Biology Chapter on Transcription and DNA Replication

A polynucleotide is a long chain of nucleotides linked together by phosphodiester bonds.

A nucleotide is made up of three parts: a sugar molecule (deoxyribose in DNA), a phosphate group, and a nitrogenous base.

The four nitrogenous bases found in DNA are adenine (A), guanine (G), cytosine (C), and thymine (T).

Adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C).

The two strands of DNA are antiparallel, meaning they run in opposite directions. This ensures that the bases can pair correctly.

The structure of DNA is a double helix, meaning it is twisted like a spiral staircase.

The sugar-phosphate backbone forms the sides of the DNA helix, while the nitrogenous bases form the rungs.

DNA is organized into chromosomes, which are long, threadlike structures found in the nucleus of cells.

DNA contains the genetic instructions for an organism, which are passed down from parents to offspring.

DNA is responsible for the inheritance of traits and plays a crucial role in protein synthesis.

The two strands of DNA run in opposite directions, meaning that the sugar molecules on one strand are upside down compared to those on the other strand.

The sugar-phosphate backbone of DNA is formed by alternating sugar and phosphate groups, creating a strong and stable structure.

Adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G) in DNA.

The process of copying DNA involves creating two identical DNA molecules from one original molecule.

DNA polymerase is an enzyme that builds new DNA strands by adding nucleotides to a growing chain, following the base pairing rules.

The double helix is the twisted ladder-like structure of DNA, where two strands of nucleotides are held together by hydrogen bonds between complementary bases.

The process of copying DNA is extremely accurate, with fewer than one in a billion bases incorrectly paired, ensuring the fidelity of genetic information.

Enzymes play a vital role in maintaining the integrity of DNA, ensuring that it is copied accurately and protected from damage.

A specific sequence of DNA nucleotides that signals where the RNA polymerase should attach to begin transcription.

The first phase of transcription where RNA polymerase attaches to the promoter on DNA and begins building the RNA molecule.

The second phase of transcription where RNA polymerase moves along the template strand of DNA, adding complementary RNA nucleotides to the growing RNA molecule.

A specific DNA sequence that signals the end of transcription, causing RNA polymerase to detach from the DNA and releasing the completed RNA molecule.

Specific starting points along the DNA molecule where replication begins to create two new strands.

Short sequences of DNA that act as primers, providing a starting point for DNA polymerase to begin adding nucleotides.

Regions where the DNA strands separate, creating a bubble-like structure, allowing for replication.

The two strands of DNA run in opposite directions, with one strand running 5' to 3' and the other 3' to 5'.

The new DNA strand built in a continuous manner, following the 5' to 3' direction of the template strand.

The new DNA strand built in a discontinuous manner, with short fragments called Okazaki fragments, due to the 3' to 5' direction of the template strand.

The process of bringing all the necessary components together to begin protein synthesis: mRNA, the first tRNA carrying the starting amino acid (methionine), and the two ribosomal subunits.

The process of adding amino acids one by one to the growing polypeptide chain, forming a protein.

The step in translation where the ribosome encounters a stop codon in the mRNA sequence, signaling the end of protein synthesis.

The site on the ribosome where the incoming tRNA carrying the next amino acid binds.

The site on the ribosome where the tRNA carrying the growing polypeptide chain resides.

The process in translation during which the tRNA in the P site detaches from the ribosome and the ribosome moves to the next codon on the mRNA molecule. This moves the tRNA carrying the growing polypeptide chain to the P site.

The three-nucleotide sequence on a tRNA molecule that is complementary to the mRNA codon.

The three-nucleotide sequence on an mRNA molecule that codes for a specific amino acid.

RNA splicing is the removal of non-coding regions (introns) from pre-mRNA, resulting in a mature mRNA molecule that can be translated into a protein.

RNA splicing is crucial for human gene expression, as it allows a single gene to produce multiple protein variants, expanding the proteome.

Ribosomes are complex molecular machines composed of ribosomal RNA (rRNA) and proteins. They act as the site of protein synthesis, reading the mRNA code and assembling amino acids into a polypeptide chain.

Transfer RNA (tRNA) molecules act as molecular interpreters during translation. Each tRNA carries a specific amino acid and recognizes a corresponding codon on the mRNA, facilitating the assembly of the polypeptide chain.

Translation is the process of converting the genetic information encoded in mRNA into a protein sequence. It occurs on ribosomes, where the mRNA sequence is read and translated into a chain of amino acids.

A codon is a three-nucleotide sequence on mRNA that specifies a particular amino acid or signals the start or stop of protein synthesis.

The genetic code is the set of rules that determines which amino acid is encoded by each codon. It is nearly universal across all living organisms, suggesting a common ancestor.

The proteome refers to the complete set of proteins expressed by a cell or organism at a given time. It is influenced by factors such as gene expression, splicing, and post-translational modifications.