Unit 3: Microscopes, cells and Viruses pp. 191-200
Modern Microscopes Compound light microscope – Contain more than one light rays lens ______ and uses _________ glass 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
Electron microscope – Uses magnets to aim a electrons beam of ________ at thin slices of cells. . Offers the advantage of much greater ____________ . There are magnification 4 types of electron microscopes: scanning electron microscope or SEM - traces the ___________ of surface the specimen and forms a 3D image
transmission electron microscope or TEM - aims electron beam through specimen. Used to examine internal ____________ cell structures. Can magnify up to 500,000X Disadvantages of these two: specimen must be kept in a vacuum ____________ ; therefore must be dead ____________________
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
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 ____________ enzymes metabolism • Not made of ________; lack a ______________ cells Cell membrane • Do contain______________________________ Genetic material • Cannot _____________ without a ________ cell reproduce host • Typically referred to as a ______________ or particle __________ virion
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. DNA RNA It can be ____________ or Single-stranded ________________, _________________ circular Double-stranded or ____________. linear
• 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 capsomeres play an important role in the _____________ of the virus. In addition, pathogenicity the capsid has ___________ ID tags carbohydrate known as _______________ which can glycoprotein __________ to enable the virus to escape mutate detection by a host cell’s immune system.
The following additional structures may be 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 phospholipids aids in the attachment of the virus to the host cell, but a virus enclosed by an envelope is also more sensitive to ______________. drying
• Tail Fibers - Viruses that infect _________ bacteria are known as ____________. They have bacteriophages “tail fibers” to aid in attachment. • Examples of viruses with envelopes are: _________________________________ HIV, flu virus, cold virus
shape proteins The ____________ of surface _______________ on a virus fits cell perfectly with the proteins embedded in the host _______ membrane ________________. As a result, a virus can only infect certain cell types of certain species. Surface protein or glycoprotein Protein capsid Viral DNA or RNA Phospholipid envelope Naked Enveloped Virus Capsid Virus
Viral Reproduction Two ways viruses reproduce using a host cell • Lytic infection - _____________ cycle in symptomatic which viruses ____________ host cell DNA. destroys Examples are _________________________ Cold, flu, rabies, measles, etc … most viruses ___________ • Lysogenic infection - _____________ cycle asymptomatic in which viral DNA is incorporated into ________________. Examples are Host cell DNA __________________ HIV, chicken pox virus
Viral Reproduction There are two initial steps that are common to all types of viral infections: 1.Virus attaches to _____________ of Cell membrane _____________. host 2.Virus releases____________ into cell, Genetic material either by _______________ typically Entering cell through ____________ or ___________ endocytosis injecting genetic material into it.
Bacteria Bacterial make up two kingdoms, the ____________ and ____________. In this Archaebacteria Eubacteria unit, we will focus on the kingdom that has the greater impact on our lives, the ________. Eubacteria • _______________&_________________ prokaryotic unicellular
Cell Structures • Cell wall composed of ________________ peptidoglycan – __________________________ Eubacteria only • ____________________ DNA – ________________________ Single, circular chromosome – Found in region known as ___________ nucleoid • ____________________ Cell membrane • ____________________ ribosomes • ____________________ Cytosol — “cell gel” or fluid
• Most bacteria are motile and have one or more ______________. flagella • Many have hair-like appendages called _________ that allow bacteria to fimbriae ________ to surfaces or other _________ bacteria adhere • Some bacteria have an outer _________; capsule helps bacterial cells attach to a substrate or deter the host’s infection -fighting cells.
Eukaryotic cell structures
What’s inside a cell? Cell organelles which means “little organs” 1 st a little clarification of a couple of terms: _______________- includes the cytoplasm ___________ or “cell gel” and the ________ cytosol organelles
Nucleus • _____________ of Control center the cell. Genetic information stored as ____________, which chromatin is _______wrapped in DNA ________________. protein Found in Both Plants & Animals
Nucleolus • Small, dense region in the nucleus. Site of ribosome ________________ production Found in Both Plants & Animals
Nuclear Envelope • Double _________________ phospholipid membrane. Has nuclear ___________ pores which allow _______ RNA to leave the nucleus Found in Both Plants & Animals
Ribosomes • Tiny, granular organelles located on Endoplasmic Reticulum _________________ or suspended in _________. Site of cytosol protein production _________________. All cells (pro & euk) have ribosomes. Found in Both Plants & Animals
Rough Endoplasmic Reticulum • Extensive network continuous nuclear envelope with _________________. Called “rough” because it has ________________ all along ribosomes the membrane. Function of the rough ER is to modify & transport proteins _____________________. Most of these proteins are vesicles packaged into _____________ (like bubbles or sacs) and shuttled to the ____________ Golgi apparatus Found in Both Plants & Animals
Smooth Endoplasmic Reticulum • Similar to rough ER in structure, except that ribosomes it lacks ___________. The smooth ER: 1. manufactures ______, 2. breaks lipidsglycogen down _______, 3. detoxifies ________, poisons and 4. _____________. stores calcium Found in Both Plants & Animals
Golgi Apparatus • Flattened, round sacs that look like a sack of ________________. Receives, modifies, pancakes and ships products by way of ___________ vesicles into the ____________________________ cytosol → cell membrane _ Found in Both Plants & Animals
Lysosome • Found in __________ animal cells only. Round sacs enzymes containing __________ that _______________ break down recycle and ______________ used cell components. Also used as defense bacteria against _______ and _______________ viruses
Vacuole • Sacs that may be used as storage for _______, _________, water Salts, proteins _________________, carbohydrates or wastes. Plants have a large central vacuole.
Mitochondria • Double-walled organelle with inner to increase folds ____________. ____________Uses surface area glucose _______ to manufacture energy in the form of ______. ATP Mitochondria have their own _______. DNA
Chloroplast • Found in ______ plant cells. Contain chlorophyll __________ (green pigment) and their DNA own ______. Chloroplasts harvest energy from the ____ sun to produce ____ ATP through __________. photosynthesis
Centrioles • Found in _________ animal cells only. Bundles of microtubules _________________ that play a role in cell division _________________
Cytoskeleton • Composed of protein fibers known as _______________ microtubules and ______________. Anchor _______________ and microfilaments organelles provide ______________. Also provide motility for some structure cilia flagella cells in the form of ___________ or ____________. More animal extensive cytoskeleton found in __________ cells.
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