Unit 7 - 1445

Describe the basic structure of insulin

2 peptide chains - A + B...linked by 2 sulfide bonds

what is adrenocorticotropic hormone (ACTH)?

ACTH is made in ant-P...stimulates adrenal cortext secrete glucocorticoids.

three glands that produce steroid hormones

Adrenal Cortex, Testes, Ovaries.

General mechanism by which many polypeptide hormones affect target cells? talk about phosphorylation cascade

After initial reception on membrane surface, relay molecule activates a protein kinase that is response for using ATP to phosphorylate another kinase...this continues until the last active kinase phosphorylates a protein that sparks the cellular response...In most pathways this includes amplification of initial signal.

Important note about hormones

Almost all hormones are derived from amino acids, polypeptides, or steroids. The hormones secreted by the adrenal cortex and gonads are steroids; all other endocrine glands secrete hormones that are derived from proteins or amino acids.

Name the type of cell in which insulin is synthesized and in which glucagon is synthesized. What other cell types make up the pancreas and what are their functions?

Alpha cells - make glucagon Beta cells - make insulin other cells - produce/secrete bicarbonate ions and digestive enzymes

What are some processes in plants controlled or aided by hormones?

Apical dominance, Aging, growth, stem-elongation, fruit growth, germination

Explain Darwin's and Went's experiments on phototropism. Where is auxin produced? Why do grasses bend towards light?

Auxin is produced by Coleoptile tip. They been to maximize light absorption. Darwin's experiments were to find what part senses light Wnt's experiments were to find how phototropism was transmitted

What are oxytocin and ADH, where are they made, and where are they stored?

Both are made in the hypothalamus and are stored in the post-P gland before being secreted when needed. Axons connect the hypothalamus to the post-P. Oxytocin: milk secretion by mammary glands, uterine contractions ADH: increased water retention by kidneys, decreased urine volume, also regulates social behavior somewhat

How do receptor tyrosine kinases work?

Exists inactive as two monomers (extracellular + a helix + tyrosine)...signal molecule binds..puts the two together and activates the dimer form. Which makes 6 ATP transfer phosphates to the 6 tryosines. Proteins attach to the phosphorylated tyrannies and cause cellular change. Basically one ligand-binding event causes many triggers for many pathways (different than G-protein)

Distinguish between exocrine and endocrine gland..give example of each

Exocrine (salivary): ducts that carry secretions into/onto body surface or cavity Endocrine: release hormones directly into surrounding fluid

What are gonadotropic hormones (FSH and LH)?

FSH and LH are made in the ant-P..stimulate sex organs

Would you expect cell's response to stimulation by a polypeptide hormone to be relatively rapid or slow? would the response be relatively short lived or long-lived?

Fast response b/c of cascade of events/amplification. Response would be short-lived as the various phosphorylations are short lived and go back to their inactive forms quickly.

Compare and contrast the functions of hormones FSH and LH in males and females

Females: FSH/LH stimulate ovaries to produce steroids. Both surge at midcycle, triggering ovulation. Males: LH stimulates cells to produce testosterone. FSH has a hand in sperm generation.

What is growth hormone (GH)?

GH is made in ant-P and stimulates growth and metabolic functions

What is gonadotropic releasing hormone (GnRH)?

GnRH is made in hypoT..and it instructs ant-P to release FSH and LH.

How does auxin travel polarity from cell to cell? How does auxin promote cell elongation at the cellular level?

High concentration of auxin transport protein always at basal end of a cell which causes movement in one direction only. as auxin from the shoot apex moves down to the region of cell elongation, the hormone stimulates growth..by binding to a receptor in the plasma membrane. growth is only stimulated at a certain concentration range.

Important note about multicellular higher animals

Hormones and local regulators regulate and coordinate the activities of the various organ systems to effect homeostasis.

How do insulin and glucagon work together to maintain homeostasis?

If blood glucose level is high/rises, insulin is released which causes uptake of glucose into body cells as well as production of glycogen from glucose until its at homeostasis. If blood glucose level is low/decreases, glucagon is released which causes liver to breakdown glycogen and release it into the blood.

Important note about flowering

In many plants, flowering is controlled by photoperiodism, the response to the length of light and dark periods. Photoperiodism relates to seasonality, promoting or inhibiting flowering.

Negative feedback control of thyroid secretion

Indirect as the thyroid hormone itself carries negative feedback and blocks TSH release from Ant-P and TRH release from hypoT.

Important note about adrenal gland

Is a dual gland: cortex and medulla are entirely separate; they are of different embryonic origins, secrete chemically different hormones that do everything differently.

Local regulator vs hormone

LR: messenger molecules that influence cells in the vicinity Hormones: specialized cells release hormones which travel via blood around the body to affect targeted cells example of local regulator: growth factors

General mechanism by which lipid soluble hormones affect target cells?

Lipid soluble hormones use transport proteins in the aqueous extracellular surfaces to transport to the cells where they enter through the membrane easily without interruption. They attach to receptor inside the cell. Steroid hormones are hydrophobic so they can pass through membrane

How do ligand-gated ion channels work?

Membrane receptor with a gate region when receptor changes shape.. Basically ligand binds, gate opens, specific ion flows through the channel changing cell concentration, starting the transduction pathways to trigger in the cell.

What is a ligand and how do they affect the receptor proteins they bind with?

Molecule that specifically binds to another molecule. They usually spark a change in shape of the receptor protein they bind.

Two advantages of the multistep pathways seen in signal transduction?

More regulation Efficiency, allows for more effect and less chance of problems

Important note about feedback loops

Negative feedback loops regulate the endocrine system. The secretion of some hormones is controlled by the simple endocrine pathways (direct feedback loops) in which the secretion of the target organ feeds back directly to the endocrine gland in a simple endocrine pathway to regulate its secretion. Other negative feedback loops are indirect: the secretion of these hormones is regulated by a complex negative feedback loop in a hormone cascade pathway involving the hypothalamus, A pit, and tropic hormones...Basically they affect the thing that affects the target gland/organ

What are two different types of responses elicited y hormonal signaling?

Nuclear réponse: synthesis, genes, etc Cytoplasmic response: activity, directly affecting function

What is difference in hormones involves in hormone cascade pathways vs simple endocrine pathways?

One in the hormone cascade pathways are hydrophobic while the hydrophilic ones are controlled by the simple endocrine pathways.

what is prolactin (PRL)?

PRL is made in ant-P...stimulates milk production/secretions

Role of PTH in regulating blood calcium levels

PTH is parathyroid hormone and is made in parathyroid glands. It raises Ca2+ levels in the blood. Calcium is stored in the bones and teeth. PTH stimulates reabsorption by kidneys and intestines and increases Ca2+ levels. Stimulates release of calcium from bone. Hormone regulation by negative feedback loop Low blood Ca2+ increases PTH secretion and vice versa. Calcitonin from thyroid decreases calcium ion levels in blood.

Important note about plant responses to hormones

Plant's response to a hormone depends on the target tissue, the concentration of the hormone, and the concentration of other plant hormones that might be present.

Important note about plant hormones

Plants rely on hormones as their primary means of communication with an organism. In general, plant hormones are not highly specific in their action. They are predominantly involved in the regulation of growth and development

Important note about steroid and polypeptide hormones

Polypeptide hormones are hydrophilic and bind to specific receptors in the cell membrane and initiate a signal-transduction pathway, without themselves crossing the cell membrane. Steroid hormones, thyroid hormones, and some local regulators are hydrophobic and enter target cells and bind with intracellular receptors to elicit a response.

Describe the structural relationship between the hypothalamus and both pituitary glands.

Post-pit is an extension of the hypothalamus. Hypothalamic axons reach into the post-pit and secrete neurohormones synthesized in the hypothalamus. Hormones that are sent to the post-pit are stored there until nerve impulses from hypothalamus signal otherwise. Ant-pit is a separate distinct endocrine gland that synthesizes and secretes hormones in response to signals from the hypothalamus. These hypothalamic signals are often in form of releasing or inhibiting hormones (that control specific ant-pit hormones) and are secreted to capillaries which drain into a portal vessel which goes to the ant-pit.

Three stages of cell signaling process

Reception: target cell's detection of a signaling molecule coming from outside the cell Transduction: binding of signal molecule changes receptor protein. Converting the signal to a form that can bring about a specific cellular response. Response: transduced signal finally triggers a specific cellular response

Explain target specificity of hormones in terms of receptors, explain why increased levels of epinephrine in a liver cell cause that cell to hydrolyze glycogen to glucose whereas an increase in epinephrine in skeletal muscle causes it to dilate

Receptors regulate what hormones act on the cell b/c you need to match with that receptor. Pathways can be different which also causes different responses Both liver and muscle receptor are the same and they both affect kinase A but after that, their cellular response is different in that the pathways have their own specific enzymes for cellular change.

List functions of ethylene

Response to mechanical stress (growing around the problem) Senescence (programmed cell death of certain cells/organ/plant) Leaf abscission (loss of leaves during climatic periods of stress) Fruit ripening

What is short-day plant? long-day?

Short-day plant requires light period shorter than the critical period of time. Long-day plant requires light period longer than the critical period of time. no flowering occurs in short-day plants if night is interrupted by flashes of light while flowering does occur in long-day plants when night is interrupted.

Cell's response to steroid hormone rapid or slow? short-lived or long lived?

Slow response because of long travel time compared to cascade of events . Long lived because the changes sparked are usually genetic in nature which take time to express and complete.

Important note about hormone-like regulators

Some hormone-like regulators are very short-lived and have mainly local effects. Thus they differ from many of the hormones (insulin, thyroid hormone, PTH, et) which are circulated throughout the body in the bloodstream.

Other effects of auxin

Stimulating cell elongation, regulating plant architecture,

What hormones are involved in apical dominance? Why pinching off tips usually causes the plant to become bushier

Strigolactones, cytokines, auxin. Polar flow of auxin down the shoot triggers the synthesis of strigolactones which repress axillary bud growth. pinching off causes loss of auxin, inhibition of axillary buds is removed, and plants grow horizontally becoming bushier

What is Thyroid stimulating hormone?

TSH is made in the ant-P..it stimulates thyroid gland

What determines which pathways will be initiated if many processes use G protein-coupled receptors?

The specificity of the receptor protein determines which pathway is started.

are the thyroid hormones hydrophobic or hydrophilic? How do they initiate the signal transduction pathway?

They are hydrophobic. They cross the membrane and attach to receptors in the nucleus. They are derived from Iodine. In target cells, T4 is converted to T3.

Chemical nature and function of hormones produced by adrenal medulla

They increase amount of energy available. hormones include norepinephrine and epinephrine. Comprise the fight or flight response when needed. Are amine hormones made from tyrosine amino acid.

What do Catecholamines do in maintaining homeostasis with respect to blood sugar?

They increase glycogen breakdown, increase glucose/fatty acids in blood... opposite of insulin pretty much

Effect of T3 and T4 on homeostasis, cellular metabolism

Too much T3 and T4 has negative feedback effect on the ant-P and hypoT stopping further release.

General nature of the signal receptor, how it recognizes a particular signal, and the general response

Usually receptors are plasma membrane proteins. After ligand binds, they usually either automatically active by changing shape or cause change in other molecules as well.

How do G protein-coupled receptors work?

When signal molecule binds to receptor, receptor changes shape. Cytoplasmic shape binds an inactive G protein causing GTP to displace the GDP, activating the GP protein. Activated G protein binds to an enzyme that triggers cell activity. G protein hydrolyzes GTP to GDP when used...Inactive goes back to normal place to be reused with the next signal molecule

Compare and contrast androgens, estrogens, and progestins in terms of their function and control of their synthesis

androgens: make male testes, puberty (testosterone is ex) estrogens: maintenance/development of female reproductive system (primarily estradiol) progestins: prep/maintain uterus tissue for embryo growth (primarily progesterone)

What is meant by circadian rhythm and explain why photoperiodism is so important in plant growth and development?

cycles of about 24 hours. Important to ensure that the right processes are occurring at the right times of the day. Different plants need different amounts of light/darkness to germinate/grow/develop.

What are phytochrome and what is their role in seed germination?

exists as Pr and Pfr...when exposed to red light converts to Pfr..vice versa when far-red light... overall.. during the day (in light) most exists as Pfr....during the night (in dark) most exists as Pr.

Three types of corticosteroids produced by adrenal cortex?

glucocorticoids, mineralocorticoids, sex hormones

How do growth factors, NO, and prostaglandins function as local regulators and give an example of a response that each elicits in particular cells

growth factors have to be present in direct extracellular environment to stimulate cell proliferation and differentiation NO activates enzyme that relaxes surrounding smooth muscle cells (NO -> vasodilation -> penile blood flow) Prostaglandins (modified fatty acids) are produced by cells and affect nearby cells... semen ->prostaglandins -> contraction of uterine wall

What is relationship between ethylene and auxin? What form is ethylene found in the plant?

high concentration of auxin applied externally causes production of ethylene.... found in gaseous form.

Where is Ca2+ highest in a cell? How is it accumulated there?

highest in the ER..Ca2+ is imported out of cytosol into extracellular matrix + ER. Ca2+ moves into cytosol when channels are open

What effect does epinephrine have on an animal?

increased blood pressure, increased heartbeat, increased glycogen breakdown, increased oxygen consumption, increased blood supply to muscles and core, decreased blood supply to unnecessary functions like digestion, etc

What is effect of glucocorticoids?

increased glucose synthesis from non-carb sources (protein)...basically opposite of insulin

How are testosterone levels regulated in the human male?

increased testosterone decreases actions by ant-P and hypo-T which inhibits FSH cells.

How is secretion of hormones from adrenal cortex regulated?

indirect in that the corticosteroids released by adrenal cortex regulate the hypoT and the ant-P.

How does insulin affect the uptake of glucose into muscle and adipose cells

insulin increases uptake

How do intracellular receptors differ in signal reception, transduction, and response from cell surface receptors?

intracellular receptors are inside the cell in cytoplasm or nucleus of the target cell. Usually uses signal molecules hydrophobic enough or small enough to pass through the plasma membrane. Most times, the receptors carry out and complete transduction themselves, whether it be a genetic change or otherwise.

What is effect of mineralocorticoids like aldosterone?

mineral metabolism. maintaining salt and water balance. increased reabsorption of sodium + water.

How does insulin affect the synthesis and degradation of protein?

stimulate protein synthesis and inhibits protein degradation

How does insulin affect the synthesis and degradation of fats?

stimulates fat synthesize, inhibits degradation

How does insulin affect synthesis and degradation of glycogen?

stimulates glycogen synthesis and inhibits degradation

Effect of T3 and T4 on growth and development. What about people with congenital deficiency of both?

they are involved in bone-forming cells + branching of the nerve cells in embryonic development of humans + other vert. Would result in retarded skeletal growth and poor mental development