TRANSCRIPTION DNA mRNA

Transcribe means to make a copy …….copy a gene

DNA mRNA Transcription is the process of copying a sequence of DNA (a gene) in the form of mRNA. DNA mRNA transcription

RNA nucleic acid RNA, like DNA, is a ____________. nucleotides RNA is also composed of ____________. mRNA

RNA RNA differs from DNA in three ways: RNA is single stranded . DNA is double stranded. The sugar in RNA is ribose, whereas the sugar in DNA is deoxyribose. 3. Both DNA and RNA contain four bases, but RNA contains Uracil (U), not thymine (T) Complementary base pairs in RNA are: A --- U C --- G

Bases in DNA are: A - Adenine T - Thymine C - Cytosine G - Guanine Base pairs in DNA are: A --- T C --- G T --- A G --- C Bases in RNA are: A - Adenine U - Uracil C - Cytosine G - Guanine Base pairs in RNA are: A --- U C --- G U --- A G --- C

There are three types of RNA: mRNA Messenger RNA--________ : a copy of a gene that contains the instruction for making a protein. rRNA Ribosomal RNA-- _______: ribosomes are made of rRNA tRNA Transfer RNA --_________: It transports amino acids to the ribosome so they can be assembled it proteins.

Overview TRANSCRIPTION DNA mRNA nucleus Copy of a gene mRNA DNA exits the nucleus T A A G C C T G A C G C T A T T A T T C G G A C T G C G A T A A DNA gene

The steps in Transcription are: 1. RNA polymerase binds to the gene’s “start site”. 2. RNA polymerase unzips and separates the two strands of DNA. 3. RNA polymerase adds and links RNA nucleotides to one strand of DNA (DNA template). As the mRNA strand grows, the two strands of DNA close up reforming a double helix. 5. RNA nucleotides are added until a “stop” signal is reached. mRNA strand detaches, exits the nucleus, and enters the cytoplasm.

RNA polymerase binds to the gene’s “start site”. DNA Polymerase nucleus DNA Polymerase DNA T A A G C C T G A C G C T A T T RNA polymerase (an enzyme) A T T C A G A C T G C G A T A A start DNA

RNA polymerase unzips and separates the two strands of DNA. nucleus T A A G C C T G A C G C T A T T A T T C A G A C T G C G A T A A start DNA

RNA polymerase adds and links RNA nucleotides to one strand of DNA (DNA template). nucleus A U G U C G DNA T A A G C C T G A C G C T A T T mRNA A T T C A G A C T G C G A T A A start DNA DNA template

As the mRNA strand grows, the two strands of DNA close up reforming a double helix.

“stop” signal is reached RNA nucleotides are added until a “stop” signal is reached nucleus A U G U C G DNA T A A G C C T G A C G C T A T T mRNA A T T C A G A C T G C G A T A A stop

and enters the cytoplasm. 6. mRNA strand detaches, exits the nucleus, and enters the cytoplasm. nucleus DNA T A A G C C T G A C G C T A T T mRNA mRNA G U C U G A A T T C A G A C T G C G A T A A stop

Let’s review transcription!

RNA polymerase binds to the gene’s “start site”. RNA Polymerase nucleus RNA Polymerase DNA T A A G C C T G A C G C T A T T RNA polymerase (an enzyme) A T T C A G A C T G C G A T A A start DNA

RNA polymerase unzips and separates the two strands of DNA. nucleus T A A G C C T G A C G C T A T T A T T C A G A C T G C G A T A A start DNA

RNA polymerase adds and links RNA nucleotides to one strand of DNA (DNA template) until stop signal. nucleus A U G U C G DNA T A A G C C T G A C G C T A T T A T T C A G A C T G C G A T A A start stop DNA template

and enters the cytoplasm. 4. mRNA strand detaches, exits the nucleus, and enters the cytoplasm. nucleus DNA T A A G C C T G A C G C T A T T mRNA mRNA G U C U G A A T T C A G A C T G C G A T A A stop

What is this process called? TRANSCRIPTION What is this? A DNA strand The DNA template What is this? What is this? mRNA What is this? RNA nucleotide What is this process called? TRANSCRIPTION What is this? A DNA molecule