Chapter 6 Flashcards
A Tour of the Cell
Microscopy
A technical field that uses microscopes to view objects and areas of objects that cannot be seen with the naked eye
Light (visible)
Visible light is passed through the specimen & then through glass lenses. Refracts light in a way, becomes bigger
380 - 700 nm.
Magnification
Ratio of an objects (visual) size to real size
Resolution
A measure of clarity of image; it is the minimum distance between 2 points that can be separated and still be distinguished as separate points. Inversely related to wavelength. As resolution increases, wavelength decreases.
Wavelength
The distance over which a wave’s shape repeats. Inversely related to resolution. As wavelength increases, resolution decreases.
Contrast
Difference in brightness between light & dark areas
Stain
A discoloration that can be clearly distinguished from the surface, material, or medium it is found upon
Condenser
Device used to condense a substance from its gaseous to its liquid state
Robert Hooke
Cells. 1665. Dead bark.
Light Microscope (LM)
visible light is passed through the specimen and then through glass lenses. The lenses refract (bend) the light in such a way that the image of the specimen is magnified as it is projected into the eye or into a camera.
Electron microscope (EM)
Focuses a beam of electrons through the specimen or onto its surface. Electron beams have much shorter wavelengths than visible light.
SEM-Scanning EM
Scans surface, usually coated w/ a thin film of gold. Beam excites electrons on surface, secondary electrons are detected by device that translates pattern of e- into an electronic signal sent to a vid screen. 3D.
TEM- Transmission EM
Internal part of cell. The TEM aims an electron beam through a very thin section of the specimen. For the TEM, the specimen has been stained with atoms of heavy metals, which attach to certain cellular structures, thus enhancing the electron density of some parts of the cell more than others. The electrons passing through the specimen are scattered more in the denser regions, so fewer are transmitted.
Centrifuge(use)
Useful in cell fractionation, takes cell apart. Spins test tubes holding mixtures of disrupted cells at different speeds->results: subset of cell component comes to rest on bottom
Cell Fractionation
Takes cell apart & separates major organelles & other subcellular structure from one another.
Prokaryota
Domain Bacteria/Archaea. Avg. bacteria: 1-5 micrometers. DNA is concentrated in a region that is not membrane-enclosed, called the nucleoid
Eukaryota
Domain Eukarya. Avg. Eukarya cell: 10-100 micrometers. DNA in an organelle called nucleus. Bound by a double membrane
Cytoplasm
Semifluid substance of a cell that’s external to the nuclear membrane, internal to the cellular membrane. Region between nucleus & plasma membrane.
Surface vs Volume of Cell
Smaller cell = greater ratio of surface area to volume. Plasma membrane to use.
Diffusion
The net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration.
Membrane Structure
Phospholipid bilayer + glycoproteins. ECM and microfilaments. Figure 6.6
Animal v Plant cells
Figure 6.8
Nucleus
Contains most of the genes in the eukaryotic cells.
Nuclear Envelope
Encloses Nucleus, separating its contents from the cytoplasm. A double membrane.
Nuclear Pores
Protein-lined channel in the nuclear envelope that regulates the entry and exit of proteins and RNAs, as well as large complexes of macromolecules
Nuclear matrix
a framework of protein fibers extending throughout the nuclear interior. Functions include gene expression, RNA splicing, and nuclear protein import/ export.
Chromatin
A complex of DNA and proteins called histones that packages the DNA double helix into a compact form that can fit in the cell nucleus.
Chromosomes
Structure that carry the genetic information. Each chromosome contains one long DNA molecule associated with many proteins.
Nucleolus
A mass of densely stained granules and fibers adjoining part of the chromatin. Where a type of RNA called ribosomal RNA (rRNA) is synthesized from genes in the DNA. Ribosomal proteins are also stored here.
Ribosomes
Complexes made of ribosomal RNAs and proteins. Site of protein synthesis.
Ribosome Function
Cellular components that carry out protein synthesis
Free vs. Bound Ribosomes
Free ribosomes are suspended in the cytosol, while bound ribosomes are attached to the outside of the endoplasmic reticulum or the nuclear envelope.
Endomembrane System
The different membrane-bounded organelles of the eukaryotic cell. Include nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, various vesicles and vacuoles, and the plasma membrane.
Endoplasmic Reticulum(ER)
An extensive network of membrane that accounts for more than 1/2 of the total membrane in many eukaryotic cells. Endoplasmic: Within the cytoplasm. Reticulum: Latin for little net. The ER consists of a network of membranous tubules and sacs called cisternae.
What is
Cytosol
Cytosol is the fluid part of cytoplasm. Similar to cytoplasm.
Cisternal Space
ER lumen (cavity). The ER membrane separates the internal compartment of the ER, called the CISTERNAL SPACE, from the cytosol.
Rough ER
Studded with ribosomes on the outer surface of the membrane and thus appears rough through the electron microscope. Connected to the smooth ER.
Functions of rough ER
Many cells secrete proteins that’re produced by ribosomes attached to rough ER. Secretory proteins. Mostly glycoproteins, proteins with carbohydrates covalently bonded to them.
Smooth ER
Outer surface lacks ribosomes. Connected to the rough ER.
Functions of Smooth ER
Diverse metabolic processes, vary with cell type. Including: Synthesis of lipids (sex hormones of vertebrates), metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions. It’s also a membrane factory for the cell; it grows by adding membrane proteins and phospholipids to its own membrane.
Golgi Apparatus
A warehouse for receiving, sorting, shipping, and even some manufacturing. Products of the ER, such as proteins, are modified and stored and then sent to other destinations. Modifies some molecules that it’s transporting. Also manufactures some macromolecules.
Golgi Apparatus “Faces”
A Golgi stack has a distinct structural directionality, with the membranes of cisternae on opposite sides of the stack differing in thickness and molecular composition. The two sides of a Golgi stack are referred to as the cis face and the trans face; these act, respectively, as the receiving and shipping departments of the Golgi apparatus. Cis face: close to ER.
Lysosomes
A membrane sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules. Inside = acidic. pH of 4-4.5ish
Vacuoles
Large vesicles derived from the ER and Golgi apparatus. Thus, vacuoles are an integral part of a cell’s endomembrane system. Vacuolar membrane is selective in transporting solutes; as a result, the solution inside a vacuole differs in composition from the cytosol. Mature plants contain a large central vacuole. Contractile vacuoles: pump excess water out of the cell.
“Non-system” membrane Organelles
Endosymbiont theory
This theory states that an early ancestor of eukaryotic cells engulfed an oxygen using non-photosynthetic prokaryotic cell. It becomes endosymbiont (cell living within another cell). Evolution-becomes a singular organism, a eukaryotic cell, endosymbiont became the mitochondrion.
Mitochondrion
Plural: Mitochondria. Sites of cellular respiration.
Cellular respiration
The metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, and other fuels.
Intermembrane space
The inner membrane enclosing the mitochondrion divides it into two internal compartments. The first is intermembrane space, the narrow region between the inner and outer membranes.
Mitochondrial matrix
The inner membrane enclosing the mitochondrion divides it into two internal compartments. The second compartment, the mitochondrial matrix, is enclosed by the inner membrane. Contains many different enzymes as well as the mitochondrial DNA and ribosomes.
Cristae
Of the two membranes enclosing the mitochondria, the inner membrane is convoluted, with infoldings called CRISTAE.
Chloroplasts
Found in plants and algae, are the sites of photosynthesis.
Stroma
The fluid inside the chloroplast, outside the thylakoids, which contains the chloroplast DNA and ribosomes as well as many enzymes.
Thylakoids
Inside the chloroplast, another membranous system in the form of flattened interconnected sacs.
Thylakoid space
A continuous exoplasmic cellular space that is poorly characterized compared to the other chloroplast compartments
Thylakoid membranes
A membrane-bound compartment inside chloroplasts and cyanobacteria that is the site of photochemical and electron transport reactions of oxygenic photosynthesis
Granum (grana)
A stack of thylakoids.
(Amyloplasts)
Colorless, non-pigment-containing organelles found in plant cells. Stores starch (amylose), particularly in roots and tubers.
(Chromoplasts)
Heterogeneous organelles responsible for pigment synthesis and storage in specific photosynthetic eukaryotes. Has pigments that give fruits and flowers their orange and yellow hues.
Peroxisomes
Specialized metabolic compartment bounded by a single membrane. Contain enzymes that remove hydrogen atoms from various substrates and transfer them to oxygen, producing hydrogen peroxide as a by-product. Immediately breakdown peroxisome afterwards.
Cytoskeleton
A network of fibers extending throughout the cytoplasm.
Motor Proteins
Cell motility generally requires interaction of the cytoskeleton and MOTOR PROTEINS. ATP powers motor protein to use the microtubule as a road to transport vesicles
Microtubules
Biggest cytoskeleton part. Hollow rods constructed from globular proteins called tubulins. Flagella and Cilia. Both arranged with 9 around and 2 in the middle (9+2), doublets of microtubules. Bases of flagella and cilia are different, arranged with 9 around and 0 in the middle (9+0(basal body)), triplets of microtubules. Consistent
Centrosome
In ANIMAL cells, microtubules grow out from a centrosome, a region that is often located near the nucleus. Within the centrosome is a pair of centrioles (made of microtubules).
Microfilaments
Smallest cytoskeleton part. Thin solid rods. Also called actin filaments because they’re build from molecules of actin, a globular protein. A microfilament is a twisted double chain of actin subunits. Can form structural networks when certain proteins bind along the side of such a filament and allow a new filament to extend as a branch. Present in all eukaryotic cells. Consistent.
Intermediate Filaments
Named after their diameter, larger than microfilaments but smaller than microtubules. Only found in the cells of some animals, including vertebrates. Specialized for bearing tension. Diverse class of cytoskeletal element. Each type is constructed from a particular molecular subunit belonging to a family of proteins. Vary.
Amphipathic
Containing both hydrophilic and hydrophobic parts.
Dynein
Large motor protein. Attached along each outer microtubule doublet. Has two “feet” that “walk” along the microtubule of the adjacent doublet, using ATP for energy.
Myosin motor activity
Thousands of actin filaments and thicker filaments made of a protein called myosin interact to cause contraction of muscle cells.
Pseudopodia
A cell crawls a long a surface by extending cellular extensions called pseudopodia. pseudes-false and pod-foot.
Cytoplasmic streaming
In plant cells, actin-protein interactions contribute to CYTOPLASMIC STREAMING, a circular flow of cytoplasm within cells. This movement is especially common in large plant cells, speeds the movement of organelles and the distribution of materials within the cell.
Microvilli
Singular: microvillus. Delicate projections that increase the cell’s surface area. The core is made up of bundles of microfilaments.
Plant Cell Walls
Extracellular structure of plant cells. Protects the plant cell, maintains its shape, and prevents excessive uptake of water. At the level of the whole plant, upholds it against gravity. Some prokaryotes, protists and fungi also have cell walls. Primary cell wall, middle lamella, and a secondary cell wall.
Primary cell wall
Relatively thin and flexible wall. First one secreted.
Middle Lamella
Between primary walls of adjacent (plant)cells. Thin layer rich in sticky polysaccharides called Pectins.
Secondary cell wall
Between the plasma membrane and the primary wall. Often deposited in several laminated layers, strong and durable matrix that affords cell protection and support. i.e. wood is mostly secondary wall.
Extracellular Matrix (ECM)
Animal version of cell wall. Mainly glycoproteins and other carbohydrate-containing molecules secreted by the cells. Most abundant glycoprotein is collagen.
Collagen
Forms strong fibers outside the cells. ECM. Accounts for about 40% of the total protein in the human body.
Intracellular Junctions
Plant cells connected via plasmodesmata channels. The plasma membrane of adjacent cells line the channel of each plasmodesma and thus are continuous.
Cell Junctions in Animal Cells
Tight Junctions, Desmosomes, and gap junctions. (Gap junctions are most like the plasmodesmata of plants, although gap junction pores are not lined with membrane-rather, they consist of proteins extending from each cell’s membrane that form a connecting pore.)
