RNA MOLECULE & TRANSCRIPTION G8

Ribonucleic Acid

RNA

• The RNA generally consists of a single strand.
• The RNA molecule is also composed of phosphate group, a pentose sugar (ribose) and nitrogenous bases.
• The nitrogenous bases present in RNA are adenine (A), guanine (G), cytosine(C) and uracil (U). In RNA the fourth base is different from that of DNA.
• RNA plays a vital role in the synthesis of proteins.
• They are the carrier of genetic information in all living cells.

RNA (ribonucleic acid)

RNA has three main roles in the cell:

• It carries the instructions from the DNA in the nucleus to the ribosomes where proteins are made in the cytoplasm of the cell.
• RNA picks up specific amino acids from the cytoplasm of the cell and delivers them to the ribosomes where protein synthesis takes place.
• It makes up around 50% of the structure of the ribosomes.

ROLES OF RNA

Video

(rRNA)

(tRNA)

(mRNA)

Transfer RNA (tRNA) is found in the cytoplasm. It is responsible for carrying amino acids from the cytoplasm to the ribosome surface, ready to make a protein as instructed by the mRNA.

Ribosomal RNA (rRNA) is produced in the nucleolus, before moving out into the cytoplasm to bind with proteins and form a ribosome.

RIBOSOMAL RNA

Transfer RNA

Messenger RNA (mRNA) molecules move to the surface of the ribosomes, carrying instructions from the DNA in the nucleus about the protein which needs to be synthesized.It is a complementary to one of the strands of DNA.

MESSENGER RNA

TYPES OF RNA MOLECULES

• Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).

• mRNA moves from the cell nucleus to the cytoplasm, where it is used for synthesizing proteins.

DNA TRANSCRIPTION

1. RNA polymerase binds to a sequence of DNA called the promoter and separates the DNA strands, providing the single-stranded template needed for transcription. 2. One strand of DNA, acts as a template for RNA polymerase, as it "reads" this template one base at a time, the polymerase builds an RNA molecule out of complementary nucleotides. The RNA transcript carries the same information as the non-template strand of DNA. 3. RNA transcript is complete, then it is released from RNA polymerase. The RNA messenger moves from the nucleus to the cytoplasm.

Transcription is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand (using a DNA strand as a template).

TRANSCRIPTION PROCESS

1. RNA polymerase binds to a sequence of DNA called the promoter and separates the DNA strands, providing the single-stranded template needed for transcription. 2. One strand of DNA, acts as a template for RNA polymerase, as it "reads" this template one base at a time, the polymerase builds an RNA molecule out of complementary nucleotides. The RNA transcript carries the same information as the non-template strand of DNA. 3. RNA transcript is complete, then it is released from RNA polymerase. The RNA messenger moves from the nucleus to the cytoplasm.

Transcription is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand (using a DNA strand as a template).

TRANSCRIPTION PROCESS

TRANSCRIPTION

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