Leys Exam III Flashcards
Proteins that have crossed a membrane are
no longer topologically inside the cell. They must recross the membrane to get back inside the cell.
Vesicles move from compartment to compartment within a cell by
budding off and membrane fusion.
Many proteins have signal sequences at their amino terminus that direct the proteins to
cross the membrane. Fewer proteins have internal signal sequences.
The nucleus is surrounded by a
double lipid membrane bilayer, however nuclear pores allow molecules, including proteins to pass from the cytosol into the nucleus and back.
Larger proteins pass through
nuclear pores by an active process
3Nuclear import receptors bind to
nuclear transport signals found on some nuclear bound proteins and facilitate transport into the nucleus.
It generally requires multiple signals to
transport proteins from the cytosol into the luman of the mitochondria.
There are multiple protein
translocators in the mitochondrial membrane. Each translocator interacts with a specific set of proteins.
Transport of protein into the mitochondria requires
energy
Proteins enter peroxisomes using a mechanism similar to
mitochondrial entry
Proteins travel from the endoplasmic reticulum (ER), through the
golgi to many sites
A signal recognition protein (SRP) binds to the
signal sequence during translation and directs the nascent peptide to the ER membrane.
Proteins bound for the mitochondria are translated in the
cytosol and than transported through the mitochondrial membrane. A process that requires ATP.
Proteins that are headed into or through the ER are transported through the
ER membrane during translation. This process does not require any additional energy.
Carbohydrate modification of proteins in the
ER helps direct them to their ultimate location
The “default pathway” if there are no other signals directing the protein to other locations, is to
send the protein to the cell surface
In regulated secretory pathway cells store proteins in secretory vesicles until they are
signaled to release them from the cell by fusion of the vesicles with the cellular membrane
signaled to release them from the cell by fusion of the vesicles with the cellular membrane
appetite, energy expenditure, genotype, digestion, metabolism, availability of food, customs and presence of disease.
Leptin, Ghrelin and Insulin are
important regulators of food intake.
Leptin circulates, in the body, at levels proportional to
body fat
Leptin signals the brain that the body has
had enough to eat, or satiety
Adipose tissue produces adipokines that regulate
metabolic processes to meet the body’s needs
AMP and AMP/ATP regulate
AMP-activated kinase (AMPK) that senses cellular energy levels
AMPK regulates
rate-limiting enzymes in energy-producing and using pathways.
High levels of AMPK activity inhibit
energy-utilizing pathways and stimulate energy generating pathways.
Increased Ghrelin increases
apetite
Ghrelin favors accumulation of
lipids in the visceral fatty tissue
Estimated average requirements (EAR) for calories changes with
age and sex. Estimated daily protein requirements vary with age and sex.
The ideal amount of calorie intake in a day is
equal to the calorie utilization for that day.
Recommended daily allowance (RDA) for a nutrient is a value that is
adequate for the great majority of individuals. The estimated average requirement (EAR) reflects amount that is adequate for half of the population.
Different nutrients have different
energy content. Fat has the highest energy content per weight. Alcohol has a high-energy content
Increases in obesity are correlated with an increase in
the use of high fructose corn syrup.
High fructose corn syrup is made by
breaking down cornstarch into glucose using amylase followed by conversion to fructose with glucose isomerase.
There are several potential health issues associated with comsumption of high fructose corn syrup including
mercury exposure, hypertension, elevated cholesterol, long-term liver damage, increased risk of diabetes and weight gain and obesity.
Protein-calorie malnutrition causes a number of health problems including:
decreased protein synthesis and glucose transport, fatty liver, liver necrosis and fibrosis, depression, hypothermia, compromised immune function and would healing, decreased cardiac and renal function, loss of muscle.
Obesity is associated with an increased risk for several conditions including
type 2 diabetes, hypertension and stroke, dyslipidemia, gall stones, respiratory disorders, musculoskeletal disorders and several cancers including breast, endometrial, ovarian, gall bladder and colon.
Trans fatty acids are
not essential and provide no benefit to human health.
Saturated fats increase levels of
LDL cholesterol (bad cholesterol
Trans fats increase levels of
LDL and also lower levels of HDL (good cholesterol); thus increasing the risk of coronary heart disease
- Drug metabolism can take place anywhere in the body (Plasma, kidney, lung, gut wall) but
liver is the prime site
- There are three potential outcomes of drug metabolism:
- 1)Increase in drug hydrophilicity and ability to be excreted (hepatic) 2)Metabolic products are less pharmacologically active than the substrate drug 3)Inactive prodrugs converted to their active forms (hepatic
- There are several mechanisms of Drug Resistance including:
1) decreased permeability 2) alteration of the target site for the drug 3) enzymatic inactivation of the drug 4) active transport of the drug out of the cell 5) amplification of the gene coding for the target of the drug.
An increase in DNA repair activity can
decrease effectiveness of drugs that target DNA.
- Multidrug resistant results from an
- increase in the amount of transporter proteins that can pump many different drugs out of the cell.
Cell proliferation
the process that results in an increase of the number of cells, and is defined by the balance between cell divisions and cell loss through cell death or differentiation. Cell proliferation is increased in tumours
Cell specialization, 3) Cell interaction
Duh
the 4 essential processes needed to develop from a single cell into a multicellular organism
1) Cell proliferation, 2) Cell specialization, 3) Cell interaction, 4) Cell movement.
cell movement
a complex phenomenon primarily driven by the actin network beneath the cell membrane, and can be divided into three general components: protrusion of the leading edge of the cell, adhesion of the leading edge and deadhesion at the cell body and rear, and cytoskeletal contraction to pull the cell
