DNA & RNA

1. DNA & RNA

2. The History of DNA In 1953, Watson & Crick used the X-ray diffraction pictures made by Franklin to determine the structure of DNA & build a model of its structure.

3. What this lead to • 1959: The first human chromosome abnormality, Down Syndrome, is identified • 1969: Isolated the first gene • 1984:Jeffreys develops genetic fingerprinting • 1989: genetic screening of embryos for their gender • 1993: the first human embryos are cloned • 1994: the first genetically modified food is sold • 1995: PCR and DNA fingerprinting play a role in OJ’s trial • 1997: Dolly, the sheep, is cloned • 2002: The first cat is cloned

4. DNA: deoxyribonucleic acid, controls the production of proteins in the cell. Nucleotides The repeating subunits of DNA & RNA DNA & RNA are both polymers

5. A nucleotide has 3 parts: A phosphate group A 5 carbon sugar called deoxyribose. A nitrogen base

6. The sugar and the phosphate groups form the backbone of the DNA molecule

7. DNA is a double helix molecule

8. DNA looks like a twisted ladder. The sides of the ladder are made of sugar & phosphate.

9. The “rungs” of the ladder are bonded pairs of nitrogen bases. The bases are bonded together by weak hydrogen bonds.

10. Nitrogen bases can be one of 4 types: purines pyrimidines adenine thymine cytosine guanine uracil In RNA only!

11. In DNA... Adenine bonds with Thymine Guanine bonds with Cytosine A - T , G - C

12. The bases on one strand of the DNA molecule are the exact compliment of the bases on the other strand. Thus, they are called complimentary strands. Complimentary Strands A G T T C C A C A A G T G T

15. How DNA makes exact copies of itself DNA replication

21. Replication begins when the enzyme DNA HELICASE attaches to the DNA molecule DNA helicase unzips the DNA by breaking the hydrogen bonds between the bases.

22. The DNA is separated into 2 strands. The unpaired bases on each strand attract the unpaired complimentary bases that float around in the nucleus. They then form new hydrogen bonds.

23. Two new DNA molecules result from replication, with the EXACT same code. Each is one half of the ORIGINAL DNA double helix.

24. Replication occurs at MANY points of the DNA molecule at once. • If not, it would take 3 days for one DNA molecule to replicate. • This way, it only takes 3 minutes to replicate.

25. RNA - Ribonucleic Acid DNA contains the information to MAKE proteins but does not actually make it – RNA does….

26. Look… no T’s They are replaced by U’s U G C A U A C C A Notice… only one strand… not two like DNA – not a double helix.

27. RNA’s sugar is RIBOSE, not deoxyribose like DNA

28. RNA exists in 3 forms: tRNA rRNA mRNA

29. mRNA – MESSENGER RNA is a single strand of RNA that copies DNA information during protein synthesis. It serves as a TEMPLATE for assembling amino acid sequences to make proteins.

30. tRNA – TRANSFER RNA is a single strand of RNA that is folded back on itself like a hairpin. There are 20 forms of tRNA that correspond to each of the 20 amino acids which bind to them.

31. rRNA – RIBOSOMAL RNA, is RNA in a globular form. They are ribosomes! Total function is unknown…….

32. Protein Synthesis • Is the formation of protein using the information coded on DNA and carried out by RNA • Protein synthesis has 2 parts: transcription & translation

33. replication (nucleus) DNA Transcription (nucleus) RNA Translation (cytoplasm) mRNA code translated into amino acid sequences Proteins

34. Transcription To transcribe means to COPY or to write something down. RNA is transcribed from DNA through this process…..

35. Transcription

36. First, the enzyme RNA POLYMERASE opens up the DNA molecule. 2. Next, RNA polymerase attaches RNA bases floating around in the nucleus to the DNA bases.

37. The transcription process stops when a termination CODE is reached on the DNA molecule. • RNA is then released & the DNA closes back up……..

38. All three types of RNA are made this way. • RNA then leaves the NUCLEUS and enters the cytoplasm. • joins up with RIBOSOMES and proteins are made.

39. Codons • The GENETIC code is the system that contains information needed by cells for proper functioning. • A CODON is a group of 3 sequential mRNA bases that recognize a specific amino acid

40. Codons UCU AGA GCU GUU CUU UAA serine serine alanine valine leucine stop

41. Codons are UNIVERSAL. • Every organism has the same genetic code for proteins……… • For example, UUU is the codon for the amino acid phenylalanine in • mice, men, & bacteria.

43. Amino acids must be in the proper sequence for proteins to function properly. The number of different kinds of proteins varies with the COMPLEXITY of an organism.

44. Translation is the process of assembling proteins from information encoded in mRNA

45. 1. MRNA enters the cytoplasm from the nucleus and finds a ribosome to hook up with. 2. tRNA’s then bring specific amino acids to the ribosomes.

46. 3. The ribosome attaches to an AUG (start codon) on mRNA. 4. TRNA attaches itself to the mRNA and passes its amino acid off to the growing protein chain.

47. 5. TRNA leaves and another tRNA takes its place with a new amino acid. This process continues until a STOP codon is reached and the protein chain is complete and falls off.

49. Protein Synthesis Animation http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a3.html Protein Synthesis Video http://vcell.ndsu.edu/animations/transcription/movie-flash.htm http://vcell.ndsu.edu/animations/translation/movie.htm

50. My Molecular Self Video Video