LS7C - Week 1

Cadherins are -proteins involved in attachment of cells to the extracellular matrix. -cell adhesion molecules found in cell junctions. -proteins involved in attachment of cells to neighboring cells. -proteins that provide a pathway for molecules to move between cells

- cell adhesion molecules found in cell junctions. - proteins involved in attachment of cells to neighboring cells

Motor proteins cause movement by: (1) undergoing a conformational change, (2) harnessing energy from ATP, and (3) binding to the cytoskeleton

1, 2, and 3

If a mutation occurred in the cadherin gene so that the cytoplasmic domain no longer attached to the cytoskeleton, which of the following would occur? - Cadherins in desmosomes would no longer be anchored to intermediate filaments. - Cadherins in hemidesmosomes would no longer be anchored to intermediate filaments. -Cadherins in adherens junctions would no longer be anchored to microtubules. -Cadherins in desmosomes would no longer be anchored to microfilaments

Cadherins in desmosomes would no longer be anchored to intermediate filaments.

What is the BEST characterization of the minus end of a dynamic filament?

It's slow growing

Vascular endothelial growth factor (abbreviated VEGF and pronounced "Veg-F") is a peptide signaling molecule related to platelet-derived growth factor. VEGF is important in the formation of the circulatory system because its signaling pathway causes the formation of blood vessels in developing embryos during normal development. Tumors also produce and secrete VEGF, causing the formation of new blood vessels that supply these tumors. Given what you know about the different kinds of cell signaling and VEGF, which one of the following statements is TRUE - VEGF is an endocrine-signaling molecule because it circulates through the bloodstream inside of platelets. - VEGF is a paracrine signaling molecule because it binds to receptors on cells at the site where new blood vessels are needed. - VEGF is an endocrine-signaling molecule because it is released from platelets into the bloodstream and is carried throughout the body, causing widespread activation of platelet-derived growth factor receptors on cells in a variety of tissues

VEGF is a paracrine signaling molecule because it binds to receptors on cells at the site where new blood vessels are needed.

Cadherins bind to which type of cytoskeletal element(s) -intermediate filaments -microtubules -both intermediate filaments and microfilaments -microfilaments

both intermediate filaments and microfilaments

T/F: Given that most ligands form covalent bonds with their associated receptors, these complexes are more or less permanent and can only be broken through the hydrolysis of ATP

false

Dynamic instability is a: - feature of microtubules. - feature of microfilaments. - feature of microtubules and microfilaments. - feature of intermediate filaments. - universal feature of the cytoskeleton

feature of microtubules

In skin, the cells of the epidermis connect to the basal lamina through cellular junctions known as hemidesmosomes. Select the cytoskeletal element that helps maintain the integrity of this connection -microfilaments -intermediate filaments -microtubules -both intermediate filaments and microfilaments

intermediate filaments

The plus ends of both microtubules and microfilaments differentiate from the minus ends in that - new tubulin or actin subunits are added more quickly - in that the end that always grows in the direction the cell is moving. - in that new tubulin or actin subunits are added rather than removed

new tubulin or actin subunits are added more quickly

The property of dynamic instability implies that the individual protein subunits of microtubules are held together by what type of bonds?

noncovalent interactions (van der waals, hydrogen bonding, etc.)

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated. This initial phosphorylation step BEST demonstrates - termination - Cellular response - Cell response or signal transduction - Receptor activation - Signal transduction

receptor activation

Figure 9.15 shows how normal signaling works with a Ras protein acting downstream of a receptor kinase. You examine a cell line in which Ras is always activated even in the absence of a signaling molecule. This causes constant activation of the kinases in the MAP kinase pathway. Which of the following conditions would be MOST likely to turn off this abnormally active signaling pathway - the addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus - the addition of a drug that prevents the dimerization of the receptor kinase - the addition of a drug that increases the binding affinity of Ras for MAP kinase enzymes in the cytoplasm - the addition of a drug that prevents the phosphorylation of the receptor kinase

the addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus

Suppose there is a mutation in a laminin-binding integrin gene that causes a loss of function in the cytoplasmic domains of the integrin. Which of the following would you expect to observe as a result of this mutation? - The integrin would be unable to signal the cytoplasm when it had bound to laminin. - Tissues would be weakened because the integrin could no longer associate with microfilaments in adherens junctions. - The integrin would function normally because the cytoplasmic domain is not responsible for binding to laminin. - Cell adhesion to laminin would decrease, but laminin-meditated gene expression would remain the same.

the integrin would be unable to signal the cytoplasm when it had bound to laminin.