Week 2 Flashcards

Question

7 steps for specific and efficient info transfer

Answer 1

1. Synthesis 2. Release 3. Transport 4. Detection 5. Transduction 6. Target cell response 7. Termination

Answer 2

Synthesis of the hormone - a hormone must be produced by a cell (this synthesis may be a regulated process i.e. only made when needed)

Answer 3

Release of the hormone - after synthesis the hormone must leave the cell that made it (this release may be regulated)

Answer 4

Transport to the target cell (a target cell is able to respond to the hormone) after release the hormone must get to where it is supposed to be acting

Answer 5

Detection of hormone by the target cell - this requires SPECIFIC binding of the hormone by the cell-receptors of the target cells

Answer 6

Transduction of the signal from the receptor this MOVES the signal from OUTSIDE -> INSIDE (therefore from extracellular to intracellular - possibly even to the nucleus of the target cell)

Answer 7

Target cell response - METABOLISM - GROWTH - DIFFERENTIATION

Answer 8

Termination of the signal if the signal is not stopped then the response does not stop

Answer 9

Measure of the ability of the receptor to distinguish between closely related substances - binding specifically is crucial for good health, hence **receptors** bind very specifically to the **hormone**

Answer 10

1. Binding a hormone with high affinity 2. Invoking a signal inside the cell to initiate a biological response - in the absence of the hormone the receptor does not convey and information = INACTIVE - changes in receptor conformation allow changes in interaction with other molecules **inside** cell = ACTIVE

Answer 11

- receptor binding of a hormone is specific, thus the receptor is a HIGH-AFFINITY binding **protein** (*Similarities can be drawn with enzymes and how they can bind their substrates through specific interactions*) - the interactions of a Hormone (H) and Receptor (R) are HIGHLY-specific (*involves **non-covalent** interaction - ionic and van der Waals*) - Binding induces CONFORMATIONAL CHANGES in the receptor which is DETECTED by INTRACELLULAR MOLECULES

Answer 12

Hormone binding allows the receptor to regulate the expression of specific genes

Answer 13

• Steroid Hormones **are derived from cholesterol** by the stepwise removal of carbon atoms and hydroxylation • Steroid hormones are synthesised in the adrenal cortex (the glucocorticoids and mineralocorticoids) and also the gonads (for oestrogens, progesterone, androgens)

Answer 14

- are small hydrophobic, lipid soluble - can diffuse through the membrane of target cells - bind to intracellular receptors - **all function in the same basic manner** - binding to the intracellular receptor affects the cells ability to transcribe specific genes - interact **DIRECTLY** with the transcription factors they control

Answer 15

• Central DNA-binding domain - the part which binds DNA • Ligand binding domain (SPECIFICITY) - hormone dependent activation (or repression) • Variable N terminal domains which may contain one or more activation domains - to alter gene transcription

Answer 16

• Receptors, in their inactive states, are bound to inhibitory proteins e.g. ER is bound to heat shock proteins (hsp90) • Binding of ligand induces a conformational change releasing the inhibitory protein and binding a co-activator protein to induce gene transcription (co-repressors e.g. tamoxifen) • Receptors can be located: 1) in the cytosol (e.g. estrogen receptor) and are transported to the nucleus after the ligand is bound 2) in the nucleus (thyroid and retinoid receptors)

Answer 17

The nucleotide binding sequence that interact with nuclear receptors are called **response elements** - the response elements lie adjacent to the genes that the hormone (ligand) regulates - they consist of 6 base pair (sometimes inverted) repeat sequences separated by 3-5 base pairs

Week 2 Flashcards

(41 cards)