Cytology The study of cells

Cell Theory All living things are composed of cells Cells are basic units of life Earth 10-20 billion years ago---life 3.5 billion years ago Life: 1996 meteorite w/amino acids landed near mexico---could have started life supernatural (no scientific explanation), organic chemical evolution New cells come from pre-existing cells

There’s always exceptions to the rule: BUT…. How did the very first cell get here???? Viruses lack typical cell structure, use host cells to reproduce Mitochondria and chloroplasts have their own genetic material/can reproduce independent of cell

Then what do they have? Prokaryotic Cells Small Simple No Nucleus No membrane bound organelles Then what do they have? Cell membrane Cytoplasm Monera Same family as bacteria responsible for cholera Plaque Bacteria, algae DNA: Circular, not in nucleus Ribosomes Bacteria

Prokaryotic Structure cytoplasm with ribosomes DNA cell membrane

Organelle: Eukaryotic Cells More complex Larger Plant cells DNA in nucleus in long strands Contain membrane bound organelles Specialized compartment with a specific function Organelle: DNA coiled Plant (euglena), animal (cheek cell), fungi (yeast), protist Animal cells Fungi (Yeast)

Pro---No Eu---Do REMEMBER YOU ARE EUKARYOTIC!

Organelles HW: give cell diagrams, label ---only checking in class

Oh where, oh where do we find cell organelles? Cytoplasm (protoplasm): The fluid inside a cell, but outside the nucleus “Holds” organelles in place Site of cellular chemical reactions Link work at school? Define organelles: “specialized organ” Elodea, chloroplasts moving---transport material within cell, inc. rate of diffusion Cyclosis: Streaming movement of cytoplasm

Cytoplasm Cytoplasm

Nucleus: Controls cell processes Contains hereditary information (DNA) Nucleolus: Ribosome formation Chromatin (uncoiled DNA)

Nucleus Nucleolus Nucleolus Nucleus

Mitochondria Release energy from food to make useable energy (ATP) Outer and inner membranes Inner membrane folded (Increased surface area) Found in: Animal cells Cellular respiration……..divide process similar to binary fission….asexual?!?!?! Art gallery example---surface area---paper/cardboard box Which cells likely to have lots of mitochondria? Plant cells Contain their own DNA!

Mitochondria Mitochondria

Chloroplasts Site of photosynthesis Convert light energy to chemical bond energy Only in plant cells Exceptions to plants: euglena-- Protist kingdom, blue green algae –monera NOT fungi (have cell walls) Endosymbiotic theory: mitochondria/chloroplasts descendents of anaerobic prokaryotes---formed relationship w/aerobic eurkaryotes (+,+) Over time, nucleus took over more and more of the DNA from mito/chloroplasts Contain their own DNA!

Chloroplasts Animal cells don’t have chloroplasts!!!

Ribosomes Site of protein synthesis Can be free in cytoplasm or attached to endoplasmic reticulum

Ribosomes Ribosomes

Endoplasmic reticulum “ER” A system of membranous sacs Assembles components of cell membrane Protein modification Protein folding Defect here may be involved in alzheimers, diabetes, ALS

Rough endoplasmic reticulum Protein synthesis Rough: Ribosomes RER Smooth endoplasmic reticulum Protein synthesis and transport----cell’s highway Contains enzymes needed for cell Ex. enzymes for lipid synthesis Smooth: No ribosomes SER

Review parts of nucleus…show attached, transport mat’ls from nucleus

Rough ER Smooth ER Smooth ER Rough ER

Golgi Who? apparatus, complex, bodies Marks proteins for use in cell or export (adds address w/proteins) Produces digestive enzymes Protein sorting, post translational modification Autolysis (break down of old cell parts)

Golgi body Golgi body

Some proteins packaged for internal use

assorted vesicles Golgi body smooth ER rough ER DNA instructions for building protein chains leave the nucleus and enter the cytoplasm. Chains are assembled on ribosomes in cytoplasm.

Lysosome Packaged by Golgi body Membranous sac filled with digestive enzymes “Suicide Sacs”

Lysosomes

Lysosome Lysosome

Vacuole Cell storage: Water Food Wastes Plants: Water—pressure in vacuoles from liquid allows them to support heavy structures Food, water----maintain homeostasis Plants: One large central vacuole Animals: Few small vacuoles Vacuoles are crucial in single-celled organisms to maintain homeostasis

Vacuole

Cell Wall Provides support Provides shape Made up mostly of cellulose Animal cells don’t have! Fungi kingdom—cell wall, some monera (algea) Masons/cement blocks arranged same as cell walls Indigestible----egestion

Cell wall Animal cells don’t have cell walls!!!

Centriole Used in cell division Animal cells only Microtubules used in cell division, right outside nuclear membrane Talk about later

Plant cells don’t have centrioles!!! Centriole

Cilia: Flagella: Locomotion Moving substances across surface of cell Humans: cilia in lungs to rid dirt, cilia in ovaries to sweep out egg

Cilia

Plasma membrane/cell membrane Plant AND animal cells Controls what goes in and out of cell Protection Support

Cell membrane Cell membrane

Lipid Bilayer Main component of cell membranes lipid bilayer fluid

Cell (Plasma) Membrane Structure ☼ 2 layers of phospholipids (lipids with phosphate groups attached) ☼ Proteins - embedded in lipid layers- for transport or receptors ☼ Carbohydrates - attached to surface proteins or lipids – markers ☼ Lipids & Proteins can move along membrane = “Fluid” FLUID MOSAIC MODEL of Cell Membrane

Receptors recognize substances (hormones etc.) Turn something on inside cell…like light switch Receptors recognize substances (hormones etc.) and allow them to enter cell

How are plant and animal cells different? Plant Cells Cell Walls Chloroplasts Centrioles Golgi Bodies Vacuoles NO YES NO YES YES NO 1 or 2 100 + Many Small Few Large

Cell wall Chloroplasts Cell membrane Vacuole Mitochondria Lysosome Ribosomes Golgi body Nucleus Rough endoplasmic reticulum Nucleolus Smooth endoplasmic reticulum Cytoplasm

Cilia Golgi body Cell membrane Centrioles Smooth endoplasmic reticulum Lysosomes Free ribosomes Mitochondria Nucleolus Rough endoplasmic reticulum Nucleus Cytoplasm

Staining Techniques Applying stain makes cell structures more visible Can be useful in identifying organisms Example: Methylene blue Iodine starch indicator (blue black in presence of starch)

Which plant, which animal (green chloroplast) importance of stains Note the large nucleus and nucleolus in the center of the cell, mitochondria (red) and plastids in the cytoplasm

Organization of Life Organelle Cell Tissue Organ Organ System Organism