Cytogenetics Lecture - Med238 Chapter 3 PDF

CYTOGENETICS LECTURE - Med238 CHAPTER 3: 5. RNA primase - enzymes that CENTRAL DOGMA synthesizes short RNA sequences...

CYTOGENETICS LECTURE - Med238 CHAPTER 3: 5. RNA primase - enzymes that CENTRAL DOGMA synthesizes short RNA sequences (primers), serves as starting point of the - systematic flow of genetic materials replication from one generation to another ➔ Leading strand - is always - important for gene expression synthesized / replicates (transcription, translation) ➔ Lagging strand - short segments - Francis Crick - first identify DNA (Okazaki segments) Nucleotides - building blocks of DNA ➔ Nicks - gap/breaks ➔ composed of sugar, nitrogen 6. DNA Polymerase III - catalyzes the base, phosphate group formation of anew phosphodiester linkage between the nucleotide and growing strand; joins the newly attached nucleotides to create one continuous strand in the 5’ - 3’ direction - elongates the DNA strands by adding new ribonucleotides ❖ 5 prime - 3 prime direction of synthesizing Transcription - DNA as template for ❖ 3 prime - 5 prime direction of RNA, and DNA is read in the nucleus reading ➔ produces mRNA - contain ❖ 3 prime - 5 prime exonuclease - codons (3 nucleotides bases mismatch nucleotides that code for particular amino acid) 7. DNA Polymerase I - remove excess Translation - process which RNA is ribonucleotides using 5’ - 3’ converted into amino acid in the exonuclease and fill the gaps ribosomes 8. DNA Ligase - seal the nick - produces proteins - codons will pair with anti codons (UGA, UAG, UAA) carried by DNA exonuclease activity; tRNA polymerase I remove RNA primers and replaces w’ DNA DNA repair function Summary of DNA replication polymerase II 1. origin of replication recognize by orc DNA main enzyme that adds (origin replication complex) polymerase III nucleotides in the 5’ - 3’ 2. Helicase (unwinding of double strand by direction ATP) Templates - 2 strands of the DNA from unwinding 3. Single stranded binding protein maintain the separation of strand 4. Topoisomerase - relive torsional strain MELISA S. MAMITA 1  TRANS: Chapter 2 RNA MOLECULES TRANSCRIPTION (RNA Sythesis) 1. contain genetic information - Process by which te DNA direct the Heterogenous synthesis of hRNA/mRNA molecules nuclear RNA that carry information needed for (hnRNA) protein synthesis 2. Messenger contain a genetic RNA information that removes TRANSCRIPTION (Formation of (mRNA) introns hnRNA) A portion of DNA unwinds by RNA 3. Small polymerase nuclear RNA Free nulceotides aligns the strand (snRNA) exposed and form new base pairs U rather than T aligns with A in 4. Ribosomal most abundant RNA base pairing process RNA (rRNA) - use for protein RNA polymerase links the synthesis ribonucleotide to the growing hnRNA molecule 5. Transfer serves as adaptor Ends when RNA polymerase RNA (tRNA) molecules that converts encounters the stop signal mRNA to protein RNA polymerase and hnRNA - Clover leaf shape released - At the 3 prime end, DNA rewinds to reform the original amino acid is double helix attached - Loop opposite the open end (anticodon POST-TRANSCRIPTION (Formation loop), contains of mRNA) anticodon - Conversion of hnRNA to mRNA - Genes contains 2 segments: Activation of tRNA: ❖ Exons - contains codes for 1. An amino acid genetic information (DNA interacts with an segments that help express a activator molecule to genetic message) form a highly ❖ Introns - portion that do not energetic complex convey genetic information 2. The complex reacts (DNA segments that interrup a with tRNA to genetic message) produce an activated tRNA POST-TRANSCRIPTION (Splicing) molecule Process of removing introns from hnRNA molecule and joining the Activated tRNA - tRNA remaining exons together to form a that has an amino acid mRNA molecule covalently bonded to it at Involves snRNA which always its 3’ end through an complexed with snRNP ester linkage Small Nuclear Ribonucleoprotein Particle - complex formed from snRNA molecule and several proteins MELISA S. MAMITA 2  TRANS: Chapter 2 Splicesomes - Large assembly of initiating codon AUG-methionine, snRNA molecules and proteins occupies the P site (peptidyl site) involved in the conversion of hnRNA ➔ Aminocycl molecules to mRNA molecules ➔ Peptidyl ➔ Empty TRANCRIPTOME All of RNA molecules that can be ELONGATION generated from the genetic material in Another tRNA with the second amino a genome acid binds at the A site The methionine transfers form P site to the A site The ribosome shift to the next codon, making it’s a site available for the tRNA carrying the third amino acid. POST-TRANSLATIONAL PROCESSING Post translational modification Gives the protein final form to be functional APOPTOSIS - programmed cell death - normal process where cell number is adjusted and controlled TRANSLATION - Remove extra tissue and eliminate Process by which mRNA codons are excess cells (damaged cells, virus cells, deciphered and a particular protein potential cancer cell) molecule is synthesized Process by which the genetic message is decoded and used to make protein’every cell contains 20 or more different tRNA, each designed to carry a specific amino acid ANTICODON - 3 nucleotide sequence on a tRNA CELL STRUCTURES AND ITS molecule that is complementary to a codon on a mRNA molecule (UGA, FUNCTIONS UAG, UAA) Cells - basic unit of the human body - Robert Hooke - first scientist that INITIATION discovered cell (plant cell), he mRNA attaches to the surface of a observed cell walls in a cork tissue small ribosomal subunit such that its - 30 trillion Human cells (80% red blood first codon, which is always the cells - most abundant cells in the body) (neurons - 100 billion the actual value is MELISA S. MAMITA 3  TRANS: Chapter 2 closer to 86 billion) + bacterial cells = Glycocalyx - mainly 68 trillion made up of - Cells undergo cell differentiation which carbohydrates cells become efficiently organized in - very delicate cell tissues with specialized functions and service coating usually changing their shapes - responsible for cell adhesion and cell Plasma “cell membrane or recognition Membrane plasmalemma” - composed of: ❖ glycolipids serves as selective barrier (outer lipids regulating the passage of that includes materials in or out of the oligosacchari cell des chain) - facilitate the ❖ Glycoproteins transport of a - proteins specific molecule linked with - Membrane proteins sugar chain - specific for recognition and signaling function, play a key role in the interaction of the cell and environment Membrane phospholipid is Ribosomes responsible for production amphipathic of proteins Polar head part - attached to rough (hydrophilic) - endoplasmic located outside reticulum or (outer) cytoplasm Non polar fatty - they are free floating acid chains tail - Assembles (hydrophobic) - polypeptides from located inside amino acid in (inner) molecules of tRNA Embedded in phospholipid in a sequence is pecifieds by mRNA Proteins that - engage in protein transport carriers syntheis Cholesterol - resposible for ENDOPLASMIC RETICULUM restrict movements, - synthesized proteins/lipids modulate fluidity of all membrane Rough membranous tubules and materials Endoplasmic flattened sacs with Channel pore Reticulum attached ribosomes MELISA S. MAMITA 4  TRANS: Chapter 2 - Synthesizes proteins - Sites of intracellular and transport them digestion and to Golgi apparatus turnover of cellular component Smooth membranous tubules and Endoplasmic flattened sac with no Proteosome tubelike protein complexes Reticulum attached ribosomes in the cytoplasm - Manufactures lipids - degrade denatured and carbohydrates non-functional metabolism polypeptides - sites for steroids - remove proteins that synthesis are no longer - detoxifies harmful needed by cells chemicals (like your - recognizes proteins alcohol) with attached - stores calcium molecules - release calcium ions (ubiquitin) when muscles need - break down proteins to contract in the cytoplasm Golgi flattened membrane sacs Mitochondria powerhouse of the cell Apparatus stacked on each other - the major site for - modifies, packages, ATP synthesis and distributes proteins, and lipids Cytoskeleton - provide support for secretion or - holds organelles in internal use place - complete - enables cells to post-translational change shape modification of - movement of proteins produced organelles and by RER cytoplasmic vesicles - allow movement of 2 phases/region: entire cells cis - receive trans - shipping contain: a. Microtubules - Lysosomes membrane-bound vesicle largest diameter, pinched off Golgi apparatus provide cell structure - contain 40 - from cilia and hydrolytic flagella enzymes abundant b. Intermediate in cells filaments - larger responsible for diameter than phagocytosis (ex. microfilaments Macrophages, - responsible neutrophils) for - contains digestive maintaining enzyme the cell shape MELISA S. MAMITA 5  TRANS: Chapter 2 c. Microfilaments - smallest, responsible for shape/movement Nucleus large organelle that houses most of a cell’s DNA - contains chromatin - control center of the cell - DNA within the nucleus regulates protein synthesis and therefore the Interphase - period between cell chemical reactions division. Chromosomes are not visible of the cell under light molecules. (resting phase / metabolic phase) ➔ G1 - period which cells accumulate the enzymes and CELL DIVISION nucleotides required for DNA - Formation of 2 daughter cells from a replication single parent cells through the ➔ S (synthesis phase) - period fro process of Mitosis and Meiasosis DNA replication, histone - Each cells contain 46 chromosomes (22 synthesis, beginning of pairs - genetic characteristics, 1 pair for centrosomes duplication sex chromosomes) ➔ G2 - gap in DNA duplication and next mitosis, relatively short phase - period for preparation for mitosis ➔ G0 - where cell cycle may be temporarily or permanently suspended MITOSIS - period of cell division that occur in all cells except sex cells - cell cycle phase that can be distinguished by light microscope - parent cell divides, and each of the 2 daughter cell receives chromosomal cell identical to the parent cell - Components: Chromatin - 2 strands of chromosomes that are genetically identical Centromer - where 2 chromatids are connected Centrioles - are small organelles compose of 9 triples MELISA S. MAMITA 6  TRANS: Chapter 2 - chromatids separate STAGES OF MITOSIS (PMAT) from two sets of chromosomes Prophase nucleus with dispersed - chromosomes chromosomes moves toward - consumed 1 hour centrioles - chromatin is condenses into chromosomes - centrioles move to opposite end Telophase cytokinesis occurring - Metaphase chromosomes aligned on cytoplasmic division of the equational plate contractionary where it - less than 1 hour formed the cleavage furrow diving cytoplasm into separate and equal portion - minutes only - where chromosomes dispersed - nuclear enveloped and nucleotide is developed - Cleavage appeared to create another cell Anaphase sister chromatids being pulled apart - 30 minutes MELISA S. MAMITA 7  TRANS: Chapter 2 REPRODUCTIVE CELL DIVISION - Mechanism that produces gametes, the cells needed to form the next generation of sexually reproducing organisms - Consist of special two step division called meiosis, in which the number of chromomes in the nucleus is reduced by half Mitosis Meiosis Somatic cells Gametes One division 2 division Interphase (copy of Interphase I (copy of DNA) -> PMAT DNA) Interphase II (no copy of DNA) - PMAT I - PMAT II Produces 2 diploid Produces 4 haploid cells cells MELISA S. MAMITA 8