3.1 Cellular Functions Flashcards

1
Q

The primary structural proteins in the body are?

A

collagen, elastin, keratin, actin, and tubulin

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2
Q

Structural Proteins

A
  • The cytoskeleton
  • have highly repetitive secondary structure
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3
Q

Motif

A
  • a super-secondary structure—a repetitive organization of secondary structural elements
    together
  • gives many structural proteins a fibrous nature
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4
Q

Collagen

A
  • trihelical fiber (three left-handed helices woven together to form a secondary right-handed helix) and makes up most of the extracellular matrix of connective tissue.
  • makes up most of the extracellular matrix of connective tissue
  • provides strength and flexibility
    —forms a unique and specific secondary helical structure based on the abundance of the
    amino acid glycine.
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5
Q

Elastin

A
  • important component of the extracellular matrix of connective tissue.
  • primary role is to stretch and then recoil like a spring, which restores the original shape of the tissue.
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6
Q

Keratins

A
  • intermediate filament proteins found in epithelial cells
  • contribute to the mechanical integrity of the cell and also function as regulatory proteins
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7
Q

Actin

A
  • makes up microfilaments and the thin filaments in myofibrils
  • the most abundant protein in eukaryotic cells
  • have a positive side and a negative side; this polarity allows motor proteins to travel unidirectionally along an actin filament, like a one-way street.
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8
Q

Tubulin

A
  • makes up microtubules
  • Microtubules are important for providing structure, chromosome separation in mitosis and meiosis, and intracellular transport with kinesin and dynein
  • Like actin, tubulin has polarity: the negative end of a microtubule is usually located adjacent to the nucleus, whereas the positive end is usually in the periphery of a cell.
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9
Q

ATPases

A
  • Enzymatic motor proteins
  • power the conformational change necessary for motor function
  • have transient interactions with either actin or microtubules
  • Myosin is the primary motor protein that interacts with actin
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10
Q

Kinesins and dyneins

A
  • motor proteins associated with microtubules
  • have two heads, at least one of which remains attached to tubulin at all times.
  • Both proteins are important for vesicle transport in the cell, but have opposite polarities
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11
Q

Kinesins

A
  • play key roles in aligning chromosomes during metaphase and depolymerizing microtubules during anaphase of mitosis
  • kinesins bring vesicles toward the positive end of the microtubule
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12
Q

Dyneins

A
  • involved in the sliding movement of cilia and flagella
  • dyneins bring vesicles toward the negative end
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13
Q

Binding Proteins

A
  • have stabilizing functions in individual cells and the body
  • transport or sequester molecules by binding to them
  • include hemoglobin, calcium-binding proteins, DNA-binding proteins (often transcription factors), and others.
  • the binding protein usually has high affinity for its target across a large range of concentrations so it can keep it bound at nearly 100 percent.
  • Transport proteins have varying affinity depending on environment
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14
Q

Cell Adhesion Molecules (CAMs)

A

are proteins found on the surface of most cells and aid in binding the cell to the extracellular matrix or other cells.

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15
Q

Cadherins

A
  • a group of glycoproteins that mediate calcium-dependent cell adhesion.
  • often hold similar cell types together, such as epithelial cells.
  • Different cells usually have type-specific cadherins
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16
Q

Integrins

A
  • group of proteins that all have two membrane-spanning chains called α and β.
  • chains are very important in binding to and communicating with the extracellular matrix
  • play a very important role in cellular signaling and can greatly impact cellular function by promoting cell division, apoptosis, or other processes.
17
Q

Selectins

A
  • unique because they bind to carbohydrate molecules that project from other cell surfaces
  • weakest bonds formed by the
    CAMs
  • expressed on white blood cells and the endothelial cells that line blood vessels
  • play an important role in host defense, including inflammation and white blood cell migration
18
Q

Antibodies (immunoglobulins (Ig)

A
  • proteins produced by B-cells that function to neutralize targets in the body, such as toxins and bacteria, and then recruit other cells to help eliminate the threat
  • Disulfide linkages and noncovalent interactions hold the heavy and light chains together
19
Q

Where is the antigen-binding region?

A
  • at the tips of the “Y
20
Q

Constant region

A
  • remaining part of the antibody molecule
  • involved in recruitment and binding of other cells of the immune system, such as macrophages
21
Q

What’re the 3 outcomes of antibodies binding to antigens?

A
  • Neutralizing the antigen
  • Marking the pathogen for destruction (opsonization)
  • Clumping together, to be phagocytized