Describe the reactions catalyzed by lactate dehydrogenase in the skeletal muscles, liver, and heart.

Lactate dehydrogenase is an enzyme that can:

•catalyzes the conversion of lactate to pyruvate and back, and

•  converts NAD+ to NADH and back.

The reaction of lactate dehydrogenase usually occurs during a tissue damage. So, pyruvate, (the final product of glycolysis), is converted to lactate when oxygen is absent (in low concentration).

When the concentrations of lactate increases (as the product of lactate dehydrogenase reaction), the enzyme exhibits feedback inhibition (negative feedback).

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.