1. Chapter 7 A tour of the Cell

2. What do all cells have in common? Phospholipid plasma membrane Cytoplasm Ribosomes Genetic Material (DNA) Prokaryotic CellsEukaryotic Cells Pro = before; Karyon = nucleus Cells w/o nucleus Circular DNA free in “nucleoid” region 1 – 10 micrometers in size (size of mitochondria) No membrane organelles Cell wall Ex. bacteria Eu = true; Karyon = nucleus Cells w/ nucleus Linear DNA contained in nucleus 10 – 100 micrometers in size With membrane- organelles (endomembrane system) Cell wall only in plants Ex. Plants and animal cells

3. Prokaryotic Bacteria

4. Animal Cells Plant Cells

5. Nucleus Contain DNA of eukaryotic cells Porous phospholipid membrane Inner membrane lined with intermediate filaments of the cytoplasm ER often is an extension of the nuclear membrane

6. Condensation of Eukaryotic Chromosomes Nucleosome = DNA coils around histone proteins Chromatin = supercoiled nucleosomes Looped Domains = supercoiled chromatin Chromosome = supercoiled looped domains

7. Ribosomes Assembles AA into polypeptide chain, which eventually folds into functional protein Made of rRNA and protein 2 subunits: large and small

8. Nucleolus Located inside nucleus makes ribosomal subunits by combining rRNA and proteins imported from cytoplasm subunits leaves nuclear pore and assembles into a ribosome in the cytoplasm

9. What is the endomembrane system?endomembrane system System of membrane-bound organelles in euk. cells that work cooperatively together to create secretory proteins, membrane-bound proteins, or plasma membrane proteins –Nucleus –ER –Golgi –Transport Vesicles –Lysosomes –Peroxisomes –Vacuoles –Plasma Membrane

10. Rough Endoplasmic Reticulum RER w/ bound ribosomes Space w/in ER = cisternae space Fcn: to fold and modify secretory proteins (glycoproteins) within cisternae space - attaches CHO called oligosaccharides to growing and folding polypeptide chain (2 o  3 o ) - vesicles bud off from RER and delivers glycoprotein to Golgi

11. Golgi Apparatus Accepts vesicles from RER (cis side) Adds and removes monomers to oligosach. of glycoproteins Adds “ID” tags (like phosphate groups) and uses these to “sort” proteins into different vesicles Dispatches vesicles w/glyco-proteins for shipping (trans side)

12. 3 destinations for proteins within Golgi vesicles 1)Secreted from cellSecreted 2)Remains within vesicles  vacuole, lysosome, peroxisome lysosome 3)Protein becomes part of plasma membrane

13. Lysosomes Membrane-bound sac of digestive enzymes Acidic env’t maintained by pumping H+ ions from cytoplasm Digests food, worn out cell parts, programmed cell death (webbing b/t fingers, tadpole tails)

14. Peroxisome Breaks down toxic substances in liver Breaks down fatty acids into CHO for use in CR In breakdown process, oxygen and hydrogen combine to create  H 2 O 2 Peroxide = metabolic waste

15. ER w/o ribosomes Makes lipids, oils, steroids Helps break down CHO Detoxifies drugs by adding –OH groups  water soluble toxins  flushed from body Smooth ER

16. Vacuoles Contractile vacuole - pumps excess water out for freshwater organisms Central vacuole - Stores water, organic compounds, ions, and helps increase turgor pressure in plant cells

17. Mitochondria and Chloroplasts Mitochondria -CR site -Generates ATP (usable E) from glucose Chloroplasts -PS site -Generates glucose (stored E) from inorganic compounds and light

18. Cytoskeleton Network of fibers in the cytoplasm that a) maintains cell shape/mechanical support b) anchors organelles c) helps w/ cell motility 3 components 1) microtubules 2) microfilaments 3) intermediate filaments

19. Microtubules Structure: Hollow tube made up of α and β tubulin polypeptide 25 nm diameter Compression Resistent  supports cell shape Forms spindle fibers for separation of chromosomes, makes up centrioles, and cilia/flagella

20. Microtubule 9 sets of 3 arrangement (ring formation) Ex. Centrioles, spindle fibers, basal body of cilia and flagella 9 + 2 arrangement (9 doublets surrounding a pair in the center) Ex. Cilia and Flagella

21. Radial Spokes and Dynein Arms of Microtubule Dynein arms “walk” along the microtubules to bend and move flagella, using ATP energy

22. Microfilaments AKA: actin fibers Structure: twisted double chain of actin protein that forms a solid rod 7 nm diameter Tension resistent (protects against “pulling” forces) Makes up microvilli core, contracts muscles, causes cytoplasmic streaming and pseudopod extensions in cellscontracts musclescytoplasmic streaming

23. Intermediate Filaments In btwn microtubules and microfilaments in size (10 nm) Fixes positions of organelles Organelles w/motor proteins can move by “walking” along intermediate filaments (as if along a track) Helps to maintain cell shape

24. Cell Wall and Plasmodesmata In plants, bacteria, protists, fungi Maintains shape, prevents excessive water uptake Cell walls are non-continuous: plasmodesmata connects cytoplasm btwn 2 plant cells and helps them communicate plasmodesmata

25. Animal Cell Junctions Tight Junctions: -Fuses cell membranes of neighboring cells; prevents leakage btwn cells (ex. Digestive tract) DesmosomesDesmosomes: AKA “anchoring” junctions -Holds together tissues under stress -Disc-shaped w/ protein fibers extended into cytoplasm Gap Junctions: Type of communicati ng junction that provides cytoplasmic channels btwn cells