Another Nucleic Acid. RNA is the second type of nucleic acid found in a cell. There are 3 different...
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Transcript of Another Nucleic Acid. RNA is the second type of nucleic acid found in a cell. There are 3 different...
RNAAnother Nucleic Acid
RNA Structure• RNA is the second type of nucleic acid
found in a cell.• There are 3 different types of RNA• Structure of RNA:• Long chain of nucleotides• 5-carbon sugar called ribose• Phosphate• Nitrogen bases- Adenine, Guanine,
Cytosine and Uracil (instead of Thymine)
• Just a single strand
Function of RNA• The function of RNA is to carry the code
from DNA in the nucleus to the ribosomes in the cytoplasm (where the code will be used to make proteins).
Quick Check• Compare the details of DNA to RNA
Feature DNA RNA
# of strands 2 1
Type of sugar Deoxyribose Ribose
Nitrogen bases A, T, G, C A, U, G, C
Location in cell Nucleus Nucleus → Ribosome in cytoplasm
Number of forms 1 3
Job description Carries genetic information
Take info from DNA to the ribosomes to make proteins
Types of RNA• Messenger RNA (mRNA)- this is the piece
of RNA that takes the code (“message”) from the DNA to the ribosome.
• Transfer RNA (tRNA)- this RNA brings (“transfers”) amino acids from the cytoplasm to the ribosome/ mRNA.
• Ribosomal RNA (rRNA)- this is the structural part of a ribosome (a ribosome is only protein and RNA)
Types of RNA
Transcription• Transcription is the process in which a
part (gene) of the DNA is copied into mRNA.
• Players• Piece of DNA• Nucleotides• Enzyme- RNA polymerase
Transcription• What happens:• RNA polymerase finds a sequence called the promoter, binds to the DNA and unzips the strands• RNA polymerase “reads” one strand of the DNA and adds the appropriate complementary RNA nucleotides• The product= a single strand of mRNA
Quick Check• 1. The three types of RNA are _______ , _______
and ______ .• 2. The process of making RNA from DNA is
called ________________.• 3. mRNA has to be made from DNA because
the DNA cannot leave the _________ and the proteins coded for by the DNA are made by the ____________ which are found in the _____________.
• 4. If the sequence of DNA is AGTAGGTCA, what is the mRNA made from it? __________________
mRNA
tRNA
rRNA
transcription
nucleus ribosom
escytoplasm
UCAUCCAGU
The Genetic Code•Proteins are continuously made by linking together amino acids.•There are 32 different amino acids.•The sequence of nitrogen bases in DNA and mRNA determine the order of amino acids in protein.•Codon= the sequence of 3 nucleotides that codes for a specific amino acid.•Anti-codon= the complementary sequence to the codon; it is found on the tRNA
Codon Chart
Quick Check• Use your amino acid chart to identify the
amino acid that goes with each codon.• 1. AUG ___________________• 2. UGA ___________________• 3. AAA ___________________• 4. GAG ___________________• 5. UCA ___________________• 6. UCC ___________________
Methionine (start)Stop
LysineGlutamat
e SerineSerine
Translation• The sequence of nucleotides in mRNA
provides the instructions to the ribosomes for putting together a protein.
• Translation- the decoding of an mRNA message into an amino acid chain (protein).
• Parts involved:•mRNA• Ribosome• tRNA• Amino acids
Translation• How it’s done:•mRNA attaches to a ribosome in the cytoplasm• The codon on the mRNA is “read” by the ribosome.• The ribosome brings in the correct anti-codon with an amino acid attached.• The anti-codon of the tRNA matches up with the codon on the mRNA.
Translation• The second codon is “read” and the ribosome brings
in the next tRNA.• A peptide bond forms between the amino acids on
the 2 tRNA’s in the ribosome.• The first tRNA loses its amino acid and it leaves the
ribosome.• The ribosome slides along continuing the process until
a STOP codon is reached.
Quick Check• Complete the remaining Quick Check in your
notes. We will go over the answers in 15 minutes.• http://www.online-stopwatch.com/countdown-time
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