DNA, Genes, & Chromosomes PDF (BIO 130 LEC)

DNA, Genes, & Chromosomes BIO 130 LEC INTARMED 2030 | Prof. Bordallo/Leonardo | LU2 SEM 1 | SY. 2023-2024 DNA Gene Chromosome TABLE OF CONTENTS...

DNA, Genes, & Chromosomes BIO 130 LEC INTARMED 2030 | Prof. Bordallo/Leonardo | LU2 SEM 1 | SY. 2023-2024 DNA Gene Chromosome TABLE OF CONTENTS Molecule of A segment of Condensed form I. Introduction to Genetics genetic material DNA sequence of DNA A. DNA vs Gene vs Chromosome Table 1: Summary of DNA vs Gene vs Chromosome B. Characteristics of Genetic Material C. Nucleic Acids OTHER TERMS TO NOTE ______________________________________________________ a. Pentose Sugar Allele b. Nitrogenous Base ➔ Alternative forms of a gene due to changes in DNA c. Phosphodiester Bond sequence D. Watson-Crick DNA Model ➔ Ex. Gene for color: allele for red, allele for blue, II. Central Dogma of Molecular Biology etc. A. Transcription Genome B. Translation ➔ Complete set of hereditary information encoded a. Genetic Code in DNA (includes protein-coding and III. Chromosomes non-protein-coding sequences) A. Organization of DNA into ➔ Contains the instructions and information for an Chromosome individual to function and grow a. Module Video ➔ Consists of ~3 billion DNA base pairs in humans B. Parts of a Replicated Chromosome C. Types of Chromosomes according to CHARACTERISTICS OF GENETIC MATERIAL Centromere Location D. Karyotypes a. Somatic vs Germ Cells Replication b. Autosomes vs Sex Chromosomes Storage of information Expression of information (From DNA > RNA > c. Homologous Chromosomes Proteins) Variation by Mutation I. INTRODUCTION TO GENETICS NUCLEIC ACIDS DNA VS GENE VS CHROMOSOME Nucleic acid ➔ Biomolecule composed of nucleotide subunits ➔ Carries genetic material (except for some viruses) DNA that influences an individual’s characteristics and ➔ Deoxyribonucleic acid form ➔ Molecule that carries genetic information in the ➔ 2 main nucleic acids: DNA and RNA form of linear sequences of nucleotides ➔ Consists of two antiparallel chains of Nucleotides deoxyribonucleotides held by hydrogen bonds ➔ Building block of nucleic acids Gene ➔ Composed of three components: (a) nitrogenous ➔ Physical and functional unit of heredity base, (b) pentose sugar, and (c) phosphate group. ➔ A specific segment of the DNA sequence that codes for the production of a functional polypeptide or RNA Chromosome ➔ Condensed form of a DNA molecule that is packed together with proteins ➔ Carries genetic information from cell to cell BIO 130 LEC LU 2 SEM 1 | IMED 2030 Page 1 of 7 SAMSON, SDAV; MUSA, GS, OLIVA, JMM; REYES, JCDC DNA, Genes, & Chromosomes BIO 130 LEC INTARMED 2030 | Prof. Bordallo/Leonardo | LU2 SEM 1 | SY. 2023-2024 2 (adenine and guanine) 3 (thymine, uracil, & cytosine) Table 3: Two Types of Nitrogenous Bases Figure 1: Parts of a nucleotide PENTOSE SUGAR _______________________________________________________ Pentose sugar ➔ Building block of nucleic acids ➔ Basis of RNA and DNA’s name (ribose and Figure 3: Pyrimidine and Purine Nitrogenous Bases deoxyribose) Complementary Base-Pairing Ribose Deoxyribose ➔ Nitrogenous bases are paired in specific combinations through hydrogen bonds. 5-membered carbon ring 5-membered carbon ring ◆ A-T: Adenosine and Thymine (DNA) with an -OH in C-2’ with only -H in C-2’ ◆ A-U: Adenosine and Uracil (RNA) (deoxy = deoxygenated ◆ G-C: Guanine and Cytosine (Both) = no oxygen) Different complimentary base-pairs have a different Less stable (oxygen in C-2’ More stable (carbons w/ -OH number of H-bonds: allows for hydrolysis) → points of linkage w/ bases ○ 3 H-bonds: adenine and thymine pair or phosphate group) ○ 2 H-bonds: guanine and cytosine pair Table 2: Summary of DNA vs Gene vs Chromosome Figure 2: Markers for the 3’ and 5’ ends NITROGENOUS BASE _______________________________________________________ Nitrogenous bases ➔ Nitrogen-containing organic compounds that make up a nucleic acid ➔ 2 types: pyrimidines and purines. Purine Pyrimidine 9-carbon, double-ring 6-carbon, single-ring Figure 4: Different # of bonds between A-T and G-C bases structure structure BIO 130 LEC LU 2 SEM 1 | IMED 2030 Page 2 of 7 SAMSON, SDAV; MUSA, GS, OLIVA, JMM; REYES, JCDC DNA, Genes, & Chromosomes BIO 130 LEC INTARMED 2030 | Prof. Bordallo/Leonardo | LU2 SEM 1 | SY. 2023-2024 Chargaff’s rule ➔ DNA nucleotide base composition varies from one species to another ➔ Percentages of specific bases are roughly the same ◆ Ex. A ≈ T or C ≈ G ➔ Percentages of base-pairs are not necessarily the same ◆ Ex. (C+G) ≠ (A+T) PHOSPHODIESTER BOND _______________________________________________________ Phosphodiester bond ➔ Bond that links two mononucleotides through the C-3’ and C-5’ carbons Figure 6: Markers for the 3’ and 5’ ends DNA vs RNA _______________________________________________________ Characteristic DNA RNA Pentose Sugar Deoxyribose Ribose Figure 5: Phosphodiester bond Nitrogenous adenine (A) adenine (A) Base guanine (G) guanine (G) 3’ end cytosine (C) cytosine (C) ➔ Has a carbon (C-3’) where an -OH (alcohol) is thymine (T) uracil (U) attached instead of a phosphate group ➔ Where the phosphate group will attach should the # of Strands 2 1 (except in some strand become longer viruses, microRNA, & siRNA) 5’ end ➔ Has a carbon (C-5’) where a phosphate group is Stability More stable Less stable (2-OH in attached ribose makes it easier to hydrolyze RNA) Table 4: Summary of DNA vs Gene vs Chromosome WATSON-CRICK DNA MODEL Watson & Crick published an analysis of the 3D structure of DNA in 1953 (after seeing Rosalind Franklin’s X-Ray diffraction photo of the DNA) BIO 130 LEC LU 2 SEM 1 | IMED 2030 Page 3 of 7 SAMSON, SDAV; MUSA, GS, OLIVA, JMM; REYES, JCDC DNA, Genes, & Chromosomes BIO 130 LEC INTARMED 2030 | Prof. Bordallo/Leonardo | LU2 SEM 1 | SY. 2023-2024 The features of the Watson-Crick DNA model are: (1) Two long polynucleotide chains coil around a central axis, forming a right-handed double helix (2) Two chains are antiparallel (C-5’ to C-3’ orientation in opposite directions) (3) Nucleotide bases: Flat, perpendicular to central axis, and “stack” with each other (3.4 Å or 0.34 nm apart) (4) Nitrogenous bases are paired through H-bonds (5) Complete turn of the helix is 34 Å (or 3.4nm) long and has 10 nucleotide base pairs (6) A larger major groove alternates with a smaller minor groove along the strand (7) Double helix diameter = 20 Å (or 2.0 nm) Figure 8: Central Dogma of Molecular Biology TRANSCRIPTION Transcription ➔ Synthesis of RNA from DNA ➔ Process wherein genetic information is rewritten ➔ DNA strand serves as a template for transcription of complementary RNA TRANSLATION Translation ➔ Synthesis of polypeptide (long chain of amino acids) from messenger RNA (mRNA) ➔ Occurs through ribosomes (protein-synthesizing complex that links amino acids together) Figure 7: Watson-Crick DNA Model GENETIC CODE _______________________________________________________ II. CENTRAL DOGMA OF MOLECULAR BIOLOGY Used to “translate” RNA codons to proteins Central Dogma of Molecular Biology ➔ Idea that the flow of genetic information only goes in one direction ➔ (DNA → RNA → Protein) or (RNA → Protein) BIO 130 LEC LU 2 SEM 1 | IMED 2030 Page 4 of 7 SAMSON, SDAV; MUSA, GS, OLIVA, JMM; REYES, JCDC DNA, Genes, & Chromosomes BIO 130 LEC INTARMED 2030 | Prof. Bordallo/Leonardo | LU2 SEM 1 | SY. 2023-2024 ORGANIZATION OF DNA INTO CHROMOSOMES Figure 9: Genetic Code III. CHROMOSOMES Figure 10: Packing of DNA into Chromosomes Thread-like structure composed of DNA found in the Histones > Nucleosome > Chromatin > Chromatin Fiber nucleus of an organism > Chromatid > Chromosome Type Description Nucleosome (6x11-nm flat disc) ○ Consists of 8 histone protein subunits attached to Prokaryotes DNA molecule containing organism’s a DNA molecule genome Octamer: 2 each of H2A, H2B, H3, and H4 Solenoid (30 nm diameter) Eukaryotes DNA molecule complexed with RNA ○ Six nucleosomes bound by H1 histone and proteins forming threadlike Chromatin structures during cell division ○ Fiber of packed nucleosomes as a result of its Contains genes arranged in a linear coiling and stacking sequence Chromatin Fiber: Chromatin structure at 300nm Table 5: Comparison of Prokaryotic and Eukaryotic diameter Chromosomes Chromatid (700-nm) ○ Attached to centromeres ○ Duplicated in S-phase By the end: 6 feet of DNA are tightly packed into chromosomes to fit into the nucleus of each cell NOTE: Chromosomes are only formed for cell division BIO 130 LEC LU 2 SEM 1 | IMED 2030 Page 5 of 7 SAMSON, SDAV; MUSA, GS, OLIVA, JMM; REYES, JCDC DNA, Genes, & Chromosomes BIO 130 LEC INTARMED 2030 | Prof. Bordallo/Leonardo | LU2 SEM 1 | SY. 2023-2024 PARTS OF A REPLICATED CHROMOSOME TYPES OF CHROMOSOME ACCORDING TO CENTROMERE LOCATION Figure 11: Parts of a Single and Duplicated Chromosome Single Duplicated Chromosome Chromosome Chromosome Figure 12: Chromosome Designation Based on Centromere Location Number of 46 92 Chromatids KARYOTYPES Number of 46 46 Chromosomes Karyotype Table 6: Comparison Between a Single and Duplicated Chromosome ○ Refers to an individual’s complete set of chromosomes ○ Consists of 22 pairs of autosomal chromosomes Part Description and 1 pair of sex chromosomes Chromatid One half of an identical replicated chromosome Sister Two parallel structures connected by Chromatid the centromere Contain identical DNA sequences Centromere Constricted region where the sister chromatids join together Telomere End/tip of the chromosome P (petite) arm: short Arms Q arm: long Figure 13: Karyotype of a Male Chromosome (colored) Table 7: Description of the Parts of a Chromosome Karyotyping ➔ Method to check one’s karyotype BIO 130 LEC LU 2 SEM 1 | IMED 2030 Page 6 of 7 SAMSON, SDAV; MUSA, GS, OLIVA, JMM; REYES, JCDC DNA, Genes, & Chromosomes BIO 130 LEC INTARMED 2030 | Prof. Bordallo/Leonardo | LU2 SEM 1 | SY. 2023-2024 SOMATIC vs. GERM CELLS _______________________________________________________ AUTOSOMES vs. SEX CHROMOSOME _______________________________________________________ Autosomes Sex Chromosomes Non-sex 23rd pair of chromosomes; Definition chromosome (XX or first 22 pairs in a XY) karyotype Define body’s Define individual’s Control general sex (male or female) characteristics Figure 14: Somatic vs. Germ Cells Partially Homologous All homologous homologous Somatic Cells Germ Cells Genetic All cells excluding X chromosome from traits/conditions germ cells (i.e. skin, Sex cells (i.e. egg Inheritance mom, X or Y from Definition are inherited muscle, and nerve and sperm cells) dad regardless of sex cells) Table 9: Comparison Between Autosomal and Sex Various; around the Production of Chromosomes Function body gametes HOMOLOGOUS CHROMOSOMES _______________________________________________________ Type Diploid (2n) Haploid (n) Cell Mitosis Meiosis Division can affect an can affect an individual but individual and CAN Mutations CANNOT be passed be passed onto onto their offspring their offspring Table 8: Comparison Between Somatic and Germ Cells Somatic cells of the same species have the same number of chromosomes Figure 15: Homologous Chromosomes ○ Homo sapiens - 46 ○ Mus musculus - 40 Set of one maternal and one paternal chromosome ○ Rana pipiens - 26 Share same gene sequence, gene location, ○ Drosophila melanogaster - 8 chromosomal length, and centromere location ○ Zea mays - 20 May differ in alleles (influence same trait but can code ○ Pisum sativum - 14 for different forms) Females: 23 homologous chromosomes; males: 22 (XY chromosomes = NOT homologous) Essential in meiosis, especially genetic recombination ○ Promotes genetic variation ○ Expands gene pool to acquire favorable genes BIO 130 LEC LU 2 SEM 1 | IMED 2030 Page 7 of 7 SAMSON, SDAV; MUSA, GS, OLIVA, JMM; REYES, JCDC