Unit 3: Microscopes, cells and Viruses

1. Unit 3: Microscopes, cells and Viruses pp. 191-200

2. Modern Microscopes Compound light microscope – Contain more than one ______ and uses _________ bent through _________ to magnify objects. Type of microscope used in the classroom, ours magnifies up to 430 times, others can magnify up to a 1000 times lens light rays glass

3. Electron microscope – Uses magnets to aim a beam of ________ at thin slices of cells. . Offers the advantage of much greater ____________. There are 4 types of electron microscopes: scanning electron microscope or SEM - traces the ___________ of the specimen and forms a 3D image electrons magnification surface

4. transmission electron microscope or TEM - aims electron beam through specimen. Used to examine ____________cell structures. Can magnify up to 500,000X Disadvantages of these two: specimen must be kept in a ____________; therefore must be ____________________ internal vacuum dead

5. scanning tunneling electron microscope (STM)- involves bringing the charged tip of a probe extremely close to the specimen so that the electrons “tunnel” through gaps between the specimen & the tip. Can create 3D computer images of objects as small as atoms & can be used on living specimens. • atomic force microscope (AFM)- measures various forces between the tip of a probe and the cell surface. Creates a visual image of a cell using a microscopic sensor that scans the cell

6. What about Viruses? Are They Alive? Based on what we learned in Unit 1, viruses would be considered non-living because they do not exhibit all the characteristics of life: • Do not contain____________ for ____________ • Not made of ________; lack a ______________ • Do contain______________________________ • Cannot _____________ without a ________ cell • Typically referred to as a ______________ or __________ enzymes metabolism cells Cell membrane Genetic material reproduce host particle virion

7. Structures of Viruses The following structures are found in all viruses: • Genetic material- The genome of a virus may be either ____ or ____, but never both. It can be ____________ or ________________, _________________ or ____________. DNA RNA Single-stranded circular Double-stranded linear

8. Protein coat- The DNA or RNA is surrounded by a protein coat called a capsid. The proteins making up the capsid are known as ___________ and play an important role in the _____________ of the virus. In addition, the capsid has ___________ ID tags known as _______________ which can __________ to enable the virus to escape detection by a host cell’s immune system. capsomeres pathogenicity carbohydrate glycoprotein mutate

9. The following additional structures maybe present: • Viral envelope- Many viruses have an outer membrane known as an envelope. A viral particle “steals” the components for its envelope from the host cell membrane, so a viral envelope is primarily composed of _________________. It aids in the attachment of the virus to the host cell, but a virus enclosed by an envelope is also more sensitive to ______________. phospholipids drying

10. Tail Fibers- Viruses that infect _________ are known as ____________. They have “tail fibers” to aid in attachment. • Examples of viruses with envelopes are: _________________________________ bacteria bacteriophages HIV, flu virus, cold virus

11. shape The ____________ of surface _______________ on a virus fits perfectly with the proteins embedded in the host _______ ________________. As a result, a virus can only infect certain cell types of certain species. proteins cell membrane Surface protein or glycoprotein Protein capsid Viral DNA or RNA Phospholipid envelope Enveloped Virus Naked Capsid Virus

12. Viral Reproduction Two ways viruses reproduce using a host cell • Lytic infection- _____________ cycle in which viruses ____________ host cell DNA.Examples are _________________________ ___________ • Lysogenic infection - _____________ cycle in which viral DNA is incorporated into ________________. Examples are __________________ symptomatic destroys Cold, flu, rabies, measles, etc… most viruses asymptomatic Host cell DNA HIV, chicken pox virus

13. Viral Reproduction There are two initial steps that are common to all types of viral infections: • Virus attaches to _____________ of _____________. • Virus releases____________ into cell, either by _______________ typically through ____________ or ___________ genetic material into it. Cell membrane host Genetic material Entering cell endocytosis injecting

14. Bacteria Bacteria make up two kingdoms, the ____________ and ____________. In this unit, we will focus on the kingdom that has the greater impact on our lives, the ________. • _______________&_________________ Archaebacteria Eubacteria Eubacteria prokaryotic unicellular

15. Cell Structures • Cell wall composed of ________________ • __________________________ • ____________________ • ________________________ • Found in region known as ___________ • ____________________ • ____________________ • ____________________ peptidoglycan Eubacteria only DNA Single, circular chromosome nucleoid Cell membrane ribosomes Cytosol — “cell gel” or fluid

16. Most bacteria are motile and have one or more ______________. • Many have hair-like appendages called _________ that allow bacteria to ________ to surfaces or other _________ • Some bacteria have an outer _________; helps bacterial cells attach to a substrate or deter the host’s infection-fighting cells. flagella fimbriae bacteria adhere capsule

17. Eukaryotic cell structures

18. What’s inside a cell? Cell organelles which means “little organs” 1st a little clarification of a couple of terms: _______________- includes the ___________ or “cell gel” and the ________ cytoplasm cytosol organelles

19. Nucleus • _____________ of the cell. Genetic information stored as ____________, which is _______wrapped in ________________. Control center chromatin DNA protein Found in Both Plants & Animals

20. Nucleolus • Small, dense region in the nucleus. Site of ________________ production ribosome Found in Both Plants & Animals

21. Nuclear Envelope • Double _________________ membrane. Has nuclear ___________ which allow _______ to leave the nucleus phospholipid pores RNA Found in Both Plants & Animals

22. Ribosomes • Tiny, granular organelles located on _________________ or suspended in _________. Site of _________________. All cells (pro & euk) have ribosomes. Endoplasmic Reticulum cytosol protein production Found in Both Plants & Animals

23. Rough Endoplasmic Reticulum • Extensive network continuous with _________________. Called “rough” because it has ________________ all along the membrane. Function of the rough ER is to _____________________. Most of these proteins are packaged into _____________ (like bubbles or sacs) and shuttled to the ____________ nuclear envelope ribosomes modify & transport proteins vesicles Golgi apparatus Found in Both Plants & Animals

24. Smooth Endoplasmic Reticulum • Similar to rough ER in structure, except that it lacks ___________. The smooth ER: 1. manufactures ______, 2. breaks down _______, 3. detoxifies ________, and 4. _____________. ribosomes lipids glycogen poisons stores calcium Found in Both Plants & Animals

25. Golgi Apparatus • Flattened, round sacs that look like a sack of ________________. Receives, modifies, and ships products by way of ___________ into the ____________________________ pancakes vesicles cytosol → cell membrane_ Found in Both Plants & Animals

26. Lysosome • Found in __________ cells only. Round sacs containing __________ that _______________ and ______________ used cell components. Also used as defense against _______ and _______________ animal enzymes break down recycle bacteria viruses

27. Vacuole • Sacs that may be used as storage for _______, _________, _________________, or wastes. Plants have a large central vacuole. water Salts, proteins carbohydrates

28. Mitochondria • Double-walled organelle with inner folds ____________. ____________Uses _______ to manufacture energy in the form of ______. Mitochondria have their own _______. to increase surface area glucose ATP DNA

29. Chloroplast • Found in ______ cells. Contain __________ (green pigment) and their own ______. Chloroplasts harvest energy from the ____ to produce ____ through __________. plant chlorophyll DNA sun glucose photosynthesis

30. Centrioles • Found in _________ cells only. Bundles of _________________that play a role in _________________ animal microtubules cell division

31. Cytoskeleton microtubules • Composed of protein fibers known as _______________ and ______________. Anchor _______________ and provide ______________. Also provide motility for some cells in the form of ___________ or ____________. More extensive cytoskeleton found in __________ cells. microfilaments organelles structure cilia flagella animal

32. Cell Wall Cell walls are the outermost boundary in __________, _______, and ___________. They are not found in _____________________. The primary function of the cell wall is to provide ___________________________. The cell wall does not regulate what _________________________ the cell. 1. Cell walls of plants are composed of ____________ 2. Cell walls of fungi are composed of _____________ bacteria plants fungi Animal cells Structure and support Enters and leaves cellulose chitin

33. Cell Membrane Everycell is surrounded by a cell membrane made of ___________________. The cell membrane is selectively permeable which means ____________________________________________. This characteristic is critical in helping the cell maintain _______________. The cell membrane is also called the ____________________ membrane Phospholipid bilayer It only allows certain substances in and certain out. homeostasis Plasma