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Cell Biology Student Outline – DNA Structure and Function I DNA Structure and Function I 1. Introduction to DNA A. Forms i. Chromatin ii. Chromosome B. Chemical Makeup i. Nucleotide a. Deoxyribose b. Phosphate Group c. Nitrogen Containing Base • • • • C. Anenine Guanine Thymine Cytosine Molecular Construction Page 1 Cell Biology Student Outline – DNA Structure and Function I i. Basic Construct ii. Double Stranded a. Complimentary Base Pairing • Thymine – Adenine • b. Guanine – Cytosine Hydrogen Bonds Page 2 Cell Biology Student Outline – DNA Structure and Function I c. 2. Double Helix Replication of DNA A. DNA Helicase B. DNA Polymerase i. Continuous ii. Discontinuous C. DNA Ligase Page 3 Cell Biology Student Outline – DNA Structure and Function I 3. Transcription and Translation A. Overview of Processes 1. 2. 3. 4. 5. 6. The genetic material for eukaryotic organisms (includes humans) is DNA. The information is divided up into functions segments called genes. Each gene will code for a particular structural or functional molecule necessary for cellular growth and maintenance. In this case we will assume that the gene codes for a particular enzymatic protein. Transcription of the information from DNA into RNA (called mRNA or messenger RNA). This transcription process is necessary as ribosomes can only work with RNA. The messenger RNA leaves the nucleoplasm via a nuclear pore and enters the cytoplasm. First the small and then the large ribosomal subunits attach the to the mRNA in order to translate the genetic material into a protein. As they translate the mRNA they add the appropriate amino acids, according to instruction, to a growing polypeptide chain. Note that multiple ribosomes can do the translation process simultaneously (called a polysome). After a ribosome has finished translating the mRNA, the two ribosomal subunits and the newly formed protein disengage the mRNA. The ribosomes can then repeat the process and translate the mRNA once again. Page 4 Cell Biology Student Outline – DNA Structure and Function I 7. B. C. The newly formed protein enters the cytoplasm to do it’s particular cellular function. Ribosomes (rRNA) i. Structure ii. Function Transcription i. RNA Polymerase ii. Nucleotides a. b. iii. DNA Nucleotides • Thymine – Adenine • Guanine – Cytosine RNA Nucleotides • Uracil – Adenine • Guanine – Cytosine Process of Transcription Page 5 Cell Biology Student Outline – DNA Structure and Function I iv. Codes and Codons v. mRNA vi. mRNA Procession a. Exons Page 6 Cell Biology Student Outline – DNA Structure and Function I b. D. Introns Translation i. Transfer RNA (tRNA) a. Anticodon b. Amino Acid Binding Site DNA Code mRNA Codon tRNA Anticodon Amino Acid TTT TGG CCG CAT CTC GAG AGA ACT AAA ACC GGC GUA GAG CUC UCU UGA UUU UGG CCG CAU CUC GAG AGA ACU Lysine Threonine Glycine Valine Glutamate Leucine Serine “Stop” Page 7 Cell Biology Student Outline – DNA Structure and Function I ii. 4. Steps of Translation a. Initiation b. Elongation c. Termination Regulation of Gene expression A. Transcription Control i. Chromatin Activation ii. Transcription Factors B. Posttranscriptional Control C. Translational Control D. Posttranslational Control Page 8