Essential knowledge 2.A.3

1. Essential knowledge 2.A.3 • Organisms must exchange matter with the environment to grow, reproduce and maintain organization • A. molecules and atoms from the environment are necessary to build new molecules • Carbon moves from the environment to organisms where it is used to build carbohydrates, proteins, lipids or nucleic acids. Carbon is used in storage compounds and cell formation in all organisms • Nitrogen moves from the environment to organisms where it is used in building proteins or nucleic acids. Phosphorus moves from the environment to organisms where it is used in nucleic acids and certain lipids

2. Essential knowledge 2.A.3 • Organisms must exchange matter with the environment to grow, reproduce and maintain organization • B. surface area-to-volume ratios affect a biological system’s ability to obtain necessary resources or eliminate waste products • 1. As cells increase in volume, the relative surface area decrease and demand for material resources increases; more cellular structures are necessary to adequately exchange materials and energy with the environment. These limitations restrict cell size. • 2. The surface area of the plasma membrane must be large enough to adequately exchange materials; smaller cells have a more favorable surface area-to-volume ratio for exchange of materials with the environment

3. Essential knowledge 4.A.2 • The structure and function of subcellular components, and their interactions, provide essential cellular processes

4. Essential knowledge 2.B.3 • Eukaryotic cells maintain internal membranes that partition the cell into specialized regions • A. internal membranes facilitate cellular processes by minimizing competing interactions and by increasing surface area where reactions can occur B. Membranes and membrane –bound organelles in eukaryotic cells localize and compartmentalize intracellular metabolic processes and specific enzymatic reactions C. Archaea and Bacteria generally lack internal membranes and organelles and have a cell wall

5. Essential knowledge 1.B.1 • Organisms share many conserved core processes and features that evolved and are widely distributed among organisms today • A. Structural and functional evidence supports the relatedness of all domains • B. Structural evidence supports the relatedness of all eukaryotes

6. Essential knowledge 4.B.2 • Cooperative interactions within organisms promote efficiency in the use of energy and matter • A. organisms have areas or compartments that perform a subset of functions related to energy and matter, and these parts contribute to the whole • At the cellular level, the plasma membrane, cytoplasm and, for eukaryotes, the organelles contribute to overall specialization and functioning of the cell • Within multicellular organisms, specialization of organs contributes to the overall functioning of the organism. • Interactionsamong cells of a population of unicellular organisms can be similar to those of multicellular organisms, and these interactions lead to increased efficiency and utilization of energy and matter

7. Overview: The Importance of Cells • All organisms are made of cells • The cell is the smallest unit of living matter • The cell is the basic unit of structure and function

8. Cell structure is correlated to cellular function

9. Cell Theory • Schleiden, Schwann, and Virchow • All organisms composed of cells (Schleiden-plants; Schwann-animals) • Cells are the basic unit of structure and function in organisms (Virchow)

10. To study cells, biologists use microscopes and the tools of biochemistry

11. Microscopy • Scientists use microscopes to visualize cells too small to see with the naked eye

12. Light microscopes (LMs) • Pass visible light through a specimen • Magnify cellular structures with lenses • Magnify objects up to ~1000-1500X

13. Different types of microscopes • Can be used to visualize different sized cellular structures Unaided eye

14. Electron microscopes (EMs) • Focus a beam of electrons through a specimen (TEM) or onto its surface (SEM)

15. The scanning electron microscope (SEM) provides for detailed study of the surface of a specimen (~60,000X)

16. The transmission electron microscope (TEM) provides for detailed study of the internal ultrastructure of cells (1-300,000X)

17. Natural laws limit cell size • Carrying out cellular metabolism sets limits on the size of cells • A cell must have enough surface area to obtain adequate nutrients and dispose of wastes

18. Cell Size • Most much smaller than one millimeter (mm) • Some as small as one micrometer (mm) • Size restricted by Surface/Volume (S/V) ratio • Surface is membrane, across which cell acquires nutrients and expels wastes • Volume is living cytoplasm, which demands nutrients and produces wastes • As cell grows, volume increases faster than surface

19. A smaller cell has a higher surface to volume ratio, which facilitates the exchange of materials into and out of the cell

20. Cell Types Two types of cells make up every organism • Prokaryotic lack a membrane enclosed nucleus • Eukaryotic have a nucleus

21. Comparing Prokaryotic and Eukaryotic Cells • All cells have several basic features in common • They are bounded by a plasma membrane • They contain a semifluid substance called the cytosol or cytoplasm • They all have ribosomes

22. Prokaryotes • Prokaryotic cells • Have their DNA located in a region called the nucleoid • Contain single chromosome and smaller circular pieces of DNA called plasmids

23. Prokaryotes • Divided into two groups based on nucleic acid base sequence differences • Domains Bacteria and Archaea • Bacteria cause disease, but also are important to environment as decomposers and for manufacturing products

24. Bacterial shapes • Bacillus - rod-shaped • Coccus - spherical-shaped • Bacilli and cocci can occur in pairs (diplo-) or chains (strepto-) • Cocci can occur in clusters (staphlyo-)

25. Prokaryotes - Bacteria • Have ribosomes, plasma membrane, but lack other organelles • Have rigid cell wall made of peptidoglycan • Some have capsule (glycocalyx) that surrounds cell wall to protect against drying out or resist host’s immune system, and helps to attach to surfaces • Flagella help in movement • Sex pili are used to exchange DNA between bacteria

26. Archaea • Prokaryotes • Cell wall composed of polysaccharides and proteins, not peptidoglycan • Base sequences of DNA and RNA more similar to eukaryotes than other bacteria • May have been first types of cells to evolve

27. Eukaryotes • Contain a true nucleus, bounded by a membranous nuclear envelope • Are generally quite a bit bigger than prokaryotic cells

28. Eukaryotes • Eukaryotic cells have internal membranes that compartmentalize their functions and partition the cytoplasm into compartments (organelles) • Specific and different chemical conditions can be maintained inside each organelle allowing metabolic processes that require different conditions to occur simultaneously inside the cell

29. Many enzymes essential to metabolic processes are part of organelle membranes • Without internal membranes, eukaryotic cells would probably not have enough membrane surface area to meet their metabolic needs

30. Plant and animal cells • Have most of the same organelles: • Nucleus • Golgi apparatus • Mitochondria • Endoplasmic reticulum • Plasma membrane • Ribosomes • Peroxisomes • Cytoskeleton

31. Plant and animal cells have organelles not found in the other • Plants have a large vacuole/tonoplast, chloroplasts, and a cell wall

32. The Nucleus: Genetic Library of the Cell • The nucleus contains most of the genes in the eukaryotic cell, and is the genetic control center in eukaryote cells • Contains nuclearenvelope - double membrane with nuclear pores • DNA contained in long fibers called chromatin • Chromatin coils to form chromosomes during cell division

33. The nuclear envelope • Encloses the nucleus, separating its contents from the cytoplasm

34. Ribosomes: Protein Factories in the Cell • Ribosomes • Are particles made of ribosomal RNA and protein • Occur freely in cytoplasm or attached to theendoplasmic reticulum

35. Carry out protein synthesis

36. Endomembrane System Many of a cell’s organelles are formed of interrelated membranes and makeup a network called the endomembrane system • These organelles work together in the synthesis, storage, and export of molecules within the cell • Composed ofnuclear envelope, rough and smooth endoplasmic reticulum, golgi apparatus, lysosomes and vacuoles/vesicles

37. The Endoplasmic Reticulum: Biosynthetic Factory • The endoplasmic reticulum (ER) • Forms vesicles that transport substances to other parts of the cell, particularly the golgi

38. The ER membrane • Is continuous with the nuclear envelope

39. There are two distinct regions of ER • Rough ER, which contains ribosomes, and is made of interconnected flattened sacs, continuous with nuclear membrane

40. Functions of Smooth ER • The smooth ER • Synthesizes lipids (fatty acids, phospholipids, steroids) • Metabolizes carbohydrates in liver cells • Detoxifies poison in liver cells

41. Functions of Rough ER • The rough ER • Has bound ribosomes • Produces proteins to be secreted and makes membranes for other organelles, which are distributed by transport vesicles • Proteins made by ribosomes on surface of RER and passed into inner compartment of ER where they are modified

42. The Golgi Apparatus: Shipping and Receiving Center • The Golgi apparatus • Receives many of the transport vesicles produced in the rough and smooth ER • The side that “receives” vesicles from the ER is called the cis face, and the side that “ships” products is known as the trans face

43. Functions of the Golgi apparatus include • Modification of the products of the rough ER (sort, modifies, labels, packages molecules into transport vesicles) • Manufacture of certain macromolecules (synthesizes polysaccharides from simple sugars and attaches proteins or lipids to form glycoproteins or glycolipids)

44. Lysosomes: Digestive Compartments • A lysosome • Is a membranous sac of hydrolytic enzymes • Can digest all kinds of macromolecules by fusing with a food vacuole and digesting nutrients • Recycle cellular material and destroy nonfunctional organelles

45. Lysosomes carry out intracellular digestion by fusing with vacuoles that have engulfed food or harmful bacteria (phagocytosis)

46. Autophagy - lysosomes fuse with vesicles to digest and recycle damaged organelles

47. Lysosomes function in apoptosis or programmed cell death

48. Peroxisomes • Peroxisomes are organelles that contain oxidative enzymes, such as oxidase, ureate oxidase, and catalase. • They may resemble a lysosome, however, they are not formed in the Golgi complex. • Peroxisomes are distinguished by a crystalline structure inside a sac. Peroxisomes function to rid the body of toxic substances like hydrogen peroxide, or other metabolites.

49. They are self replicating, like the mitochondria. Components accumulate at a given site and they can be assembled into a peroxisome. They enlarge and bud to produce new peroxisomes. • In plant cell, peroxisomes oxidize fatty acids into molecules that are converted to sugars

50. Vacuoles: Diverse Maintenance Compartments • Vacuoles contain membranes and are used to store substances • They can store water, sugar, salts, pigments as well as waste products and toxins