Cell Biology RADL 70 Kyle Thornton This material will not be covered in class, but will be on the...
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Transcript of Cell Biology RADL 70 Kyle Thornton This material will not be covered in class, but will be on the...
Cell Biology
RADL 70
Kyle Thornton
This material will not be covered in class, but will be on the midterm exam.
Note: This material will not be covered in class, but will be on
the midterm exam.
Properties Of A Cell
All living things are made up of protoplasm A thick viscous, suspension substance that constitutes the
physical basis of all living activities
The smallest unit of protoplasm is the cell Most responses to radiation occur first at the
cellular level All radiation damage is at the cellular or subcellular level
Cell Properties
Assimilation Growth Motility Secretion Irritability Reproduction
The Levels Of Organization
Simple life forms consist of one cell More complex forms are made up of many types of
cells Cells are modified and specialized for specific activities
Muscle cells Designed for contraction
Red blood cells Carry oxygen to body tissues
Nerve cells Receive and send electrical impulses
Levels Of Organization
Groups of cells that perform the same activity are tissues Epithelial, connective, muscular, and nervous
Groups of tissues that perform a specialized function are organs The stomach – composed primarily of epithelial and muscle tissue
A group of organs form a system Consists of organs working together to perform a specific function
GI or Respiratory system The organism is the highest level of organization
A living being
Chemical Components Of A Cell
Organic compounds Carbon, hydrogen, oxygen
Inorganic compounds Salts, water, minerals
Both are suspended or dissolved in water Water makes up 80% of a cell
Water helps hold and transport substances in the cell Chemical activities take place in the cell Water helps maintain constant temperature
Without water, cells would be vulnerable to extreme changes in temperature
Cell Physiology
Cells move water in and out by osmosis The amount is determined by osmotic pressure Osmotic pressure is determined by the
concentration of mineral salts inside or outside of the cell
Too much water can rupture a cell Too little water can make a cell collapse Either way, the cell cannot complete its biological
function
Osmotic Pressure
Too little sodium inside the cell, or too little potassium outside the cell will cause water to be pulled outside the cell causing collapse
Hypertonic A solution that causes a cell to shrink
Hypotonic A solution that causes a cell to swell
Isotonic Having an osmotic pressure equal to that of circulating blood
Benefits of Mineral Compounds and Salts
Mineral compounds prevent cramping Salts aid in the production of energy and the
conduction of nerve impulses
The Major Classes Of Organic Compounds
Proteins Lipids Carbohydrates Nucleic Acids
Proteins
Macromolecules – Polymers Large molecules formed by joining together
simple units known as monomers into a long chain
Make up about 15% of a cell Considered the building block of a cell Integral to structure of skin, bone, tendons,
ligaments, hair, silk, and collagen
Protein Functions
Building of new tissue Repair of injured or broken down tissue Intercellular messengers Composition of enzymes
Enzymes are large protein molecules that control the speed of most chemical reactions inside the cell
Other Protein Functions
Protect the organism as it makes up antibodies Antibodies protect the organism from infections and are
essential to clotting and wound repair
Transfer information from one cell to surrounding cells Help maintain the well-being of the organism
Made up of enzymes Essential to the chemical release of energy from food
Amino Acids
The basic composition of proteins About 80 are found in nature, 20 are
essential to humans
Lipids
Fats Makes up about 2% of a cell
Excess energy is stored for later use Sugar molecules, from which cells usually get their
energy, are converted into lipids for storage if not needed for current use
Lipids are not water soluble, but are in alcohol, ether, oil, and chloroform
Classifications Of Lipids
Those stored in the inside the cell for energy Those used to form the cell membranes and as a
thermal cushion Also for production of steroids, cholesterol, testosterone,
and estrogen Long chain lipids important for pigmentation such as
eye color A type of fatty acid involved with muscle contraction,
blood vessel constriction, cell reproduction, and inflammatory response
Functions Of Lipids
Storage of energy Integral component of cell membrane Protection against cold and heat Assistance in digestive process Components of substances such as hormones
Carbohydrates
Make up about 1% of the cell Provide most of the cell’s energy Sugars and starches are typical carbohydrates Stored primarily in the liver and muscles They release large amounts of energy when
the bonds are broken through metabolism
Classifications of Carbohydrates
Monosaccharides Glucose or fructose
Primary source of cell energy
Disaccharides Sucrose, lactose, and maltose
Not easily metabolized Storage form of energy that can be converted to glucose and used for energy
requirements
Polysaccharides Starch, dextrin, cellulose, and glycogen
Used as an energy source Cellulose is used for structural purposes
Nucleic Acids
Macromolecules Blueprint for reproduction A template for protein synthesis Transport mechanism to join materials necessary to build
proteins Control mechanism to regulate the cell’s metabolism and
reproduction Two types of nucleic acids
DNA and RNA
Cell Structure
Two major sections of the cell Cytoplasm Nucleus
Both are filled with protoplasm Nucleoplasm – protoplasm inside the nucleus Cytoplasm – protoplasm outside the nucleus
Structures within the protoplasm are called organelles Each organelle has a function necessary for cell health and
survival
The Cell
The Nucleus
Contains the genetic and metabolic information of the cell
Similar to the brain of the organism This controls how that organism functions in its
environment
Nuclear Components
Nuclear envelope Chromosomes Nucleolus Nuclear sap – the liquid portion of a cell
nucleus
Nuclear Envelope
Membrane Separates the nucleus from the cytoplasm A double-walled structure with a space within
the walls The only known materials that can pass through
this membrane are RNA’s and some proteins that are incorporated into the nuclear structure
Chromosomes
Linear threads in the nucleus Composed of protein and DNA
DNA encodes the information that controls that cell’s metabolism and reproduction
DNA is considered the genetic material It serves as a template to
produce an exact copy of itself used in cell division
Humans contain 46 (23 pairs) of somatic chromosomes
DNA Structure
Consists of deoxyribose Sugar in the backbone
Phosphoric acid A phosphate in the backbone
Four nitrogenous bases Adenine, guanine, thymine, cytosine
The actual genetic code
DNA Structure
DNA looks like a twisted ladder The bases are the rungs The backbones are the sides
The backbones are made up of sugar, deoxyribose, and phosphoric acid
The backbones are twisted around each other, forming a double helix
Genes
The basic unit of heredity Made up of long sequences
of DNA on a chromosome Genes are found in pairs Some govern the number
of organs and limbs Others determine height,
skin and eye color, and gender
Nucleolus
A single spherical structure usually found in the nucleus
Composed of RNA (ribonucleic acid)
Controls protein synthesis Similar to DNA in structure Its sugar is ribose as
opposed to deoxyribose The base uracil replaces
thymine It is a single helix
DNA v. RNA
The Forms Of RNA
Messenger RNA Carries the code for specific
amino acid sequences from DNA to cytoplasm for protein synthesis
Transfer RNA Transfer amino acid groups to
ribosome for protein synthesis Ribosomal RNA
Exists in the ribosomes Thought to assist in protein
synthesis
Cytoplasm
All metabolic functions occur here
The duplication of DNA, production of hormones, and converting of sugars to starches
Anabolism The breaking of the carbon-
hydrogen bond to release the energy of glucose
Catabolism These functions are used in
energy conversion This serves to store or release
energy
Cell Membrane
A selectively permeable structure
Analogous to the skin of an organism – a limiting mechanism
Composed of lipids and membranes
Transport proteins assist in the passage of substances through the membrane and throughout the cell
Ribosomes
Function to synthesize proteins
Made of ribosomal RNA
Endoplasmic Reticulum
A connecting network between the nucleus and cytoplasm
Used to build carbohydrates and lipids and detoxification
Mitochondria
The source of energy in the cell
Contain their own DNA Cardiac muscle cells
have the greatest number of mitochondria because of their great need for energy
Golgi Apparatus
Located near the nucleus Collect molecules
produced in one part of the cell, modify, or synthesize new molecules, package and distribute them to other parts of the cells
Analogous to the digestive system
Lysosomes
Part of the intracellular digestive system Break down proteins, carbohydrates, lipids,
and nucleic acids and recycle them Analogous to the stomach
http://www.youtube.com/watch?v=ekdIEpSf-1I
Location and Function of Organelles
Cell DivisionSomatic Cells
Mitosis Each daughter cell contains the same number of
chromosomes as the parent cell This cycle has 5 phases
Four are cell-reproduction phases Interphase Prophase Metaphase Anaphase Telophase
Interphase
The period between cell division Three subphases
G1 – The first subphase where the cell spends most of its life and where it grows
S – The DNA is replicatedbut stays attached to the centromere – a region in the middle of each chromosome
G2 – The final subphase in which the organelles are reporducedSpiral filaments called chromatids reproduce
Prophase
The chromatin granules of the nucleus become organized into chromosomes
Each consist of two chomatids Chromosomes become shorter and more compact The nuclear membrane and nucleoli disappear, the
centriole divides, and two daughter cells move to opposite poles of the cell
Metaphase
The paired chromatids arrange themselves in an equatorial plane midway between the two centrioles forming the plane
Cell division can be stopped and radiation damage can be examined under a microscope
Anaphase
The chromotids are now called daughter chromsomes
They move toward their respective centrosomes
The end of their migration marks the beginning of the next phase
Telophase
Each daughter cell now contains the same genetic material as the parent cells
Two complete cells result from the cytoplasm’s becoming separated into two parts
Mitosis
http://www.cellsalive.com/mitosis.htm
The Cell Cycle
Germ Cells
Meiosis Cell division that produces germ cells or
reproductive cells Consists of two successive divisions of the
mother cell Produces four daughter cells
Contains only half the number of chromosomes present in somatic cells
Malignant Cells
Cancer cells Divide abnormally and much more
often than normal cells Differ physically from normal cells
by virtue of having an increased number of chromatin and an increased ratio of nuclear material to cytoplasm
In normal tissue, cells usually stick together
Some types of cancers metastasize by allowing cells to break free of the tumor cite
Cancer cells show increased mitotic activity
http://www.youtube.com/watch?v=rrMq8uA_6iA
http://www.youtube.com/watch?v=r_2bUhSwdvY
Normal Cells v. Cancer Cells
Cell Death - Apoptosis
http://www.youtube.com/watch?v=qjjHKDn12qI
Helpful Websites
http://www.des.umd.edu/rs/material/tmsg/rs5.html http://radtechstudy.nci.nih.gov/ http://suite101.com/article/understanding-lenzs-
law-a54846 This is actually for 50B, but thought you could use it for
Registry review later on
http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/part020-1201.html
Helpful Websites
http://www.srs.gov/general/pubs/radreport.pdf http://www.nrc.gov/reading-rm/basic-ref/
glossary/total-effective-dose-equivalent-tede.html
http://w3.health.state.ny.us/dbspace/NYCRR10.nsf/0/8525652c00680c3e85256530006531d8?OpenDocument
Helpful Websites
http://www.ucsf.edu/news/2009/12/8215/new-research-ct-radiation-exposures-risks-fuels-growing-concern
http://www.ratical.com/radiation/CNR/PP/chp2.html
http://www.umich.edu/~radinfo/introduction/source.htm
Helpful Websites
http://holbert.faculty.asu.edu/eee460/radeffects.html
http://www.radiation-scott.org/radsource/1-0.htm