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Histology M1 > Histology: Intro to Cell Plasma Membrane > Flashcards

Histology: Intro to Cell Plasma Membrane Flashcards

1
Q

What are the 3 main components of the human body?

A
  1. Cells 2. Extracellular Matrix (ex. Basal lamina, collagen) 3. Extracellular Fluid (ECF) (ex. Blood plasma, lymph CSF)
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2
Q

What does the cell theory consist of?

A
  1. All organisms are composed of one ore more cells 2. The cell is the basic unit of structure and organization in organisms 3. All cells come from preexisting cells
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3
Q

Who invented the first optical microscope?

A

Zacharias Jansen; but Leeuwenhoek, Hooke and Newton are claimed to have discovered the microscope

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4
Q

Who is known as “the Father of Microbiology”, and considered to be the first microbiologist?

A

Van Leeuwenhoek

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5
Q

How did Antonie Leewenhoek discover bacteria and what did he call them?

A

He discovered bacteria by looking at dental scrapings and called them Animalcules

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6
Q

How did Robert Hooke discover cells?

A

my looking at cork

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7
Q

Who made the first statement of the cell theory and how did it come about?

A

Matthias Jakob Schleiden. He studied plant tissues and stated that all plants are aggregates of individual cells which are fully independent.

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8
Q

What was Schleiden’s conclusion?

A

He concluded that all plant parts are made of cells and that an embryonic plant organism arises from one cell.

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9
Q

Who was Theodor Schwann?

A

He observed animal tissues and concluded that all animal tissues are composed of cells.

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10
Q

What tissues did Schwann primarily study and what did he discover?

A

His attention was directed to the nervous and muscular tissue. He discovered the cells which envelope the nerve fibers, now called Schwann cells.

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11
Q

Who is the “father of modern pathology?

A

Rudolph Carl Virchow

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12
Q

What did Virchow publish?

A

In 1858, he published “every cell originates from another existing cell like it.”

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13
Q

How many types of cells are in the human body?

A

200 different types

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14
Q

What is the smallest functional unit of the body?

A

Cells

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15
Q

When cells are grouped together, what is formed?

A

Tissues and each type has a specialized function such as blood, muscle, bone.

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16
Q

When tissues are grouped together what is formed?

A

Organs, examples include heart, stomach brain

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17
Q

When organs are grouped together what do they form?

A

Systems. Each system performs a particular function that maintains homeostasis and contributes to the health of the individual.

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18
Q

What is the difference between prokaryotic and eukaryotic cells?

A

Prokaryotic- nucleus is not defined by a membrane (bacteria) Eukaryotic- nuclear envelope surrounds the genetic material (characteristic of multicellular organisms or “higher animals”)

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19
Q

How many activities do differentiated cells typically specialize in?

A

One

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20
Q

What specialized cells typically are for movement?

A

Muscle and other contractile cells

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21
Q

What specialized cells form adhesive and tight junctions between cells?

A

Epithelial Cells

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22
Q

What specialized cells synthesize and secrete components of the extracellular matrix?

A

Fibroblasts, cells of bone and cartilage

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23
Q

What specialized cells convert physical and chemical stimuli into action potentials?

A

Neurons and sensory cells

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24
Q

What specialized cells conduct synthesis and secretion of degradative enzymes?

A

Cells of digestive glands

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25
Q

What specialized cells conduct synthesis and secretion of glycoproteins?

A

Cells of mucous glands

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26
Q

What specialized cells conduct synthesis and secretion of steroids?

A

Certain cells of the adrenal gland, testis, and ovary

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27
Q

What specialized cells conduct ion transport?

A

Cells of the kidney and salivary gland ducts

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28
Q

What specialized cells conduct intracellular digestion?

A

Macrophages and neutrophils

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29
Q

What specialized cells conduct lipid storage?

A

Fat Cells

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30
Q

What specialized cells conduct metabolite absorption?

A

Cells lining the intestine

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31
Q

What do cells consist of?

A
  1. Cytoplasm (cell functions) 2. Nucleus (genetic reservoir)
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32
Q

Cytoplasm is separated from external environment by?

A

Plasma membrane

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33
Q

What is cytosol?

A

A watery like fluid inside the cytoplasm that suspends a number of organelles, cytoskeleton and inclusions.

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34
Q

What do organelles have?

A

Individual and highly specialized functions, and are often enclosed in their own membrane within the cytosol.

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35
Q

How thick is the plasma membrane?

A

7.5-10nm thick

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36
Q

Plasma membrane and other cytoplasmic membranes are called?

A

Unit Membranes

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37
Q

What is a unit membrane?

A

Structure of two electron dense lines of 2.5 nm thick separated by an electron lucent layer of 3nm

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38
Q

The plasma membrane consists of what?

A

Two layers of phospholipids (fatty substances) with protein and sugar molecules attached or embedded in them.

39
Q

What is composed of membrane lipids, membrane carbohydrates, and membrane proteins?

A

Cell or Plasma membrane

40
Q

What type of molecule is the plasma membrane?

A

Phospholipid molecule containing: 1. Hydrophilic head, which is electrically charged 2. A hydrophobic tail which has NO charge

41
Q

How is the phospholipid bilayer arranged?

A

Like a sandwich with the hydrophilic heads aligned on the outer surfaces of the membrane and the hydrophobic tails forming a central water-repelling layer.

42
Q

What is the phospholipid function?

A
  1. Structural framework for the membrane 2. Barrier for indiscriminate movement of water soluble material.
43
Q

What is in the outer leaflet of the plasma membrane, inner leaflet of the plasma membrane, and what is a major membrane component.

A
  1. Outer Leaflet- consists mainly of phosphatidylcholine, sphingomelin, and phosphatidlethanolamine. Glycolipids are found only in the outer leaflet with their carbohydrate portion exposed to the extracellular space. 2. Inner Leaflet- consists mainly of phosphatidylserine, phoshatidylinositol, and phosphatidylethanolamine. The head groups of phosphatidylserine and phosphatidylinositol are negatively charged, so the cytosolic face of the plasma membrane has a net negative charge. Phosphatidylinositol plays a significant role in signaling. 3. Cholesterol is a major membrane component but it does not form the membrane itself. Cholesterol has an effect on membrane fluidity by modulating the movement of fatty acid chains of phospholipids in a temperature-dependent manner.
44
Q

Cholesterol helps to?

A

Helps to lightly immobilize the outer surface of the membrane and make it less soluble to very small water-soluble molecules that could otherwise pass through more easily.

45
Q

What would happen to the cell membrane without cholesterol?

A

The cell membrane would be: -too fluid -not firm enough -too permeable to some molecules

46
Q

What does cholesterol do at high temperatures?

A

Cholesterol helps separate the phospholipids so that the fatty acid chains can’t come together and crystallize.

47
Q

What does cholesterol help prevent?

A

Helps prevent extremes (too fluid or too firm) in the consistency of the cell membrane.

48
Q

What is a lipid raft?

A

It is a localized region within the plasma membrane containing high concentration of cholesterol and glycosphingolipids.

49
Q

What causes a lipid raft?

A

The high concentration of cholesterol and the presence of longer, highly saturated fatty acid chains, the lipid raft area is thicker and exhibits less fluidity than the surrounding plasma membrane.

50
Q

What does a lipid raft contain?

A

It contains a variety of integral and peripheral membrane proteins involved in cell signaling.

51
Q

How are membrane proteins situated?

A

Asymmetrically situated so properties of one side of membrane are different from the other side.

52
Q

What are 3 types of membrane protein locations?

A
  1. Integral Proteins- Transmembrane proteins that pass through the lipid bilayer. 2. Peripheral Protiens- located outside the lipid bilayer on cytoplasmic surface. Linked to lipid layer by non-covalent bonding. 3. Lipid-anchored Proteins- Located outside the lipid bilayer, on extracellular or cytoplasmic surface. Linked to lipid layer by covalent bonds
53
Q

Integral Proteins are?

A

Inserted into the lipid bilayer. (goes from extracellular space to intracellular space)

54
Q

Peripheral Membrane proteins are?

A

Are linked indirectly to the plasma membrane by protein-protein interactions.

55
Q

The extracellular portion of integral and peripheral membrane proteins are generally_____?

A

Glycosylated

56
Q

The intracellular portion of membrane proteins are bound to ________?

A

Cytoskeletal components

57
Q

What type of membrane proteins are most integral membrane proteins?

A

Transmembrane Proteins spanning the membrane through alpha-helical regions.

58
Q

Transmembrane proteins can conduct what types of transport, single-pass or multi-pass?

A

Both.

59
Q

What is a uniporter, symporter, and antiporter when discussing transmembrane proteins?

A

Uniporter- Carries a single molecule from one side of the membrane to the other. Symporter- A co-transporter carries two molecules simultaneously or sequentially in the same direction Antiporter- A co-transporter carries two molecules simultaneously or sequentially in the opposite direction.

60
Q

What is a glycocalyx?

A

A coat of 10-20nm that covers the external surface of the cell membrane.

61
Q

What consists of glycocalyx?

A

It is carbohydrates attached to proteins (glycoproteins) or to lipids, (glycolipids) on the outer surface forms cell coat or glycocalyx. This functions in cell metabolism, cell recognition, cell association and as receptors.

62
Q

What are the 4 functions of the glycocalyx?

A
  1. Cushions the plasma membrane and protects it from chemical or mechanical injury or shear stress in the case of endothelium 2. Enables the immune system to recognize and selectively attack foreign organisms 3. Has a role in cell adhesion, strengthening the binding of cells to each other 4. Especially in the small intestine, it crates a meshwork of high enzyme concentration secreted by the absorptive cells that are essential for the final steps of digestion of proteins and sugars.
63
Q

What do Peripheral Membrane Proteins provide, what do they function as, and what do they transmit?

A

Provide mechanical support, function as enzymes, and transmit transmembrane signals.

64
Q

What type of bonding do peripheral membrane proteins do and with what?

A

They associate by weak electrostatic bonding and they attach to the hydrophilic heads of lipid groups or integral proteins of plasma membrane. (non-covalent bonding)

65
Q

The membrane proteins function as branched carbohydrate molecules attached to the outside of some membrane protein molecules that give the cell what identity?

A

Immunological identity

66
Q

Membrane Proteins can act as?

A

Specific receptors for hormones and other chemical messengers

67
Q

Some membrane proteins are?

A

enzymes

68
Q

Some membrane proteins are involved in?

A

transport across the membrane

69
Q

What are the six functions of Integral membrane proteins?

A
  1. Pump 2. Channels 3. Receptors 4. Linkers 5. Enzymes 6. Structural Proteins
70
Q

What are the five functions of the Plasma Membrane?

A
  1. Determines physical state of membrane 2. Influences activity of membrane proteins 3. Provide precursors of chemical messengers 4. Selective barrier- semipermeable membrane: regulates cell content/volume. (transport) 5. Communication (signal transduction)
71
Q

In plasma membrane transport, what type of transport is dependent upon the concentration gradient?

A

Passive Diffusion

72
Q

In plasma membrane transport, what type of transport is is passive but requires carrier proteins or gated pore?

A

Facilitated Diffusion

73
Q

In plasma membrane transport, what type requires energy?

A

Active Transport

74
Q

In plasma membrane transport, what type of transport utilizes endocytosis, pinocytosis, and phagocytosis?

A

Bulk Transport

75
Q

In transporting molecules across the plasma membrane, there are active and passive transports. What are they?

A
  1. Simple Diffusion (passive) 2. Ion Channel Proteins (passive and active) 3. Carrier Protein (active and passive) 4. Channel proteins have 3 types: 4a) Voltage gated ion channels (membrane potentials) 4b) Ligan-gated ion channels (neurotransmitter) 4c) Mechanically-gated ion channels (vibrations such as in the ear)
76
Q

In Bulk Transport, what type of endocytosis is considered fluid (hint: cell drinking)

A

Fluid phase pinocytosis via pinocytotic vesicle

77
Q

Explain the process of pinocytosis (over view).

A

Fluid on the outside of the phospholipid bilayer will accumulate, the cell membrane then encloses around the liquid and acts a vesicle around the water to bring it through the phospholipid bilayer and into the cell.

78
Q

Endocytosis is different than pinocytosis in that?

A

It uses receptor mediated coated vesicles to bring in non-liquid substances into the cell.

79
Q

Explain the endocytic pathway and membrane trafficking process (from entering to leaving the cell).

A

Entering the Cell: 1. Ligand Binds to Receptor on the exterior of the plasma membrane. 2. Coating proteins located on the interior of the plasma membrane form a “bubble” around the proteins on the receptors. (this is to create a traveling vesicle to transport the substance inside the cell) 3. Once the “travel bubble” is inside the cell the coating proteins drop off and the bubble fuses with an early endosome. (the receptors release the ligands and the carrier proteins pinch off and are in their own bubble 4a. The carrier protein bubble returns to the cell membrane where it waits to receive more ligands and repeat the process 4b. The ligands, inside the endosome, get digested by a lysosome.

80
Q

Explain receptor mediated endocytosis.

A

Low Density Lipoprotein (LDL) receptors are on the exterior of the cell membrane.

  1. The LDL ligand binds to the receptor on the exterior of the membrane, the coating proteins create a “bubble” around the LDL ligand-bound receptors.
  2. Once fully engulfed and the bubble is compeltely inside the cell, coating proteins release and return to the inner plasma membrane, ready to repeat the process.

3A. Inside the vesicle (bubble without the coating “endosome”), the ligand releases from the receptors and the receptors return to the exterior surface of the plasma membrane.

3B. The endosome with the LDL inside will fuse with the lysosome and the lysosome will digest it.

81
Q

What are the two pathways for Exocytosis and which is the default pathway?

A
  1. Regulated Secretory Pathways
  2. Constitutive Secratory Pathways (default pathway)
82
Q

When is Constitutive Secretion used?

A

It is used for molecules being transfered from the Golgi to the outer surface of the cell. This is the default pathway for most molecules going to the plasma membrane since it is used to replenish material at the plasma membrane and some membrane-bound organelles.

83
Q

Explain the Constitutive Secretion pathway.

A

Secretion occurs without external factors or signals (continuous).

  1. The newly synthesized unmodified protein exits the Trans-Golgi network in a secretory vessicle. (the unmodified means they do not have a signal on them directing them to a specific location).
  2. The secretory vesicle travels to the plasma membrane and there is not control mechanism so it is continuous.
  3. Once the vesicle reaches the cell membrane, it fuses with the plasma and releases its cargo protein into the intermembrane space.
  4. The vesicle itself will contribute new lipids and its membrane to the plasma membrane of the cell.
84
Q

Explain the Regulated Secretory Pathway for exocytosis.

A

The secretory vessicle leaves the trans portion of the Golgi with the modified protien. The vessicle reamains near the cell surface and stayd until a specific signal arrives that triggers the secretion of the modified protein.

An example of this would be insulin inside of the Beta Cell of the pancreas. The secretory vessicle, filled with insulin, moves to the cell membrane and releases once the signal is received for it to release insulin into the blood stream. (this is actually a complicated signaling process involving glucose but not needed to know right now to understand the basic concept of the Regulated Secretory Pathway)

85
Q

What is an example of cell communication and two types?

A

Cell communication involves signaling molecules or messengers and can receive messages from outside of the cell to the interior of the cell. An example would be hormones.

Another type of cell messaging involves between cells such as Gap Junctions.

86
Q

Why are membrane proteins an excellent target for chemotherapeutic drugs?

A

It disrupts the messaging (very basic explanation)

87
Q

Extracellular signaling molecules or mesengers mediate 4 kinds of communication between cells. What are they?

A
  1. Endocrine Signaling
  2. Paracrine Signaling
  3. Autocrine Signaling
  4. Synaptic signaling
88
Q

Explain endocrine signaling by giving an example.

A

Hormone discharged into the blood and transported to the effector cell.

89
Q

Explain paracrine signaling.

A
90
Q

Explain autocrine signaling.

A

Chemical mediators acts on the cell that produces it

91
Q

Explain Synaptic signaling.

A

neurotransmitter acts only on adjacent nerve cells through synapse.

92
Q

What are two types of signal receptors and how do they work?

A
  1. Hydrophobic signaling molecules: Steroid and thyroid hormones, diffuse through plasma membrane of the target cell and activate receptor proteins inside the cell.
  2. Hyrophilic signaling molecules: Neurotransmitters, most hormone and local chemical mediators (paracrine signal) activate receptor protein on the surface of gtarget cell which triggers a series of events inside the cytoplasm that direct the signal to either the cytoplasm or nucleus. The best example is G-protein (because they bind to guanine nucleotides)
93
Q

Explain how a G-protein activates in the presence of a ligand binding to a receptor.

A
  1. G proteins consist of alpha, beta, and gamma subunits, which are bound by the Guanosine Diphosphate (GDP). They have no contact with the receptors.
  2. When a messenger or hormone binds to a receptor, the receptor causes the G-protein to exchange GDP for the Guanosine Triphosphate, which activates the G-Protein.
  3. The G-Protein (bound to the alpha subunit) diffuses along the membrane and binds to an effector, which activates it.
  4. The alpha subunit converts GTP back to GDP and inactivates itself. The alpha subunit reattaches to the Beta-Gamma compex.
94
Q

Give an example of a disease caused by defective receptors.

A

Laron Syndrome- a type of dwarfism is due to defective receptors. Pseudohypoparathyroidism is due to nonfunctioning parathyroid and growth hormone receptors. In these two conditions the glands produce the hormones, but the target cells do not respond (they lack normal receptors)

Histology M1 (2 decks)

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