DNA Replication and Telomeres

False (B)

telomerase

<p>50-70</p> Signup and view all the answers

<p>Embryonic Stem cells = Telomerase expressed Adult Stem cells = Telomerase expressed Cancer cells = Telomerase expressed Differentiated cells = Telomerase not expressed</p> Signup and view all the answers

<p>5' to 3' only (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>DNA Ligase</p> Signup and view all the answers

<p>leading</p> Signup and view all the answers

<p>Leading strand = Synthesized continuously Lagging strand = Synthesized discontinuously DNA Ligase = Joins DNA fragments Telomeres = Protective repetitive sequences at chromosome ends</p> Signup and view all the answers

<p>To protect the ends of chromosomes from degradation due to the shortening of lagging strand during replication (A)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>loss of important genes</p> Signup and view all the answers

The 3' end of a DNA strand where nucleotides are added during DNA replication.

DNA polymerase can only add nucleotides to the 3' end of a DNA strand, resulting in a continuous leading strand and a discontinuous lagging strand.

Short sequences of RNA that initiate DNA synthesis by DNA polymerase.

The process of removing RNA primers and replacing them with DNA nucleotides during DNA replication.

An enzyme that joins fragments of DNA together, forming a continuous strand.

Repetitive nucleotide sequences at the ends of chromosomes that protect them from degradation.

The loss of DNA at the ends of chromosomes during DNA replication due to the inability to replace the final RNA primer on the lagging strand.

Prokaryotes have circular DNA, while eukaryotes have linear DNA.

The ends of chromosomes are called telomeres. These are made up of repeating sequences, like 'AGGGTT', which are repeated thousands of times.

Telomeres shorten with each cell division. A newborn has about 11,000 bases in each telomere, but an older person might have less than 4,000 bases.

The Hayflick Limit refers to the limited number of times a cell can divide before stopping. This limitation is linked to the shortening of telomeres.

Telomerase is an enzyme that adds lost DNA sequences back to telomeres. It's found in embryonic cells, stem cells, and cancer cells, allowing them to divide indefinitely.

The lagging strand in DNA replication can't be copied completely, causing some loss of DNA at the end of the chromosome. This is where telomeres come in.