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Pathology > Cell Biology > Flashcards

Cell Biology Flashcards

1
Q

What is the function of the membrane systems?

A

To maintain and compartmentalize the organelles and their contents.

  • Plasma membrane
  • ER
  • Golgi
  • Lysosome
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2
Q

What is the common structure of the Membrane systems?

A

Thin film of lipid and proteins that maintain the separation between the contents of organelle and cytosol. Dynamic fluid structures.

  • Amphipathic double layer
  • Phospholipids (polar head group, non-polar fatty acid tails)
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3
Q

What does the lipid bilayer contain?

A

Lipids and other proteins.

  • Cholesterol
  • Glycolipids
  • Proteins (transmembrane/integral, surface and peripheral)
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4
Q

What does it mean when you say that the plasma membrane is semi-porous?

A

Small molecules can pass freely (O2, CO2, Water) while there is regulated transport of larger molecules.

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5
Q

What molecules affect the molecular dynamics and fluidity of the plasma membrane? (Fluid Mosaic)

A

Cholesterol and glycolipids

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6
Q

What is the structure of the ER?

A

Network of flattened sacs and branching tubules, interconnected by a single continuous membrane to form one internal space, the ER lumen.

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7
Q

What is the ER lumen continuous with?

A

The layers of the nuclear envelope.

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8
Q

What is the function of the RER and what is it covered with?

A

Synthesizes proteins, covered with ribosomes.

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9
Q

What is the function of the SER?

A

Synthesizes lipids and steroids, metabolizes carbs and steroids, regulates Ca concentration and drug detoxification.

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10
Q

What are cisternae?

A

Series of cup-shaped, membrane covered sacs.

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11
Q

What is the function of the golgi apparatus?

A

Receiving, shipping and distribution of cellular products.

Receives proteins and lipids synthesized in the ER, modifies them (glycosylation and phosphorylation) and then directs them to their final destination inside or outside of the cell.

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12
Q

What is the function of the mitochondria?

A

Power generator through oxidative metabolism and production of ATP.

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13
Q

What is the structure of the mitochondria?

A

Outer and inner membrane. It contains circular DNA inherited through maternal lineage.

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14
Q

What is the function of peroxisomes?

A

Remove toxic substances from the cell.
Convert hydrogen peroxide to water.
Synthesis of ether lipid and bile acid formation.
Catabolism of long fatty acid chains, purines, prostaglandins and leukotrienes.
Alcohol detoxification in liver.

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15
Q

How do peroxisomes replicate?

A

Self replicate by fission.

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16
Q

What is the function of lysosomes?

A

Autophagy, digestion and recycling of cellular proteins.

Digestion of macromolecules from endocytosis and phagocytosis.

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17
Q

Where do lysosomes originate from?

A

Vesicles that bud off of the Golgi Apparatus. Develop from late endosomes, or vesicles involved in endocytosis.

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18
Q

What is the difference between peroxisomes and lysosomes?

A

Peroxisomes remove/degrade toxic stuff including hydrogen peroxide, fatty acids and alcohol. Lysosomes digest and recycle intracellular proteins as well as molecules from endocytosis and phagocytosis.

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19
Q

What is the function of the cytoskeleton?

A

A dynamic structure that reorganizes when the cell changes shape or moves. Connects protein complexes and organelles. Functions as transport tracks.

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20
Q

What are the microfilaments function?

A

5-7 nm diameter filaments that play a role in locomotion, movement of organelles and force generation.

Muscle contraction.

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21
Q

What is the function of intermediate filaments?

A

8-11 nm diameter filaments are required to prevent mechanical injury in tissues such as the epidermis and muscle.

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22
Q

What is the structure of microtubules?

A

Long, hollow cylinders of tubulin heterodimers that are ~25 nm in diameter.

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23
Q

What is the function of microtubules?

A

Found both in the cytoplasm and as major components of cilia and flagella.
Required for spindle formation during cell division.
Intracellular transport of organelles and vesicles.

Drugs used in cancer treatment can disrupt microtubule structure and prevent cell division.

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24
Q

What is the structural component of cilia and flagella?

A

Microtubules.

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25
Q

What is heterochromatin?

A

Chromatin that is highly condensed that tends to pack along the nuclear membrane. Transcriptionally inactive.

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26
Q

What is chromatin?

A

DNA associated proteins that comprise the chromosomes and nuclear matrix. Present in interphase or non-dividing cells as a complex fibrillar organization with two distinct structures: Heterochomatin and euchromatin.

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27
Q

What is euchromatin?

A

Chromatin that is is less condensed and tends to be areas of DNA that contain genes that are actively transcribed.

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28
Q

What are the basic unit of the chromatin fiber and gives chromatin the ‘bead on a string’ appearance?

A

Nucleosomes.

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29
Q

What does each nucleosome bead consist of?

A

DNA wound around a core or histone proteins that form a fiber.

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30
Q

Modification of histone proteins by acetylation and/or phyosporylation is thought toe be responsible for changing the DNA into a more ________ structure required for active ________.

A

Open, transcription

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31
Q

What is the nuclear matrix?

A

An internuclear matrix of fibrous proteins that is thought to be important for the organization of chromatin and possibly movement of nuclear proteins and RNAs.

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32
Q

What is the organelle where rRNA is transcribed and the ribosomal subunits are assembled?

A

Nucleolus. The size and number of the nucleoli are a reflection of how active the cell is in synthesizing proteins.

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33
Q

What does the nuclear envelope include?

A

The nuclear lamina, inner and outer nuclear membranes.

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34
Q

What is contiguous with the ER and often has attached ribosomes?

A

The outer membrane of the nuclear envelope.

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35
Q

What part of the nuclear envelope has contact with the nuclear lamina?

A

Inner membrane.

36
Q

What is the nuclear lamina?

A

A meshwork of fibrous proteins that are related to the intermediate filaments of the cytoskeleton. Provides structural integrity of the nucleus.

37
Q

What are the nuclear pores and what is their function?

A

Large multi-protein structures that span across both nuclear membranes. The pores are required for the transport of RNA and protein between the nuclear and cytoplasmic compartments. Large proteins require a nuclear localization or export signal.

38
Q

What is synthesized on free ribosomes?

A

Cystosolic proteins and peripheral membrane proteins.

39
Q

What is the Cis Golgi network.

A

Side closest to ER. Protein loaded lipid vesicels from the ER enter here and are modified by post translational steps such as glycosylation.

40
Q

What happens in the trans golgi network?

A

It is the exit side that faces away from the ER. The vesicles bud off from the golgi and make their way to the destinations. Some proteolytic processing of precursor proteins occur here. (preproinsulin to insulin)

41
Q

Where does endocytosis primarily occur?

A

Specialized areas called coated pits.

42
Q

What is the fluid phase of endocytosis called?

A

Pinocytosis.

43
Q

What is receptor mediated endocytosis?

A

Requires binding of the molecule or particle to a specific receptor in the coated pit and then internalization. (LDL particles)

44
Q

Phagocytosis

A

“Cell eating” carried out primarily by macrophages and neutrophils.

45
Q

A substantial part of the volume of most tissues is taken up by an intricate network of macromolecules. What is this called?

A

The extracellular matrix.

46
Q

What does the extracellular matrix primarily consist of?

A

Fibrous proteins embedded in a polysaccharide gel. (90% protein, 10% polysaccharide chains)

47
Q

What are some functions of the ECM?

A

Regulating cell development, migration, proliferation and function.

48
Q

What constitutes the bulk of the gel and occupies most of the volume of the ECM?

A

Glycosaminoglycan chains. (GAGs) They are hydrophilic, so most of the space is taken up by H2O

49
Q

What is the native state of GAGs?

A

Covalently bound to proteins. They exist as proteoglycans.

50
Q

Where are core proteins found in the proteoglycans and where are the GAGs added?

A

RER, Golgi

51
Q

Where is the GAG hyaluronic acid found?

A

skin, cartilage

52
Q

Where is the GAG Chondroitin sulfate found?

A

Cartilage, bone

53
Q

Where is the GAG Dermatan sulfate found?

A

Skin, blood vessels, heart

54
Q

Where is the GAG Heparin sulfate found?

A

Basal lamina.

55
Q

Where is the GAG Keratan sulfate found?

A

Cartilage, intervertebral discs.

56
Q

What is the major protein of the ECM?

A

Collagen

57
Q

What secretes collagen?

A

Connective tissue cells.

58
Q

What is the most abundant type of collagen?

A

Type I

59
Q

Where is Type I collagen normally found?

A

Tendons, skin, ligaments, bone and internal organs.

60
Q

Where is Type II collagen normally found?

A

Cartilage, intervertebral discs

61
Q

Where is Type III collagen normally found?

A

Skin, blood vessels, internal organs.

62
Q

Where is Type IV collagen normally found?

A

Basal lamina

63
Q

What is found linked to each other and interwoven with collagen

A

Elastin. Provides elasticity

64
Q

What are the glycoproteins that bind to specific cell plasma complexes and play an important role in adhesion of cells to the ECM?

A

Fibronectin

65
Q

What is a glycoprotein that is important in the adhesion of epithelial cells to the basal lamina or basement membrane?

A

Laminin

66
Q

Tight junctions

A

Occluding junction. Seal neighboring cells together to prevent leakage of molecules. Selective barrier between epithelial sheets. Claudin and Occludin.

67
Q

Adherens junctions

A

Cell to cell. Connect actin bundles from one cell to actin bundles of another cell.

68
Q

Desmosomes

A

Cell to cell. Connect intermediate filaments from one cell to another. Desmogleins, desmocollins/cadherins.

69
Q

Gap junctions

A

Communicating junction. Allows passage of small molecules from one cell to another. Connexins. Direct cell-cell.

70
Q

Hemidesmosomes

A

Connect intermediate filaments to basement membrane.

71
Q

Integrins

A

Involved in cell-matrix interaction, motility and signaling. THey connect intermediate filaments (hemidesmosomes) actin cytoskeleton (focal adhesion)

72
Q

What anchors cadherins to the actin skeletin?

A

Catenins.

73
Q

Cadherins

A

Transmembrane proteins that play important roles in cell adhesion, by forming adherens junctions to bind cells within tissues together.

74
Q

What are the phases of the Cell cycle?

A

G1–>S–>G2–>M

75
Q

What happens in G1?

A

Follows immediately after mitosis. The cell prepares for DNA synthesis. 2N DNA content.

76
Q

What happens in S phase?

A

DNA synthesis occurs. At the beginning of S, cells have 2N DNA content, at the end, they have 4N.

77
Q

What happens in G2?

A

The period of time after the cessation of DNA synthesis and the start of mitosis.

78
Q

What happens during M phase?

A

Mitosis! Physical process of cell division.

79
Q

What are the steps of mitosis?

A

Prophase, metaphase, anaphase, telophase, cytokinesis.

80
Q

What happens during prophase?

A

Chromosomes begin to condense, the bipolar spindle apparatus begins to form.

81
Q

What happens during prometaphase?

A

The nuclear envelope disassembles, the spindle microtubules enter the nuclear region and begin to associate with specialized regions on the paired centromeres of the chromosomes called kinetochores.

82
Q

What happens during metaphase?

A

Chromosomes align along the metaphase plate. Held in place at the kinetochores by microtubules attached to the opposite poles of the spindle apparatus.

83
Q

What happens during anaphase?

A

The chromosomes separate.

84
Q

What happens during telophase?

A

The separated chromatids arrive at the spindle poles and the kinetochore microtubules begin to disappear. The nuclear membrane and other nuclear structures begin to reassemble.

85
Q

What happens during cytokinesis?

A

The cytoplasm divides by a process known as cleavage, to produce 2 new daughter cells.

Pathology (6 decks)

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