What Does The Cell Look Like?

What Is A Cell? Cells Provide Structure And Function For All Organisms From Microorganisms To Human Beings. Scientists Believe That They Are The Smallest Form Of Life. Cells Are Biological Machines That Produce Proteins, Chemicals And Signals And Are Responsible For Everything That Happens In Our Bodies. What Does The Cell Look Like? Cells Have Different Shapes, Round, Flat, Long, Star Shaped, Cubic, Or Even No Shape. Most Cells Are Colorless And Transparent. The Size Of Cells Also Varies. Some Of The Smallest Are Single Celled Bacteria. They Are Too Small To Be Seen By The Naked Eye, With A Diameter Of One Millionth Of A Meter (micrometer). The Largest Cell Of A Plant Is 10-100 Micrometers In Diameter. The Largest Human Cell In Diameter Is The Egg. It Is About The Same Diameter As A Hair (80 Microns)& Nbsp; How Many Different Types Of Human Cells Are There? The Trillions Of Cells That Make Up Humans Are Organized Into About 200 Major Types. All Cells Of A Person Contain The Same Set Of Genes. Because Each Cell Type Will "turn On" Different Gene Patterns, Which Determines Which Proteins The Cell Produces. In Different Cell Types, A Unique Set Of Proteins Enables Them To Perform Special Tasks. For Example, Red Blood Cells Carry Oxygen Throughout The Body. White Blood Cells Kill Bacterial Invaders. Intestinal Cells Release Molecules That Help Digest Food. Nerve Cells Send Out Chemical And Electronic Information To Generate Thinking And Movement. Heart Cells Contract And Pump Blood In Unison& Nbsp; What Are Eukaryotic Cells And Prokaryotic Cells, And What Are Their Differences? When Classifying Cells, Scientists Can Distinguish Between Eukaryotic Cells And Prokaryotic Cells Because They Look Different. Eukaryotes Comprise Animals, Plants, Fungi And Some Unicellular Organisms. They Have Many Structures In Their Bodies, Called Organelles. The Most Prominent Organelle Is The Nucleus, Which Contains The Genetic Material Of The Cell. The Prokaryotic Cell Has No Nucleus Or Other Organelles. They Are Unicellular Microorganisms, Often Smaller Than Eukaryotic Cells. The Most Typical Are Prokaryotic Bacteria And Archaea& Nbsp; Fibroblasts Have Nuclei (blue, Round, Center), Energy Factories (green, Around The Nucleus) And Actin Cytoskeleton (red, Outermost) Dylan Burnette And Jennifer Lippincott Schwartz, Photographed By Eunice Kennedy Shriver At The National Institute Of Child Health And Human Development, National Institutes Of Health& Nbsp; What Are The Main Organelles In Human Cells& Nbsp; In Addition To The Nucleus, The Most Prominent Organelles Include Mitochondria, Which Are The Power Device Of Cells. They Convert The Energy In Food Into Adenosine Triphosphate (ATP), The Main Energy Source Of The Human Body. Ribosome: It Is A Molecular Factory For Making Proteins. Endoplasmic Reticulum (ER): It Is A Network Composed Of Interconnected Capsules, Which Processes Newly Generated Secretory And Membrane Proteins, And Produces Fatty Substances Called Lipids. Golgi Complex: It Receives Proteins And Lipids From The Endoplasmic Reticulum, Packages Them, And Delivers Them To The Final Destination Inside Cells, Inside Cell Membranes, Or Outside Cells. Lysosomes: Garbage Dumps Of Cells That Break Down Waste And Treat Or Recycle It& Nbsp; Researchers Use Fluorescent Markers To Illuminate The Complex Network Of Microtubules (yellow, Central Filament) And Actin (purple, Outermost) Fibers That Make Up The Cell Structure Torsten Wittmann Scripps Research Institute  Shooting& Nbsp; How Do Cells Move? Many Types Of Cells Can Move. Single Celled Organisms Move In Search Of Food. Even Cells In Multicellular Organisms Need To Move Around. For Example, The Cells Of The Immune System Must Move Towards The Invader. Sperm Need To "swim" To Fertilize Eggs. Cells Move In Many Ways. Some Just Float In Water Or Other Liquids. Some People Use Long And Thin Protein Flagella And Cilia To Push Themselves Forward. The Cilia Attach To The Cell Membrane And Swing Around. Some "crawling" Cells Use The So-called Amoeba Movement, In Which Cytoplasmic Protrusions Push The Cells Forward. Within Cells, Nutrients And Organelles Move Around To Perform Various Cellular Functions. This Internal Movement Is Called Cyclones, Or Cytoplasmic Flow. The Internal Structure Of A Cell Is Called Cytoplasm, Which Generates A Directional Flow Force To Push The Substances In The Cell To Flow Around. Scientists Can Better Understand How Cells Work By Studying Cell Movement, Including How Cancer Cells Move From One Tissue To Another, And How White Blood Cells Move To Heal Wounds And Attack Invaders& Nbsp; How Do Scientists Study Cells? Cell Biologists Rely On A Range Of Tools To Observe The Body And Examine Cells. Imaging Technology Can Magnify Organelles And Track Cells During Cell Division, Growth, Interaction And Other Important Tasks. Biochemical Or Genetic Tests Enable Researchers To Study Cells' Responses To Environmental Stresses, Such As Elevated Temperatures Or Toxins. These Tests Can Also Use Fluorescent Tags And Other Chemicals To Label Specific Proteins, So That Scientists Can Visually See The Proteins Working In Cells. Use Advanced Computing Tools, And Then Integrate And Analyze All The Data. This Is A Dividing Pig Cell. The Image Shows Chromosomes (purple, Short, Middle) And Cytoskeleton (green, Fibrous, Outer). The Image Is From Nasser Rusan, National Heart, Lung, And Blood Institute, National Institutes Of Health. How Do Our Bodies Make More Cells? The Cell Divides In Two During Mitosis. Mitosis Produces Two "daughter" Cells With The Same Gene From A Single Parent Cell. Another Type Of Cell Division, Meiosis, Produces Four Daughter Cells That Are Genetically Different From Each Other And From The Original Mother Cell. Only A Few Special Cells Can Undergo Meiosis, Such As Those That Will Become Eggs In Females And Sperm In Males& Nbsp; How Do Cells Die? Cells Carry What They Need To Self Destruct. This Is Called Programmed Cell Death, Or Apoptosis. It Plays A Healthy And Protective Role In Our Body. For Example, It Helps Shape Our Fingers And Toes Before Birth And Kills Diseased Cells In Our Lives. Another Kind Of Cell Death Called Necrosis Is Unplanned And Unprotected. Necrosis May Occur After Sudden Trauma, Infection Or Exposure To Toxic Chemicals. What Are Stem Cells? Stem Cells Can Self Renew Millions Of Times, But Other Cells In The Body, Such As Muscle And Nerve Cells, Cannot. Embryonic Stem Cells Are Undifferentiated, Which Means They Can Be Transformed Into Any Type Of Cell In The Body. Tissue Specific Stem Cells (sometimes Referred To As Adult Stem Cells) Appear At The Late Stage Of Development, And They Can Also Supplement Cells. The Main Function Of Tissue-specific Stem Cells Is To Maintain And Repair Their Tissues. How Do Problems In Cells Lead To Disease? Changes In Genes Within Cells Are Called Mutations, Which Can Change The Ability Of Cells To Divide, Make Proteins, Remove Waste Or Perform Other Tasks. Excessive Gene Mutation Can Lead To Birth Defects, Cancer And Other Diseases. In Extreme Cases, Cells Damaged By Body Trauma Or Infection Can Lead To Harmful Inflammation And Organ Dysfunction. This Picture Shows The Uncontrolled Growth Of Cells In The Second Most Common Skin Cancer, Squamous Cell Carcinoma Markus Schober And Elaine Fuchs, The Rockefeller University, New York, N.Y. Laboratory& Nbsp; How Can Studying Cells Help Us Understand Human Health And Disease? Understanding How Cells Work And What Happens When They Don't Work Properly Can Teach Us The Biological Process Of Keeping Healthy. It Also Reveals New Ways To Treat Diseases. Cell Research Has Brought Cancer Treatment, Antibiotics, Cholesterol Lowering Drugs And Improved Drug Delivery Methods. However, Much Remains To Be Discovered. For Example, Understanding How Stem Cells And Some Other Cells Regenerate Can Help Us Understand How To Repair Damaged Or Lost Tissue.