β-Carotene is the precursor of vitamin A1.
Oxidation at C-15 converts retinol to the aldehyde, retinal, and further oxidation produces retinoic acid, a hormone that regulates gene expression. 

TLS Online TPP Program

#Id: 1063

#Unit 5. Developmental Biology

The ER-localized protein, FT INTERACTING PROTEIN1 (FTIP1), is required for FT movement into the phloem translocation stream.

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#Id: 2054

#Unit 8. Inheritance Biology

Leber hereditary optic neuropathy (LHON)- People who have this disorder experience rapid loss of vision in both eyes, which results from the death of cells in the optic nerve.

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#Id: 5205

#Unit 7. System Physiology – Animal

Anticlotting mechanisms  The tendency of blood to clot is balanced in vivo by reactions that prevent clotting inside the blood vessels, break down any clots that 

do form, or both.

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#Id: 7027

#Unit 11. Evolution and Behavior

Proximate causes - The subject of cell biology, neurobiology, and many other biological disciplines

Ultimate causes - Their historical causes, especially the action of natural selection

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#Id: 6151

#Unit 3. Fundamental Processes

Even if cells cannot repair these lesions, there is a fail-safe mechanism that allows the replication machinery to bypass these sites of damage or tolerate the DNA damage. One mechanism of DNA damage tolerance is translesion synthesis. Although this mechanism is, as we shall see, highly error-prone and thus likely to introduce mutations, translesion synthesis spares the cell the worse fate of an incompletely replicated chromosome. A key feature of DNA damage tolerance is that the DNA lesion remains in the genome. DNA repair pathways can subsequently correct the lesion.