Chapter 5 Macromolecules and molecular genetics The key informational macromolecules in prokaryotic and eukaryotic cells are DNA RNA, and protein Molecular genetics deals with the mechanisms by which the information in DNA is replicated and by which it can be transcribed into rna and translated into specific proteins
Chapter 5 Macromolecules and Molecular Genetics The key informational macromolecules in prokaryotic and eukaryotic cells are DNA, RNA, and protein. Molecular Genetics deals with the mechanisms by which the information in DNA is replicated, and by which it can be transcribed into RNA and translated into specific proteins
Central Dogma of Molecular Biology 中心法则 One-way transfer of genetic information from nucleic acid Replication to protein is call Central Dogma of DNA Molecular Biology Transcription RNA Translation Protein
Central Dogma of Molecular Biology 中心法则 One-way transfer of genetic information from nucleic acid to protein is call Central Dogma of Molecular Biology
Information ransfer in Prokaryotes and Eukaryotes Prokaryotes Gene A Gene B DNA Transcription mRNA Coding region A Coding region B Translation Prot A B
Information Transfer in Prokaryotes and Eukaryotes Prokaryotes
NUCLEUS DNA Exon 1 Intron 1 Exon 2 I Intron 2 3 ↓ Transcription Primary RNA [Exon 1I Intron 1T Exon 2 intron 2 Exon 3 transcript RNA processing Introns excised during processing Mature mRNA Transport to the cytoplasm mRNA Eukaryotes CYTOPLASM
Eukaryotes
DNA SYnthesis proceeds 523 5- Groving strand 3 A: Adenine 2 G: Guanine OH 2 T: Thymine 3 OH C: Cytosine 2 2 CH? CH2 P 2 3+ Parental strand -5
DNA Synthesis proceeds 5’ 3’ A: Adenine G: Guanine T: Thymine C: Cytosine
Replication of dna proceeds by insertion of a new nucleoside triphosphate at the free 3-hydroxyl end, with loss of two phosphate Chain Elongation p P 5- Growing strand 3 OH 尺 人 CH 2 OH 2 CH2 P 2 CH2 Parental strand 5
Replication of DNA proceeds by insertion of a new nucleoside triphosphate at the free 3’-hydroxyl end, with loss of two phosphate
helical DnA double tum helix groove any important proteins interact backbone with the mayor groove o DNA double hel
DNA double helix Many important proteins interact with the major groove of DNA double helix
How DNA is supercoilded and relaxed Enzyme involved in supercoiling (in bacteria) DNA gyrase(旋转酶): DNA Topoisomerase I(DNA拓朴异构酶I) Enzyme involved in removing supercoiling DNA gyrase DNA TopOISOmerase I Two antibiotics(Nalidixic acid and Novobiocin) inhibit the action of DNA
How DNA is supercoilded and relaxed Enzyme involved in supercoiling (in bacteria): – DNA gyrase (旋转酶）： • DNA Topoisomerase II (DNA拓朴异构酶II) Enzyme involved in removing supercoiling: – DNA gyrase: • DNA Topoisomerase I Two antibiotics (Nalidixic acid and Novobiocin) inhibit the action of DNA
Secondary Structure of DNA DNA bending: involving several runs of five to six adenines(in the same strand), each separated by four or five bases, Inverted repeat: regions of DNA containing repeated sequences in inverse orientation, leading to a stem-loop(茎—环); Sticky end: DNA with single-strand complementary sequences at the end, this can form a hairpin, linear DNA can form a cycle with their sticky end These structures influence dna interaction with proteins
Secondary Structure of DNA DNA bending: involving several runs of five to six adenines (in the same strand), each separated by four or five bases; Inverted repeat: regions of DNA containing repeated sequences in inverse orientation, leading to a stem-loop (茎—环）; Sticky end: DNA with single-strand complementary sequences at the end, this can form a hairpin, linear DNA can form a cycle with their sticky end. These structures influence DNA interaction with proteins
The effect of temperature on DNA Structure Two hydrogen bonds hold adenine-thymine(A-t) together Three hydrogen bonds hold guanine-cytosine(G C)together; Thus, G-C pairs are stronger than A-T pairs The separation of double stranded dna by heating is called melting DNA with higher GC content has higher melting temperature Organisms living at high T has higher GC content
The effect of temperature on DNA structure Two hydrogen bonds hold adenine-thymine (A-T) together; Three hydrogen bonds hold guanine-cytosine (GC) together; Thus, G-C pairs are stronger than A-T pairs; The separation of double stranded DNA by heating is called melting; DNA with higher GC content has higher melting temperature; Organisms living at high T has higher GC content