Part 5: Differential cell fate

Question 1

How is cell differentiation achieved?

Answer 1

Through environmental signals (from outside the cell)

Question 2

Cell communication happens through the means of

Answer 2

• Receptor and ligand interactions

- Physical change (light, temperature)

Question 3

Define signal transduction

Answer 3

Series of events activated by the receptor-ligand interaction that lead to differential gene expression

Question 4

What are two types of receptors? Give examples

Answer 4

1) Cytoplasmic (steroid receptors)

2) Transmembrane (tyrosine kinase receptore)

Question 5

When we talk about cell fate, we often use terms such as “specified”, “determined” and “differentiated”. Which of the following statements about them is not correct?

a) A cell specified to a particular fate can still assume a different fate if given the right signals
b) A cell can be determined to have a particular cell fate without changing their morphology or behavior
c) A cell determined to a particular fate can no longer respond to certain signals
d) ‘Differentiated’ means function-specific proteins have been produced to allow a cell to do its job

Answer 5

None

Question 6

Describe the sequence of events in steroid hormones receptor

Answer 6

Signal is detected by receptor (TF), which is bound to the anchor protein. Upon hormone binding, anchor protein is released and TF can travel into the nucleus and regulate transcription

Question 7

The regulatory molecule is:

a) DNA
b) mRNA
c) Protein

Answer 7

mRNA, since it gives another layer of control such as when and where to translate

Question 8

Where is the regulatory molecule

coming from?

Answer 8

From maternal tissue, where regulatory molecules are asymmetrically distributed

Question 9

At the two-cell stage, cells in a human embryo are:

a) Equivalent to each other
b) Specified by asymmetric distribution of regulators

Answer 9

Cells are equivalent, cell separation at this stage is the reason why we get twins

Question 10

Mechanism of transmembrane receptor action

Answer 10

Signal is detected by receptor (transmembrane protein),, docking proteins are recruited (G-Proteins) and activated by replacement of GDP with GTP. G-Protein activates Serine/Threonine kinases, which in turn activates TF that travels inside the nucleus and regulates transcription