7c pcrqs

T/F: The ability of cells to adhere to one another is fundamental to multicellularity.

True

For multicellularity to develop, there must be a mechanism signaling among cells in the multicellular organism. What structure in the cell membrane receives signals from the environment or from other cells?

receptors

What is not a general requirement for complex multicellular life?

individual cells must retain a full range of functions, including reproduction

Many of the signaling pathways used for signaling between cells in complex multicellular organisms first evolved in:

unicellular eukaryotes

T/F: Signaling pathways have been conserved in a way range of organisms

True

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated. This initial phosphorylation step best demonstrates:

receptor activation

T/F: A cell can only respond to signals from other cells, not from the physical environment.

False

What is an example of a cellular response to signal transduction?

• a change in the proteins found in the cytosol

• a change in the activity of an enzyme

• the release of signaling molecules from the cell

 

Growth factors such as platelet-derived growth factor (PDGF) function in:

paracrine signaling

Kohler and Lipton first discovered platelet-derived growth factor (PDFG) by observing that fibroblasts:

grew better in cell culture containing blood serum containing proteins released by platelets during clotting

List the types of cellular communication from shortest to longest distanced traveled by the signaling molecule to its responding cell:

autocrine, paracrine, endocrine

Notch and Delta are both transmembrane proteins involved in cell communication in the developing nervous system of vertebrate animals. What makes Notch different from Delta?

Notch is a receptor; Delta is a signaling molecule

What is one example of a cell-surface receptor?

a protein that forms a channel that allows to enter the cell when a ligand binds

Which type of protein adds a phosphate group to another molecule?

kinase

In the context of cell signaling, to what does the term ligand refer to?

a signaling molecule that binds to the receptor

A researcher is using a small molecule inhibitor that prevents phosphorylation as a tool to manipulate a signaling pathway. What is the most likely target of this small molecule inhibitor?

a receptor kinase

The first step following platelet-derived growth factor (PDGF) binding of the receptor is:

dimerization of the receptor

Why are some mutations of Ras associated w/ cancer?

Ras activates the MAP kinase signal transduction pathway that regulates cell division

If two signaling pathways are activated simultaneously:

• they may strengthen e/o

• they may inhibit e/o

• one may inhibit the other

What is the end-result of activating the MAP kinase pathway?

a change in gene expression

T/F: As cells differentiate, they lose their ability to become other cell types because they delete subsets of genes

False

Cells differentiate through:

gene regulation

Signal transduction is the process by which:

an extracellular molecule activates a membrane protein, which in turn activates molecules inside the cell

What type of tissue helps form a barrier between the body and the external environment?

epithelial tissue

What type tissue can perform absorption or secretion in the body?

epithelial tissue

A pathologist is carrying out an autopsy. Upon opening the chest cavity, the pathologist sees a thick, fibrous tissue surrounding the heart. This is likely:

connective tissue

Could melanin granules be moved by dynein and kinesin along an actin microfilament?

No, these motor proteins are specific to microtubules and cannot move along microfilaments

Myosin is a motor protein that associates with:

microfilaments

Motor proteins cause movement by:

• undergoing a conformational change

• harnessing energy from ATP

• binding to the cytoskeleton

Which of the cell junctions is involved in creating a barrier between cells

tight junction

Gap junctions and plasmodesmata have what feature in common?

They both allow direct transport of materials between cells

Cadherins bind to what type of cytoskeletal element(s)?

both intermediate filaments and microfilaments

_____ is a component of the extracellular matrix produced by an animal cell.

collagen

The extracellular matrix is:

a network of proteins and polysaccharides outside the cell that play a role in structural support

The strength of collagen comes from:

its triple helical structure and bundling