Transcript Slide 1
DNA Replication Vocabulary: Replication - Synthesis of an identical copy of a DNA strand. http://www.lewport.wnyric.org/jwanamaker/animations/DNA%20L ecture.html In which cell replicated? organelle is DNA Nucleus When does DNA cell replication occur? Before a cell divides Mitosis & Meiosis When DNA replicates, it results in __________ of the number of chromosomes in a cell? DNA DEOXYRIBONUCLEIC ACID Is the blueprint of life (has the instructions for making an organism) established by James Watson and Francis Crick -codes for your genes -shape of a double helix -made of repeating subunits called nucleotides Nucleotide - consists of a sugar, phosphate and a base Nitrogenous Bases Adenine, Thymine, , Guanine, Cytosine or A, T, G, C Nucleotides pair in a specific way - called the Base-Pair Rule Adenine pairs to Thymine Guainine pairs to Cytosine To make a copy of any thing, you need an original or template. DNA has the template build in. Replication begins when the double helix unzipping. A enzyme breaks the __________ bonds in the DNA exposing the template. If you know the sequence of base on one strand, you can predict the sequence on the other strand. (Base ? ___________) What is the sequence of nitrogen bases on the left side of the DNA molecule below? ______________________________________________________________ Predict the sequence of nitrogen bases on the right side of the DNA molecule below? __________________________________________________________ http://www.eduref.org/Virtual/Lessons/Science/Genetics/GET0201.pdf http://www.lewport.wnyric.org/jwanamaker/animations/DNA%20Lecture.html HW Read Page 413-416 and answer pg 416 #7,12, 13,14 15 Q&A on LL What are Genes? Genes are areas on the DNA molecule that code for the synthesis of specific proteins. -Proteins determine the traits in organisms so therefore, genes determine the specific traits of an organism. What is The Genetic Code? It is three adjacent nucleotides (“letters”) in mRNA that specify an amino acid in a polypeptide, (_________) molecule. Protein Synthesis Is a process whereby DNA encodes for the production of amino acids and proteins. This process can be divided into two parts: 1. Transcription 2. Translation Vocabulary Transcription - Synthesis of mRNA Translation - Synthesis of polypeptide from amino acids. Codon - Base triplet on mRNA. Anticodon - Complementary triplet on tRNA. Polypeptide - ______ molecule DNA is too large to leave the Nucleus, so how does the information (genetic codes) within the DNA molecule get to the ribosome’s where proteins are synthesized? An intermediate molecule is needed. http://www.lewport.wnyric.org/JWANAMAKER/animations/Protein%20Synthesis%20-%20long.html RNA is that molecule. It is single stranded and thus is smaller than DNA & able to leave the nucleus through the nuclear pores and carry the codes to the ribosome Uracil (U)* instead of Thymine (T) RNA NOTE: DNA Uracil (U)* instead of Thymine (T) in the RNA PROTEIN SYNTHESIS Two parts: 1. Transcription 2. Translation Step 1 of Protein Synthesis TRANSCRIPTION One strand of the DNA double helix is used as a template by the RNA polymerase to synthesize a messenger RNA (mRNA). The mRNA then migrates from the nucleus to the ribosome. The DNA molecule unzips /opens up on one side only and the base sequence is transcribed into a complementary sequence of bases forming a mRNA molecule. Remember Uracil (U)* instead of Thymine (T) What will the sequence of bases in the mRNA? DNA Sequence (left side) __A C A____G G A______C G A______ mRNA Sequence _________________________________________ What is a Codon? A sequence of three nucleotides that encode for an amino acid or signifies a start or stop signal. NOTE* AUG = Start & Methionine Amino Acid UAA = Stop The Genetic Code Codons cont There are 64 possible codons corresponding to 20 amino acids. NOTE * The Start codon corresponds to the amino acid methionine and the stop codon have no amino acids attached. Step 2 of Protein Synthesis Translation - What is it? The coded information flows from the DNA to the ribosome via the mRNA and then tRNA brings the corresponding amino acid. Where does it take place? Ribosome 2. Translation Steps in Translation (1)Initiation (2) Elongation (3) Termination http://www.lewport.wnyric.org/JWANAMAKER/animations/Protein%20Synthes is%20-%20long.html Step 1. Initiation______ (1) Initiation The ribosome binds to the mRNA at the start codon (_____) that is recognized only by the initiator tRNA. Step 2. Elongation whereby the correct amino acid is brought to the ribosome and a peptide bond forms between adjacent amino acids and the entire assembly moves one position along the mRNA. The polypeptide chain continues to grow.. Step 3. Termination Termination which happens when a stop codon is reached, there is no amino acid to be incorporated and the entire assembly dissociates to release the newlysynthesized polypeptide. What are the stop codons? _____________ SUMMARY Summary - - Information flows from DNARNAProteins RNA serves as the intermediary between DNA and proteins. There are three types of RNA. mRNA, rRNA and tRNA. The Genetic Code represents 64 possible codons corresponding to 20 different amino acids, start signal and stop signals. The process of TRANSLATION takes place within the cytoplasm on a ribosome. The process of TRANSLATION involves: initiation, elongation and termination. In what cell organelle are proteins synthesized ? Ribosome's Which cell organelle controls the manufacture of proteins in the ribosome? Nucleus What is in the nucleus contains the information for protein synthesis • DNA 20 AMINO ACIDS There are twenty amino acids required for human life to exist. Adults have eight essential amino acids that they cannot synthesize. The other twelve can be produced within our bodies. Alanine Arginine Asparagine Aspartic Acid Cysteine Glutamic Acid Glutamine Glycine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Proline Serine Threonine Tryptophan Tyrosine Valine Essential amino acids histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. What in the nucleus controls cell activities? What in the nucleus contains the codes for protein synthesis? Answer: The The DNA information within the DNA molecule is encoded within the sequence of the nitrogenous bases.