1. The Components and Structure of DNA
Structure: Deoxyribonucleic acid
Found in all living things

2. Double Helix
DNA strands were twisted around each other like the coils of a spring, a shape known as a double helix.
A double helix looks like a twisted ladder or a spiral staircase.

3. How could DNA, or any other molecule, do the three critical things that genes were known for? :
Genes had to carry information from one generation to the next.
Put the information to work by determining the heritable characteristics of organisms.
Be easily copied, because all of the cell’s genetic information is replicated every time a cell divides.

4. DNA is a long molecule made up of units called nucleotides.
Each nucleotide is made up of three basic components:
5-Carbon sugar called deoxyribose
Phosphate group
Nitrogenous base
Nucleotides

5. Bonds in DNA
Nucleotides are held together by covalent bonds
2. Hydrogen Bonds: 2 bases make up the “rungs” of the double helix and this is the bond they are held together by. S P B
Covalent bonds

6. 4 Kinds of Nitrogenous Bases
Purines: made of 2 carbon rings
Adenine (A) & Guanine (G)
Pyrimidines: made of 1 carbon ring
Cytosine ( C) & Thymine (T)

7. Base Pairing Rules Guanine only bonds with Cytosine (G) = (C)
Adenine only bonds to Thymine
(A) = (T)
Guanine only bonds with Cytosine
(G) = (C)

8. The function of DNA is to store and transmit genetic information that tells cells which proteins to make and when to make them.
Functions

9. Matching 2 sides of DNA are complementary to one another.
If you know one side of the helix you can figure out the other side.
TACGTCGTA
ATGCAGCAT

10. Replicate DNA
DNA “unzips” at one end by breaking up the hydrogen bonds between bases
Free floating nucleotides pair with the open bases on each side of the double helix.

11. 3. Continues until DNA double helix “unzips” and 2 double helixes are made. Each double helix has one new strand and one old strand. Both are identical to each other and to the original.

12. RNA Ribonucleic acid Single strand no double helix
Made of repeating monomers called nucleotides

13. Nucleotides Each nucleotide consists of 3 parts:
5-Carbon sugar called ribose
Phosphate group
Nitrogenous base
Nucleotides

14. 4 Types of Bases Purines: Adenine (A) & Guanine (G)
Pryimidines: Cytosine ( C) & Uracil (U)

15. Base Pairing Rules In RNA Adenine only bonds to Uracil
(A) = (U)
Guanine only bonds with Cytosine
(G) = (C)

16. Messenger RNA (mRNA) 3 Types of RNA
3 nucleotide bases on RNA are called a codon
Holds genetic info from a DNA strand and translated into protein.

17. Transfer RNA (tRNA) 3 Types of RNA
Each tRNA bonds only to specific amino acids
Has location called the anticodon, a 3 nucleotide base sequence.

18. Ribosomal RNA (rRNA) 3 Types of RNA Makes up a ribosome
“reads” the mRNA strand

19. For a cell to make a protein, the information from a gene is copied, base by base, from DNA into new strands of mRNA. The mRNA travels out of the nucleus into the cytoplasm, to ribosomes. mRNA directs assembly of amino acids that fold into completed protein molecules.

20. Genetic Code Proteins are made of amino acids 20 known amino acids
Sequence of nucleotides (bases) on DNA determines what amino acids are put into proteins.

21. How many nucleotides (bases) are used to code for each amino acid? 3
Read 1 base=at most only 4 combinations
Read 2 bases=at most only 16 combinations
Read 3 base=at most only 64 combinations

22. 3 bases must be read at one time to code for 1 amino acid
A 3 base sequence found on an mRNA is called a codon
60 combinations of 3 bases code just for amino acids

23. 1 combination codes for a start as well as an amino acid
1 combination codes for a start as well as an amino acid. (AUG-Methionine). Methionine is the only amino acid specified by just 1 codon, AUG.
3 combinations code for a stop codon. The stop codons are UAA, UAG, and UGA. They encode NO amino acid. The ribosome passes ad falls off the mRNA .

24. Transcription
Process where part of DNA double helix (a gene) is “read” and a strand of mRNA is created.

25. Steps
DNA double helix “unzips” down the center between the bases at a certain location of the helix.
One side of the double helix is “read” starting at a certain base and “read” to a certain base (gene)

26. 3. A complementary strand of mRNA is created.
4. DNA double helix “zips” back up.
5. Strand of mRNA leaves the nucleus.

27. Translation
Process where a mRNA strand is “read” and a protein is produced.

28. Steps
A ribosome (which is made of rRNA) attaches to the strand of mRNA at a certain spot (AUG-start codon)
Ribosome reads the first 3 bases (called a codon) on the mRNA strand.

29. 3. A tRNA that has an anticodon, that is a complement to the codon being read, attaches to the mRNA. Remember that tRNA’s have an amino acid attached to them
Ex. Codon(on mRNA)- AUG
Anticodon(on tRNA)= UAC

30. 4. The tRNA leaves the rRNA but leaves the amino acid
5. Ribosomes reads the next codon on mRNA.
6. Repeat steps 3-5 until the certain codon is read called the stop codon.

31. 7. Ribosome lets go of the mRNA strand.
8. All the amino acids that were brought by the tRNA are linked together producing a protein.
9. (Practicing)
DNA mRNA strand  Protein

32. Mutations Most are minor Many are harmful Some are lethal
Very few are helpful

33. Types of Mutations
Point Mutations- changes involving one nitrogen base
Frameshift Mutations- that Addition or Deletion of a nitrogen base, causing the gene sequence to read out of sequence

34. Types of Mutations Insertion-
Ex. ACG/TAG/GTA
ACG/TTA/GGT/A
Deletions: A piece of chromosome breaks off and is lost
Ex. ACG/TAC/GTA
ACG/TACG/TA

35. B. Base Substitution-
Ex. ACG/TAC/GTA
ACG/TAA/GTA

36. Types of Mutations II. Chromosome Mutations- Involve segments of DNA
Inversion: Reinsertion of a sequence backwards
EX.
AGCTAGCTA  AGGATCCTA

37. Types of Mutations
B. Translocation- A piece of a different chromosome is added to another
EX.
AGCTAGCTA  AGCTAGCTATCCAG