Preview Questions

1. Preview Questions • Describe a typical prokaryote cell. • Describe a typical eukaryote cell. • Explain the differences between a prokaryote and eukaryote cell. • How has the simplicity of prokaryotes affected their ability to adapt and survive / thrive? • How has the complexity of eukaryotes affected their ability to adapt and survive / thrive?

2. Cell theory • All living things are made of cells • Cell can only come from other cells • All functions of a living thing are carried out in cells • Reminder: the functions of living things are: respiration, metabolism, growth, adaptations to the environment, reproduction, homeostasis and interdependence

3. Different Types of Cells An overview

4. There are two main groups of cells, prokaryotic and eukaryotic cells. Similarities: all are alive, all belong to one of the five life kingdoms. Differences: appearance, structure, reproduction, and metabolism. • biggest differences are between cells of different kingdoms . 

5. Where to begin? • Prokaryotes are simpler, so we will start with them. VS Diagrams courtesy - http://www.cod.edu/people/faculty/fancher/ProkEuk.htm

6. Prokaryotes were formed about 3.5 billion years ago,or 3,500,000,000 years

7. Prokaryotesfrom the Greek meaning “before nuclei”

8. Why “before nuclei?” • Prokaryotic cells have no nucleus. • Prokaryote’s DNA is circular (it has no ends). • Small circlets of DNA are called Plamids. • Prokaryotic DNA is “naked” – it has no histones associated with it and does NOT form chromosomes

9. bacteria Cyanobacteria also known as blue-green algae All Prokaryotes are in the monera kingdomdomains Bacteria and Archaea

10. Prokaryote Characteristics • Simplest organisms: Very small size. • Lack membrane-bound organelles inside the cell • have few internal structures that are distinguishable under a microscope. • genetic information is in a circular loop called a plasmid (instead of having chromosomal DNA) • Strong cell walls: resistant to environmental changes

11. Size • Bacterial cells are very small, • about 1-2µm in diameter and 10 µm long • One micrometer = 1/1000 mm. • Imagine looking at a dime from its thinnest side and trying to slice it into a thousand pieces; that is the same as 1 µm.

12. 2. Lack membrane-bound organelles inside the cell

13. 3. have few internal structures that are distinguishable under a microscope. http://www.umanitoba.ca/science/biological_sciences/lab3/biolab3_2.html#Examine

14. 4. genetic information is in a circular loop called a plasmid • E. coli cell dividing. • E. Coli Grows in human intestine; • Has a single, circular chromosome • contains DNA as plasmids • Plasmids are extra-chromosomal DNA http://www.bio.mtu.edu/campbell/prokaryo.htm

15. 5. Strong cell walls: resistant to environmental changes

16. Bacterial Structure

17. 3 basic shapes Cocci - sphereBacilli - rodsSpirilla – spirals 2 basic groupings Staph - in clustersStrep - in chains Spiral Rod shaped Spherical Shapes This spiral shaped bacteria is the causitive agent of syphilis Treponema pallidum Streptococcus sp. Chains of nearly-spherical bacteria.From The Rockefeller University.

18. Replication • Binary fission • one cell splits into two cells, see diagram • offspring are genetically identical to parent

19. Bacterial conjugation • a form of sexual reproduction where bacteria exchange genetic information before dividing • offspring have new genes (and new traits) Figure 1. Schematic drawing of bacterial conjugation. 1- Donor cell produces pilus; 2- Pilus attaches to recipient cell, brings the two cells together; 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipent cell; 4- Both cells recircularize their plasmids, synthesize second strands, and reproduce pili. Both cells are now viable donors. http://parts.mit.edu/igem07/index.php/Boston_University/Conjugation

20. Transformation • bacteria incorporate genes from dead bacteria • Transduction • viruses insert new genes into bacterial cells. • This method is used in biotechnology to create bacteria that produce valuable products such as insulin

21. Movement Some prokaryotes can't move, while others have long threadlike flagella. If bacteria doesn’t move, how does it get from person to person? E.Coli flagella

22. Prokaryote Functions • decomposers • agents of fermentation • play important roles in digestive systems • involved in many nutrient cycles • ex: the nitrogen cycle, which restores nitrate into the soil for plants. • diverse array of metabolic functions. • For example, some bacteria use sulfur instead of oxygen in their metabolism.

23. Bacteria images / resources • http://www.ulb.ac.be/sciences/biodic/ImBacterie2.html • http://www.buckman.com/eng/micro101/bacteria.htm • Discovery school video: Understanding Bacteria

24. Eukaryotes From the Greek for “true nucleus”

25. Plant (elodea) animal cells (blood vessel lining) Example cells from the plantae and animalia kingdoms

26. Eukaryote characteristics All eukaryotes have … 1) A Cell membrane 2) A Central nucleus 3) Organelles in cytoplasm (like ER, vacuoles, mitochondria, etc.)

27. Theories of the Origin or organelles • Symbiosis: two organisms live closely together • Endosymbiosis: one organism lives inside another (bacteria in us) Theory explaining why mitochondria and chloroplasts are found in cells: • It's thought that mitochondria (m) and chloroplasts (c) were types of prokaryotic cells that lived inside other cells. The m & c helped keep the cell alive and so were retained. • Evidence on relationship of mitochondria and chloroplasts to prokaryote cells: • a. mitochondria and chloroplasts are both surrounded by double membranes (like bacteria are). • b. mitochondria and bacteria have similar size. • c. mitochondrial ribosomes resemble bacterial ribosomes. • d. mirochondria and chloroplast DNA is circular like bacteria.

28. size and shape are related tocell function. For Example: 2. 1. 3. 4. 5.

29. Structure – animal cell

30. Structure – plant cell

31. *Mitosis – body cells *Meiosis – gametes (egg & sperm) reproduction

32. Movement Internal • The centriole • The cytoskeleton • Actin and tubulin proteins External 4. Flagella 5. cilia 1. 2. 3. 4. 5.

33. images • http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm • http://www.cellbio.com/images.html

34. Review

35. Prokaryote & Eukaryote similarities Both have • DNA • A cell membrane • Ribosomes • Diverse forms (meaning a lot of shapes and sizes)

36. Prokaryotes & Eukaryotes differences **Organelles are tiny structures inside cells that do a certain job.

37. Complete this Vinn Diagram worksheet and turn it in Eukaryote Prokaryote Write the things that are Different here Write the things that are Different here Write things that are the Same here

39. Review Questions • Describe a typical prokaryote cell. • Describe a typical eukaryote cell. • Explain the differences between a prokaryote and eukaryote cell. • How has the simplicity of prokaryotes affected their ability to adapt and survive / thrive? • How has the complexity of eukaryotes affected their ability to adapt and survive / thrive?