Chapter 3.2

Question 1

What occurs during the initial stage of cell specification and determination

Answer 1

Specification
->cells is reversibly designated to a specific cell type

Determination

• > cell commits to a particular function in the future
• > after determination, the cell cannot become any other type of cell

Question 2

What determines the process of determination? Discuss mRNA and morphogens

Answer 2

• presence of specific mRNA/protein molecules may result in determination
• morphogens may also be the result of determination
• > morphogens are molecules secreted from nearby cells
• > these molecules cause cells to follow a particular developmental pathway

Question 3

During determination, has the cell produced the products it needs to carry out its function? If not, when does this happen

Answer 3

• no
• > this happens during differentiation

-during determination, cells just commit to a certain type

Question 4

What occurs during differentiation

Answer 4

• cell must undergo changes that cause the cell to develop into the determined cell type
• > this includes changing structure, function and biochemistry of the cell to match the cell type

Question 5

What is meant by the term potency

Answer 5

-it is the tissues a particular stem cell can differentiate into

Question 6

What is meant by the term totipotent? Give an example.

Answer 6

• totipotent are cells with the greatest potency
• > include embryonic stem cells
• > totipotent cells can differentiate into any type of cell

Question 7

What is meant by the term pluripotent cells? When do these cells exist?

Answer 7

• when the topitent cells differentiate into the three germ cell layers
• these cells can differentiate into any cell type except for placental structures

Question 8

What is meant by the term multipotent cells?

Answer 8

• this is when the cells begin to become more specialized

- at this point cells can differentiate into multiples types of cells within a particular group

Question 9

Do stem cells only exist in embryos

Answer 9

• no

- >they exist in full grown adults as well

Question 10

What are autocrine signals

Answer 10

-they are signals that act on the same cell that secreted the signals in the first place

Question 11

What are paracrine signals

Answer 11

-they are signals that act on a local area

Question 12

What are juxtacrine signals

Answer 12

• they are signals that do not involve diffusion

- >rather a cell stimulating receptors of the adjacent cell

Question 13

What are endocrine signals

Answer 13

-they are signals that involve the secretion of hormones

Question 14

What are the function of inducers? Are they specific to a cell or can act across various cell types

Answer 14

• they are growth factors
• > peptides that promote differentiation and mitosis in certain tissues
• most growth factors function on only specific cell types in specific areas
• > therefore, most growth factors can code for particular tissue types

Question 15

Give an example of cell migration involving neural crest cells

Answer 15

• neural crest cells form at the neural folds
• > they then go and migrate throughout the body to form different structures
• > those being Schwann cells, adrenal medulla, etc

Question 16

What is the difference between apoptosis and necrosis?

Answer 16

• apoptosis is programmed cell death
• necrosis is cell death during injury
• > internal substances of the cell can be leaked and can cause an immune response

Question 17

What comes first. Apoptotic blebs or apoptotic bodies?

Answer 17

• apoptotic blebs become apoptotic bodies

- >these bodies are then taken up by other cells

Question 18

What does senescence refer to? What do telomeres have to do with this?

Answer 18

• senescence is biological aging
• > occurs as changes accumulate
• > results in failure of cells to divide, normally after 50 divisions
• failure to divide after 50 divisions may be due to shortened telomeres(ends of chromosomes)
• > telomeres shorten during each round of DNA synthesis
• > eventually they become too short and the cell is no longer able to replicate

Question 19

Describe the enzyme telomerase. What is its role? Also describe its relationship to senescence

Answer 19

• it is a reverse transcriptase
• > that is able to synthesize the ends of chromosomes
• in terms of senescence
• > it prevents senescence
• > allows cells to divide indefinitely