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Chapter 10 Notes
Chapter 10 - DNA, RNA, and Protein Synthesis Notes
| Term | Definition |
|---|---|
| Chapter 10 DNA, RNA, and Protein Synthesis Notes | |
| Section 1 Discovery of DNA | |
| Fredrick Griffin | -1928 British officer studying Streptococcus pneumoniae |
| - Working on developing a vaccine | |
| - Virulent-disease causing | |
| - Used two types of S. pneumonia | - Smooth (S) strain - which is disease-causing - Has a smooth outer capsule of polysaccharides - Rough (R) strain - NON Disease causing - Lacks outer capsule |
| - Griffith's Experiments | - Griffith's experiments showed that heredity material can pass from one bacterial cell to another - The transfer of genetic material from one cell to another or from one organism to another organism is called transformation |
| - Griffith's Results | - The heated S strain released the genetic information, which was transferred to the genetic material in the non-virulent R strain |
| - Oswald Avery's experiments Avery's work showed that DNA is the heredity material that transfers information between bacterial cells | - He designed 3 experiments - Used a protease to destroy proteins found in the cells - Used a RNase to destroy the RNA - Used a DNase to destroy the DNA |
| - Avery's Results | - When the RNA and protein were destroyed the mice still died - When the DNA was destroyed the mice survived - DNA is needed to transfer information; DNA is needed for transformation |
| Hershey-Chase Experiment | - 1952, American researchers, Martha Chase and Alfred Hershey - Designed an experiment to determine if protein or DNA was transferred when viruses enter bacterium - Bacteriophages(phages) - Bacteria infected with virus material |
| - Used radioactive sulfur and radioactive phosphorus to identify protein and DNA in the virus - E.Coli (bacteria) was then infected with the virus - Using a blender, they removed the phage coats from the bacteria | |
| - Using a centrifuge, they separated the phage from the bacterial cells | |
| Hershey-Chase Results | - They found that the radioactive DNA was in the bacteria cells - They did not find the radioactive protein - Conclusion: DNA and not protein was transferred from the virus to the bacteria |
| Section 2 DNA Structure | - DNA Double Helix - 1950's James Watson, Francis Crick, Maurice Wilkins, and Rosalind Franklin all contributed to the model of the structure of DNA - Wilkins and Franklin - x-ray diffraction photographs of DNA crystals |
| - Found that DNA is made up of two chains that wrap around each other in the shape of a double helix - DNA - deoxyribonucleic acid - genetic material that organisms inherit from their parent | |
| - DNA nucleotides | - Made of: - Phosphate group - Five carbon sugar - Nitrogenous base - Nitrogen - Carbon - And will form a Polynucleotide chain |
| - DNA Bases | - Adenine - Purine - Thymine(T) - Pyrimidine - Guanine(G) - Purine - Cytosine(C) - Pyrimidine |
| -DNA Structure | - 1949 Erwin Chargaff discovered: - Percentage of thymine equaled same percentage as adenine - Percentage of cytosine equal same as percentage of guanine |
| - Base-pair rule - cytosine on one strand pairs with guanine on the opposite strand; thymine on one strand pairs with adenine on the opposite strand | |
| -DNA Structure | - Two long polynucleotide chains of nucleotides - Hydrogen bonds hold the polynucleotide chains together - Alternating phosphate group and sugar group are the "sides" of the ladder - Pairs of nitrogenous bases are the rungs of the ladder |
| Section 3 DNA Replication | How DNA Replication Occurs: - DNA Replication is a process which copies each strand of DNA in the cell - This occurs before mitosis or meiosis or binary fission - Replication is completed by pairing the template strand with matching bases |
| - Steps of DNA Replication | - 1.) Enzymes called Helicases separates DNA strands - 2.) Enzymes called DNA polymerase add complementary bases - 3.) DNA polymerase finishes replicating DNA then falls off |
| - Steps of Replication Cont. | - Replication Fork - Helicase separates the DNA strands - As the replication fork moves along the original DNA, synthesis of one strand follows the movement of the replication fork |
| - The other strand moves in the opposite direction away from the replication fork - Leaving gaps which are joined together by DNA ligase | |
| Semi-conservative Replication | - Each double helix contains one strand from the original molecule and one strand that is considered new |
| DNA Replication | 1. Prokaryotic Cells 2. - Circular chromosomes - Replication continues along the circle until each fork meets 3. Eukaryotic Cells - Long strands - Helicase stars the process at many different points called origins |
| - DNA ligase attaches the pieces of DNA | |
| - Genetic Changes | - Mutations - any changes in the DNA sequence - Can be beneficial - Can be detrimental (harmful) - Normally errors that occur are corrected with a DNA polymerase enzyme that "checks" the sequencing for mistakes |
| Mutations in the body cells | - Some mutations of DNA that's involved in cell division - Can result in cells growing and dividing rapidly producing cancer - Point mutation - a change in a single base pair in DNA |
| Example: - THE DOG BIT THE CAT - THE DOG BIT THE CAR | Frame shift mutation - it shifts the reading of codons by one base, a single base is either added or deleted Example: THE DOG BIT THE CAT THE DOB ITT HEC AT |
| Section 4 Protein Synthesis | |
| DNA vs. RNA | - Genetic information is found on DNA - RNA is the intermediate molecule that is directed by DNA - RNA helps "make" protein |
| - Comparison - RNA | - There are 3 major types of RNA - mRNA - messenger RNA tRNA - transfer RNA rRNA - ribosomal RNA |
| - Messenger RNA | - Messenger RNA (mRNA)- single-stranded RNA molecule that carries the instructions from a gene to make a protein - Carries the genetic "message" from DNA - Is made with the DNA as a template |
| - Transfer RNA | Transfer RNA (tRNA)- transfers amino acids to the ribosome to make a protein |
| - Ribosomal RNA | - Ribosomal RNA (rRNA)- part of the structure of ribosomes - Site where protein synthesis occurs |
| - Flow of Genetic Information | - Gene - segment of DNA that is located on a chromosome and codes for a heredity information - RNA is the intermediate between DNA and Protein |
| - Two step process - Transcription - DNA is a template for building the RNA - Translation - TNA guides the assembly of amino acids forming proteins | |
| - Protein Synthesis | - Formation of proteins - DNA -> RNA -> Proteins - Proteins are important molecules that carry out many functions - Structural - Contractile - Defensive - Transport - Signal - Enzyme |
| - Transcription | -3 Steps: 1. RNA polymerase binds to the promoter nucleotides - Promoter - specific nucleotide sequence that RNA polymerase binds to - Triggers the start of transcription - AUG |
| After the RNA polymerase binds to the promoter, the DNA strands unwind and separate | |
| - Transcription | - Step 2 - RNA polymerase adds free RNA nucleotides that are complementary to the nucleotides on one of the DNA strands - A-U, C-G - Resulting chain is an RNA molecule |
| - Transcription | - Step 3 - RNA polymerase reaches a termination signal - a specific sequence of nucleotide that marks the end of a gene - UAG - UGA - UAA - Once the RNA reaches the "stop" signal, RNA polymerase releases both the DNA and the newly formed RNA |
| - Transcription | Can make and of the 3 types of RNA: mRNA,tRNA and rRNA |
| The Genetic Code | - The nearly universal genetic code identifies the specific amino acids coded for by each three -nucleotide mRNA codon - More than one codon for each amino acid - Helps prevent errors in the amino acid sequence |
| Translation | - Steps of Translation - During translation, amino acids are assembled from information encoded in mRNA - As the mRNA codons move through the ribosome tRNAs add specific amino acids to the growing polypeptide chain |
| - The process continues until a stop codon is reached and the newly made protein is released | |
| Steps of Translation | - 5 Steps 1.) Initiation - The ribosomal subunits, the mRNA,and the tRNA carrying the start code(AUG) 2.) Elongation - peptide bond forms between amino acids - Polypeptide chains begin to form |
| 3.) Elongation (continues) - Polypeptide chain continues to grow -mRNA moves along the ribosome - New tRNA moves in and attaches the amino acid | |
| Steps of Translation Cont. | 4.) Termination - the process ends when a stop codon is reached - There is no tRNA to pair with it - Polypeptide (protein) falls off - 5.) Disassembly - the ribosome complex falls apart |
| - Translation - Human Genome | The entire gene sequence for the human being (Homo sapiens) - 23 chromosomes - 3.2 billion base pairs - About 30,000 genes on the 23 chromosomes |
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