Notes: Chapter 13: RNA & Protein Synthesis
description
Transcript of Notes: Chapter 13: RNA & Protein Synthesis
![Page 1: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/1.jpg)
Notes: Chapter 13: RNA & Protein Synthesis
• 2 steps:– Transcription (DNA
is made into mRNA in the nucleus)
– Translation (mRNA is made into proteins by ribosomes in
the cytoplasm or ER)
![Page 2: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/2.jpg)
RNA Structure• Similar to DNA, but with some
important differences:– Single strand (DNA double)– Ribose is the sugar (not deoxyribose like
DNA)– Uracil matches adenine (instead of
thymine like DNA)– Shorter than DNA
![Page 3: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/3.jpg)
RNA Functions• Three different types
of RNA:–mRNA (messenger)
used as template to make proteins
– rRNA (ribosomal) makes up ribosomes
– tRNA (transfer) matches amino acids
to mRNA to help make proteins
![Page 4: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/4.jpg)
Transcription• transcribe (to copy)• happens in the nucleus• DNA’s code is copied
onto RNA– 1. RNA polymerase binds
to beginning of a gene (promoter) and unwinds DNA
– 2. Complementary bases copied from 1 side of DNA
– 3. Termination (end) signal reached, mRNA and DNA free
• http://www.youtube.com/watch?v=ztPkv7wc3yU
![Page 5: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/5.jpg)
Translation• RNA’s “language” is translated into
amino acids (which will become a protein)• RNA’s language is set of three nucleotides
called a codon…3 nitrogen bases in a row• Codons match with specific amino acids to
make polypeptide chain (which will be modified to make a protein)
• 20 amino acids all together• More than 20 codons, so some amino
acids have more than one codon. There is also 1 start codon and 3 stop codons.
![Page 6: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/6.jpg)
Translation
![Page 7: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/7.jpg)
Translation1. ribosome attaches to mRNA2. tRNA with amino acid matches mRNA codon
(area on tRNA that matches called an anticodon). This process is called initiation. 2 tRNAs can fit at one time.
3. ribosome moves down and matches next codon. 4. Amino acids form peptide bond and protein
continues to grow, 1 amino acid at a time. This process is called elongation.
5. ribosome reaches stop codon, mRNA, tRNAs, protein and ribosome released. This process is called termination.
The product is called a polypeptide. Modified in ER or Golgi to make a protein.
![Page 8: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/8.jpg)
Translation
• Each mRNA can be used more than once, by more than 1 ribosome at a time, so many proteins can be translated from 1 transcribed piece mRNA.
• http://www.youtube.com/watch?v=-zb6r1MMTkc
![Page 9: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/9.jpg)
Gene expression• The whole
process of going from DNA to RNA to a protein that runs a cell process is called gene
expression
![Page 10: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/10.jpg)
Gene expression• After the polypeptide
chain is made, it is often modified in the ER or
Golgi Apparatus• The finished product
is a protein and it has a three dimensional shape that decides its
function
![Page 11: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/11.jpg)
Mutations• Certain things can cause changes to the
DNA/RNA code. They are called mutagens and cause mutations.
• e.g. UV light, smoking, X rays, exposure to chemicals
• Not all are bad…some allow for adaptation and evolution
![Page 12: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/12.jpg)
Point mutations• Occur to one base or a small number
of bases on DNA or RNA• Most are harmless, as many codons
often code for the same amino acid.• 3 kinds:– Substitution: one base is used instead of
another– Insertion*: one base is added– Deletion*: one base is left out– * lead to a frameshift mutation, where
everything is “off by one” base.
![Page 13: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/13.jpg)
Point mutations
![Page 14: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/14.jpg)
Chromosomal mutations• Change to a gene, series of genes or
an entire chromosome• These are often helpful in plants, e.g.
polyploidy…chromosomes do not separate during meiosis. Leads to seedless fruit that are bigger
• In animals, they are often harmful or even lethal. You might be researching one disorder in the next unit on genetics…
![Page 15: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/15.jpg)
Chromosomal mutations• Deletion: one or more genes
is/are left out when copied• Duplication: one or more genes
is/are copied more than once• Inversion: one or more genes
is/are copied backwards• Translocation: one or more
genes is/are moved from 1 chromosome to another
• Nondisjunction (not shown): homologs fail to separate during meiosis
![Page 16: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/16.jpg)
![Page 17: Notes: Chapter 13: RNA & Protein Synthesis](https://reader035.fdocuments.net/reader035/viewer/2022062315/5681642e550346895dd5f797/html5/thumbnails/17.jpg)
Transcription