Transcript rna and protein synthesis

RNA
Ribonucleic Acid
Question
1. Use the following diagram to locate the
nucleus and ribosomes on the cell.
Key Terms
Ribose: sugar molecule of every RNA
nucleotide
Transcription: process by which genetic
information is copied from DNA to RNA
The structure of RNA
Like DNA, RNA is
a nucleic acid
made of repeating
nucleotides.
3 Differences Between RNA and
DNA
1. The sugar molecule
of RNA nucleotides
is ribose.
2. Uracil usually
replaces thymine in
RNA. U- replaces T
3. RNA is single strand
3 Types of RNA
Messenger RNA (mRNA): mRNA carries
genetic info. from DNA in the nucleus to
the cytosol inside the cell.
Transfer RNA (tRNA): binds to amino
acids
3 Types Continued…
Ribosomal RNA (rRNA): most abundant
form of RNA, RNA makes up ribosomes
where proteins are made.
Transcription
Transcription is the formation of
RNA from a DNA template.
The RNA formed may be rRNA,
tRNA, or mRNA.
Steps of Transcription
Inside the nucleus, an enzyme, RNA
polymerase, binds to bases on the DNA
of the gene to be expressed.
This starting sequence is the promotor.
Steps of Transcription
1. The DNA begins to unwind and the
strands begin to separate.
2. The RNA polymerase begins to move
along one strand of the exposed DNA,
linking ribonucleotides together in order
specified by the sequence of bases on
the DNA.
3. Transcription (literally "rewriting")
continues until the RNA polymerase
reaches a "stop" message on the DNA (a
termination signal).
4. The unzipped DNA closes back up and
the mRNA is released into the nucleus
prior to the next stage in the production
of a protein.
Products of Transcription
The RNA formed may be rRNA (ribosomal
RNA), tRNA (transfer RNA) or mRNA
(messenger RNA).
1. What would the complementary RNA
strand be for these DNA sequences?
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TACG
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ATTAGTC
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GATTACA
What would the complementary RNA strand
be for these DNA sequences?
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TACG
AUGC
ATTAGTC
UAAUCAG
GATTACA
CUAAUGU
Protein Synthesis
(translation)
Making proteins
The mRNA now takes the message from
DNA to the ribosome to make proteins
What’s the big Deal about
proteins????
Proteins run our show.
Muscles, organs, hair, bone, and skin either
contain or are made of proteins.
They are a major component in all of our cells.
Enzymes that run the chemical reactions in our
bodies are proteins.
Proteins help us move, send messages
(hormones and nerve receptors), fight off
disease (antibodies), and transport other
molecules and atoms around our bodies.
Proteins
Like DNA and RNA, proteins are
polymers.
Proteins are made up of one or more
polypeptides, each of which consists of a
specific sequence of amino acids.
There are 20 different amino acids
The function of a protein depends how it
binds with other molecules in the cell.
Cracking the code
The code for proteins is held in the RNA
(originally from the DNA)
3 base pairs on mRNA makes up a codon
A codon chart is used to tell what 3 base
pairs codes for what amino acids.
Translation
Translation is the process of reading the
mRNA code and using the code to
assemble amino acids to make proteins.
Start and Stop
Start codons tell translation to begin
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AUG = start, also codes for the amino acid
methionine
Stop codons tell translation to stop
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There are three stop codons
These do not code for an amino acid
UAA, UAG, UGA
tRNA
tRNA contains 3 base pairs that
compliment the mRNA codons.
The 3 base pairs of tRNA are called anti
codons.
tRNA links the Amino Acids together with
the help of the ribosome to form proteins.
tRNA
Role of the Ribosome
Ribosome are composed of rRNA and
proteins.
Membrane proteins and proteins to be
shipped out of the cell made by ribosome
on rough ER.
Ribosome
Ribosome have three binding sites
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One for mRNA
Two for holding matching tRNAs
Several ribosome can work on a single
mRNA transcript
Completion of a Protein
After the primary structure is complete a
protein will fold to form secondary and
tertiary structures.
It is at this time you have a completed
functional protein.