DNA Structure and Technology

1. DNA Structure and Technology By: Amber Tharpe

2. DNA Structure • Monomers are nucleotides • 3 parts of a nucleotide • Phosphate group • Deoxyribose sugar • Nitrogen base • 4 different bases • Cytosine (C) - thymine (T) • Adenine (A) - Guanine (G)

3. DNA Structure • Double helix- shape of 2 chains of DNA in a twisted spiral • 2 chains held together by H-bonds between the bases

4. DNA Nucleic acid that serves as the “blueprints of life” Housed in the nucleus Determines what traits are inherited from one generation to the next Leads to the variation in all living things

5. Base Pairing Rules • A always bonds with T • C always bonds with G

6. Base Pairing Practice If one strand of DNA is ACACAC, what is the other strand? If one strand of DNA is TGAC, what is the other strand? If one strand of DNA is CTGCTA, what is the other strand?

7. Replication DNA has the ability copy itself An enzyme “unzips” the 2 strands A single DNA strand serves a template or pattern for making a new strand Free bases bind based on the base pairing rules 2 identical strands are formed

8. Replication Terms • Template strand • DNA strand that is being copied • Complimentary strand • New DNA strand that is formed by pairing nucleotides to the template strand • DNA polymerases • Enzymes that bond nucleotides together to form complimentary strands

9. Central Dogma • DNA→ RNA→ Protein • DNA- RNA is transcription • RNA- Protein is translation • In eukaryotes, replication and transcription occurs in the nucleus, while translation occurs in the cytoplasm

10. RNA Single-stranded nucleotides with U’s bonding to A’s

11. Transcription • Process of using a strand of template DNA to make a complimentary strand of RNA • RNA polymerases • Enzymes that bond nucleotides together to make a new RNA molecule

12. Transcription Practice • Transcribe a strand of DNA that is ACACAC. • If a strand of DNA is TGAC, what strand of RNA will it make? • Convert a strand of DNA that is CTGCTA to RNA.

13. 3 Types of RNA • Messenger RNA (mRNA) • Code translated to form a protein • Ribosomal RNA (rRNA) • Forms part of ribosomes to make protiens • Transfer RNA (tRNA) • Brings amino acids from the cytoplasm to make proteins • Has an anticodon on one end

14. Transcription Does not transcribe the whole DNA molecule Only transcribes the portions of DNA (gene) needed for cell function at that specific time

15. Translation • The process that converts mRNA into a polypeptide (or protein) • The code for nucleic acids is 4 nucleotides: • A,G,C, and T or U • The code for proteins 20 different amino acids • Nucleotides are like letters, while amino acids are like words

16. Codons • 3 nucleotide sequence that codes for a particular amino acid • Considered a triplet code, since 3 nucleotides are used to make each amino acid • Many amino acids are coded for by more than 1 codon • Anticodon • Set of 3 nucleotides found on tRNA that is complimentary to an mRNA codon

17. Translation Occurs in the cytoplasm mRNA is pulled through the ribosome exposing one codon at a time to pair with the complimentary tRNA The ribosome forms a peptide bond between the amino acids brought in by the tRNA This process continues as the polypeptide grows and eventually a stop codon is reached

18. Translation Practice p. 244 • If a strand of RNA is ACACAC, what amino acids does this make? • Translate a strand of RNA is UGACUC. • If a strand of DNA is CUGCUA, what amino acids does this make?

19. Mutation Change in an organism’s DNA Can occur in DNA replication or in meiosis Substitution (point mutation) One nucleotide is substituted for an incorrect one May alter an amino acid in a protein Ex: sickle cell anemia

20. Frameshift Mutation Frameshift mutation Insertion or deletion of a nucleotide in DNA Makes an abnormal protein Reading frame is shifted because DNA is read in a triplet code THE CAT ATE THE RAT Remove the first E What does the sentence say?

21. Nondisjunction When chromosomes fail to separate properly in meiosis Ex. Down Syndrome- 3 copies of chromosome 21

22. Mutagens Agents in the environment that can change DNA Ex: UV light, radiation, chemicals in tobacco products Often lead to cancer

23. Biotechnology The use of organisms or their products to improve human health or food production Types DNA Fingerprinting Genetic Engineering Genetic Screening

24. DNA Fingerprinting Gel electrophoresis Used for comparing DNA samples DNA is cut and run through the gel based on electric charge Smaller fragments move farther than large fragments The different size fragments make bands on the gel that can be compared

25. DNA Fingerprinting Uses Paternity testing Forensics Identifying dead bodies Solving crimes Compare DNA left at crime scene to suspects’ DNA

26. Genetic Engineering Genes are transferred from 1 organism to another Recombinant DNA When DNA from 2 different sources are combined Used in medicine (gene therapy) and agriculture Modify plants to grow larger, faster, and more disease resistant Use the gene for making insulin to treat diabetes

27. Cloning A normal cell is taken from the organism that is being cloned An egg cell from an organism of the same species is taken and the nucleus removed The 2 cells are fused and the embryo is placed in the uterus of a female to develop and be born