2. Regents Biology Monday, 12/8 Today’s Agenda: 1. Turn in HW (Cell Craft) 2. Go over Limits To Cell Size lab 3. Lecture on viruses and bacteria 4. Time to work on HW or project Bell Ringer (Answer in your notes WITHOUT looking back at them!): 1. What are the 3 main jobs of organelles? Which organelles carry out these functions?

3. Regents Biology  Cells have 3 main jobs  make energy  need food + O 2  cellular respiration & photosynthesis  need to remove wastes  make proteins  need instructions from DNA  need to chain together amino acids & “finish” & “ship” the protein  make more cells  need to copy DNA & divide it up to daughter cells Cell Summary Our organelles do all those jobs!

4. Regents Biology cell membrane  cell boundary  controls movement of materials in & out  recognizes signals cytoplasm  jelly-like material holding organelles in place mitochondria  make ATP energy from sugar + O 2 nucleus  protects DNA  controls cell ribosomes  builds proteins ER  helps finish proteins  makes membranes Golgi apparatus  finishes, packages & ships proteins lysosome  food digestion  garbage disposal & recycling vacuole & vesicles  transport inside cells  storage centrioles  cell division

5. Regents Biology Limit To Cell Size Lab 5 questions were graded: 1, 4, 5, 7, and 8 1. As the cube increases in size the increase in volume is greater than the increase in surface area, therefore the SA:V ratio decreases. 4. The greater the SA:V ratio, the less time it takes for diffusion to occur. 5. As cells get larger they become less efficient at transporting essential nutrients/molecules to the center and have difficulty eliminating waste products and may essentially starve or become too toxic to survive.

6. Regents Biology 7. Oddly worded question – 2 points depending on your response 8. Discuss

7. Regents Biology Ch. 19 - Viruses Overview: A Borrowed Life  Viruses called bacteriophages can infect and set in motion a genetic takeover of bacteria, such as Escherichia coli  Viruses lead “a kind of borrowed life” between life-forms and chemicals  The origins of molecular biology lie in early studies of viruses that infect bacteria © 2011 Pearson Education, Inc.

8. Regents Biology Figure 19.1 0.5 mm

9. Regents Biology Concept 19.1: A virus consists of a nucleic acid surrounded by a protein coat Structure of Viruses  Viruses are not cells  A virus is a very small infectious particle consisting of nucleic acid enclosed in a protein coat and, in some cases, a membranous envelope © 2011 Pearson Education, Inc.

10. Regents Biology Viral Genomes  Viral genomes may consist of either  Double- or single-stranded DNA, or  Double- or single-stranded RNA  Depending on its type of nucleic acid, a virus is called a DNA virus or an RNA virus © 2011 Pearson Education, Inc.

11. Regents Biology Capsids and Envelopes  A capsid is the protein shell that encloses the viral genome  Capsids are built from protein subunits called capsomeres  A capsid can have various structures © 2011 Pearson Education, Inc.

12. Regents Biology Figure 19.3 Capsomere of capsid RNA Capsomere DNA Glycoprotein Glycoproteins Membranous envelope RNA Capsid Head DNA Tail sheath Tail fiber 18  250 nm 80  225 nm 70–90 nm (diameter) 80–200 nm (diameter) 20 nm 50 nm (a) Tobacco mosaic virus (b) Adenoviruses (c) Influenza viruses(d) Bacteriophage T4

13. Regents Biology  Some viruses have membranous envelopes that help them infect hosts  These viral envelopes surround the capsids of influenza viruses and many other viruses found in animals  Viral envelopes, which are derived from the host cell’s membrane, contain a combination of viral and host cell molecules © 2011 Pearson Education, Inc.

14. Regents Biology  Bacteriophages, also called phages, are viruses that infect bacteria  They have the most complex capsids found among viruses  Phages have an elongated capsid head that encloses their DNA  A protein tail piece attaches the phage to the host and injects the phage DNA inside © 2011 Pearson Education, Inc.

15. Regents Biology Overview: Masters of Adaptation  Utah’s Great Salt Lake can reach a salt concentration of 32%  Its pink color comes from living prokaryotes Ch. 27 - Prokaryotes © 2011 Pearson Education, Inc.

16. Regents Biology  Thrive almost everywhere, including places that are too:  Acidic  Salty  Cold/Hot  Most are microscopic, but what they lack in size they make up for in #s  There are more in a handful of fertile soil than the number of people who have ever lived  Prokaryotes are divided into two domains:  Bacteria  Archaea © 2011 Pearson Education, Inc. Prokaryotes

17. Regents Biology Concept 27.1: Structural and functional adaptations contribute to prokaryotic success  Most likely 1 st organisms on Earth  Most are unicellular, although some species form colonies  Sizes are usually 0.5–5 µm  Eykaryotic cells are usually 10–100 µm  Come in a variety of shapes, the 3 most common shapes are:  spheres (cocci)  rods (bacilli)  spirals © 2011 Pearson Education, Inc.

18. Regents Biology Cell-Surface Structures  Cell wall:  Maintains cell shape  Protects the cell  Prevents cell from bursting in a hypotonic environment  A eukaryotic cell wall is made of cellulose or chitin  Bacterial cell walls contain peptidoglycan  A network of sugar polymers cross-linked by polypeptides © 2011 Pearson Education, Inc.

19. Regents Biology  Archaea contain polysaccharides and proteins but lack peptidoglycan  Scientists use the Gram stain to classify bacteria by cell wall composition  Gram-positive bacteria have simpler walls with a large amount of peptidoglycan  Gram-negative bacteria have less peptidoglycan and an outer membrane that can be toxic © 2011 Pearson Education, Inc.

20. Regents Biology Figure 27.3 (a) Gram-positive bacteria: peptidoglycan traps crystal violet. Gram-positive bacteria Peptido- glycan layer Cell wall Plasma membrane 10  m Gram-negative bacteria Outer membrane Peptido- glycan layer Plasma membrane Cell wall Carbohydrate portion of lipopolysaccharide (b) Gram-negative bacteria: crystal violet is easily rinsed away, revealing red dye.

21. Regents Biology  Many antibiotics target peptidoglycan and damage bacterial cell walls  Gram-negative bacteria are more likely to be antibiotic resistant  A polysaccharide or protein layer called a capsule covers many prokaryotes © 2011 Pearson Education, Inc.

22. Regents Biology Figure 27.4 Bacterial cell wall Bacterial capsule Tonsil cell 200 nm

23. Regents Biology  Some prokaryotes have fimbriae, which allow them to stick to their substrate or other individuals in a colony  Pili (or sex pili) are longer than fimbriae and allow prokaryotes to exchange DNA © 2011 Pearson Education, Inc.

24. Regents Biology Figure 27.5 Fimbriae 1  m

25. Regents Biology Motility  In a heterogeneous environment, many bacteria exhibit taxis:  the ability to move toward or away from a stimulus  Chemotaxis is the movement toward or away from a chemical stimulus  Towards nutrients  Away from toxins © 2011 Pearson Education, Inc.

26. Regents Biology  Most motile bacteria propel themselves by flagella scattered about the surface or concentrated at one or both ends  Flagella of bacteria, archaea, and eukaryotes are composed of different proteins and likely evolved independently © 2011 Pearson Education, Inc.

27. Regents Biology Figure 27.6 Flagellum Hook Motor Filament Rod Peptidoglycan layer Plasma membrane Cell wall 20 nm

28. Regents Biology Evolutionary Origins of Bacterial Flagella  Bacterial flagella are composed of a motor, hook, and filament  Many of the flagella’s proteins are modified versions of proteins that perform other tasks in bacteria  Flagella likely evolved as existing proteins were added to an ancestral secretory system  This is an example of exaptation, where existing structures take on new functions through descent with modification © 2011 Pearson Education, Inc.

29. Regents Biology Internal Organization and DNA  Prokaryotic cells usually lack complex compartmentalization  Some prokaryotes do have specialized membranes that perform metabolic functions  These are usually infoldings of the plasma membrane © 2011 Pearson Education, Inc.

30. Regents Biology  The prokaryotic genome has less DNA than the eukaryotic genome  Most of the genome consists of a circular chromosome  The chromosome is not surrounded by a membrane; it is located in the nucleoid region  Some species of bacteria also have smaller rings of DNA called plasmids © 2011 Pearson Education, Inc.

31. Regents Biology Figure 27.8 Chromosome Plasmids 1  m

32. Regents Biology  There are some differences between prokaryotes and eukaryotes in DNA replication, transcription, and translation  These allow people to use some antibiotics to inhibit bacterial growth without harming themselves © 2011 Pearson Education, Inc.

33. Regents Biology Reproduction and Adaptation  Prokaryotes reproduce quickly by binary fission and can divide every 1–3 hours  Key features of prokaryotic reproduction:  They are small  They reproduce by binary fission  They have short generation times © 2011 Pearson Education, Inc.

34. Regents Biology  Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries © 2011 Pearson Education, Inc.

35. Regents Biology Figure 27.9 Coat Endospore 0.3  m

36. Regents Biology  Their short generation time allows prokaryotes to evolve quickly  For example, adaptive evolution in a bacterial colony was documented in a lab over 8 years  Prokaryotes are not “primitive” but are highly evolved © 2011 Pearson Education, Inc.