DNA, RNA, PROTEIN

• Protein synthesis involves transcription (DNA to mRNA) and translation (mRNA to protein).
• DNA structure:

  • DNA is a polymer of nucleotides
  • Each nucleotide composed of four DNA base
• DNA: Complimentary base pairing:

  • A pairs with T
  • C pairs with G
• DNA replication:

  • DNA is a double helix
  • Enzyme DNA topoisomerase untangles the coils
  • Enzymes Helicase unzip the DNA molecule exposing both strands of nitrogenous bases
  • DNA polymerase pairs the bases A-T and G-C
  • DNA ligase bonds the nucleotides together
  • DNA replication begins at specific sites called origins of replication
  • Replication bubbles are created as the copying proceeds outward in both directions
  • End product: two double-stranded DNA molecules, each with one new and one old strand
• RNA structure:

  • RNA is Ribonucleic Acid
  • RNA contains ribose sugar
  • Bases in RNA are A, G, C, and U (Uracil)
  • RNA is single-stranded and shorter
• Central Dogma:

  • Central Dogma involves DNA, RNA, and Proteins
  • Three different RNA molecules involved in protein synthesis: mRNA, rRNA, tRNA
  • Transcription occurs in the nucleus
  • Translation occurs in the cytoplasm
• Transcription:

  • Transcription occurs in the nucleus
  • mRNA is formed by base pairing with the parent strand of DNA
  • mRNA carries the message from DNA to the ribosome
  • Enzymes remove Introns and leave Exons
• Translation:

  • Translation synthesizes a code from amino acids according to mRNA sequences
  • Translation occurs at the ribosome in the cell cytoplasm
  • tRNA brings specific amino acids to the ribosome
  • Ribosomes are the sites of translation
• Transfer RNA (tRNA):

  • tRNA is a transport molecule that carries specific amino acids to a ribosome
  • Each tRNA recognizes the correct codon on the mRNA molecule
• Protein synthesis:

  • Protein synthesis occurs in the cytoplasm of the cell
  • Codons are read in one direction only
  • Redundancy exists in the genetic code
• Mutations:

  • Changes in the DNA sequence that may be passed to future generations
  • Types of mutations: point mutations, deletion, insertion, frame-shift mutation
  • Somatic mutations occur in body cells and do not lead to gametes
• Transcription occurs in the nucleus, while translation takes place on ribosomes in the cytoplasm.
• The ribosome acts as the factory of the cell by synthesizing proteins from the instructions contained in mRNA molecules.
• Translation is the process by which genetic information encoded in mRNA is used to assemble amino acids into proteins.
• Transcription is the process by which information from a gene is copied into an mRNA molecule.
• The Central Dogma states that DNA makes RNA, and RNA makes Protein.
• The process of transcription involves the formation of messenger RNA (mRNA) through base pairing between complementary bases on the template strand of DNA.
• During translation, transfer RNA (tRNA) brings specific amino acids to the ribosome based on their corresponding anticodons.
• Point mutations involve changes in a single base pair, while deletions or insertions can result in frameshift mutations if they occur within a gene's coding region.
• During transcription, the DNA double helix unwinds and separates into two strands, with one serving as a template for the formation of an mRNA copy.
• In eukaryotes, the process involves three types of RNA: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).
• once mRNA is formed, enzyme in the nucleus remove the Introns and leave the exons
• introns (noncoding message) while exons (good message)
• Translation is the second step of gene expression, during which the genetic information encoded in mRNA is used to synthesize proteins.
• The mRNA molecule then moves out of the nucleus through nuclear pores and enters the cytoplasm where translation occurs.
• Once intron are removed from mRNA, it leaves only coding region which will be translated to protein
• A chromosome consists of smaller segments called genes
• Recombinant DNA technology involves manipulating and isolating DNA segments to create recombinant DNA with new functions
• DNA Replication

  The process is fast and accurate

  an error occurs in only about one of a

  billion nucleotides.
• DNA replication begins at specific

  sites called origins of replication.
• dna replication End product: two double-stranded DNA

  molecules, each with one new and one

  old strand.
• 3 different RNA molecules involved in

  protein synthesis:

  mRNA (messenger RNA)

  rRNA (ribosomal RNA

  tRNA (transfer RNA)
• PROTEIN SYTNESIS

  1 step: Transcription

  occurs in the nucleus

  2 step: Translation

  occurs in the cytoplasm
• Transcription: DNA 🡪 RNA

  Transcription occurs in the nucleus

  First: DNA unwinds in a section

  Next: mRNA (messenger RNA) is formed by base pairing

  with the parent strand of DNA. This begins transcription.

  Then: mRNA carries the message about what type of protein to

  make from the DNA in the nucleus to the ribosome
• The genetic code consists of 64 codons,

  but only 61 code amino acids.

  Three codons act as

  signal to stop the process

  One codon, AUG, codes

  for methionine, and is also

  the Start signal for translation.
• Translation: RNA 🡪 Protein

  Translation: synthesizing a code from amino

  acids, according to the sequences of the

  nucleotides in mRNA.

  Occurs at the ribosome, in cytoplasm of cell

  Ribosomal RNA, rRNA, is needed for protein

  synthesis – helps mRNA bind to the ribosome

  tRNA, brings specific amino acids to the

  ribosome to be assembled as proteins.
• Steps in Translation

  mRNA leaves the nucleus and migrates to ribosome

  mRNA binds to small ribosomal subunit

  tRNA brings an amino acid to the ribosome, where

  anticodon on the tRNA binds to the codon of the

  mRNA

  The amino acid bonds to its adjoining amino acid to

  form a growing polypeptide molecule

  The tRNA without the amino acid is released from the

  ribosome

  Other tRNA’s bring amino acids to the ribosome to

  complete the protein molecule
• Mutations: changes in the DNA sequence, that may be

  passed along to future generations.
• Point mutations: a single base substitution
• Deletion: a small DNA segment is lost