DNA (Deoxyribonucleic Acid)

1. DNA(Deoxyribonucleic Acid)

2. GHSGT Science Review • Domain 1: Cells and Heredity • DNA and protein synthesis • Ppt. 5

3. Genetic material of cells… • GENES – units of genetic material that CODES FOR A SPECIFIC TRAIT • Called NUCLEIC ACIDS • DNA is made up of repeating molecules called NUCLEOTIDES

4. Phosphate Group O O=P-O O 5 CH2 O N Nitrogenous base (A, G, C, or T) C1 C4 Sugar (deoxyribose) C3 C2 DNA Nucleotide

5. DNA had specific pairing between the nitrogen bases: • ADENINE – THYMINE • CYTOSINE - GUANINE

6. “Rungs of ladder” Nitrogenous Base (A,T,G or C) “Legs of ladder” Phosphate & Sugar Backbone DNA Double Helix

7. A or G T or C Nitrogenous Bases • PURINES 1. Adenine (A) 2. Guanine (G) • PYRIMIDINES 3. Thymine (T) 4. Cytosine (C)

8. Genetic Diversity… • Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.

9. The Code of Life… • The “code” of the chromosome is the SPECIFIC ORDER that bases occur. A T C G T A T G C G G…

10. DNA Replication • DNA must be copied • The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing: A-T, G-C • Each strand of the original DNA serves as a template for the new strand

11. Replication Quiz 1. Why is replication necessary? 2. When does replication occur? 3. Describe how replication works. • Use the complementary rule to create the complementary strand: A---? G---? C---? T---? A---? G---? A---? G---? C---? A---? G---? T---?

12. Replication Quiz 1. Why is replication necessary? So both new cells will have the correct DNA 2. When does replication occur? During interphase (S phase). 3. Describe how replication works. Enzymes unzip DNA and complementary nucleotides join each original strand. 4. Use the complementary rule to create the complementary strand: A---T G---C C---G T---A A---T G---C A---T G---C C---G A---T G---C T---A

13. …DNA controlled cell function by serving as a template for PROTEIN structure. • 3 Nucleotides = a triplet or CODON (which code for a specific AMINO ACID) • AMINO ACIDS are the building blocks of proteins.

14. DNA Transcription • DNA can “unzip” itself and RNA nucleotides match up to the DNA strand. • Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids.

15. DNA Translation • The cell uses information from “messenger” RNA to produce proteins

16. Translation start codon A U G G G C U C C A U C G G C G C A U A A mRNA codon 1 codo2 codon 3 codon 4 codon 5 codon 6 codon 7 stop codon Amino acids methionine glycine serine isoleucine glycine alanine Primary structure of a protein aa2 aa3 aa4 aa5 aa6 aa1 peptide bonds

17. Transcription/Translation Quiz • Why is transcription necessary? • Describe transcription. • Why is translation necessary? • Describe translation. • What are the main differences between DNA and RNA.

18. 1. Why is transcription necessary? Transcription makes messenger RNA (MRNA) to carry the code for proteins out of the nucleus to the ribosomes in the cytoplasm. 2. Describe transcription. RNA polymerase binds to DNA, separates the strands, then uses one strand as a template to assemble MRNA. 3. Why is translation necessary? Translation assures that the right amino acids are joined together by peptides to form the correct protein.

19. 4. Describe translation. The cell uses information from MRNA to produce proteins. 5. What are the main differences between DNA and RNA. DNA has deoxyribose, RNA has ribose; DNA has 2 strands, RNA has one strand; DNA has thymine, RNA has uracil. • Using the chart on page 303, identify the amino acids coded for by these codons: UGGCAGUGC tryptophan-glutamine-cysteine

20. LET’S REVIEW DNA… • Summarize the relationship between genes & DNA. • Describe the overall structure of the DNA molecule. • What are the 4 kinds of bases? • What is replication? • What are the two phases of protein synthesis?