Cell Signalling And Apoptosis

Question 1

Define neurotransmitters

Answer 1

are chemicals released by a neuron axon into the synaptic cleft between it and the target cell. diffused locally

Question 2

What are the key features of steroid hormones?

Answer 2

• produced by endocrine glands(ductless)
• travel in circulatory systems
• longer lasting cholesterol based structure
• lipophilic

Question 3

What are the key features of peptide hormones?

Answer 3

• produced by endocrine glands(ductless)
• travel in circulatory systems
• structure usually contains nitrogen
• hydrophilic

Question 4

Define cytokines

Answer 4

cytokines are peptide, protein or glycoprotein molecules that act as messengers between cells and elicit response in the receiving cell. regulate many parts of immune system

Question 5

What are the key features of cytokines?

Answer 5

-produced by immune cells

Question 6

Define pheromones

Answer 6

are chemicals that when released by one animal elicit a response in another animal of the same species. can be sex, trail,alam and territorial

Question 7

What are plant hormones/growth regulators

Answer 7

they are produced by the plant cell and cause a response(tropism)
-lack a circulatory system instead they have a vascular system

Question 8

What are the main similarities between plant hormones and animal hormones?

Answer 8

• both use signalling molecules to communicate

- complimentary shapes between signalling molecules and receptors

Question 9

What are the specific types of local and long distance cell communications?

Answer 9

• cell junctions
• autocrine signalling
• paracrine signalling
• endocrine signalling
• cell-cell recognition

Question 10

What are the key features of cell junctions(aka as plasmodesmata in plant cells)?

Answer 10

• cells can communicate via direct contact

- cell junctions allow molecules to readily pass between adjacent cells without crossing the membrane

Question 11

What forms of variations are there in signalling molecules?

Answer 11

• differences in chemical structures; vary in size, different in affinity for H2O
• different functional group
• differences in scope; some signalling molecules effect over a distance while some work locally

Question 12

What is the characteristic which all signalling molecules share?

Answer 12

they bind to sites on specific receptors which are complementary to signalling molecule on target cell.

Question 13

Explain Long distance travel to target cell/endocrine signalling

Answer 13

are signalling molecules that travel long distances in the circulatory system to reach target cells anywhere in the body

Question 14

Explain travel to nearby cells/paracrine signalling

Answer 14

chemical signals released by signalling cells and diffuse locally, triggering a response in a nearby neighbouring cell in interstitial fluid (local mediators)

Question 15

Explain one cells sends and receives signal/Autocrine signalling

Answer 15

chemical signal is diffused locally, triggering a response in the same cell/s that secreted the message (immune T cells)

Question 16

Explain direct cell to cell contact in plants

Answer 16

cell to cell contact signalling in plants use plasmodesmata to transfer signalling molecules. plasmodesmata are gaps in cell walls as well as continuous plasma membrane which forms lining of plasmodesma

Question 17

Explain cell to cell contact in animals

Answer 17

gap junctions are used to send signalling molecules between cells directly contact. gap junctions are protein lines pores in the plasma membrane of adjacent cells

Question 18

Explain signalling cells that carry signals to target cells/ cell-cell recognition

Answer 18

some signalling cells are highly mobile and deliver signal to their target cell. signalling molecule is connected to signalling cell by membrane

Question 19

What are the three stages of cell signalling?

Answer 19

• signal reception
• signal transduction
• cellular response

Question 20

Define signal reception

Answer 20

is the first step of cell signalling and is the reception of a ligand(signalling molecule)

Question 21

Explain signal reception in hydrophobic signalling molecules

Answer 21

hydrophobic molecules can readily pass the lipid bi-layer of the pasta membrane, therefor it binds to receptors in cytosol or nucleus fluid, these receptors are known as intracellular fluid

Question 22

Explain signal reception in hydrophilic signalling molecules

Answer 22

hydrophilic polar molecules cannot readily pass through the lipid bilayer therefor they bind to cell surface receptors which are either trans membrane proteins on their own or operate as a complex, linking exterior and interior of cell(Gprotein)

Question 23

As cell surface receptors have several domains what are two vital domains?

Answer 23

• exposed to the outside= signal binding domain

- in contact with cytoplasm=intracellular domain

Question 24

Define signal transduction

Answer 24

a process that converts a signal from outside a cell into a response within the cell

Question 25

Describe the process of signal transduction for a hydrophobic signalling molecule

Answer 25

1. from signal reception a conformational shape change occurred exposing a region of receptor
2. hormone receptor complex moves from cytoplasm to nucleus
3. exposed region of receptor protein attaches to a target DNA and activates genes

Question 26

Describe the process of signal transduction for a hydrophilic signalling molecule

Answer 26

1. in transduction conformation shape change in cell surface receptor occurs
2. receptor in turn activates enzymes embedded in membrane
3. activated enzymes catalyse the production of multiple copies of second messenger (amplifying)
4. 2nd messenger molecule activates copies of key enzymes in turn activating the next enzyme in relay
5. eventually relayed to nucleus where specific genes are activated

Question 27

Define cellular response

Answer 27

effector proteins are produced by gene activity stimulates directly or indirectly. these proteins produce the cellular response the regional messenger sent

Question 28

Signalling molecule may create multiple responses rather than linear T or F

Answer 28

True

Question 29

What are some common examples of cellular responses?

Answer 29

• cell mitigation= production of structural proteins
• changes in metabolism=making or regulation of enzymes
• cell division= dan synthesis
• apoptosis=production of caspase