1. DNA

2. Deoxyribonucleic Acid
DNA is found:
In the nucleus
In mitochondria and chloroplasts
Functions of DNA: Control functions of cell by controlling protein production
Pass on hereditary information to the next generation

4. General Structure of DNA
Polymer, with many repeating units called nucleotides
Subunits:
a five carbon sugar
Deoxyribose
a phosphate group
a nitrogenous base
Adenine
Thymine
Guanine
Cytosine
(guanine, cytosine, adenine thymine)
(Deoxyribose)

5. General Structure of DNA
Nucleotides form long chains between the phosphate groups and the #3 carbon of the sugar molecule
This is called the backbone

6. The bases pair up and are held together with hydrogen bonds:
Structure of DNA
The bases pair up and are held together with hydrogen bonds:
G (guanine) always pairs with C (cytosine)
A (adenine) always pairs with T (thymine)

7. G always binds to C A always binds to TP D P A T D P A T D P D G C C G

8. A and T as well as C and G are called complementary base pairs
Humans have about 3 billion (that is 3,000,000,000) base pairs

9. Structure of DNA
Two polymer chains are connected by weak hydrogen bonds and are twisted into a double helix

11. DNA Replication Why? To repair damage and grow, new cells are made.
The Cell copies its own DNA
Why?
To repair damage and grow, new cells are made.
Each new cell needs to have a complete DNA record

12. DNA Replication Basic Steps of Replication: Unwinding –
DNA strands uncoil and separate
Synthesis –
complementary sequence of nucleotides are made along each original strand

13. P D P G C A T A D P T D P D G C
unwinding

14. Complementary base pairingD A T G C D P G C A T D T P D A P
Complementary base pairing

15. Complementary base pairing
New strands P D A T G C D P G C A T P D A T G C D P G C A T
Complementary base pairing

16. This is called semi-conservative replication
DNA Replication
Each new DNA contains one of the strands from the original DNA and a completely new strand
This is called semi-conservative replication

18. DNA Replication: The Details
Unwinding and separating
occurs at more than one place along the molecule
forms replication bubbles and replication forks
speeds the process – replicates multiple areas at the same time
Helicase – Enzyme that unwinds and separates DNA

19. DNA Replication: The Details
Synthesizing New Strands
RNA Primase adds a starter strip to the DNA
DNA polymerase adds a new nucleotide to the new strand at the #3 carbon

20. DNA Replication: The Details
DNA is replicated continuously in one direction and discontinuously in the other
The short strips are called Okazaki fragments
DNA polymerase then replaces the RNA bases on the primer strips with DNA bases
The enzyme Ligase joins the ends of the sections

21. Two molecules of DNA are created through replication
DNA Replication: The Details
Two molecules of DNA are created through replication

22. http://www. fed. cuhk. edu

23. From DNA to Protein Protein synthesis:
Occurs in the cytoplasm at the ribosomes
Creates polymers from amino acids by dehydration synthesis
Is directed by DNA in the nucleus
Requires RNA – mRNA and tRNA
Involves two main steps – Transcription and Translation

24. RNA Structure Nucleotide
Sugar – Ribose
Phosphate group
Nitrogenous Bases
Adenine, Guanine, Cytosine, Uracil
Single stranded - does not form a double helix

25. (Uracil instead of Thymine)
RNA Structure
DNA
RNA
Double stranded
Sugar = deoxyribose
Bases = A, T, C, G
Single stranded
Sugar = ribose
Bases = A, U, C, G
(Uracil instead of Thymine)

26. RNA Structure Types of RNA:
1) messenger RNA (mRNA): formed during transcription transports code for protein to cytoplasm 
transfer RNA (tRNA): carries amino acids binds to mRNA during translation, forming protein
ribosomal RNA (rRNA): comprised of 2 subunits holds the tRNA and mRNA during translation

27. Protein Synthesis Transcription: Translation:
Cell makes RNA code for amino acid sequences
Occurs in nucleus
Translation:
Cell constructs protein molecule using RNA
Occurs in the cytoplasm

28. Transcription DNA  mRNA DNA Unwinds
RNA base pairs are added to one side of the DNA
Pairs: C-G T-A A-U
The new RNA strand is called messenger RNA (mRNA)

29. Transcription RNA Processing:
DNA has spacers between its information areas
The spacers are called introns
The information areas are called exons
exon
intron
exon
intron
exon

30. Transcription - RNA Processing
RNA is capped on both ends –(modified guanine on one end - a string of adenosines called poly-A on the other)
The introns are removed
The exons are spliced together
Ready to move to the Ribosomes!

31. Translation mRNA has the coded informationP A R
mRNA has the coded information
A sequence of three bases (codon) codes for a specific amino acid
Codon P U R P R G C
mRNA

32. Translation
The codons must be translated into the proper amino acid (Don’t worry – they made a chart.)

33. Translation tRNA (transfer RNA):
amino acid carriers – brings amino acids to ribosomes one by one
anti-codon – complementary bases on tRNA that pair to mRNA codon
The anticodon fits the codon of the mRNA

34. Translation Ribosomes are made up of one large and one small subunit
Sub Units
Ribosomes are made up of one large and one small subunit
mRNA
The mRNA binds where the subunits meet

35. Translation
tRNA molecules bring amino acids to the ribosome following the order of the codons of the mRNA
Next amino acid
Each amino acid is added to the growing polymer by dehydration synthesis

36. Ribosomes can form an assembly line and follow each other down the mRNA strand, starting another protein before the first one is finished.

37. Translation
Strings of polypeptides come streaming out of the ribosome units
When the protein is complete, the mRNA and ribosome separate

38. Errors in decoding cause mutations that can be passed along to the next generation
Protein Synthesis:
A difference of one amino acid changes the shape of normal hemoglobin and causes sickle cell anemia

40. Translation Recap

41. What you need to know:
Characteristics of DNA
Characteristics of RNA
Know the complementary base pairs for DNA and RNA
What is replication, when does it occur (or why is it important)?
Be able to describe the replication process
Be able to describe the protein synthesis process. Know the two steps and where each step takes place.
Know the difference between mRNA, tRNA and rRNA and how each one is used in protein synthesis.