integration of metabolism: cellular signaling Flashcards
How are metabolic pathways connected?
They share some molecules and can work simultaneously.
A central process in metabolism that breaks down molecules for energy and builds important molecules for the body.
the Citric Acid Cycle
what are the 3 main points that citric acid cycle plays a central role in metabolism
- Plays a part in the catabolism of carbohydrates, lipids and proteins
- Assists in the anabolism of sugars, lipids, and amino acids
- Has a relationship with individual metabolic pathways
macronutrients vs micronutrients
macronutrients:
needed in large amts
- carbs, fats and proteins
- Na, K, Cl, Mg, Phosphorus, Ca
* u usually get enough of these minerals (except calcium) from a regular diet
micronutrients:
needed in small amts
- vitamins (compounds that are necessary for metabolic processes)
- minerals (inorganic substances required as the ion or free element)
- scientists are still figuring out exactly how much we need of some of them.
- Chromium: Helps your body process sugar.
- Manganese: Important for building strong bones.
- Requirements are well established for iron, copper, zinc, iodide, and fluoride
required nutrients
High Fat, Low Protein Concern: Many people in the U.S. eat diets high in fat, but they might not get enough good-quality protein.
No Protein Storage: The body doesn’t store protein like it does fats or carbohydrates, so you need to eat enough protein every day.
Essential Amino Acids: Proteins are made from building blocks called amino acids. Some of these are “essential,” meaning the body can’t make them, so you must get them from food.
Constant Protein Breakdown: Your body is always breaking down proteins (like the ones in muscles or enzymes), so it needs a regular supply of protein from your diet to replace and repair these.
Needs are easily met by dietary sources, and overdoses can be toxic
copper and zinc
What happens if you don’t get enough iodide and how to prevent it?
The thyroid gland can become enlarged, causing a condition called goiter.
Hence, to prevent it, use iodized salt.
Administered to prevent tooth decay in children
fluoride
Part of the structure of the ubiquitous heme proteins
iron
- Women of childbearing age are more susceptible to deficiencies (especially during mestruation)
Graphic display that focuses on a diet sufficient in nutrients but without excesses
Food Guide Pyramid
- approach to publicizing healthful food selection
New Food Pyramid
- distinguishes btwn healthy and unhealthy types of fat and carbs
HDL vs LDL
HDL (High-Density Lipoprotein):
Known as “good cholesterol” because it helps remove bad cholesterol from your body, keeping your heart healthy.
Think of it as a “clean-up crew” for your blood vessels.
LDL (Low-Density Lipoprotein):
Known as “bad cholesterol” because it can build up in your arteries, leading to heart problems.
Think of it as “clogging up the pipes.”
what protein is the key role in regulating appetite and weight
leptin
- found in the ob gene of mice
*If there’s a mutation in the ob gene (responsible for leptin production), leptin might not work properly, leading to increased appetite and weight gain.
function of leptin
Helps burn fat by increasing fatty acid oxidation and helps muscles take up glucose for energy.
Reduces the production of an enzyme (stearoyl-CoA desaturase) that makes fats, so the body produces less fat.
Works on the brain (hypothalamus) to suppress appetite by turning off specific neurons.
Leptin and Enzyme Control
Leptin activates AMP-activated protein kinase in muscles.
This enzyme deactivates acetyl-CoA carboxylase (ACC), which is crucial for making fats.
By turning ACC off, leptin slows down fat production.
what are hormones
They are like messengers inside your body.
Made by glands (without ducts) in the endocrine system.
Travel through the bloodstream to specific parts of the body where they perform their job.
types of hormones
Steroids:
estrogens (important for reproduction)
androgens (like testosterone).
Polypeptides:
insulin (controls blood sugar)
endorphins (reduce pain and make you feel good).
Amino Acid Derivatives:
epinephrine and norepinephrine (help with the “fight or flight” response).
functions of hormones
- Maintaining homeostasis
Keeping the body in balance (e.g., temperature, sugar levels). - Mediating responses to external stimuli
Helping you react to changes around you (e.g., stress or danger). - Regulating growth and development
Ensuring proper physical growth and maturity.
how does hormone work
Hormones are released and target specific cells in the body to do their job.
Control can be:
- simple (feedback loops, like a thermostat)
- complex, involving the hypothalamus, pituitary gland, and specific endocrine glands working together.
Adrenocortical Hormones
- Glucocorticoids:
Help control how your body uses carbohydrates.
Reduce inflammation.
Help the body respond to stress. - Mineralocorticoids:
Regulate the levels of minerals like sodium and potassium, which control water balance in the body.
Steroid Hormones:
Adrenocortical Hormones:
Steroid Sex Hormones:
Steroid Hormones:
Made from cholesterol and play important roles in the body.
Adrenocortical Hormones:
Produced in the adrenal glands and help manage stress and balance body functions.
Steroid Sex Hormones:
Produced mainly in the gonads (testes in males, ovaries in females)
Steroid Sex Hormones
Androgens: Hormones like testosterone that influence male characteristics.
Estrogens: Hormones like estradiol that influence female characteristics.
What happens if there is an overproduction of Growth Hormone (GH) while the skeleton is still growing?
It leads to gigantism, causing excessive growth in height.
What happens if there is an overproduction of GH after the skeleton has stopped growing?
It leads to acromegaly, characterized by enlarged hands, feet, and facial features.
What condition occurs due to GH underproduction?
Dwarfism, characterized by short stature.
How can dwarfism caused by GH underproduction be treated?
By injecting human GH (HGH) before the skeleton matures.
Substances produced or released by a cell in response to hormone binding to a receptor on the cell surface
Second Messengers
- Elicit the actual response in a cell
Examples of Second Messengers:
Cyclic AMP (cAMP): Helps amplify signals inside the cell.
Calcium Ion (Ca²⁺): Plays a role in muscle contractions and other processes.
Receptor Tyrosine Kinase: Activates signals for growth and repair inside cells.
How Cyclic AMP Works
When a hormone (like adrenaline) binds to a receptor on the cell’s surface (either β1 or β2 adrenergic receptors), it starts a chain reaction.
This triggers the enzyme adenylate cyclase to produce cAMP from ATP (energy currency in the cell).
G Protein Activation:
The binding of the hormone to the receptor activates a G protein inside the cell.
The α-subunit of the G protein binds to GTP (another form of energy) and releases GDP.
The active G protein then slowly breaks down GTP, turning back to its inactive form.
Role of G Protein and Adenylate Cyclase:
Both the G protein and adenylate cyclase are attached to the plasma membrane of the cell.
Once cAMP is created, it moves into the interior of the cell to act as a second messenger, carrying out the hormone’s signal inside the cell.
Where are the G protein and adenylate cyclase located in the cell?
They are bound to the plasma membrane.
Protein Kinase A Activation
cAMP activates protein kinase A (PKA).
PKA then phosphorylates (adds a phosphate group to) many enzymes and transcription factors.
This process turns various cellular processes on or off, depending on the context.
PIP2 and Ca²+ as Secondary Messengers
Ca²+ and PIP2 are part of another second-messenger system.
Ca²+ binds with calmodulin, a calcium-binding protein. This complex activates a cytosolic protein kinase, which then phosphorylates target enzymes.
Diacylglycerol (DAG), a lipid molecule, diffuses through the cell membrane and activates a protein called protein kinase C (PKC), which is involved in cell signaling.
Receptor Tyrosine Kinase
This type of receptor spans the cell membrane. When it binds to its specific ligand (like a hormone), it phosphorylates tyrosine residues on the inside of the cell.
The receptor has two parts:
1. A hormone-binding site on the outside of the cell.
2. A tyrosine kinase portion on the inside of the cell, which adds phosphate groups to specific tyrosine residue
Epinephrine, Glucagon and Insulin
function:
effect:
structure:
origin:
EPINEPHRINE
Function: It helps raise blood glucose levels quickly when needed.
Effect: Acts on muscle tissue to release glucose into the blood during times of stress or energy demand.
Origin: Released from the adrenal glands in response to stress.
Structure: It is derived from the amino acid tyrosine.
GLUCAGON
Function: It helps increase the availability of glucose when blood sugar levels are low.
Effect: It acts on the liver, prompting it to release stored glucose.
Structure: It is a peptide hormone made up of 29 amino acid residues.
Origin: Produced by the α-cells of the islets of Langerhans in the pancreas.
INSULIN
Function: It helps control glucose levels in the blood.
Effect: It triggers a feedback response to ensure that glucose levels do not become excessively high.
Origin: Produced by the β-cells of the pancreas.
a peptide hormone that is secreted by the pancreas.
insulin
- regulate glucose levels in the body
Structure of Insulin
The active form of insulin is a 51-amino-acid peptide.
It consists of two chains: the A chain and the B chain.
These two chains are connected by disulfide bonds.
it is the precursor of insulin which is later processed into active insulin.
proinsulin
- consisting of 86 amino acids
What happens when insulin binds to its receptor on the cell membrane?
It triggers the β-subunit of the receptor to autophosphorylate a tyrosine residue on its interior portion.
it is a target proteins that get phosphorylated by the insulin receptor, acting as second messengers.
insulin-receptor substrates (IRSs)
- trigger a wide variety of cellular effects, regulating processes like glucose uptake.
What does the autophosphorylation of the β-subunit in the insulin receptor lead to?
phosphorylation of tyrosines on insulin-receptor substrates (IRSs), activating cellular responses.
effect of insulin on metabolism
ppt
Type I and Type II Diabetes
TYPE I DIABETES
Insulin-dependent diabetes: The body can’t produce enough insulin.
Cause: The body’s immune system destroys the beta cells in the islets of Langerhans in the pancreas.
Treatment: People with Type I diabetes need regular insulin injections to manage their blood sugar levels.
TYPE II DIABETES
Non-insulin-dependent diabetes: The body’s cells don’t respond correctly to insulin.
Adult-onset diabetes: Typically starts later in life, and is often linked to obesity.
Cause: Dysfunction of muscle mitochondria is thought to be involved in Type II diabetes.
Link Between Type II Diabetes and Alzheimer’s Disease
People with Type II diabetes may have an increased risk of developing Alzheimer’s disease.
Insulin appears to increase the levels of β-amyloid protein, which forms plaques in the brain associated with Alzheimer’s.
Insulin-degrading enzyme (IDE):
- This enzyme binds to and clears insulin and β-amyloid protein from the brain.
- When insulin levels are high (such as in Type II diabetes), IDE has less time to clear β-amyloid, which could contribute to Alzheimer’s risk.
what dysfunction is suggested to contribute to Type II diabetes?
Type II diabetes is linked to dysfunction of muscle mitochondria.
