, & anaphase death.

False: metaphase death

T/F:Direct ionizations = initial radiation usually with no charge or mass.

False:Indirect ionizations = initial radiation usually with no charge or mass. Direct ionization = initial radiation WITH charge and mass.

T/F:The sequence of amino acids determines the type of carbohydrate that is formed, and the type of carbohydrate molecules that any given cell contains determines the characteristics of that cell.

False:The sequence of the amino acids determines the type of protein that is formed, and the type of protein molecules that any given cell contains determines the characteristics of that cell.

T/F: Indirect ionization occurs as a result of radiation interactions with water molecules?

False:The word ionization makes this false. Indirect action occurs as a result of radiation interactions with water molecules. Indirect ionizations occur with radiations having no mass and no charge (such as gamma, x rays neutrons

Cell membrane

Frail, semipermeable, flexible structure encasing and surrounding the cell. Made up of lipids and proteins, functions as a barricade, and controls passage of water and other materials in and out of cell. Also functions to remove wastes and refine materials for energy through breakdown.

Dizygotic twins

Fraternal twins, two separate ovums

Monozygotic twins

Identical twins, One ovum splits after fertilization producing two twins.

Point mutations:

If ionizing radiation interacts with a DNA macromolecule, the energy transferred could rupture on of its chemical bonds and possibly sever one of the sugar phosphate chain side rails, or strands, of the ladderlike molecular structure. (single-strand) Can result in gene abnormality.

Which of the following is most harmful to the human body? a.Direct action b.Indirect action c.Epideiologic action d.Mitotic action

Indirect action= involves the radiolysis of water which produce toxic substances that damage key molecules. Most interactions within the tissue are indirect because 80% of the cell is water and less than 1% is DNA.

The above process is called ?

Ionization/Ionization is the foundation of the interactions of gamma rays with ANY atoms or molecules within human tissue.

Cytoplasm

Is the protoplasm that exists outside the cells nucleus, composed of water and

One of the factors that affects the degree of biologic damage is how much energy is deposited along the path, or track, of the radiation. This concept is know as:

Linear Energy Transfer: LET is measured as the average energy deposited per unit length of track. Biologic tissues are often measured in microns, also called micrometers

The dose response model(s) that is accepted by the NRC is/are the

Linear-No Threashold Model

Centrosomes

Located in the center of the cell near the nucleus. They contain centrioles (pair of small hollow cylindrical structures at right angles to each other, embedded in the mass of 100 proteins.) plays a part into the formation of the mitotic spindle.

Point mutation commonly occur with _______ radiation and are reversible through the action of repair enzymes

Low-LET

two LET categories:

Low-LET High-LET

The chromosomes are the most radiosensitive during the ___ phase of mitosis.

M phase, in which the chromosomes are condensed and paired, is the most radiosensitive

Cells are most sensitive during ______________.

M phase/The speed at which cells complete the full cycle of mitosis and interphase varies considerably. Cells complete the full reproduction cycle at different rates based on their function, as well as on other factors such as the person's age and stress levels.

Carbs

Make up about 1% of cell content Include starches and various sugars Range from simple to complex Function as short-term energy warehouses for the body Primary purpose is to provide fuel for cell metabolism Most abundant in the liver and in muscle tissue Important structural parts of cell walls and intercellular materials

Deoxyribonucleic Acid (DNA): The Master Chemical

Nitrogenous bases are classified as derivatives of 2 parent compounds, pyrimidine and purine. Pyrimidines: thymine & cytosine Purines: adenine & guanine *Adenine is ALWAYS paired with Thymine *Guanine is ALWAYS paired with Cytosine 5th letter is used for genetic code transfer. Uracil replaces Thymine_ in RNA

Interphase

Normal function cell stage. Occurs before mitosis begins >Duplication of DNA / chromosomes are copied; also DNA-RNA protein synthesis occurs Chromosomes are NOT visible; chromatin material is in nuclei

Mitochondria

Produce energy (Adeonsine triphosphate ATP)for cellular activity by breaking down nutrients through the process of oxidation. "Powerhouse"

Organic compounds

Proteins , Carbs, Lipids, Nucleic acids (DNA)

Stem cells are ?

Radiosensitive

What is the role of protoplasm?

Regulates the process of metabolism in cells,Provides cells with oxygen and food, & Removes waste from cells

Genes

Segments of DNA that serve as the basic units of heredity Each one contains information responsible for directing cytoplasmic activity, controlling growth and development of the cell, and transmitting hereditary information Control the formation of proteins in every cell through the intricate process of genetic coding

Meiosis

Special type of gonadal sex cell division in which 1 diploid cell containing 2 copies of each chromosome go through 2 rapid cell divisions and produces 4 haploid cells containing 1 copy of each chromosome. Chromosomes only duplicate once and the # is reduced by ½. Cell division is regulated by DNA.

Prophase

Step 1 in mitosis The DNA molecules progressively shorten and condense by coiling, to form chromosomes. The nuclear membrane and nucleolus are no longer visible. The spindle apparatus has migrate to opposite poles of the cell.

Low-LET radiation: What does the "shoulder" represent in the cell survival curve?

This shoulder to the curve at lower doses indicates the cells ability to repair some damage at low doses

Chromosomes

Tiny rod-shaped bodies that under a microscope appear to be long threadlike structures that become visible only in dividing cells Composed of protein and DNA :Normal human has 46 different chromosomes (23pairs) in each somatic cell (DIPLOID CELL) :Reproductive cells(germ cells) have only 23 chromosomes each ( Haploid cell)

T/F: Anything in excess can be toxic?

True

T/F: The effects of ionizing radiation depend on total dose and exposure rate.

True

T/F:If EM radiation has a high enough frequency, it can transfer sufficient energy to the electrons to remove them from the atoms to which they were attached.

True

T/F: Hypoxic cells are more difficult to destroy than normally oxygenated cells.

True.

T/F: LET can influence cell radiosensitivity.

True. As LET increases (radiation transfers more energy per unit) ability to cause biologic effects also increases.

Golgi apparatus

Unites large carb molecules with proteins to form glycoproteins. Concentrates, packages, and transports enzymes , hormones, and proteins.

Functions of water

Within the cell ▬ Is the medium in which the chemical reactions that are the basis of metabolic activities occur: Anabolism and catabolism ▬ Acts as a solvent, keeping compounds dissolved so that they can more easily interact and their concentration may be regulated Outside the cell ▬ Functions as a transport vehicle for materials the cell uses or eliminates ▬ Is responsible for maintaining a constant body core temperature of 98.6oF (37oC) ▬ Lubricates both the digestive system and skeletal articulations ▬ Protects organs such as the brain and lungs

types of Low-LET radiation:

X-rays gamma rays

Inorganic compounds

acids, bases, and salts(electrolytes) acids= hydrogen containing bases=alkali or alkaline OH salts= action of an acid and base on each other

types of High-LET radiation:

alpha particles beta particles

linear energy transfer (LET)

average energy deposited per unit length of track

Oxygen effect

biologic tissue is more sensitive to radiation when irradiated in an oxygenated/aerobic state (vs. anoxic/hypoxic)

High-LET radiation damage

can cause irreparable damage to DNA by multiple-strand breaks that cannot be undone by repair enzymes

Low-LET radiation interacts with biologic tissue resulting in -->

cell damage primarily by indirect action, involving production of free radicals (molecules)

Some consequences of ionization in human cells include:

creation of unstable atoms, production of free electrons, & creation of reactive free radicals capable of producing substances poisonous to the cell

Direct action

damage occur from ionization of atoms on essential molecules that may cause functionally to be altered(DNA) MOST HARMFUL

High-LET is characterized by:

dense ionization per unit of distance travelled (more likely to interact with tissue); energy exhausted in shorter length of track

Oxygen enhancement ratio (OER)

describes oxygen effect numerically; ratio of radiation dose required to cause particular response of cells in oxygen-deprived environment to radiation dose require to cause same response in oxygenated conditions

Relative biologic effectiveness (RBE)

describes relative capabilities of radiation with differing LETs to produce a particular biologic reaction

units for LET:

kiloeletron volts per micron (keV/um)

Most radio-sensitive cells are:

lymphocytes (manufactured in the bone marrow)

DNA regulates cellular activity indirectly by reproducing itself in the form of ______________ to carry genetic information from the cell nucleus to ribosomes located on the cytoplasm.

mRNA:DNA reproduces itself in the form of mRNA to be transferred outside the nucleus. mRNA is responsible for making proteins out of amino acids.

Gamma rays are carriers of

manmade, electromagnetic energy

Nucleolus

manufactures and holds a large amount of RNA. Contains at least one very small round body.

Polyzygotic siblings

more then two

Oxygen present when a tissue is irradiated causes the formation of ____ free radicals, ____ the indirect damage potential of the radiation

more; increasing

The law of Bergonie and Tribondeau:

most pronounced radiation effects occur in cells having: -less maturity and specialization -greatest reproductive activity -longest mitotic phase

Most radio-resistant cells are:

nerve cells

x-rays/gamma rays can also be referred to as streams of particles called ____

photons (each has no mass and no charge)

Indirect action

refers to effects caused by free radicals created by the interaction of radiation with water (H2O molecules)

Mitosis

(a process in which the nucleus first divides, followed by the division of the cytoplasm ▬ Process that occurs when all Somatic cells divide The multiplication process whereby one cell divides to form two or more cells Results in an approximately equal distribution of all cellular material between the two daughter cells M(mitosis phase), G1(pre-DNA phase), S(synthesis phase), G2(Post-DNA phase). Then divides into four subphases PMAT

Ionizing radiation damages systems by ____

ionization (removing electrons) of atoms, compromising molecular structures

Metaphase

2nd step in mitosis The spindle fibers attach themselves to the centromeres of the chromosomes and align the chromosomes at the equatorial plate

Anaphase

3rd step in Mitosis The spindle fibers shorten and the centromere splits, separated sister chromatids are pulled along behind the centromeres.

Telophase

>4th and final step in mitosis Plasma membrane indents Chromosomes uncoil; 2 nuclei form All organelles also duplicated

High doses of radiation exposure tend to be ?

>50 rad:

Structural and Enzymatic Proteins

>Provide the body with its shape and form Provide a source of heat and energy for the body >Function as organic catalysts Control the cell's various physiologic activities Cause an increase in cellular activity that in turn causes biochemical reactions to occur more rapidly to meet the needs of the cell

Cell structure

1. Cell membrane 2. Cytoplasm 3. Cytoplasmic organelles a. Endoplasmic reticulum b. Golgi apparatus or complex c. Mitochondria d. Lysosomes e. Ribosomes f. Centrosomes 4. Nucleus

With regards to pair production, when a photon of high energy ( >_______ MeV) interacts with atoms, the incident photon can be spontaneously converted into the mass of an electron and _____________ pair in the vicinity of the nucleus.

1.02; positron

Two types of Protoplasm

1.Organic compounds- contain Carbon, hydrogen, & Oxygen 2. Inorganic compounds- Do not contain Carbon

Annihilation radiation is used in which of the following modalities?

PET: Annihilation event: A process that occurs after pair production. The positron (positive electron) that is created in pair production travels until it strikes an electron with which it interacts. The positron's and electron's mass disappears and is converted into two (511 keV) photons that radiate out of the atom. We image the 511 keV photons in PET.

__________________ occurs when _________ energy gamma rays interact near the nucleus and the photon is _____________ absorbed.

Pair production, high, completely >Photons may lose SOME or ALL of its energy in a single interaction. Compton scatter = medium energy partial absorption. Photoelectric effect = low energy complete absorption. Pair production = high energy complete absorption.

Radiation Biology

The study of the effects of Ionizing radiation on living organisms. Ionizing radiation: Photons (basic unit of light) energetic enough to detach electrons from atoms, therefore ionizing (converting an atom to an ion by adding or removing charged particles such as e-) them. Factors involved: Total dose(mrem) Dose rate( mR/hr) Age Type of radiation (Alpha, beta, gamma)

Antioxidants block _______ __________ from recombining into hydrogen peroxide

free radicals, hydroxyl

With respect to the Law of Bergonie & Tribondeau, which of the following would best complete this statement? "The most pronounced radiation effects occur in cell having the

greatest reproductive activity, longest mitotic phases, and least maturity. >The radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation. So the most pronounced radiation effects occur in cells having the least maturity and specialization/differentiation; the greatest reproductive activity; and the longest mitotic phases.

If the RBE increases, then the LET ____

increases

Lysosomes

small pealike sacs or single membrane spherical bodies that aide in digestion. Dispose of bacteria and food , contains hydrolytic enzymes that can break down proteins as well as the cell itself if the surrounding membrane breaks.

Free radicals:

solitary or combination of atoms that are chemically reactive as the result of unpaired electrons

Protoplasm

the chemical building material for all living things the living contents of a cell that is surrounded by a plasma membrane. It is a general term for the cytoplasm.

RBE of a type of radiation is defined as:

the ratio of the dose of a reference radiation to the dose of radiation of the type in question to produce same biologic reaction in experiment

Radiation weighting factor:

used to calculated equivalent dose and determine ability of a dose (of any type of ionizing radiation) to cause biologic damage

cell survival curve

used to display the radiosensitivity of a particular type of cell

Ribosomes

very small spherical organelles that attach to the ER. Consist of : 2/3 RNA and 1/3 protein manufacture proteins by using the blueprints form mRNA.

Cytokensis

when the cytoplasm divides into two

Benefit of proper cell function

▬ Enables the body to maintain homeostasis or equilibrium

Requirements of the body

▬ Provide food as a source of raw material for the release of energy ▬ Supply oxygen to help break down food ▬ Have enough water to transport inorganic substances into and out of the cell