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