Module 01 Flashcards Preview

MCELLBIX116 - Cell Biology > Module 01 > Flashcards

Flashcards in Module 01 Deck (28)
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1
Q

Function of Smooth Endoplasmic Reticulum

A

Synthesis of fatty acids and phospholipids.

2
Q

Function of Rough Endoplasmic Reticulum

A

Site of synthesis of membrane proteins and proteins to be secreted out of the cell.

3
Q

Function of Golgi complex

A

Proteins are modified and sorted before being transported to their final destination.

4
Q

Function of Peroxisomes

A

Contain oxidase enzymes that use molecular oxygen to oxidize fatty acids and detoxify harmful substances.

5
Q

Site of TCA cycle

A

Mitochondrial Matrix

6
Q

Membranes of the Nucleus

A

Outer Membrane - continuous with the ER.

Inner Membrane - contains the genetic material.

7
Q

Primary Cell Cultures

A

Prepared directly from tissues of an organism. They have a definite life span.

8
Q

Transformed Cell Lines

A

Derived from oncogenically transformed cells and are able to grow indefinitely.

9
Q

CAMs

A

Cell-adhesion molecules are cell surface proteins that cells use to bind to adjacent cells as well as to components of the extracellular matrix (ECM), such as collagen of fibronectin.

10
Q

Fibroblasts

A

The predominant cells in connective tissue and normally produce extra-cellular matrix components such as collagen that bind to cell-adhesion molecules, thereby anchoring cells to a surface.

11
Q

Aneuploid

A

Cells with an abnormal number of chromosomes.

12
Q

Distinguishing characteristics of Bacteria

A
Small genomes
Single chromosomal genome
Small cell
Single cell
Prokaryote (no organelles)
Circular DNA genome
13
Q

Distinguishing characteristics of Archaea

A
Small genomes
Multiple chromosome genome
Small cell
Single cell
Cell membranes have chemical properties that differ dramatically from those of bacteria and eukaryotes. Many grow in unusual, often extreme, environments.
14
Q

Distinguishing characteristics of Eukaryotes

A

Large genomes
Multiple chromosome genome
Large cells
Single or multi cellular

15
Q

FACS (Fluorescence-activated cell sorter)

A

A method of separating cells that are phenotypically different from each other.

Cells are passed through a vibrating nozzle in single file in droplets. As the cells flow down the stream they are scanned by a laser. Some of the laser light is scattered by the cells and that’s how the cells are counted. This scattered light can also be used to measure the size of the cells. If you wanted to separate a subpopulation of cells, you could do so by tagging those of interest with an antibody linked to a fluorescent dye. The antibody is bound to a protein that is uniquely expressed in the cells you want to separate. The laser light excites the dye which emits a color of light that is detected by the photomultiplier tube, or light detector. By collecting the information from the light (scatter and fluorescence) a computer can determine which cells are to be separated and collected. The final step is sorting the cells which is accomplished by electrical charge. The computer determines how the cells will be sorted before the drop forms at the end of the stream. As the drop forms, an electrical charge is applied to the stream and the newly formed drop will form with a charge. This charged drop is then deflected left or right by charged electrodes and into waiting sample tubes. Drops that contain no cells are sent into the waste tube. The end result is three tubes with pure subpopulations of cells. The number of cells is each tube is known and the level of fluorescence is also recorded for each cell.

16
Q

Fractionation

A

Separation of homogenized cell contents by increasingly higher centrifugation speeds. Cells are first disrupted to release their contents, suspended in a solution of neutral salt and pH.

Sequential differential centrifugation of the cell homogenate yields fractions of partly purified organelles that differ in mass and density. Increase higher speeds to separate organelles.

Equilibrium density-gradient centrifugation separates cellular components according to their densities and can further purify cell fractions obtained by differential centrifugation.

17
Q

Magnification vs. Resolution of microscopes

A

Resolution is the ability of a microscope to distinguish between two very closely positioned objects. Like clarity, sharpness of the image.

Magnification is the enlargement of the image can blur the image. Like blowing up the picture.

Large magnification with poor resolution will look blurry and can’t be resolved, or identified.

18
Q

Bright-field Microscopy

A

Page 407

19
Q

Phase Contrast Microscopy

A

Page 407

20
Q

DIC (Differential Interference Contrast) Microscopy

A

Page 407

21
Q

Fluorescence

A

Absorption of one wavelength of light and emits another, longer wavelength. Typically used as part of a fluorescent probe to locate specific molecule within a cell. Much like probes in PCR.

E.g. shine blue light and read green light.

22
Q

TEM (Transmission Electron Microscopy)

A

TEM sends electrons from a heated filament through the specimen and absorbed on a detector. This process occurs in a vacuum and is not suitable for a living sample.

In preparation, the fixation process kills the cells but preserves the specimen’s components.

23
Q

SEM (Scanning Electron Microscopy)

A

SEM sends electrons from a heated filament towards the specimen that’s metal coated. The scattered electrons are collected by a detector.

24
Q

Fixing samples for microscopy

A

Specimens for light and electron microscopy are commonly fixed wtth a solution containing chemicals that cross-link most proteins and nucleic acids. Formaldehyde, a common fixative, cross-links amino groups on adjacent molecules; these covalent bonds stabilize protein-protein and protein-nucleic acid inter- actions and render the molecules insoluble and stable for sub- sequent procedures. After fixation, a tissue sample for examination by light microscopy is usually embedded in paraf- fin and cut into sections about 50um thick.

Cultured cells growing on glass coverslips are thin enough so they can be fixed in situ and visualized by light microscopy without the need for sectioning.

25
Q

Identify the relationship between light microscopy wavelength and resolution

A

Because the limit of resolution is given by D = (0.61/(N sin ), shorter wavelength light (e.g., blue) will provide better resolution than longer wavelength light (e.g., red).

D is the MINIMUM distance between two objects that can be clearly identified, or resolving power. The smaller D, shorter the distance between two objects, the greater the resolving power.

26
Q

Complications introduced by using fixatives

A

Most fixatives are cross-linking agents that immobilize proteins and other cellular molecules. As part of the fixation process, samples are often also dehydrated. Such chemical changes may alter the normal structure and spatial relationship of cellular components, and this must be taken into account when interpreting images of fixed specimens.

27
Q

Technique for separating T-cells from other immune system cells

A

Flow cytometry and fluorescence-activated cell sorting is used to select and isolate T cells away from the excess number of other cell types. Briefly, T cells, unlike other cells, express CD3 and Thy1.2 proteins on their cell surface. Antibodies specific to these markers are linked to a fluorescent dye and incubated with the pool of cells. The antibodies bind the cell-surface markers on the T-cell surface and when all cells are placed in the FACS machine, a laser is used to excite the dye causing it to fluoresce. Fluorescing T cells, selectively sorted from the non-fluorescing cells, can be cultured in vitro.

28
Q

Fluorescent properties of the dye FURA-2

A

Fura-2 binds to Calcium ions in the cell, and will give data as to the concentration of Ca2+ ions in specific regions of the cell.