DNA and Protein Synthesis PDF

Nucleic Acid and Protein Synthesis Mind mapping and discussion Q1. Describe the di erence and similarity between the DNA and RNA: Similarities : Both have 4 types of bases Both have pentose sugar in their structure Both are long polymers made of nu...

Nucleic Acid and Protein Synthesis Mind mapping and discussion Q1. Describe the di erence and similarity between the DNA and RNA: Similarities : Both have 4 types of bases Both have pentose sugar in their structure Both are long polymers made of nucleotides Nucleotides bond by Phosphodiester bond Di erence : DNA has deoxyribose sugar (less o2 molecule) while RNA has Ribose sugar(more O2), DNA is double stranded while RNA is single stranded , DNA can replicate while RNA can’t replicate , DNA is more stable while RNA is less stable , DNA has 4 bases that are ‘A,G,C,T’ while RNA has 4 bases that are ‘A,C,G,U” so in RNA thymine is replaced by uracil Q2. Mention the types of nitrogen bases and the di erence between them : Can come as a Type 1: purines which are of double rings (large), and drawing and u should identify consist of adenine and guanine which base Type 2 : pyrimidines which are of single ring (small), and belongs to which consist of thymine , uracil and cytosine family Q3. Discuss the importance of hydrogen bonds or base pairing : Maintain the 3D shape of DNA molecule known as double helix Make DNA molecule stable Responsible for genetic stability and formation of 2 genetically identical daughter cells Allow DNA molecule to replicate Can be easily broken down during replication Q4. Explain Why DNA is Stable: It’s double stranded , follows the rule of base pairing (A=T,C=-G) and is extra protected and enclosed inside the nucleus Q5.Explain why DNA carry genetic information : As DNA is stable can replicate and produce protein , enclosed inside the nucleus Q6. What’s meant by semiconservative replication : Each parental strand acts as template to form a new complementary DNA by this 2 DNA will be produced each has 1 new and other complementary(old) strand ff ff ff Q7. Where and how does DNA replicates : DNA replicates during interphase more speci cally in the S phase by semiconservative replication as DNA unwinds due to breakage of hydrogen bonds by DNA Helicase enzyme, each strand acts as template to form new complementary strand by attracting activated nucleotides according to the base pairing rule (A=T,C=-G) with the help of DNA polymerase enzyme by this 2 DNA will be produced each has 1 new and 1 old complementary strand. Q8. Mention the importance of base pairing rule : Allows DNA to replicate , maintains genetic stability , allows storage of information in genes Q9. How’s protein synthesized: It’s synthesized by transcription followed by translation Transcription (occurs in the nucleus ) where part of DNA that’s needed to be transcripted unwinds due to breakage of hydrogen bonds by Hellicase enzyme , free activated RNA nucleotides pair up with their complementary ones and sugar phosphate groups are then bounded by RNA polymerase enzyme to form sugar phosphate backbone ,the formed mRNA leaves the nucleus through nuclear pore in the nuclear envelope and attaches to the ribosome in the cytoplasm nally DNA winds Explain how red again blood cells/ Translation (occurs in the cytoplasm and the ribosome is the plasma cells/ main involved organelle) : mRNA binds to the small subunit of antibodies / the ribosome and 6 bases become exposed to the large subunit enzymes develop of the ribosome the rst 3 exposed bases are AUG ‘start codon methionine’ ,tRNA with complementary anticodon bonds with codon and bring on speci c amino acid , second tRNA bonds with the second codons and bring on another amino acid the 2 amino acids bond together with peptide bond catalyzed by Peptidyltransferase enzyme, the ribosome moves along mRNA elongating the amino acid chain until reaching stop codon then the protein is released In case the question is asking about certain protein how is it synthesized and takes its nal 3D shape continue ur The strand needed for answer by mentioning that :the amino acid sequence is protein synthesis then packaged into shuttle vesicles and pinches out the is the sense / rough endoplasmic reticulum moving along cytoplasm exon /codon guided by cytoskeleton till reaching Golgi body where its strand further modi ed , processed thus protein X takes its nal 3D. Q9. Why DNA can be coded by more than 1 codon : As triplet bases are degenerate Q10. Mention the properties of the genetic code : Genetic code is universal’ same triplet genetic code codes for the same amino acid in all living organisms’, degenerate’ amino acid can be coded by more than one codon fi fi fi fi fi fi fi  Note: DNA= code mRNA =codon tRNA= anticodon Q10. De ne the following ( gene, allele, code, mutation): Gene: part of DNA molecule where nucleotide sequence codes for just one polypeptide Allele: di erent variant of gene which originally arose by mutation Code: triplet of 3 bases representing one amino acid on the sense strand Mutation : random and spontaneous change in the nucleotide sequence of gene resulting in an altered polypeptide Q11. Mention the e ect of gene mutation : Due to change in the DNA base sequence mRNA will change so , during translation new amino acid will replace the original ones thus sequence of amino acid will change changing the primary structure of protein and its 3D shape will change ,giving functionless protein Q12. Mention types of genetic mutation in terms of leading to frame shift : Base insertion and base deletion will lead to frame shift while base substitution won’t lead to frame shift but could lead to silent mutation. Q13. Why might base substitution lead to silent mutation: As the genetic code is degenerate and amino acid can be coded by more than one code so the substituted base may also result in production of the same amino acid Q14. Explain how red blood cells develop in bone marrow : The genes responsible to code for the hemoglobin production unwinds mRNA will be transcribed , during translation at the ribosome 2 tRNA carrying speci c amino acid will move to the ribosome where their anticodons on mRNA are present bringing amino acid in its proper sequence , the polypeptide chain then enters the Golgi body to be chemically modi ed by adding iron ions to form hemoglobin and gene coding for carbonic anhydrase unwinds and codes for carbonic anhydrase. Carbonic anhydrase is a protein(enzyme) found in the red blood cells nally nucleus disappears and cell takes its biconcave shape Q15. How does genetic mutation leads to sickle cell anemia : Change in sequence of DNA of beta polypeptide chain due to base substitution where ‘A’ replaces’T’ changing the code in DNA from ‘CTT’ to ‘CAT’ during transcription the mRNA will have a di erent codon ‘GUA’ instead of ‘GAA’ , during translation valine will replace glutamic acid (glutamine ) by this sequence of amino acid will be changed primary structure of protein will change thus the nal 3D shape of hemoglobin will change giving abnormal hemoglobin fi ff fi ff fi fi ff fi  Q16.Discuss the role of mRNA: Codes for production of amino acid sequence Carries complementary basses of genes in the form of codons due to transcription mRNA ts to ribosomes for translation Each mRNA must have a start and stop codon mRNA is short limit as it’s unstable and must allow the production of many protein molecules Polyribosomes will move along mRNA to form many polypeptides Q17. Discuss the role of tRNA: Has 2 ends at one end speci c to bind a speci c amino acid and the other end it has anticodon Each tRNA carries its speci c amino acid will be activated using energy from hydrolysis of ATP tRNA will move to the ribose where anticodons base pair with their complementary codon on mRNA bringing amino acid in its proper sequence A condensation reaction takes place between the 2 amino acids by peptidyl transferase to form a peptide bond The rst tRNA will be released to be reused The ribosome will move along the mRNA one codon after another until reaching a stop codon fi fi fi fi fi