STEROIDShandouts - STEROIDS BILE ACIDS STEROID HORMONES...

Info icon This preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
STEROIDS, BILE ACIDS, STEROID HORMONES Vitamins D
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Steroids form an important group of compounds based on the fundamental saturated tetracyclic hydrocarbon : cyclo- pentanoperhydrophenanthrene (sterane). The prefix „perhydro ” refers to the fact that all the necessary hydrogen atoms have been added to the compound to make it fully saturated
Image of page 2
Steroid nucleus Steroid nucleus consists of three cyclohexane rings and one cyclopentane ring fused together. The four rings in steroid nucleus are designated A, B, C, and D .
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Steroids are three-dimen- sional . Thus, the constituent carbon atoms and the hydrogen atoms of their substituents lie in different planes, giving rise to isomers
Image of page 4
Conformation There are four rings in a steroid skeleton and hence there are three fusion points. A/B, B/C and C/D rings share two carbons each (fusion).
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Natural steroids have two methyl groups Two methyl groups attached to C-10 and C-13 lie above the plane of the molecule and are customarily the points of reference for the describing the spatial orientation of other substituents in the steroid nucleus.
Image of page 6
For two-ring system, the structures of cis - and trans -fused rings look like this: When there are directed on the same side, it is called cis . When the tow hydrogens are oriented opposite to each other with the ring system thought to as forming a plane, the ring fusion is called trans.
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Cholesterol is one of the most important and abundant steroids in the body
Image of page 8
Cholesterol Composed of the steroid nucleus with methyl CH 3 – groups, an alkyl chain, and a hydroxyl group –OH attached CH 3 HO CH 3 CH 3 CH 3 CH 3
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Slightly less than half of the cholesterol in the body derives from biosynthesis de novo . Biosynthesis in the liver accounts for approximately 10%, and in the intestines approximately 15%, of the amount produced each day. Cholesterol synthesis occurs in the cytoplasm and microsomes from the two-carbon acetate group of acetyl-CoA .
Image of page 10
Biosynthesis of Cholesterol The process has five major steps : 1. Acetyl-CoAs are converted to 3-hydroxy-3-methylglutaryl- CoA (HMG-CoA) 2. HMG-CoA is converted to mevalonate 3. Mevalonate is converted to the isoprene based molecule, isopentenyl pyrophosphate (IPP ), with the concomitant loss of CO 2 4. IPP is converted to squalene 5. Squalene is converted to cholesterol.
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Cholesterol Cholesterol is an extremely important biological molecule that has roles in membrane structure as well as being a precursor for the synthesis of the
Image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern