Bio 110 Flashcards
Exam 1
How many different types of cells does E. coli have?
one type of cell
How many different cell types does yeast have?
three types: haploid, diploid
How many different cell types does Hydra have?
20-25
How many different cell types does a California Black Oak have?
one
How many different cell types do YOU have?
200
What types of microscopes are there?
Light, fluorescence, electron
what does a microscopy do
DECTECTS, MAGNIFIES, AND RESLOVES
what is resolution?
The ability to distinguish between two closely positioned objects
What is absorption?
When light passes through an object the intensity is reduced depending upon the color
absorbed
What is refraction?
Direction change of a ray of light passing from one transparent medium to another with different
optical density
What is diffraction?
Light rays bend around edges; this affects the image produced
What is dispersion?
Separation of light into its constituent wavelengths when entering a transparent medium - the change of refractive index with wavelength
Brightfield Microscopy
Modern microscopes magnify both in the objective
and the ocular and thus are called “compound
microscopes”
Ocular: Re-magnifies the specimen and
allows for visualization of the specimen
Prism (not shown): bends the light rays that
come from the objective into the ocular
Objective: magnifies the specimen
Condenser: focuses light through the specimen
Light source: illumination
Fluorescence Microscopy
A fluorescence microscope uses fluorescence instead of, or in addition to, reflection and absorption to study properties of cells
Fluorescence Microscopy uses filters to spectrally
separate light according to wavelength
Scanning Electron Microscopy (SEM)
Allows for visualization of biological structures
and surfaces
Resolution is limited to about 10 nm
Stained (metal coated) areas are dark because
the metal scatters the electrons away from the
detector
Pros and Cons of Electron Microscopy
Pros:
* Magnification and resolution is vastly improved compared to light
microscopy
* Cons:
* Requires fixations and special preparation (cannot view live cells)
* Preparation can introduce artifacts
Which of the following statements is true?
The fluorescence microscope could use fluorescence, as well as reflection and absorption, to visualize specimens.
Which lens focuses light on the sample?
The condenser lens.
What is the total magnification of a sample if you use a 100X objective combined with a 10X ocular lens in a compound microscope?
1000X
What is the liquid bilayer made up of?
A hydrophilic head and a hydrophobic tail
What is amphipathic?
To a molecule that
has hydrophilic and hydrophobic
portions
Cell Membranes
Structure and Functio
Composed of phospholipids, proteins, and carbohydrates.
Functions include compartmentalization, selective permeability, communication, and structural integrity.
Factors Affecting Membrane Fluidity
Lipid Composition: Cholesterol modulates fluidity; saturated vs. unsaturated fatty acids impact movement.
Lipid Structure: Cis-unsaturated fatty acids increase fluidity.
Temperature: Higher temperatures increase fluidity; lower temperatures decrease it.
Experimental Techniques for Membrane Fluidity
FRAP (Fluorescence Recovery After Photobleaching): Measures lateral diffusion of membrane components.
Electron Spin Resonance (ESR): Assesses membrane lipid mobility
Protein Structure and Membrane Embedding
Alpha helices and beta sheets provide stability within the membrane.
Alpha helices span the membrane; beta barrels form pore-like structures
Lipid-Linked Proteins
Attached via lipid anchors (GPI-anchored, prenylated, myristoylated proteins).
Molecular Transport in Membranes
Carrier vs. Channel Proteins: Channels allow passive diffusion; carriers undergo conformational changes.
Passive vs. Facilitated Diffusion: Passive (e.g., oxygen diffusion), Facilitated (e.g., glucose transport via GLUT).
Active Transport Proteins: Examples include Na+/K+ pump, H+ ATPase, Ca2+ ATPase.
Electrochemical Gradients
Formed by ion pumps (e.g., Na+/K+ ATPase).
Drive secondary active transport and maintain membrane potential.
Key Transport Terms
Uniport, Symport, Antiport: Types of transport mechanisms.
Facilitated Diffusion, Osmosis: Passive transport processes.
Membrane Potential, Solute, Solvent, Solution, Aqueous Solution: Key terms in transport.
Experimental Techniques for Membrane Transport
Patch-Clamp: Measures ion channel activity.
Radioactive Labeling: Tracks solute movement.
Neuronal Signaling and Membranes
Electrical to Chemical to Electrical Conversion: Action potentials trigger neurotransmitter release, which binds to receptors to regenerate electrical signals.
Channels Involved: Voltage-gated Na+/K+ channels, ligand-gated ion channels.
Sodium-Potassium Pump: Uses ATP to maintain ion gradients.
Ion Concentration Inside vs. Outside the Cell
Na+ (low inside, high outside)
K+ (high inside, low outside)
Ca2+ (very low inside, high outside)
Cl- (low inside, high outside)
Membrane Adaptations in High-Temperature Environments
Increased saturated lipid content.
Enhanced cholesterol levels for stability.
Specialized heat shock proteins to maintain function.
Brightfield Microscopy
Magnification: Up to ~1000x
Resolution: ~200 nm
Contrast Mechanism: Uses staining techniques to enhance contrast.
Experimental Use: Used for viewing fixed, stained specimens such as bacteria and tissue sections.
Scanning Electron Microscopy (SEM)
Magnification: Up to ~500,000x
Resolution: ~1-10 nm
Contrast Mechanism: Electron beams scan the surface, secondary electrons provide contrast.
Experimental Use: Used for detailed 3D surface imaging of cells and materials.
Transmission Electron Microscopy (TEM)
Magnification: Up to ~2,000,000x
Resolution: ~0.1 nm
Contrast Mechanism: Electron beams pass through thin sections, staining with heavy metals enhances contrast.
Which of the following is not a cell membrane function?
Transfer of genetic material
The two layers of the lipid bilayer are identical.
False
Which of the following statements is true about the eukaryotic cell membrane?
Saturated lipids make the membrane less fluid
Phospholipids are synthesized in the Golgi apparatus.
False
The microscopy method to determine whether a membrane is fluid is called:
Fluorescence Recovery After Photobleaching (FRAP)
Alpha-helices and beta-sheets are common protein folding patterns.
True
Membrane transport proteins are most likely
which type of membrane protein?
Transmembrane
Ion channels mostly likely contain which type
of protein domains?
Beta barrel
The alpha-helices of a multi-pass
transmembrane protein are not amphipathic
False
The surface localization of some membrane proteins is restricted to
specific areas of the plasma membrane. Which of the following is
NOT a mechanism for this restriction:
Proteins localized within lipid rafts
Glycoproteins are glycosylated exclusively in
the external region of the protein
True
Which of the following is not a function of
membrane proteins:
Permeability barrier
The process of active transport
could be coupled to ATP hydrolysis.
