Bio Module 4

A cell releases signals that affect both itself and close by cells. What type of signaling is this?

autocrine and paracrine signaling

A chemical signal is released from a nearby cell and binds to an intracellular receptor on another cell. What type of hormone is this?

A steroid or lipid-soluble hormone

A ligand binds to a receptor, causing the two pieces of the receptor to join together and phosphorylate each other. What type of signaling pathway is this?

Receptor kinase signaling pathway

A ligand is injected near target cells, but does not cause activation of a pathway. What is one possible reason for this?

The target cells may lack the correct receptor for the ligand

A molecule of the surface of the cell has an extracellular domain that binds to collagen and an intracellular domain bound to actin. What is the name of this?

Integrin

Discuss which cytoskeletal proteins are using in the process of cell division?

Microtubules (for spindle formation), actin (for cytokinesis), and intermediate filaments (for nuclear envelope breakdown)

Two cells are bound by tight junctions. How would they send chemical signals back and forth between them? Can plants do this?

They would likely use gap junctions; in plants, plasmodesmata serve a similar function.

What happens in G1? What happens if this does NOT happen in G1?

In G1, the cell grows, produces proteins, and checks for DNA damage. If this does not happen, the cell may not enter S phase, leading to cell cycle arrest.

In S phase, DNA is copied semi-conservatively. True or False?

True

Describe in your own words, a telomere.

A telomere is a protective cap at the end of a chromosome made of repetitive DNA sequences. It prevents the loss of essential genetic information during cell division and shortens with each replication, eventually leading to cell aging or death.

Each chromosome, maternal and paternal, contains a/an _____________, which is a version of a gene that describes a certain trait.

Allele

You swap out a single base pair in a DNA strand. When this happens, the protein that gene was coding for is produced, but is truncated and thus can’t fold properly. What is likely the mutation that caused this?

Nonsense mutation

Describe genotype.

Genotype refers to the genetic makeup of an organism—the specific DNA sequence that codes for traits.

Describe phenotype.

Phenotype is the observable expression of those genes, such as physical appearance or behavior, influenced by both genetics and the environment.