Biology Chapter 4

 Know when microscopes were first created. 1590

Know who first observed cells using the microscope. Robert Hooke

Light Microscopes (LM): visible light is passed through the specimen and then through glass lenses. 

Electron Microscopes (EM): focuses a beam of electrons through the specimen or onto its surface 

Scanning Electron Microscope (SEM): used for detailed study of the topography of a specimen. Result is an image of the specimens surface that appears 3D

Transmission Electron Microscope (TEM): used to study the internal structures of cells

Resolution: measure of clarity of the image

Magnification: the ratio of the size of an image to the size of the original object

Contrast: difference in brightness between the light and dark areas of an image

Be able to describe how the advantages and disadvantages of a light vs. electron microscope: 


Light Microscope

Electron Microscope

Advantages 

  • Cheaper

  • Easy to operate

  • Smaller

  • Shows natural color

  • Simple prep

  • Ultra High resolution

  • Large magnification

  • Detailed images 

Disadvantages

  • Low resolution

  • Lower magnification

  • Requires a lot of adjusting to get the result you want

  • Super Expensive

  • No color

  • No Live Specimens

  • Complex prep

  • Hard to Operate







Know when to use each microscope


Light Microscope

Electron Microscope

Transmission Electron Microscope

Scanning Electron Microscope

When to use it

When viewing live organisms and need it to be in color. Also, when you don’t need it to be super in depth 

When it is too small to be seen with a light microscope and you need to magnify something extremely

When you need to see the internal structures of organisms in a detailed way. 

When you need high resolution and 3D images of a cell or object's surface. 



Cell fractionation: A technique used to study cell structure and function where broken-up cells are centrifuged until a pellet is formed from cell components. (Fraction = smaller)

How is cell fractionation useful? It allows people to see each part of a cell broken up and individually instead of seeing it all as one. 

Know and be able to describe the differences and similarities between prokaryotic and eukaryotic cells.

Similarities

Differences

  • Both contain DNA

  • Both have a Plasma Membrane

  • Both have Cytoplasm

  • Both have Ribosomes

Prokarytotic:

  • Smaller

  • No Nucleus

  • No Membrane - Bound Organelles



Eukaryotic:

  • Larger

  • Has a nucleus

  • Has Membrane-Bound Organelles



Prokaryotic Cells:  A cell lacking a membrane-bound nucleus and containing its DNA in an unbound region called a nucleoid. 

Eukaryotic Cells: A cell characterized by containing a nucleus bounded by a double membrane as well as membrane-enclosed organelles. 

Organelles: Membrane-enclosed structures within eukaryotic cells.

Nucleus: Enclosed most of the DNA in eukaryotic cells and most of the genes in Eukaryotic Cells. 

Ribosomes: Cellular complexes made of rRNA and protein that carry out protein synthesis.

Identify the parts of the endomembrane system

  • Endomembrane system functions: synthesize, modify, package, and transport proteins and lipids

  • Smooth Endoplasmic Reticulum:The portion of the endoplasmic reticulum lacking ribosomes, involved in lipid synthesis, drug detoxification, and storage of Ca2+ ions.

  • Rough Endoplasmic Reticulum: The portion of the endoplasmic reticulum studded with ribosomes on its outer surface, responsible for producing secretory proteins and membrane components.

  • Nuclear Envelope: A double membrane perforated by pore structures that encloses the nucleus, separating its contents from the cytoplasm.

  • Golgi apparatus: An organelle composed of flattened sacs (cisternae) that modifies, stores, sorts, and ships products received from the endoplasmic reticulum.

  • Lysosomes: membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules

  • Vesicles: Stores, transports, or digests cellular products and waste 

  • Vacuoles:  large vesicles derived from the ER and the golgi apparatus. Selective in transporting solutes There are food vacuoles, contradictile vacuoles, and the central vacuole. 

  • Cell membrane: Made of a double layer of phospholipids and other lipids The primary function of the cell membrane (plasma membrane) is to separate the cell's interior from its external environment while acting as a selective barrier that regulates the movement of substances in and out of the cell

  • Nuclear lamina: netlike array of protein filaments, that maintains the shape of the nucleus by mechanically supporting the nuclear envelope

  • Chromatin:  complex of DNA and proteins making up chromosomes. 

  • Ribosomes: complexes made of rRNA and protein; cellular components that carry-out protein synthesis. 

  • mRna: carries instructions for making proteins from DNA in the cell nucleus to the protein-building machinery in the cytoplasm

  • rRna: Forms the structure of ribosomes

  • Free ribosomes: suspended in the cytosol

  • Bound Ribosomes: attached to outside of endoplasmic reticulum or nuclear envelope

  • Mitochondria: : site of cellular respiration; powerhouse of the cell

  • Know how smooth and rough ER functions differ: The smooth ER synthesizes lipids, produces steroid hormones, detoxifies chemicals, and stores calcium ions. The Rough ER Synthesizes and folds proteins 

  • What makes up the Golgi apparatus? How do those two sides differ? It is a series of flattened, membrane-bound sacs called cisternae. There is the Cis face and the Trans Face. 

  • What is the Cis face responsible for? The side that receives products from the ER.

  • What is the trans face responsible for?  The side that ships products to other destinations.

  • Glycoproteins do what? They help the cell identify their components from foreign invaders. 

  • Autophagy: Recycling of the cell's own organic material using hydrolytic enzymes.

  • Excessive leakage of lysosomal enzymes can lead to what?  destroy a cell through self-digestion

  • Lysosomal enzymes are synthesized in the Rough Endoplasmic Reticulum and processed in the Golgi Apparatus  before being transported to lysosomes.

  • The number of mitochondria in a cell correlates with what? The Energy Demand in a cell

Chloroplasts

  • Chloroplasts: Sites of photosynthesis, converting solar energy to chemical energy.

  • Stroma: The fluid outside of thylakoids containing chloroplast DNA and enzymes.

  • Thylakoid:  flattened interconnected sacs

  • Three compartments that convert light energy. Intermembrane space, Stroma, Thylakoid space

Cytoskeleton and Cell Motility

Components of the Cytoskeleton

  • Cytoskeleton: network of fibers extending throughout the cytoplasm and plays a major role in organizing structures and activities of the cell. The roles of the cytoskeleton: support and mobility. 

  • Micotubules: thick fibers that maintain cell shape, cell motility; chromosome movements in cell division; organelle movements

  • Microfilaments:  thinnest fibers; maintain cell shape; changes in cell shape; muscle contraction; cell motility; cytoplasmic streaming (plant cells); cell division (animal cells)

  • Intermediate filaments:  diameter in middle range; maintain cell shape; anchorage of nucleus and certain other organelle; formation of nuclear lamina

  • Cell motility: movement) can involve the cytoskeleton. Includes change in cell location and more limited movements of cell parts

  • Motor proteins:  used interactively with the cytoskeleton in order to produce cell motility

  • Cilia: help with cell or fluid movement; signal-receiving antennae

  • Flagella:  hair-like structures that protrude from certain plant and animal sperm cells; help with cell motility

  • Cell wall:  extracellular structure of plant cells and gives structure to cells

  • Primary cell wall:  thin and flexible wall secreted by a young plant

  • Secondary cell wall: has strong and durable matrix that affords cell protection and support

  • Extracellular matrix (ECM): provide structural support and biochemical support to surrounding cells

  • Plasmodesmata: membrane-lined channels filled with cytosol

  • Tight junctions: plasma membranes of neighboring cells are tightly pressed against each other bound by specific proteins

  • Desmosomes: fasten cells together into strong sheets

  • Gap junctions: provide cytoplasmic channels from one cell to an adjacent cell