BI 253 Chapter 6
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Who invented the microscope & when?
Zaccharias & Janssen in the 1590s
In the 1600's ___ ___ coined the term cells & 1st studied ___ ___ under a microscope.
Antony van Leeuwenhoek is called the ____ ____ & coined the term ___ in the late ___.
- Father of Microbiology
Who started cell theory & when?
Mathias Schleiden & Theodore Schwan in 1838
What are the 3 postulates of Schleiden & Schwan's Cell Theory?
- 1. Cells are basic structure & physiological units of life
- 2. Cells are distinct entities AND bldg blocks for more complex organisms
- 3. Cell origin unk but thought to arise fr nonliving materials (aka spontaneous generation)
What was Pasteur & Redi's contribution to Schleiden & Schwan's theory?
In 1859 proved that life must be present to generate new life
Cell biology is the study of what & includes what 3 areas?
- Studying all life
- Cell Structure, division, communications
What is classification of prokaryotic or eukaryotic based on?
The location within the cell where most genetic material is stored
What are 4 characteristics of ALL cells?
- Surrounding membrane
- Contents in thick fluid (cytoplasm)
- Organelles (structures for cell function)
- Ctrl center w/DNA
Prokaryotes have no ___ & ___ ___ ___.
- Membrane-bound Organelles
Eukaryotic cells have both a ___ & ___ ___ ___.
- Membrane-bound organelles
What is the general shape of grps of prokaryotic cells w/an example?
- Grape like structures - Staph
- Strip like structures - Strep
What are the 3 basic structures within a prokaryotic cell?
- Plasma membrane
What is the function of he plasma membrane?
- Provides cell "skin"
- Regulates flow in & out of cell
What is located in the nucleoid?
What are the 2 structures in the cytoplasm?
- Cytosol - Fluid, dissolved ions & certain molecules
- Ribosomes - Site of protein synthesis & only true organelle
What is capsule?
Slimy, polysaccharide layer that aids in attachment & prevents cell fr drying out
Flagella are . . . .
Structures responsible for cell locomotion
What do pili do?
Help cell with attachment
What are 4 basic characteristics of Eukaryotic cells?
- Four Kingdoms
- Membrane bound nucleus w/genetic info
- Up to 10x larger than prokaryotic cells
- Membrane bound organelles
An organelle subunit is. . . .
Compartment w/own distinct shape & function
What are 2 functions of membranes surrounding organelles?
- Keep out inappropriate molecules that might disturb function
- Act as traffic regulators for raw materials in & out
What are 4 characteristics of the nucleus?
- Largest organelle
- Site of DNA duplication
- Site of genetic ctrl of cell activities
- Contains Nucleolus
What does the nucleolus do?
Non membrane bound region where ribosomes are initially assembled (HR dept)
What cells is the nucleoid located in?
- Prokaryotic w/NO membrane
- NucleoiD is DEVOID
Where is a nucleus found & what is within it?
- Membrane bound in Eukaryotic cells
- Nonmembrane bound NUCLEOLUS where ribosomes are made
What are 2 basic characteristics of nucleus structure?
- Surrounded by phospholipid bilayer forming nuclear envelope
- Nuclear pores that connect interior of nucleus w/cytoplasm
Explain the nuclear pore complex.
- 8 very lg protein granules arranged in an octagon around each pore
- Ctrl mvmt of molecules in & out
What do ribosomes do?
- They're the main processing plant for cell
- Site of protein synthesis
What cells are ribosomes found in?
Prokaryotic & eukaryotic cells
What comprises the structure of ribosomes?
- Ribosomal rRNA
- >50 other proteins
What structures comprise the endomembrane system?
ER, Golgi apparatus, Lysosomes, vacuoles/vesicles, nuclear envelope & plasma membrane
What does the endomembrane sys accomplish?
Manufacture, process & transport of lipids & proteins
Describe 5 characteristics of the ER.
- Puts finishing touches on proteins being shipped out of cell
- Located in cytoplasm
- Linked to nuclear membrane
- Contains most of membrane of cell
- 2 types - rough & smooth
What is the difference between rough & smooth ER.
Rough has ribosomes & processes proteins for transport where as smooth makes lipids
Ribosomes are found in what structures in Eukaryotic cells?
RER, Mitochondria & chloroplasts
What "finishing touches" does RER put on proteins?
- Forms disulfide bridges
- Glycosylation - Attach carb grps
What is glycosylation?
Attachment of carb grps to proteins in the RER
What do ribosomes do in the RER?
Synthesis proteins directly into the lumen of the RER
Define the RER & give 1 example of cells it is located in.
- Specialized cells that synthesize proteins for extracellular export
- β cells in endocrine pancreas
What are 3 responsibilities of the SER?
- Chem mod of other molecules
- Site of lipid & steroid hormone synthesis
- Storage of Ca Ions
What 3 things does the SER do in liver cells?
- Synthesis & hydrolysis of glycogen
- Detox of drugs & pesticides
- Production of cholesterol
What are the functions of Golgi Apparatus(2).
- Receives & modifies proteins fr RER
- Concentrates, sorts & packages (vesicles) proteins for export
The structure of the Golgi Apparatus is called ____ & it consists of?
- Flattened membrane sacs w/membrane bound vesicles
What are 3 compartments of the Golgi Apparatus?
- Cis region - Closest to nucleus & ER
- Medial region - Middle
- trans region - Closest to plasma membrane & outside of cell
What is an important thing to remember about the compartments of the Golgi Apparatus?
Each compartment has different functions & different associated enzymes
Describe mvmt of protein thru endomembrane sys.
- Vesicles fr ER fuse to cis region
- Fr cis region vesicles move to medial region
- Then to trans compartment
- Some vesicles then fuse w/plasma membrane & are released to outside cell
Describe a vesicle.
- Transport containers for material into/out of a cell
- Made up of at least 1 layer of phospholipid-bilayer
- Classified as organelle
Give 2 ways vesicles are formed.
- 1. Part of membrane of ER or golgi apparatus pinches off
- 2. Obj outside cell surrounded by cell membrane
What are lysosomes?
Body's waste disposal sys created by the golgi & containing digestive enzymes
Phagocytosis is what?
Cellular process of cell membrane engulfing macromolecules & foreign material creating phagosomes
What is a phagosome?
Vesicle in which pathogenic microorganisms can be killed & digested
What structure creates primary lysosomes & what do they contain?
- Golgi Apparatus
- Digestive enzymes
What makes up a secondary lysosome?
Primary lysosome + a phagosome
What do secondary lysosomes do?
Hydrolyze or break down macromolecules into monomers which then diffuse into cytoplasm. "Used" secondary lysosome then fuses w/plasma membrane & releases undigested contents
What is Autophagy?
Digestion of spent cellular components
What are the function of peroxisomes?
Break down of toxic hydrogen peroxides (byproducts of cellular reactions) utilizing catalases (specializes enzymes)
Where is most of O₂ taken in by eukaryotic organism used?
What are some characteristics of mitochondria?
- Perform Cellular respiration
- Conversion of fuel into energy
- Aerobic functions
- Can replicate independently of the cell
- Supports endosymbiotic theory
Describe structure of mitochondria.
- Outer phospholipid bilayer
- Inner membrane highly folded w/cristae & matrix creating greater surface area
Describe cristae part of the mitochondria.
Contains protein complexes necessary for production of ATP via cellular resp
Describe the matrix in mitochondria.
Contains enzymes, ribosomes & DNA needed to make protein complexes needed for cellular resp
What parent does mitochondrial DNA come fr?
What are chloroplasts?
- Contain chlorophyll & provide site for photosynthesis
- Found in plant cells & some protozoans but NOT IN ANIMAL CELLS
Chloroplasts have both an ____ & ____ ____.
Inner & outer membrane
What are the 2 parts of the inner membrane of a chloroplast?
- Stacks of Grana made up of thylakoids
What does grana do & where is it located?
- Traps solar energy
- Located in chloroplasts of plant cells
Thylakoids are what?
- Individual compartments of grana in chloroplasts
- Location where ATP production occurs, much like cristae
- Fluid filled inner membrane of a chloroplast
- Similar to mitochondrial matrix
- Contains sm amts of DNA & some ribosomes
What are the functions of vacuoles?
- Storage - Waste & toxic by-products
- Structure - Maintenance of support & rigidity
- Reproduction - Anthocyanins
- Digestion - Enzymes to hydrolyze proteins
What are anthocyanins?
- Pigments that provide visual cues for pollinators
What role do vacuoles play in digestion?
- Provide enzymes used to hydrolyze proteins
- Similar to lysosomes in animal cells
Where are food vacuoles found & what are they similar to?
- Single celled protists
- Similar to phagosomes
Where are contractile vacuoles found & what do they do?
- Freshwater protists
- Elimination of excess H₂O to restore Na balance in cytoplasm
What is the basic structure of the cytoskeleton?
Set of long, thin fibers found in cytoplasm
What are 5 functions of cytoskeleton?
- Support & maintenance of shape
- Provides for cell mvmt
- Positions organelles within cell
- Anchors cell in place
- Provides tracks for "motor proteins"
What are the 3 types of cytoskeleton?
- Intermediate filaments
Explain the structure of Microfilaments?
- Single filaments, in bundles, or in networks
- Smallest of cytoskeleton components - 7nm in diameter
- Made of actin - Interacts w/another to form double helical microfilament
What are the 4 functions of microfilaments?
- Cell contraction
- Add structure to plasma membrane & Shape to cells
- Cytoplasmic streaming
- Pseudo-podia (fake feet)
Explain cytoplasmic streaming.
Flowing mvmt of cell fluids bearing specific organelles & proteins
Microfilaments have microvilli which are what?
- Fine plasma membrane covered projections that increase surface area of some cells
- Made up of protein cross-linked actin bundles
Where are intermediate filaments found?
Only in multicellular organisms
Explain intermediate filaments.
- Rope like assemblages
- 8 - 12nm in diameter
What are 3 main functions of Intermediate Filaments?
- Stabilize cell structure
- Resist tension
- Maintain positions of nucleus & other organelles
What are 2 main functions of microtubules?
- Provide rigid intracellular skeleton
- Tracks motor proteins can move along within the cell
Explain the structure of microtubules.
- Hollow cylinders - 25nm thick
- Tubulin subunits made up of α-tubulin & β-tubulin dimers
What do tubulin subunits do in microtubules?
α-tubulin & β-tubulin dimers can be added or subtracted at either end of microtubule to lengthen or shorten it
What differentiates flagella from cillia?
Flagella are longer than cilia & usually only 1 or 2 per cell whereas cilia are present in great numbers & in epithelial tissue
Explain the 9+2 array of cilia & flagella.
- 9 fused prs of microtubules arranged to form outer cylinder
- 2 unfused are located in ctr of cylinder
Cilia & flagella are what?
Plasma membrane covered cell projections
Where are centrioles found?
In an organizing ctr near cell nucleus
What are centrioles made of?
9 sets of 3 fused microtubules
What function do centrioles provide?
- Help mvmt of chromosomes during cell division
- Involved in formation of mitotic spindle
- Crucial for proper cell division
Explain features of the basal body.
- Organizing area at base of structures
- No central microtubule
- Each of 9prs has additional microtubule fused with it making triples rather than doubles
Where are extracellular structures located & what are they made of?
- Outside cell membrane
- Made of fibrous molecule & gel-like medium
What is structure of extracellular matrix?
Fibrous proteins such as collagen & gel like matrix of glycoproteins called proteoglycans
What are 4 functions of extracellular matrix?
- Supports tissue functions in animals
- Holds cells together in tissues
- Provides physical props to cartilage, skin, bone
- Helps filter materials passing fr other tissues
The extracellular structure of plant cells is made up of what?
Cellulose fibers embedded in polysaccharides & proteins
What carries instructions, for making proteins, fr nucleus into cytoplasm?
What name is given to strands containing DNA + an associated protein?
What are membrane lined channels that connect cytoplasmic fluid of 1 plant cell to another called?
What is a type of intercellular junction in animal cells that prevents leakage of material between cells?
What type or intercellular junction in animal cells functions as an anchor?
What type of intercellular junction in animal cells allows passage of material or current between cells?
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