1. DNA

3. DNA is… DNA is… –Your genetic code –What tells your cells which proteins to make and when to make them –The code that makes up your genes –Located on chromosomes (chromosomes are long strands of DNA) –What makes you who you are –What makes you different from the 6 billion other people on the planet –What enables your cells to have different forms and perform different functions –Unique to you

4. DNA is a nucleic acid (organic molecule) DNA is a nucleic acid (organic molecule) DNA (as with all nucleic acids) are made up of repeating subunits called nucleotides DNA (as with all nucleic acids) are made up of repeating subunits called nucleotides Each DNA molecule is made up of 2 long chains of nucleotides Each DNA molecule is made up of 2 long chains of nucleotides Deoxyribonucleic Acid Deoxyribonucleic Acid

5. DNA Structure A DNA nucleotide has 3 parts A DNA nucleotide has 3 parts –A sugar molecule called deoxyribose –A phosphate group –A nitrogen-containing base The deoxyribose sugar and the phosphate group are identical in all DNA nucleotides The deoxyribose sugar and the phosphate group are identical in all DNA nucleotides Nitrogen base may be any one of four different kinds Nitrogen base may be any one of four different kinds

6. Nitrogen bases The four nitrogen bases found in DNA nucleotides are The four nitrogen bases found in DNA nucleotides are –Adenine: A –Guanine: G –Cytosine: C –Thymine: T

7. Purines: 2 rings of Carbon and Nitrogen Purines: 2 rings of Carbon and Nitrogen –Adenine –Guanine Pyrimidine: 1 ring of Carbon and Nitrogen Pyrimidine: 1 ring of Carbon and Nitrogen –Cytosine –Thymine

8. Double Helix James Watson and Frances Crick James Watson and Frances Crick 2 nucleotide chains wrap around each other to form a double spiral: a double helix 2 nucleotide chains wrap around each other to form a double spiral: a double helix

9. Complementary Base Pairing Cytosine bonds with Guanine Cytosine bonds with Guanine –C = G Adenine bonds with Thymine Adenine bonds with Thymine –A = T A A A T C T G A T G C T A

10. Replication of DNA DNA must replicate in order to pass exact copies of its DNA to daughter cells DNA must replicate in order to pass exact copies of its DNA to daughter cells

11. Connected to each other with Hydrogen Bonds Connected to each other with Hydrogen Bonds Cytosine and Guanine form 3 H bonds Cytosine and Guanine form 3 H bonds Adenine and Thymine form 2 H bonds Adenine and Thymine form 2 H bonds One nucleotide chain in DNA molecule is an exact complement of the nucleotide sequence of another chain One nucleotide chain in DNA molecule is an exact complement of the nucleotide sequence of another chain

12. DNA Replication Replication: the process of copying DNA in a cell Replication: the process of copying DNA in a cell The 2 nucleotide chains separate by unwinding The 2 nucleotide chains separate by unwinding Each chain serves as a template for a new nucleotide chain Each chain serves as a template for a new nucleotide chain http://www.dnalc.org/resources/3d/15- translation-basic.html http://www.dnalc.org/resources/3d/15- translation-basic.html

13. 1 st step: 1 st step: –Separate the 2 nucleotide chains The point at which the 2 chains separate is called the replication fork (think: a fork in a road is when a road separates) The point at which the 2 chains separate is called the replication fork (think: a fork in a road is when a road separates)

14. The nucleotide chains are separated by enzymes called helicases The nucleotide chains are separated by enzymes called helicases Helicase enzymes move along the DNA molecules, breaking Hydrogen bonds between complementary bases, and the chains separate. Helicase enzymes move along the DNA molecules, breaking Hydrogen bonds between complementary bases, and the chains separate.

15. DNA polymerase: enzymes that bind to the separate chains of DNA for copying DNA polymerase: enzymes that bind to the separate chains of DNA for copying As polymerase moves along the chains, new chains are assembled using nucleotides in the surrounding medium that are complementary to the existing DNA chains. As polymerase moves along the chains, new chains are assembled using nucleotides in the surrounding medium that are complementary to the existing DNA chains. They are joined to the original nucleotide chain by H bonds They are joined to the original nucleotide chain by H bonds

16. This is why DNA has complimentary base pairs: for accurate DNA replication This is why DNA has complimentary base pairs: for accurate DNA replication OriginalChain 1Chain 2 OriginalChain 1Chain 2 A-TA-T- A-TA-T- G-CG-C- G-CG-C- T-AT-A- T-AT-A- G-CG-C- G-CG-C- C-GC-G- C-GC-G- A-TA-T- A-TA-T-

17. DNA polymerase attaches at many different spots on the DNA chains, it does not begin at one end and end at the other. DNA polymerase attaches at many different spots on the DNA chains, it does not begin at one end and end at the other. This is for faster DNA replication This is for faster DNA replication In fruit flies replication is initiated simultaneously at about 6,000 sites In fruit flies replication is initiated simultaneously at about 6,000 sites

18. Mutations Replication occurs with a high degree of accuracy. Replication occurs with a high degree of accuracy. A change in the nucleotide sequence at even one location can have serious effects A change in the nucleotide sequence at even one location can have serious effects Proofreading and repair keeps error to 1 in a billion nucleotides Proofreading and repair keeps error to 1 in a billion nucleotides Enzymes proofread and repair Enzymes proofread and repair Errors may still occur Errors may still occur Errors can also be caused by a variety of agents, including chemicals and UV exposure Errors can also be caused by a variety of agents, including chemicals and UV exposure

19. RNA Like DNA, RNA is a nucleic acid, but differs in its structure Like DNA, RNA is a nucleic acid, but differs in its structure Sugar molecule is ribose (in DNA it is Deoxyribose) Sugar molecule is ribose (in DNA it is Deoxyribose) Instead of thymine, RNA contains the nitrogen base uracil Instead of thymine, RNA contains the nitrogen base uracil Uracil pairs with adenine Uracil pairs with adenine One strand One strand

20. 3 different types of RNA Messenger RNA: carries genetic information from the DNA in the nucleus to the cytosol Messenger RNA: carries genetic information from the DNA in the nucleus to the cytosol Transfer RNA: binds to specific amino acids to carry them to ribosomes. NITROGEN BASES ARE COMPLIMENTARY TO NITROGEN BASES ON mRNA Transfer RNA: binds to specific amino acids to carry them to ribosomes. NITROGEN BASES ARE COMPLIMENTARY TO NITROGEN BASES ON mRNA Ribosomal RNA: joined by proteins. Makes up the ribosomes where proteins are made Ribosomal RNA: joined by proteins. Makes up the ribosomes where proteins are made

21. Transcription: genetic information is copied from DNA to RNA Transcription: genetic information is copied from DNA to RNA RNA polymerase: synthesizes RNA copies of specific sequences of DNA RNA polymerase: synthesizes RNA copies of specific sequences of DNA RNA polymerase binds to specific spots of DNA called promoters RNA polymerase binds to specific spots of DNA called promoters When polymerase binds to promoters, the DNA molecule in that region separates When polymerase binds to promoters, the DNA molecule in that region separates Only one of the separated DNA chains, called the template, is used for transcription Only one of the separated DNA chains, called the template, is used for transcription

22. RNA polymerase adds complementary RNA nucleotides to the newly forming RNA molecule RNA polymerase adds complementary RNA nucleotides to the newly forming RNA molecule Transcription continues until the RNA polymerase reaches a DNA region called the termination signal Transcription continues until the RNA polymerase reaches a DNA region called the termination signal

23. Translation- translating RNA codons into amino acids (which will build a protein) Translation- translating RNA codons into amino acids (which will build a protein) DNA  RNA  amino acids  proteins DNA  RNA  amino acids  proteins Codons- segments of RNA that contains 3 nucleotides (nitrogen bases). Codes for amino acids. Codons- segments of RNA that contains 3 nucleotides (nitrogen bases). Codes for amino acids.

24. Mutations Substitution (Point mutation)- a mutation that exchanges one base for another (switching an A to a G, for example) Substitution (Point mutation)- a mutation that exchanges one base for another (switching an A to a G, for example)

25. Insertion- mutations in which extra base pairs are inserted into a new place in the DNA Insertion- mutations in which extra base pairs are inserted into a new place in the DNA

26. Deletion- mutations in which a section of DNA is lost, or deleted Deletion- mutations in which a section of DNA is lost, or deleted

27. Frameshift- since protein coding DNA is divided into codons, each of which code for a protein, insertions and deletions can alter a gene so that its message no longer codes for the correct amino acids and the correct protein is not produced. Frameshift- since protein coding DNA is divided into codons, each of which code for a protein, insertions and deletions can alter a gene so that its message no longer codes for the correct amino acids and the correct protein is not produced.