1. Ch 10: How Proteins Are Made

2. Investigate! Death Cap Mushrooms
Row 1
Who? Genus species name
What? Why are these mushrooms called “death cap”?
Row 2
Where? Where can this mushroom be found? In what areas of the US and world does it live?
Why? Why is it poisonous? What does it do?
Row 3
Identification? – What does this mushroom look like?
Symptoms and treatment?
Row 4
January 2007 poisonings Santa Cruz?
What parts of the body are most impacted – why?
GROUP SUMMARY

3. How Proteins Are Made

4. Protein synthesis

5. 10.1: From genes to proteins
Traits are determined by proteins that are both built according to instructions coded in DNA.
Proteins have many functions:
Act as enzymes
Cell membrane channels etc
Proteins are not made directly from DNA – are made from RNA

8. RNA: Ribonucleic Acid
gets its name from the sugar group in the molecule's backbone - ribose.
Is a nucleic acid
- a molecule made of nucleotides linked together

9. DNA vs RNA DNA RNA Double stranded Sugar deoxyribose Bases A, T, C, G
Single stranded
Sugar ribose
Bases A, U, C, G
Has Uracil instead of Thymine
U pairs with A

10. Ribose sugar contains
one more Oxygen
atom than deoxyribose
sugar.
RNA has U (Urasil)
DNA has T (Thymine)
RNA single strand
DNA double strand

11. RNA Base Pairs

12. The RNA is then “deciphered” during translation to make a protein.
The instructions for building a protein are found in a gene and are rewritten to a molecule of RNA during transcription
The RNA is then “deciphered” during translation to make a protein.
See Figure 1 . P. 208

13. Gene expression or protein synthesis – is the entire process by which proteins are made based on information encoded in the DNA.
Transcription- Instructions for making a protein, “rewritten” from DNA to RNA
Translation- cell uses 2 types of RNA to read instructions and put together amino acids to make a protein

14. Transfer of Information from DNA to RNA

15. Step 1: RNA polymerase binds to the gene’s promoter.
Figure 2 p. 209 TRANSCRIPTION
Step 1: RNA polymerase binds to the gene’s promoter.
- promoter- a specific sequence that acts as a “start” signal for transcription.

16. -Follows base pairing rules
Step 2: RNA polymerase unwinds and separates the two strands of the double helix, exposing the DNA nucleotides on each strand.
Step 3: RNA polymerase adds complimentary RNA nucleotides as it “reads” the gene.
-Follows base pairing rules
A=U, C=G
- eventually reaches a “stop” signal in the DNA.
- in eukaryotes: is a sequence of bases
- in prokaryotes: is the end of a set of genes

17. Transcription – Key points
RNA is made from DNA.
As the RNA polymerase adds nucleotides they are attached with covalent bonds.
Behind the RNA polymerase, the two strands of DNA will close up by forming hydrogen bonds and reforming the double helix shape
Many identical RNA molecules are made simultaneously from a single gene.
In prokaryotes – occurs in cytoplasm
In eukaryotes – occurs in nucleus

18. Transcription vs DNA replication
RNA polymerase
RNA nucleotides linked
An RNA molecule is formed
Only one part of strand is used as a template
DNA Replication
DNA polymerase
DNA nucleotides are linked
A DNA molecule is made
Both DNA strands serve as templates

19. 3 types of RNA tRNA (transfer RNA) mRNA (messenger RNA)
3 types of RNA are made during transcription, depending on the gene being expressed.
tRNA (transfer RNA)
mRNA (messenger RNA)
rRNA (ribosomal RNA)

20. Messenger RNA (mRNA)
form of RNA that carries the instructions for making a protein from a gene and delivers it to the site of translation.
RNA instructions are written as a series of 3-nucleotide sequences on the mRNA called codons.

21. Each codon along the mRNA strand corresponds to an amino acid or can signal a start or stop
Genetic Code
See Figure 4 p. 211
The genetic code (codons) used by most organisms to translate mRNA is nearly universal.

22. EX: UCUGUA
UCU = Serine
GUA Valine

23. Decoding DNA - Turn to page 211
The DNA code is
TACAACGTA
The MRNA code will be
TACAACGTA (DNA CODE)
AUGUUGCAU
The amino acid sequence will be
AUG UUG CAU break into 3 letter codons
AUG = start
UUG = Leucine
CAU = Histidine

24. Translation: putting together amino acids to make proteins
Translation takes place in the cytoplasm.
tRNA and ribosomes help in the synthesis of proteins.
tRNA (trasnfer RNA)– single strands of RNA that temporarily carry a a specific amino acid on one end.
Anticodon: 3-nucleotide sequence on a tRNA that is complimentary to an mRNA codon
rRNA (ribosomal RNA) –part of the structure of ribosomes

25. Translation Figure 5 p. 212 ( Do NOT have to memorize)
Know main ideas only

26. Part 1

27. Part 2

29. Review

30. 10.2: Gene Regulation & Structure
Prokaryotic and eukaryotic cells are able to control which genes are expressed and which are not depending on the cell’s needs.

31. Prokaryotes: gene expression is regulated by operons.
Gene expression is switched OFF when REPRESSOR proteins block RNA polymerase from transcribing a gene.
Eukaryotes: an enhancer must be activated for a eukaryotic gene to be expressed. Transcription factors initiate transcription by binding to enhancers and to RNA polymerases.

32. Introns and Exons
Many eukaryotic genes are interrupted by segments of DNA that do not code for proteins
Introns: long segment of nucleotides that have No Coding Information
Exons: portion of gene that is translated into proteins
After transcription, the introns are cut out, and the exons are joined.
The exons are then translated.

33. Working copy of gene
Enzymes cut out introns & keep exons
Molecule used to make protein

34. Mutations Changes in DNA.
Gene alterations are a mutation that changes a gene.
Mutations can involve a change in a single molecule or an entire gene.
Remember mutations from Ch 6?
Rearrangement (translocation)
Alteration (deletion, insertion, inversion, duplication)

35. Mini quiz
The making of a RNA based on the sequence of nucleotides in DNA is called
DNA replication
Translation
Transcription
Gene regulation

36. The making of proteins from the information carried from the mRNA is called
DNA replication
Translation
Transcription
Gene regulation

37. A change in the genetic code is called
Mutation
Operon
Codon
Operator

38. Mutations that change one nucleotide in a gene are called
Operon mutation
Codon mutation
Repressor protein
Point mutation

39. Anticodons are found on the ______ molecule.
mRNA
DNA
rRNA
tRNA

40. Unlike DNA, RNA contains
The sugar deoxyribose
The nitrogen base uracil
A phosphate group
nucleotides

41. Transcription and Translation video 4 min