Chapter 4 (Exam Two) Flashcards
The cellular level of organization. A detailed study of the cell in what year? This is a (blank) concept in biology
1830’s; unifying
Detailed studies of the cell originated from the works of biologists (blank) and (blank) in what years?
Schleiden and Schwann in 1838-1839
In the cell theory, what two scientists came up the concept that organisms are composed of cells? (country, type of scientist)
German botanist; Matthias Schneiden
German zoologist Theodor Schwann
In the cell theory, what scientist came up with the concept all cells come only from preexisting cells because
cells are self-reproducing? (country, type of scientist)
German physician Rudolph Virchow
Cells range in size from what to what in diameter?
one millimeter (mm) down to one micrometer (μm) in diameter.
Cells need a large surface area of plasma membrane to
to adequately exchange materials.
What does the surface-area-to-volume ratio require?
that cells be small
What is the surface-area-to-volume ratio in large cells?
surface area relative to volume decreases which also decreases the efficiency of transporting materials in and out of the cell
What is the surface-area-to-volume ratio in small cells?
Small cells – larger surface-area-to-volume ratio is advantageous for exchanging molecules
How do we see through a compound light microscope?
Light is passed through the specimen. Then it is focused by a series of glass lenses. It forms an image on the human retina.
In a compound light microscope, the maximum magnification is about
1000X
The compound light microscope resolves objects separated by (blank) μm,. How much better is this than the human eye?
0.2, 500X better than the human eye (Assuming the resolving power of the human eye is 1.0)
How do we see through a Transmission Electron Microscope? (3 steps)
- Electrons are passed through specimen and then they are focused by a set of magnetic lenses.
- An image is formed on a fluorescent screen similar
to a TV screen. - The image is then photographed.
What provides greater magnification, a compound light microscope or a TEM microscope?
TEM
TEM microscope resolves objects separated by (blank) μm,. How much better is this than the human eye?
0.0002, 100,000X better than human eye.
How do we see through a Scanning Electron Microscope? 6 steps
- The specimen is sprayed with a thin coat of metal.
- Then an electron beam is scanned across the surface of the specimen.
- The surface metal emits secondary electrons.
- The emitted electrons are detected and focused by magnetic lenses.
- A 3-dimensional image is formed on a fluorescent screen similar to a TV screen.
- Image is then photographed
Magnification is the ratio between?
the size of an image and its actual size.
Resolution in a microscope?
the minimum distance between two objects that allows them to be seen as two separate objects.
Contrast in a microscope?
the difference in shading of an object compared to its background.
(blank) can be bent (refracted) and focused as they pass through glass, but (blank) can’t
light rays; electrons
How are electrons seen through the glass in a microscope? 2 steps
- Electrons have a charge and can be focused by
electromagnetic lenses. - The electrons leaving the specimen are then directed to a screen or photographic plate, which is sensitive to electrons which can be viewed by humans.
How does confocal microscopy work? 5 steps
- A narrow laser beam is scanned across a transparent specimen.
- The beam is focused on one very thin plane in the
cell. - A microscopist can “optically section” a specimen by
focusing up and down. - Sections are made at different levels.
- This allows assembly of a 3-dimensional electronic image on a computer screen that can be displayed and rotated on the screen.
How does Video-Enhanced Contrast Microscopy work? 4 steps
- The microscope image can be recorded by a TV
camera. - In video-enhanced contrast microscopy, a TV camera converts the light image into an electronic image, which is entered into computer.
- The computer makes the darkest areas of the image darker and the lightest areas lighter.
- The result is a high-contrast image which can be manipulated further for greater contrast.
Prokaryotic lack a what?
membrane bound nucleus
Prokaryotic cells are what compared to eukaryotic?
smaller and simpler
Prokaryotic cells are placed in what two taxonomic
domains?
Bacteria and Archaea
What do prokaryotic cells in Domain Bacteria do?
Cause diseases but are also environmentally important as
decomposers
Can be useful in manufacturing products and drugs
What do prokaryotic cells in Domain Archaea do?
live in extreme habitats
How are two prokaryotic domains similar different?
structurally similar but biochemically different
A prokaryotic cell can come in what 3 basic shapes?
Spherical coccus
Rod-shaped bacillus
Spiral spirillum (if rigid) or spirochete (if flexible)
The cell envelope in a prokaryotic cell includes what 3 stuctures?
plasma membrane, cell wall, glycocalyx
The plasma membrane in the cell envelope in the prokaryotic cell is what?
lipid bilayer with embedded and peripheral proteins
Can form internal pouches (mesosomes), which increase surface area
The cell wall in the cell envelope of a prokaryotic cell is what?
maintains the shape of the cell and is strengthened by
peptidoglycan
The glycocalyx in the cell envelope of a prokaryotic cell is what?
layer of polysaccharides on the outside of the cell wall
Well organized and resistant to removal (capsule)
Name prokaryotic cytoplasm (4) and external structures (3)
Cytoplasm, Nucleoids, Plasmids, Ribosomes
External structure: flagella, fimbriae, conjugation pili
Describe cytoplasm in a prokaryotic cell
Semifluid solution
Encased by plasma membrane
Contains water, inorganic and organic molecules, and enzymes
Describe nucleoids in a prokaryotic cell
a region that contains the single, circular DNA molecule.
Describe plasmids in a prokaryotic cell
small accessory (extrachromosomal) rings of DNA.
Describe ribosomes in a prokaryotic cell
tiny structures in the cytoplasm that synthesize proteins.
Describe flagella on a prokaryotic cell
they provide motility
Describe fimbriae on a prokaryotic cell
small, bristle-like fibers that sprout from the cell surface
Describe conjugation pili on a prokaryotic cell
rigid tubular structures used to pass DNA from cell to cell (singular pilius)
Eukaryotic cells contain what? What distinguishes it from a prokaryotic cell?
Membrane-bound nucleus that houses DNA
Specialized organelles
Plasma membrane
The first two distinguish eukaryotic from prokaryotic cells
What does the plasma membrane do in a eukaryotic cell? (3)
separates cell contents from environment
regulates passage of materials in and out
is composed of a phospholipid bilayer with embedded proteins
Eukaryotic cells are compartmentalized. What does this mean?
Eukaryotic cells are compartmentalized.
They contain small structures called organelles which perform specific functions and isolate reactions from other reactions
The fossil record suggest that the first cells were
prokaryotes.
Biochemical data shows eukaryotes are more closely related to what than what?
archaea than bacteria.
The nucleus is believed to have evolved by
invagination of the plasma membrane.
The invagination process also explains origins of what two things?
endoplasmic reticulum and Golgi.
Energy organelles, mitochondria and chloroplasts, may
have originated when. What is this theory called?
a eukaryotic cell engulfed smaller prokaryotic cells. Eukaryotic cell would have benefitted the from ability to utilize oxygen or synthesize organic food.
Endosymbiotic theory
two classes of organelles?
Endomembrane system and Energy-related organelles
What type of organelles are in the endomembrane system?
Organelles that communicate with one another
Via membrane channels
Via small vesicles
What type of organelles are in the energy-related organelles?
Mitochondria and chloroplasts
Independent and self-sufficient
The cell is a system of interconnected (blank) that work together.
organelles
Production of specific molecules takes place in or
on organelles by
enzymes in membranes
Products are transported around cell by
vesicles
What are vesicles?
Sacs made of membrane material
Vesicles move around using
cytoskeletal network.
Plant cells, fungi, and many protists have this organelle
cell wall
Plant cell walls contain
cellulose, a structural polysaccharide
The nucleus is the
command center of cell, usually near center
The nucleus is separated from cytoplasm by
nuclear envelope
The nuclear envelope consists of
double layer of membrane
in the nuclear envelope, (blank) permit exchange between nucleoplasm and cytoplasm
nuclear pores
The nucleus contains (blank) in semifluid (blank)
chromatin; nucleoplasm
Chromatin contains (2)
proteins and nucleic acids
chromatin condenses to form
chromosomes
chromosomes are formed during (blank) and are carriers of (blank)
cell division; genetic information