Telomerase, also called telomere terminal transferase, is an enzyme made of
protein and RNA subunits
that elongates chromosomes by adding TTAGGG sequences to the end of existing chromosomes.
Is telomerase made of protein?
Telomerase is a unique reverse transcriptase that consists of
a protein and an RNA molecule
combined to form a ribonucleoprotein complex. Telomerase was first discovered in 1985 in the protozoan Tetrahymena thermophila by Carol Greider and Elizabeth Blackburn.
What is telomerase composed of?
Telomerase consists of two essential components: one is
the functional RNA component
(in humans called hTR or hTERC) (64), which serves as a template for telomeric DNA synthesis; the other is a catalytic protein (hTERT) with reverse transcriptase activity (98, 123, 149, 163).
What do telomeres contain?
Telomeres do indeed play an essential role in stabilizing the ends of chromosomes, but they do not contain active genes. Instead, telomeres contain
an array of highly repeated DNA sequences and specific binding proteins
that form a unique structure at the end of the chromosome.
Does telomerase contain DNA?
Telomerase is
an RNA-dependent DNA polymerase
, meaning an enzyme that can make DNA using RNA as a template. … When the overhang is long enough, a matching strand can be made by the normal DNA replication machinery (that is, using an RNA primer and DNA polymerase), producing double-stranded DNA.
Is telomerase good or bad?
Too
much telomerase
can help confer immortality onto cancer cells and actually increase the likelihood of cancer, whereas too little telomerase can also increase cancer by depleting the healthy regenerative potential of the body.
Can telomerase reverse aging?
An enzyme called
telomerase can slow, stop or perhaps even reverse the telomere shortening that happens as we age
. The amount of telomerase in our bodies declines as we age. Telomerase maintains and may even lengthen telomeres.
Do humans have telomerase?
Telomerase has
been detected in human cancer cells
and is found to be 10-20 times more active than in normal body cells. This provides a selective growth advantage to many types of tumors.
What happens if telomerase is blocked?
However, blocking telomerase activity could affect cells where telomerase activity is important, such as sperm, eggs, platelets and immune cells. Disrupting telomerase in these cell types could affect
fertility, wound healing
and the ability to fight infections.
What is the purpose of telomerase?
Telomerase is the enzyme
responsible for maintenance of the length of telomeres by addition of guanine-rich repetitive sequences
. Telomerase activity is exhibited in gametes and stem and tumor cells.
What happens if telomeres are too long?
It was known that very short telomeres cause harm to a cell. But what was totally unexpected was our finding that damage also occurs when telomeres are very long.” … As telomeres shorten over time, the chromosomes themselves become vulnerable to damage.
Eventually the cells die
.
How long are telomeres in humans?
Humans have relatively short telomere lengths from
5 to 15 kb
(1⇓–3), and yet humans have much longer life spans than mice, which can start with telomere lengths around 50 kb (4, 5).
What DNA is found at telomeres?
Telomeres are made up of repeated segments of DNA that consist of the
sequence 5′-TTAGGG-3′
(in which T, A, and G are the bases thymine, adenine, and guanine, respectively). Some human cells contain as many as 1,500 to 2,000 repeats of this sequence at each end of each chromosome.
What does telomerase do to telomeres?
In egg and sperm cells, an enzyme called telomerase
keeps adding more of the repeating sequence onto the end of DNA strands
, so that the telomeres in these cells don’t shorten. In other cells, telomerase is less active, leading to the gradual shortening of telomeres over time.
What is the best supplement for telomeres?
Vitamin D
promotes activity of telomerase, the repair enzyme that steadily adds to telomere length. Vitamins C and E preserve telomere length by reducing the chemical stresses that contribute to telomere shortening. Gamma-tocotrienol in particular may reverse telomere shortening and attendant cellular aging.
