Unit 6- Genetic, Biotech, and Decision-making

DNA

DNA is a nucleic acid that contains nucleotides. Nucleotides consist of a phosphate group, a sugar (deoxyribose), and a nitrogenous base. The nitrogenous bases are adenine, guanine, cytosine, and thymine, which are paired based on their charges and lengths. Adenine and guanine are purines that have two rings and cytosine and thymine are pyrimidines that have one ring.

  • General structure

    • Nucleic Acid

      • Nucleotide- building blocks

        • phosphate

        • sugar

          • deoxyribose

        • nitrogenous base

          • paired for charges and lengths

            • purines

              • adenine

              • guanine

              • two rings (longer)

            • pyrimidines

              • cytosine

              • thymine

              • one ring (shorter)

  • Role of DNA

    • Chapter 13, p. 417

    • Carries instructions to create proteins

    • Stays in the nucleus to protect instructions

  • Replication

  • DNA carries instructions to create proteins and is located in the nucleus for protection. There are two types of cells: eukaryotic and prokaryotic. In eukaryotic cells, DNA replication is semiconservative, which means that each strand of DNA separates and becomes a template for the synthesis of two new complementary strands. In prokaryotic cells, replication starts from a single point and goes in both directions until completed. An enzyme called polymerase joins nucleotides and proofreads the newly synthesized strands to ensure accuracy.

    • Eukaryotic

      • Two strands of DNA separate/untwist

      • each strand becomes a template

      • two new complementary strands can be synthesized

      • begins at many places at once

      • semiconservative

    • Prokaryotic

      • Replication starts from a singular point and goes in both directions until finished.

    • Polymerase

      • enzyme that joined nucleotides

      • “proofreads”

    • Telomeres

      • the tip of eukaryotic chromosomes

      • the enzyme telomeres add short, repeated DNA sequences to telomeres as the chromosomes are replicated

RNA

RNA plays a crucial role in protein synthesis and gene expression. All RNA is produced in the nucleus before traveling to the cytoplasm. There are three types of RNA, each with its own function. Messenger RNA (mRNA) is a copy of the portion of DNA that will be used to produce a protein. Transfer RNA (tRNA) carries amino acids from the cytoplasm to the mRNA. Ribosomal RNA (rRNA) is part of ribosomes, which consist of two subunits made of ribosomal proteins and RNA.

  • General structure

    • a single-stranded molecule composed of nucleotides. It consists of a sugar-phosphate backbone with four nitrogenous bases: adenine (A), cytosine (C), guanine (G), and uracil (U). RNA plays a crucial role in protein synthesis and gene expression.

  • Different types and their functions

    • All RNA is made in the nucleus and then travels to the cytoplasm

    • Messenger RNA (mRNA)

      • copy of the portion of DNA that will be used to make a protein.

    • Transfer RNA (tRNA)

      • carry amino acids from the cytoplasm to the mRNA

    • Ribosomal RNA (rRNA)

      • ribosomes consist of two subunits which are made of ribosomal proteins and RNA.

  • Transcription

    RNA polymerase binds to and separates DNA strands to assemble complementary mRNA nucleotides, binding only to specific base sequences in promoter regions.

    • RNA synthesis

    • Segments of DNA serve as templates to produce a complementary mRNA molecule

      • RNA polymerase

        • binds to DNA, separates strands

        • assembles RNA nucleotides

        • binds only to regions of DNA that have specific base sequences

          • promoter region

  • Translation

    • starts when a ribosome attaches to an mRNA molecule. Then, tRNA molecules, carrying amino acids with them, bind to mRNA codons. The ribosome helps form a peptide bond.

      • it breaks the bond holding the tRNA molecule to its amino acid.

    • The ribosome reaches a stop codon releasing the newly synthesized polypeptide and the mRNA molecule.

    • When a gene is used to build a protein, scientists say that the gene has been expressed.

      • Codon chart

        • Three consecutive bases that specify a single amino acid are shown through codon charts.

        • stop and start codons

        • there are 20 amino acids

Mutations 

  • Horrible change in genetic information

  • Gene mutation

    • formation shift

      • substitution

      • insertion

      • deletion

    • silent

      • Point

        • change in a single nucleotide

  • Chromosomal 

    • change in the structure of the chromosome or number of chromosome

    • deletion, duplication, inversion, translocation

Vocabulary

  • Anticodon

    • a sequence of three nucleotides in a transfer RNA molecule that is complementary to a codon in messenger RNA during protein synthesis.

  • Codon

    • three-letter sequence found in an RNA molecule

    • codes for amino acids

    • The genetic relationship

      • all organisms read code this way

      • most amino acids are specified more than one codon

Prokaryote vs. eukaryote

  • Prokaryote DNA:

    • Found in the nucleoid region, a region within the cytoplasm where genetic material is located.

    • Prokaryotic DNA is typically circular in shape, unlike the linear structure found in eukaryotic cells.

    • Prokaryotic DNA lacks introns, which are non-coding segments of DNA that interrupt the protein-coding sequences.

  • Eukaryote DNA:

    • Eukaryotic DNA is contained within the nucleus, a membrane-bound organelle that houses the genetic material of the cell.

    • Unlike prokaryotic DNA, eukaryotic DNA has a linear structure with distinct ends.

    • One of the key differences is that eukaryotic DNA contains introns, segments of DNA that do not directly code for proteins and must be removed through RNA splicing during gene expression.