Genetics and Genetic Engineering Lecture 2 (10-10-2024) PDF

lecture 2 (10-10-2024) Genetics and genetic engineering  Cytogenetics CHROMOSOMES  CONTENTS OF THIS lecture CHROMOSOMES Chromatin 01 02 Structure Euchromatin and types of 03 04...

lecture 2 (10-10-2024) Genetics and genetic engineering  Cytogenetics CHROMOSOMES  CONTENTS OF THIS lecture CHROMOSOMES Chromatin 01 02 Structure Euchromatin and types of 03 04 Heterochromatin Heterochromatin Histone Proteins and 05 Packaging of 06 the Nucleosome Chromosomes 07 Bacterial Chromosomes  CHROMOSOMES 1-Chromosomes are the units in which the genes reorganized. 2-In eukaryotic cells, each chromosome consists of a continuous thread of DNA double helix and associated proteins. 3-The term chromosome, delved from Greek for "colored thread. Chromatin Structure The two basic types of chromatin are: 1-Euchromatin,which undergoes the normal process of condensation and decondensation in the cell cycle 2- heterochromatin, which remains in a highly condensed state throughout the cell cycle, even during interphase  Euchromatin and Heterochromatin : Regulation of Gene Function 1-Regions of the chromosome in which genes can be transcribed differ structurally from inactivated regions. 2-it has been known that transcription takes place from euchromatin, not heterochromatin. 1-Euchromatin 1-is loosely organized, extended, and uncoiled. 2-This chromatin contains active, early replicating genes and stains lightly with G banding techniques. 3-contains the majority of the structural genes. 2-Heterochromatin 1-is densely compacted at cell division and remains compacted at interphase. 2-It is largely concentrated around the nuclear periphery and nucleolus and is relatively inactive in transcription (not transcribed). 3- late replicating during the synthesis (S) phase of mitosis and are highly contracted. There are two types of Heterochromatin 1-Constitutive Heterochromatin 2-Facultative Heterochromatin  The Chemistry and Packaging of Chromosomes Histone Proteins and the Nucleosome 1-Histones are low molecular weight, basic proteins that have a high binding affinity for deoxyribonucleic acid, or DNA. 2-There are positively charged proteins of five major types histones, called H1, H2A, H2B, H3, and H4. 3- All histones have a high percentage of arginine and lysine, positively charged amnio acids that give them positive charge.  Packaging of Chromosomes 1-There are positively charged proteins of five major types histone, called( H1, H2A, H2B, H3, and H4 ) 2-The positive charges attract the negative charges on the phosphates of DNA and hold the DNA 3-The best characterized component of chromatin structure is the nucleosome. 4-Nucleosome is a core particle _consisting of DNA wrapped about two times around an octamer of eight Histone proteins (two copies each of H2A, H2B, H3 and H4), much like thread wound around a spool 5-The fifth type of histone, H1, is not a part of the core particle. 6-Together, the core particle and its associated H1 histone are called the chromatosome Bacterial Chromosomes 1-This is usually a circular DNA duplex. 2-The chromosome has at least three functional elements. 3-The replication origin is the location of the start of DNA synthesis. 4- The termination region provides a mechanism for stopping DNA synthesis of the two divergent replication forks. THANKS! DO YOU HAVE ANY QUESTIONS? CREDITS: This presentation template was created by Slidesgo, and includes icons by Flaticon, and infographics & images by Freepik