Which enzyme maintains the ends of the linear chromosomes?

Which enzyme maintains the ends of the linear chromosomes?

telomerase enzyme

What kind of enzyme is telomerase?

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. Telomerase is found in fetal tissues, adult germ cells, and also tumor cells.

What are the ends of chromosomes called?

At the end of each chromosome is a repetitive nucleotide sequence cap called a telomere. In vertebrates, the telomere is a TTAGGG sequence repeated to approximately 15,000 base pairs.

What is telomere replication?

Telomeres are the physical ends of eukaryotic chromosomes. They protect chromosome ends from DNA degradation, recombination, and DNA end fusions, and they are important for nuclear architecture. Telomeres provide a mechanism for their replication by semiconservative DNA replication and length maintenance by telomerase.

Is DNA a primer in telomere synthesis?

Reading: Telomeres In the leading strand, synthesis continues until the end of the chromosome is reached. On the lagging strand, DNA is synthesized in short stretches, each of which is initiated by a separate primer.

What is telomerase in DNA replication?

Telomerase adds complementary RNA bases to the 3′ end of the DNA strand. Once the 3′ end of the lagging strand template is sufficiently elongated, DNA polymerase adds the complementary nucleotides to the ends of the chromosomes; thus, the ends of the chromosomes are replicated.

Is telomerase in all cells?

Telomerase is an RNA-dependent DNA polymerase, meaning an enzyme that can make DNA using RNA as a template. Telomerase is not usually active in most somatic cells (cells of the body), but it’s active in germ cells (the cells that make sperm and eggs) and some adult stem cells.

Which answer best describes the role of telomerase in replicating the ends of linear chromosomes?

Which answer best describes the role of telomerase in replicating the ends of linear chromosomes? It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity.

What does telomerase mean?

: a DNA polymerase that is a ribonucleoprotein catalyzing the elongation of chromosomal telomeres in eukaryotic cell division and is particularly active in cancer cells.

Why is RNA synthesis called transcription?

Why is RNA synthesis called ‘transcription’ and protein synthesis called ‘translation?’ RNA synthesis makes a complementary copy of the DNA using nucleic acid and protein synthesis requires the information in the RNA to be changed into a different type of molecule. D.

What proteins are crucial for creating and maintaining DNA replication forks?

What proteins are crucial for creating and maintaining DNA replication forks? Choose the best explanation. Helicase creates the replication fork; single-strand binding proteins keep the single strands from reuniting.

Which enzyme is responsible for putting together new DNA segments?

DNA polymerase

What molecule connects sugars in a strand of DNA?

​Phosphate Backbone Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups. Attached to each sugar is one of four bases–adenine (A), cytosine (C), guanine (G), or thymine (T).

What does gene expression refer to?

Gene expression is the process by which the information encoded in a gene is used to direct the assembly of a protein molecule.

What is gene expression example?

Some simple examples of where gene expression is important are: Control of insulin expression so it gives a signal for blood glucose regulation. X chromosome inactivation in female mammals to prevent an “overdose” of the genes it contains. Cyclin expression levels control progression through the eukaryotic cell cycle.

Where Does gene expression occur?

Prokaryotic gene expression (both transcription and translation) occurs within the cytoplasm of a cell due to the lack of a defined nucleus; thus, the DNA is freely located within the cytoplasm. Eukaryotic gene expression occurs in both the nucleus (transcription) and cytoplasm (translation).

What are the two stages of gene expression?

Transcription: the production of messenger RNA (mRNA) by the enzyme RNA polymerase, and the processing of the resulting mRNA molecule. Translation: the use of mRNA to direct protein synthesis, and the subsequent post-translational processing of the protein molecule.

What controls gene expression?

Gene expression is primarily controlled at the level of transcription, largely as a result of binding of proteins to specific sites on DNA. Regulation of protein production is largely achieved by modulating access of RNA polymerase to the structural gene being transcribed.

What are the 3 parts of a gene?

Each gene can be broken down into important parts: A promoter, coding region, and terminator.

What factors increase gene expression?

The expression of genes in an organism can be influenced by the environment, including the external world in which the organism is located or develops, as well as the organism’s internal world, which includes such factors as its hormones and metabolism.

What are three factors that affect gene expression?

Various factors, including genetic makeup, exposure to harmful substances, other environmental influences, and age, can affect expressivity. Both penetrance and expressivity can vary: People with the gene may or may not have the trait and, in people with the trait, how the trait is expressed can vary.

What are five examples of genetic factors?

What You Need to Know About 5 Most Common Genetic Disorders

• Down Syndrome. Typically, the nucleus of an individual cell contains 23 pairs of chromosomes, but Down syndrome occurs when the 21st chromosome is copied an extra time in all or some cells.
• Thalassemia.
• Cystic Fibrosis.
• Tay-Sachs disease.
• Sickle Cell Anemia.
• Learn More.
• Recommended.
• Sources.

What does gene expression depend on?

However, two different cells of the same type may also have different gene expression patterns depending on their environment and internal state. Broadly speaking, we can say that a cell’s gene expression pattern is determined by information from both inside and outside the cell.

How genes are switched on and off?

Genes are turned on and off in different patterns during development to make a brain cell look and act different from a liver cell or a muscle cell, for example. Gene regulation also allows cells to react quickly to changes in their environments.

Are epigenetic tags passed to daughter cells?

Are epigenetic tags passed to daughter cells? Yes so that it can rumba what to do for its specialized functions, others are erased in the zygote or in the egg or sperm.

What are 2 causes of mutations?

Mutations arise spontaneously at low frequency owing to the chemical instability of purine and pyrimidine bases and to errors during DNA replication. Natural exposure of an organism to certain environmental factors, such as ultraviolet light and chemical carcinogens (e.g., aflatoxin B1), also can cause mutations.

What are the 4 mutations?

There are three types of DNA Mutations: base substitutions, deletions and insertions.

• Base Substitutions. Single base substitutions are called point mutations, recall the point mutation Glu —–> Val which causes sickle-cell disease.
• Deletions.
• Insertions.

What are the 3 causes of mutation?

Mutations may be caused by exposure to specific chemicals or radiation. These agents cause the DNA to break down. 1) de aminating amino groups. 3) cause cross linking of DNA strands….

• DNA fragmentation.
• thymidine dimerisation.
• shift in the equilibrium of tautomeric forms of bases.