DNA, RNA, and Protein Synthesis Table of Contents Relate how Griffith s bacterial experiments showed that a hereditary factor was involved in transformation. Summarize how Avery s experiments led his group to conclude that DNA is responsible for transformation in bacteria. Describe how Hershey and Chase s experiment led to the conclusion that DNA, not protein, is the hereditary molecule in viruses. Griffith s Experiments Griffith s Discovery of Transformation Griffith s experiments showed that hereditary material can pass from one bacterial cell to another. The transfer of genetic material from one cell to another cell or from one organism to another organism is called transformation. Transformation Avery s Experiments Avery s work showed that DNA is the hereditary material that transfers information between bacterial cells.
Hershey-Chase Experiment Hershey and Chase confirmed that DNA, and not protein, is the hereditary material. The Hershey-Chase Experiment Hershey and Chase s Experiments Evaluate the contributions of Franklin and Wilkins in helping Watson and Crick discover DNA s double helix structure. Describe the three parts of a nucleotide. Summarize the role of covalent and hydrogen bonds in the structure of DNA. Relate the role of the base-pairing rules to the structure of DNA. DNA Double Helix Watson and Crick created a model of DNA by using Franklin s and Wilkins s DNA diffraction X-rays. DNA Double Helix DNA is made of two nucleotide strands that wrap around each other in the shape of a double helix.
DNA Double Helix, continued A DNA nucleotide is made of a 5-carbon deoxyribose sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), guanine (G), cytosine (C), or thymine (T). DNA Nucleotides, continued Bonds Hold DNA Together Nucleotides along each DNA strand are linked by covalent bonds. Complementary nitrogenous bases are bonded by hydrogen bonds. Complementary Bases Hydrogen bonding between the complementary base pairs, G-C and A-T, holds the two strands of a DNA molecule together. Summarize the process of DNA replication. Identify the role of enzymes in the replication of DNA. Describe how complementary base pairing guides DNA replication. Compare the number of replication forks in prokaryotic and eukaryotic cells during DNA replication. Describe how errors are corrected during DNA replication. How DNA Replication Occurs DNA replication is the process by which DNA is copied in a cell before a cell divides. How DNA Replication Occurs, continued Steps of DNA Replication Replication begins with the separation of the DNA strands by helicases. Then, DNA polymerases form new strands by adding complementary nucleotides to each of the original strands.
DNA Replication How DNA Replication Occurs, continued Each new DNA molecule is made of one strand of nucleotides from the original DNA molecule and one new strand. This is called semi-conservative replication. Replication Forks Increase the Speed of Replication DNA Errors in Replication Changes in DNA are called mutations. DNA proofreading and repair prevent many replication errors. DNA Errors in Replication, continued DNA Replication and Cancer Unrepaired mutations that affect genes that control cell division can cause diseases such as cancer. Outline the flow of genetic information in cells from DNA to protein. Compare the structure of RNA with that of DNA. Describe the importance of the genetic code. Compare the role of mrna, rrna,and trna in translation. Identify the importance of learning about the human genome.
Flow of Genetic Information The flow of genetic information can be symbolized as DNA RNA protein. RNA Structure and Function RNA has the sugar ribose instead of deoxyribose and uracil in place of thymine. RNA is single stranded and is shorter than DNA. Comparing DNA and RNA RNA Structure and Function, continued Types of RNA Cells have three major types of RNA: messenger RNA (mrna) ribosomal RNA (rrna) transfer RNA (trna) RNA Structure and Function, continued mrna carries the genetic message from the nucleus to the cytosol. rrna is the major component of ribosomes. trna carries specific amino acids, helping to form polypeptides. Types of RNA
Transcription Transcription During transcription, DNA acts as a template for directing the synthesis of RNA. Genetic Code Translation The nearly universal genetic code identifies the specific amino acids coded for by each threenucleotide mrna codon. 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. Translation: Assembling Proteins The Human Genome The entire gene sequence of the human genome, the complete genetic content, is now known. To learn where and when human cells use each of the proteins coded for in the approximately 30,000 genes in the human genome will take much more analysis.