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General Biology - 183 > Chapter 4 ~ A Tour Of The Cell > Flashcards

Chapter 4 ~ A Tour Of The Cell Flashcards

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1
Q

Light Microscope (LM)

A
  • Likely used in laboratory settings
  • Visible light passes through specimen and glass lens, magnifying the specimen
  • Magnifies 1000x the size of the specimen
  • Cannot resolve more data than 0.2 micrometers (200 nm)
  • Stain or label cell components for this microscope
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2
Q

Electron Microscope (EM)

A
  • Beam of electrons through the specimen (its surface)
  • Electron beams have shorter wavelengths than light
  • 0.002 nm ; in practice, cannot resolve smaller than 2 nm
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3
Q

Scanning Electron Microscope (SEM)

A
  • Detailed study of topography of specimen
  • Specimen coated with thin film of gold
  • Beam excites electrons on the surface, secondary electrons are detected and translated into electronic signals (results are 3D)
  • Electromagnets as lenses to bend path of electrons
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4
Q

Transmission Electron Microscope (TEM)

A
  • Internal structure of cells
  • Electron beam through thin section of a specimen
  • Specimen is stained with atoms of heavy metals that attach to certain cellular structures
  • Fewer electrons are transmitted; the transmitted ones are displayed as an image
  • Electromagnets as lenses to bend path of electrons
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5
Q

Cell Fractionation

A

Broken up cells are placed in a centrifuge, causing the largest cell components to settle at the bottom (pellet) ; liquid formed is taken and centrifuged at higher speed and for longer (process is repeated)

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6
Q

Eukaryotic Organization

A
  • Bound by plasma membrane
  • Cytosol (with sub cellular components)
  • Chromosomes (carry genes)
  • Ribosomes (make proteins)
  • DNA is found in the nucleus
  • Cytoplasm that holds organelles (btwn nucleus and plasma membrane)
  • Large in cell size
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7
Q

Prokaryotic Organization

A
  • Bound by plasma membrane
  • Cytosol (with sub cellular components)
  • Chromosomes (carry genes)
  • Ribosomes (make proteins)
  • DNA is concentrated in nucleoid (not membrane enclosed)
  • Cytoplasm with no organelles
  • Small in size
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8
Q

Role of the Nucleus in Eukaryotic Cells

A
  • Nuclear envelope: double membrane enclosing the nucleus; regulating entry and exit of proteins, RNAs, and large macromolecules
  • Nucleolus: (nonmembranous) production of ribosomes (cell may have one or more)
  • Chromatin: DNA and proteins (visible in a dividing cell)
  • Nucleus houses most of the cell’s DNA
  • DNA is organized as chromosomes
  • Directs protein synthesis by synthesizing mRNA
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9
Q

Role of Ribosomes in Protein Synthesis

A
  • Not considered organelles (since they are not membrane bound)
  • Build proteins
  • Free ribosomes: suspended in cytosol
  • Bound ribosomes: attached to ER or nuclear envelope (make proteins that are destined for insertion into membranes, for packaging within lysosomes, or for export from the cell
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10
Q

Parts of the Endomembrane System (Hint: 6)

A

Nuclear envelope
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Various vesicles and vacuoles
Plasma membrane

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11
Q

Functions of the Endoplasmic Reticulum (ER)

A
  • Accounts for more than 1/2 the total cell membrane
  • Cisternae: Network of tubules
  • ER membrane: separates lumen (internal compartment) from the cytosol
  • ER membrane is continuous with nuclear envelope and with the lumen of the ER
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12
Q

Smooth ER

A
  • Outer surface lacks ribosomes
  • Synthesis of lipids (done by enzymes)
  • Metabolism of carbs
  • Detoxification of drugs and poisons (adding OH to make them more soluble)
  • Storage of calcium ions (pumps Ca atoms from cytosol into ER lumen)
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13
Q

Rough ER

A
  • Outer surface contains ribosomes
  • Membrane factory for the cell
  • Makes phospholipids
  • RER membrane expands and parts can form vesicles
  • Secretes proteins (polypeptide chain is threaded into ER lumen, folding as it enters)
  • Glycoproteins: proteins with carbs covalently bonded to them
  • Secretary proteins are separated from proteins in the cytosol by the ER
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14
Q

Golgi Apparatus

A
  • Receiving, sorting, shipping, and manufacturing of macromolecules
  • contains cells specialized in secretion
  • Made of cisternae (pita bread packet)
  • Cis face (receiving: ER to Golgi) and Trans face (shipping: Golgi to other sites)
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15
Q

Lysosomes

A
  • Membranous sac of hydrolytic enzymes that digest macromolecules
  • Work best in acidic environments
  • Made by RER then transferred to Golgi (some come from Trans Golgi)
  • Intracellular digestion (phagocytosis) of simple sugars, amino acids, + others
  • Autophagy
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16
Q

Vacuoles

A
  • Large vesicles derived from ER and Golgi
  • Selective in transporting solutes
  • Food vacuoles: formed by phagocytosis
  • Contractile vacuoles: pump excess water out of the cells
  • Central vacuole: cell sap (K and chloride), enlarges as water is absorbed
17
Q

Mitochondria

A
  • Convert energy to forms the cell can use
  • Sites of cellular respiration
  • 2 membranes enclosing it are phospholipid bilayers
  • Outer membrane is smooth but inner membrane contains cristae
  • Mitochondrial matrix: contains different enzymes, mitochondrial DNA, & ribosomes
18
Q

Chloroplasts

A
  • Convert energy to forms the cell can use
  • Sites of photosynthesis (solar E to chemical E)
  • Contain chlorophyll, enzymes, & molecules that function in the production of sugar
  • Contents are partitioned from cytosol by envelope of 2 membranes
  • Thylakoids: flattened, interconnected sacs (each stack is a granum)
  • Stroma: fluid, contains chloroplast DNA, ribosomes, & enzymes
19
Q

Origins of Mitochondria and Chloroplasts

A
  • Endosymbiont theory: early ancestor of eukaryotic cells engulfed O2-using-non photosynthetic prokaryo cell
  • Endosymbiont: cell living in another cell
  • eventually merged a eukaryo with a mitochondrion
  • Mito and Chloros have 2 membranes, contain ribosomes, multiple circular DNA molecules; are autonomous
20
Q

Cytoskeleton

A

A network of fibers extending through the cytoplasm and plays a major role in organizing structures and activities of the cell

21
Q

Microtubules

A
  • Hollow tubes
  • Tubulin polymers
  • Maintenance of cell shape, cell motility, chromosome movements in cell division, organelle movements
  • Shape and support the cell & serve as tracks which organelles can move
  • Thickest of the fibers
22
Q

Microfilaments

A
  • Actin filaments
  • Two intertwined strands of actin
  • Thinnest of the fibers
  • Maintenance of cell shape, changes in cell shape, muscle contraction, cytoplasmic streaming (plant cells), cell division (animal cells), cell motility, bear tension
23
Q

Intermediate filaments

A
  • Diameters are in the middle range of the filaments
  • Fibrous proteins coiled into cables
  • One of several different proteins (keratins)
  • Maintenance of cell shape, anchorage of nucleus and other organelles, formation of nuclear lamina, bearing tension
  • Found in the cells of vertebrates
24
Q

Cell Wall

A
  • extracellular structure of plant cells
  • protects, maintains shape, prevents excessive build up of water, hold the plant up against gravity
  • prokaryotes, fungi, and some unicellular eukaryotes have a cell wall
25
Q

Extracellular Matrix (ECM)

A
  • Made of glycoproteins (mainly collagen) & other carbo- containing molecules
  • Proteoglycan: molecule that consists of small core protein and many carbohydrate chains
  • Fibronectins
  • Integrins: span the membrane and bind on their cytoplasmic to microfilaments; transmit signals btwn ECM and cytoskeleton
  • Regulates cell behavior
26
Q

Cell Movement through ECM

A

Cells in a developing embryo migrate by matching the orientation of their microfilaments to the ECM

27
Q

Plasmodesmata

A

Membrane-lined channels filled with cytosol, they unify most of a plant into one living continuum

28
Q

Tight Junctions

A

Plasma membranes of neighboring cells are tightly pressed against each other, bound by proteins; this prevents leakage pf extracellular fluid across epithelial cells

29
Q

Desmosomes

A

An anchoring junction, fastening cells into strong sheets; intermediate filaments anchor the desmosomes in the cytoplasm, desmosomes attach muscle cells to each other

30
Q

Gap Junctions

A

(AKA communicating junctions) provide cytoplasmic channels from one cell to an adjacent cell; they consist of membrane proteins that surround pore through which ions, sugars, amino acids, and other small molecules pass

General Biology - 183 (4 decks)

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