Lesson 4: Central Dogma of Molecular Biology PDF

Lesson Number 03 for Quarter 3 Dates January 06 – 17, 2025 Subject Science 10 Lesson Title Central Dogma of Molecular Biology  Give examples of physical manifestations of chromosomal mutation Learning  Differentiate between numeric...

Lesson Number 03 for Quarter 3 Dates January 06 – 17, 2025 Subject Science 10 Lesson Title Central Dogma of Molecular Biology  Give examples of physical manifestations of chromosomal mutation Learning  Differentiate between numerical and structural Targets chromosomal mutations  Describe the types of chromosomal mutations, and their effects  Science 10 Breaking Through Science 10 (2nd Edition) Reference(s) Pp 204-221 Source(s)  Exploring Life Through Science  Baguio, S., Felicerta C., et al. Authors  Bayquen, A., Pavico, J., et al.  3 CENTRAL DOGMA MOLECUL of BIOLOGY AR QUARTER 3 | LESSO BIOLOGY N LESSON OBJECTIVES: At the end of the lesson, students should be able to; 1. Enumerate the different nucleotides in both DNA and RNA 2. Describe how mRNA is involved in the transcription and translation of genes 3. Explain how protein is made using information from the DNA sequence  CENTRAL DOGMA OF LIFE The central dogma of molecular biology describes the flow of genetic information in cells from DNA to messenger RNA (mRNA) to protein. GENE S A gene is a segment or segments of a DNA molecule, which in turn, make up a chromosome. Genes control the production of proteins- substances that determines the traits of an organism. CHROMOSO A chromosome is a thread- ME like structure that contains the DNA or the genetic information. Chromosomes are found inside the nucleus of a cell. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). LEVENE’s NUCLEOTIDES In 1920’s, American biochemist Phoebus Levene established the fact that DNA is composed of four nitrogenous bases, a deoxyribose sugar, and a phosphate group. He laid the groundwork for the building block of DNA known as Nucleotide. NUCLEOTID ES A nucleotide is the basic building block of nucleic acids. The nitrogenous bases are either double-ringed purines (Guanine [G] and Adenine [A]), or a single-ringed pyramidines (Cytosine [C], Thymine [T], and Uracil [U]). CHARGAFF RULES In the late 1940’s, Australian biochemist Erwin Chargaff analyzed the proportion of the nitrogenous bases in the DNA of various species. Rules for Pairing of Nitrogenous Bases: 1. DNA contains A, T, G, and C in proportions that vary from species to species. 2. Within the species, the amount of base pairs are equal that is, A=T and G=C WATSON-CRICK DNA MODEL Physical Properties of DNA 1. DNA is a double-stranded helix, which consists of two polynucleotide chains. 2. Both the polynucleotide strands of DNA have the opposite polarities, which mean that the two strands will run in the antiparallel direction, i.e. one in 5’- 3’ and other in 3’-5’ direction. 3. The diameter of ds-stranded DNA helix is 20 angstrom. WATSON-CRICK DNA MODEL Physical Properties of DNA 4. The distance between the two nucleotides or internuclear distance is 3.4Å. The length of DNA helix is 34Å after a full turn (360°) and it possesses 10 base pairs per turn. 5. The DNA is twisted in “Right-handed direction” or we can say in a “Clockwise direction”. 6. Turning of DNA causes a formation of wide indentations, i.e. “Major groove”. The distance between the two strands forms a narrow indentation, i.e. “Minor groove”. WATSON-CRICK DNA MODEL Chemical Properties of DNA 1. There are four nucleotide bases present in the polynucleotide chain like adenine, guanine, cytosine and th ymine. 2. The two strands are joined together by the “Complementary base pairing” of the nitrogenous bases. 3. The nucleotide bases in the polynucleotide strands of DNA will join with each other through a strong hydrogen bond. WATSON-CRICK DNA MODEL Chemical Properties of DNA 4. Adenine complementarily pairs with thymine through two hydrogen bonds, whereas guanine complementarily pairs with cytosine by means of three hydrogen bonds. 5. Polynucleotide strands of DNA consist of three major components, namely nitrogenous bases, deoxyribose sugar and a phosphate group. 6. The backbone of DNA consists of the sugar- phosphate backbone. What is the difference between RNA and DNA? DNA and RNA DNA RNA Deoxyribose Ribose Sugar () () Strand Double-Stranded Single-Stranded Adenine Adenine Nitrogenous Thymine Uracil Bases Cytosine Cytosine Guanine Guanine Mostly in the Mostly in the nuclues, cytoplasm. But but may also found in Location may also be the cytoplasm and found in the mitochondria. nucleus. Blueprint of biological Assists in carrying guidelines that living out DNA’s Function organisms must follow blueprint to exist and function guidelines. properly. Key Features of DNA DNA is STORED Organized into genes and packaged chromosomes. DNA is REPLICATED Duplicates genetic information with high fidelity. DNA is EXPRESSED Provided with mechanism to affect phenotypes. DNA is DIVERSIFIED Ability to mutate to produce variation and drive evolution. Genetic Code In genetic language, the material found inside the nucleus which makes up an organism’s complete set of genes called genotype must be expressed as an observable characteristics or phenotype. This means proteins (phenotype) are produced using the language coded in the DNA (genotype) Genetic Code PROTEIN SYNTHESI S PROTEIN SYNTHESIS Protein synthesis involves three major processes- replication, transcription and translation. A process that takes place in the ribosomes through which the cell generate new proteins. REPLICATIO N Cells need to make identical copies of their genetic information for growth and repair. Replication happens before cell division as each new cells are required to have an exact copy of the parent cell’s DNA. REPLICATIO N Two DNA strands connected by hydrogen bonds separate from each other. Each old strand of the parent DNA is then used as a template for the building of new strand in the daughter DNA and this process is called semiconservative replication. REPLICATIO N The process consists of three steps – unwinding, base pairing, and joining. REPLICATIO N 1. UNWINDING Replication begins with an enzyme, DNA Helicase, it breaks the hydrogen bonds between the nucleotides. This divides the DNA into two single strands. As the helix unwinds, new nucleotides are added to the parental template strand by the enzyme, DNA Primase. REPLICATIO N 2. BASE PAIRING The DNA Polymerase then continues to add more complementary base pairs such that A binds only to T, and C only to G. DNA Polymerase does proofreading to avoid mistakes. REPLICATIO N 3. JOINING At the end of the process, the enzyme DNA ligase seals any breaks in the new DNA strand. Both DNA polymerase and DNA ligase also repair the DNA strands when damaged by harmful radiation or toxic chemicals. TRANSCRIPTI ON It is the RNA’s job to make blueprint copies of the DNA’s instructions. Three kinds of RNA are involved in the process of protein synthesis, namely, the messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). TRANSCRIPTI ON Before protein can be synthesized, the DNA information or code must first be copied or transcribed to a type of RNA called mRNA (messenger RNA). The DNA coded that are transcribed into mRNA are carried as units called codons. Each codon consists of three nitrogenous bases coding for a particular amino acid. TRANSCRIPTI ON The enzyme RNA polymerase initiates the DNA transcription which ensures the right sequences are transcribed and produces a complementary strand. TRANSCRIPTI ON To form the RNA strand, mRNA bases pair up with existing DNA bases. This process is very similar to replication, except that it uses Uracil instead of Thymine, to pair with Adenine. The mRNA leaves the nucleus with the copy of the genetic instructions and enters the cytoplasm. TRANSLATI ON Translation is the last stage in gene expression, which leads to the formation of protein. Specifically, translation is the process involved when genetic information is used to create amino acids and the corresponding proteins. The process of translation takes place in the ribosome. TRANSLATI ON The transfer RNA (tRNA) attaches to the mRNA inside the ribosome. Acting as an interpreter, the bases on the tRNA are special triplet of bases called anticodons. Anticodons “read and translate” the message by pairing up an equivalent three-letter code to the codons of the mRNA. TRANSLATI ON The transfer RNA (tRNA) attaches to the mRNA inside the ribosome. Acting as an interpreter, the bases on the tRNA are special triplet of bases called anticodons. Anticodons “read and translate” the message by pairing up an equivalent three-letter code to the codons of the mRNA. CODON TABLE AMINO ACIDS 20 Amino Acids Phenyl-alanine- Phe Glutamine- Gln Leucine- Leu Asparagine- Asn Isoleucine- Ile Lysine- Lys Methionine; Start Aspartic Acid- Asp codon- Met Glutamic Acid- Glu Valine- Val Cysteine- Cys Serine- Ser Tryptophan- Trp Proline- Pro Arginine- Arg Threonine- Thr Glycine- Gly Alanine- Ala Tyrosine- Tyr Histidine- His Processing Question: 1.What happens during DNA replication? 2.What are the different enzymes crucial in the success of DNA replication? 3.What will happen if the DNA strand is not transcribed to mRNA? 4.What will happen to the mRNA if the codons are not properly translated into amino acids? 5.How importance is the codon table? LET’S TRY TRANSLATING! 1. Identify the corresponding amino acids of the following mRNA codons. GCU: Alanine- Ala UCG: GGU: AAC: CGC: LET’S TRY TRANSLATING! 1. DNA to Protein DNA: CCA-TAT-AGA-ATT-TGC mRNA: Amino Acid: LET’S TRY TRANSLATING! 1. DNA to Protein DNA: TAC-ACG-GAA-CCG-ATC mRNA: AUG-UGC-CUU-GGC-UAG Amino Acid: Methionine-Cysteine-Leucine- Glycine-Stop or Met-Cys-Leu-Gly- Stop LET’S TRY TRANSLATING! 1. DNA to Protein DNA: TAC-CCA-TAT-AGA-ATT mRNA:AUG-GGU-AUA-UCU-UAA Amino Acid:Met-Gly-Ile-Ser-Sto LET’S TRY TRANSLATING! 2. DNA to Protein DNA: TAC-GGT-TGC-ATA-ATT mRNA:AUG-CCA-ACG-UAU-UAA Amino Acid: Met-Pro-Thr-Tyr-Sto LET’S TRY TRANSLATING! 2. DNA to Protein DNA: TAC-TAG-GCA-CTA-ACT mRNA:AUG-AUC-CGU-GAU-UGA Amino Acid: Met-Ile-Arg-Asp-Sto IT’S BEADS TIME! Bring the following materials tomorrow: Beads (Different Colors, Shapes, Style, Sizes, and etc) Beads String ASSIGNMENT: ½ Crosswise Research the following: 1. How does the processing of genetic information cause genetic variation? 2. How does mutation influence heredity and variation?