START exam 2- quiz lectures 5&6

zinc is transported OUT of the enterocyte into the circulation by

Zn transporter ZnT1

free iron in the body is dangerous because it can promote

oxidative stress

what food is highest in zinc content

oysters

which of the following dietary substances decrease the heme iron absorption in the gut?

phosvitin

which compounds inhibit zinc absorption

phytate (phytic acid)

which of the following dietary components inhibits copper absorption

phytate (phytic acid)

what are functions of ceruloplasmin

-Cp carries Cu in blood -Cp is an enzyme that oxidizes iron

what is true of IRP1?

-IRP1 is an intracellular cytosolic sensor; it binds iron-sulfer clusters -IRP1 is a moon-lighting enzyme that has aconitase activity when intracellular iron is high -IRP1 binds iron response elements in mRNAs encoding ferritin and the transferrin receptor when cellular iron is low -IRP1 binding the 5' UTR-IRE block ferritin translation, decreasing cellular ferritin -IRP1 binding the 3' UTR-IRE inhibits transferrin receptor degredation, increasing transferrin mRNA translation and cellular transferring receptor levels

populations at risk for iron deficiency include

-children and infants -adolescence -females of childbearing years and pregnant women -vegetarians

what are functions of copper

-component of cytochrome C oxidase -component of lysyl oxidase (LOX) -involved in dopamine conversion to norepinephrine - melanin formation

Menke's disease is a lethal x-linked disease that results in a copper _________, resulting from a defect in the gene encoding _____. This protein is involved in the transport of copper ______.

-deficiency -ATP7A protein -out of enterocytes

acrodermatitis enteropathica is a gene mutation based disease leading it:

-deficient Zn absorption -mutation of the Zip4 transporter

clinical signs of copper deficiency are:

-microcytic hypochromic anemia -impaired nervous system function -changes in hair and skin pigmentation -impaired growth

zinc has following biochemical roles in human physiology

-structural: stabalizing the structure of key proteins e.g. transcription factors -catalytic: a co-factor in metallo-proteins e.g. Cu, Zn-SOD1 -regulatory: involved in cell signaling, hormone release

what is true of hemochromatosis?

-too much iron absorption and storage -inherited disorder, frequency of occurance is 1 in 200 -mutation in the human hemostatic iron regulatory protein (HFE) -failure to sense iron stores and failure to down regulate iron absorption

RDA for iron intake for adults

8 mg/day

RDA for copper for adults

900 micrograms / day

wilson's disease is an inherited genetic disorder of copper toxicity as a result of defect in

ATP7B

what IS a transport mechanism for zinc entry into enterocytes

Zip4

what is not a function of copper

component in superoxide dismutase 2 (SOD2)

what is the link between copper deficiency and iron deficiency anemia?

copper (Cu2+) bond to ceruloplasm is required for iron oxidation (Fe2+ --> Fe3+) which is required for iron binding to transferrin and transport to cells

the iron hormone, hepcidin, _________ iron export from the enterocyte by binding to and promoting the internalization and lysosomal degradation of _______.

decreases, ferroportin

what plays a role in non-heme entry into enterocytes?

divalent metal transporter 1 (DMT1)

cytochrome p450, catalase and peroxidases require non-heme iron for function

false

food products derived from animals contain only heme iron

false

heme oxygenase (Hmox) removes ferric iron (Fe3+) from heme in the enterocyte for storage in ferritin

false

the majority of iron in the body is found in the bone

false

zinc is a transition element with high redox chemistry

false

DRI for zinc intake in males and female adults is 3 and 2 mg/day respectively

false,

which group is at risk for iron toxicity:

hemochromatosis patients

which protein and mineral are critical for oxidizing iron to Fe3+ so it can be loaded onto transferrin for delivery to the tissues from the gut and liver?

hephaestin, copper

what plays a role in controlling the uptake and storage of iron in non-intestinal cells

transferrin, transferrin receptor, ferritin, divalent metal transporter 1 (DMT1) and six transmembrane epithelial antigen of the prostate (Steap3)

ferritin is a key intracellular and plasma iron storage complex consisting of 24 light and heavy protein chains

true

insertion of copper into metallo-enzymes require copper chaperones

true

iron in enterocytes is ferrous iron Fe2+ iron in the blood is ferric iron Fe3+

true

lab tests for iron are sensitive markers of iron deficiency or iron excess

true

red blood cells contain the most functional iron

true

reductases on the apical surface (brush boarder) of the enterocyte convert dietary ferric iron (Fe3+) to ferrous iron (Fe2+) to facilitate transport into the enterocyte by DMT1

true

whole body content of iron, copper, zinc in a 70 kg human is : iron (2.8-3.5 g) copper (100 mg) zinc (1.5-2.5 g) ...respectively

true

zinc deficiency exists in the US and globally

true