1. Unit 3: Heredity: Inheritance and Variation of Traits
Part 1 Notes

2. DNA Structure
Polymer (Nucleic Acids) made of many nucleotides (the monomer)
Consist of a five-carbon sugar, a phosphate group, and a nitrogenous base

3. DNA Base Pairing Rules Adenine pairs with thymine
Guanine pairs with cytosine
Write the complementary strand:
ACGTCC
TGCAGG

4. Central Dogma
DNARNAProtein

5. What is RNA? Ribonucleic Acid Contains the sugar ribose
Usually is single stranded
Four bases:
Adenine
Uracil (No thymine, which means Adenine pairs with Uracil)
Cytosine
Guanine

6. RNA Base Pairing Rules Adenine pairs with Uracil
Guanine pairs with Cytosine

8. RNA Messenger RNA (mRNA)
RNA nucleotides that are formed complementary to one strand of DNA and carries that information from the nucleus to the ribosomes
Ribosomal RNA (rRNA)
Associates with proteins to form ribosomes in the cytoplasm
Transfer RNA (tRNA)
Smaller segments of RNA nucleotides that transport amino acids to the ribosome

9. RNA Comparison

10. Protein Synthesis Composed of two parts Creates proteins Transcription
DNARNA
Translation
RNAProtein
Creates proteins
Long chains of amino acids held together by peptide bonds

11. Transcription
Through transcription, the DNA code is transferred to mRNA in the nucleus
DNA is unzipped in the nucleus and RNA polymerase binds to a specific section where an mRNA will be synthesized
A  U
T  A
G C
C  G

12. RNA Processing
The code on the DNA is interrupted periodically by sequences that are not in the final mRNA
Intervening sequences are called introns
Remaining pieces of DNA that serve as the coding sequences are called exons

13. The Code
Experiments during the 1960s demonstrated that the DNA code was a three-base code
The three-base code in DNA or mRNA is called a codon
Ex: ACG or UGC

14. Translation
In translation, tRNA molecules act as the interpreters of the mRNA codon sequence; bring the amino acids to the ribosome
At the middle of the folded strand, there is a three-base coding sequence called the anticodon
Each anticodon is complementary to a codon on the mRNA

15. Translation A  U U  A G C C  G
Use the table to determine the amino acid based on the codons (three bases on the mRNA strand)
Many amino acids form a protein
During translation, if you get a stop codon, you no longer need to continue translation

17. One Gene—One Enzyme Hypothesis
The Beadle and Tatum experiment showed that one gene codes for one enzyme. We now know that one gene codes for one polypeptide

18. Let’s Practice!

19. Translate the mRNA to Amino Acids using your chart
mRNA: AUG AGC CCC GCG UAG GUU CUC Amino Acids: Met (Start) Ser Pro Ala Stop mRNA: AUG CUA GCU AUC GAU CGA UCG AA: Met (Start) Leu Ala lle Asp Arg Ser mRNA: AUG UGC AUA GAA CCG AUC GAU AA: Met (Start) Cys lle Glu Pro lle Asp

20. Translate your mRNA strand to Amino Acids and determine the anticodon (tRNA)
mRNA: AUGAGCCCCGCGUAGGUUCUC
Amino Acids: Met (Start) Ser Pro Ala Stop
tRNA: UAC UCG GGG CGC AUC CAA GAG
mRNA: AUG CUA GCU AUC GAU CGA UCG
AA: Met (Start) Leu Ala lle Asp Arg Ser
tRNA: UAC GAU CGA UAG CUA GCU AGC
mRNA: AUG UGC AUA GAA CCG AUC GAU
AA: Met (Start) Cys lle Glu Pro lle Asp
tRNA: UAC ACG UAU CUU GGC UAG CUA

21. Mutations
A permanent change that occurs in a cell’s DNA is called a mutation
Types of gene mutations
Point mutation or substitution
missense, silent and nonsense
Insertion
causes frameshift
Deletion

22. Mutations Types of chromosome mutations Deletion Duplication Inversion
Translocation

23. Gene Mutations

24. Gene Mutations

25. Chromosome Mutations

27. Causes of Mutation Can occur spontaneously
Chemicals and radiation also can damage DNA
High-energy forms of radiation, such as X rays and gamma rays, are highly mutagenic

28. Body-Cell vs. Sex-Cell Mutation
Somatic cell mutations (body cells) are not passed on to the next generation
Mutations that occur in sex cells (gametes-sperm and egg) are passed on to the organism’s offspring and will be present in every cell of the offspring