1. DNA and Protein Synthesis
What are proteins?
What’s the big deal anyway?

2. DNA Replication
Before a cell can divide by mitosis or meiosis, it must first make a copy of its chromosomes.
The DNA in the chromosomes is copied in a process called DNA replication.
Without DNA replication, new cells would have only half the DNA of their parents.
DNA Replication

3. The blue strands represent the original DNA strands.
DNA Replication
The blue strands represent the original DNA strands.
The red strands are the new, synthesized strands.
DNA
Replication
Replication
DNA Replication

4. DNA Replication https://www.youtube.com/watch?v=zdDkiRw1PdU

5. Why are proteins important? List as many reasons as you can.

6. Genes and Proteins
The sequence of nucleotides in DNA contain information that is put to work through the production of proteins.
Proteins fold into complex, three-dimensional shapes to become key cell structures and regulators of cell functions.
Genes and Proteins

7. Genes and Proteins
Some proteins become important structures, such as the filaments in muscle tissue.
Other proteins, such as enzymes, control chemical reactions that perform key life functions— breaking down glucose molecules in cellular respiration, digesting food, or making spindle fibers during mitosis.
Genes and Proteins

8. In fact, enzymes control all the chemical reactions of an organism.
Genes and Proteins
In fact, enzymes control all the chemical reactions of an organism.
Thus, by encoding the instructions for making proteins, DNA controls cells.
Genes and Proteins

9. Remember, proteins are polymers of amino acids.
Genes and Proteins
Remember, proteins are polymers of amino acids.
The sequence of nucleotides in each gene contains information for assembling the string of amino acids that make up a single protein.
Genes and Proteins

10. How does DNA tell the cell which protein to make? RNA
RNA is a little different than DNA:
RNA has the sugar ribose instead of deoxyribose.
RNA is only a single strand.
RNA contains the nitrogenous base uracil instead of thymine.
* Uracil bonds with adenine.

12. RNA is the BLUEPRINT Architect DNA Blueprint RNA Workers Ribosomes
Use bricks to Use amino acids to
build buildings build proteins

13. 3 types of RNA
1. mRNA – messenger RNA- carries instructions to build protein to the ribosome.
2. rRNA – ribosomal RNA – what the ribosome is made of. Reads the instructions
3. tRNA – transfer RNA- picks up the amino acids and brings them to the rRNA to build the protein.

14. 2 Events of Protein Synthesis
TRANSCRIPTION – The instructions from DNA are copied (transcribed)into a mRNA molecule which carries the instructions from the nucleus to the ribosome. (occurs in nucleus)
TRANSLATION – The instructions are read (translated) by the ribosome. A tRNA molecule is sent to pick up and deliver the correct amino acid to the ribosome so it can build the protein(occurs at ribosome)

15. Transcription:
An enzyme, helicase… “unzips” part of the double helix.

18. Transcription: 2. There is a “start” and “stop” sequence
in the DNA to tell the mRNA where to start and stop.
UGA = stop
AUG = start UAA = stop
UAG = stop

19. Transcription:
3. RNA nucleotides pair up to DNA nitrogenous bases and…bond in a chain

20. Transcription:
The mRNA travels to the ribosome, where the protein will be assembled.
(Note: DNA never leaves the nucleus!)

21. Transcription
The main difference between transcription and DNA replication is that transcription results in the formation of one single-stranded RNA molecule rather than a double-stranded DNA molecule.
Transcription

22. Transcription
DNA strand
RNA strand
Transcription

24. In your own words explain transcription

25. Translation takes place at the ribosomes in the cytoplasm.
The process of converting the information in a sequence of nitrogenous bases in mRNA into a sequence of amino acids in protein is known as translation.
Translation takes place at the ribosomes in the cytoplasm.
Translation

26. Translation
In prokaryotic cells, which have no nucleus, the mRNA is made in the cytoplasm.
In eukaryotic cells, mRNA is made in the nucleus and travels to the cytoplasm.
Translation

27. TRANSLATION 5. When mRNA binds to the ribosome,…
production of a protein begins

28. A sequence of three nitrogenous bases makes a codon.
Each codon is a code for one of 20 amino
acids!
There are 64 different combinations of three letters, so there are 64 different codons. Some amino acids have more than one code.

29. TRANSLATION
6. The mRNA code is read and converted into a specific amino acid sequence in a protein chain.
7. This process continues until…
a functional protein is made.

31. Amino Acid Codon Chart

32. In your own words explain translation

33. Replication = copying DNA Transcription = using DNA to make RNA
Summary
Replication = copying DNA
Transcription = using DNA to make RNA
Translation = using RNA to make protein
The Role of tRNA