Mod8-Obj2: Hormones

Question 1

Hormones

Answer 1

Blood-borne chemical message that has an effect on target cells that are distant from the cell that secreted it

Question 2

If the receptor is not present…

Answer 2

The hormone cannot bind

Question 3

Hormone binding to a receptor or target cell activates…

Answer 3

A receptor protein, triggering a series of further changes in the cell (immediately or taking time)

Question 4

The action of hormones on a target cell may…

Answer 4

-Alter permeability of the plasma membrane -Alter membrane potential of cell -Stimulate protein synthesis -Activate or deactivate enzymes -Increase or decrease secretory activity -Stimulate cell division (mitosis)

Question 5

The effects of hormones on target cell activation depends on…

Answer 5

-The amount of hormone that is circulating in the blood -The relative number of receptors on/in the target cell for the hormone to bind -The affinity of binding between the receptor and hormone

Question 6

Water-soluble (amino acid bases hormones) include:

Answer 6

1.) Biogenic amines 2.) Small peptides 3.) Proteins

Question 7

Water-soluble (amino acid bases hormones) include: Biogenic amines

Answer 7

Amino acid derivatives such as adrenalin and noradrenalin which are synthesised from the amino acids tyrosine and tryptophan

Question 8

Water-soluble (amino acid bases hormones) include: Small peptides

Answer 8

Small chains of amino acids i.e.) Insulin

Question 9

Water-soluble (amino acid bases hormones) include: Proteins

Answer 9

Chains of amino acids that are longer than those the small peptides i.e.) Thyroid hormones

Question 10

The mechanisms of action of each amino acid based hormone is the same, except for the thyroid hormones…

Answer 10

Although they are amino acid based, the thyroid hormones are lipid-soluble an their mechanism of action is similar to that of lipid-soluble hormones

Question 11

Lipid-soluble (steroid hormones) are synthesis from…

Answer 11

Cholesterol, made by the adrenal glands, the testes and the ovaries

Question 12

Lipid-soluble hormones include:

Answer 12

-Testosterone -Progesterone -Cortisol

Question 13

Action of a hormone on its target cell depends on whether the hormone is…

Answer 13

Water-soluble or lipid-soluble and the location of the receptor it needs to bind

Question 14

Amino-acid based hormones

Answer 14

all (except for thyroid hormones) are hydrophilic and cannot pass through the plasma membrane of a cell

Question 15

Receptors for amino-acid based hormones are located…

Answer 15

On the surface of the plasma membrane

Question 16

Because amino-acid based hormones cannot enter the cell…

Answer 16

These hormones utilise a second-messenger system. These receptors are usually coupled through G-proteins to intracellular second messengers that mediate target cells response to hormones

Question 17

Second-messenger system (7 steps)

Answer 17

1. ) Hormone binds to its receptor on the plasma membrane
2. ) Receptor-hormone complex activates a G-protein
3. ) G-protein activates adenyl cyclase
4. ) Adenyl cyclase converts ATP to cAMP (second-messenger)
5. ) cAMP then activates a protein kinase (enzyme can initiate reaction)
6. ) Kinase triggers the response of the target cell
7. ) Response of target cells may include the synthesis of proteins, activation of enzymes, stimulation of secretion of substances or opening of ion channels

Question 18

Summary of amino-acid based hormones

Answer 18

• Are hydrophilic and cannot enter the cell
• Bind to receptors on the plasma membrane
• Act via G-protein second messengers to trigger a response in the target cell

Question 19

Steroid (and thyroid hormones)

Answer 19

Are lipid-soluble, thus are hydrophobic and are abe to pass through the plasma membrane of a target cell.

• Hormone act on receptors in the cytoplasm, inside the cell
• When hormone bind to its intracellular receptor it forms a receptor-hormone complex, can directly activate genes

Question 20

Steroid hormone system

Answer 20

1. ) Steroid hormones travel bound to binding hormone-cross membrane
2. ) Receptors on cytoplasm of the cell
3. ) Binding of hormone to receptor-Translocation to nucleus & affect on RNA transcription

Question 21

Summary of steroid based hormones

Answer 21

• Are lipid-soluble and can cross the plasma membrane and enter the cell
• Bind to intracellular receptors to form a receptor-hormone complex
• Enter the nucleus as a receptor-hormone complex to directly activate genes to produce new proteins