Science - Chapter 11 Cheet Sheet

Final Version

DNA Cheat Sheet

11.1

• DNA controls you by giving the necessary instructions your body needs to produce the proteins you need.

• DNA stands for Deoxyribo-Nucleic Acid.

• DNA is a double helix.

• Nucleotides are made of:

  • A simple sugar (ribose)

  • A phosphate group

  • A nitrogen base

    • Nitrogen base – carbon ring structure that contains one or more atoms of nitrogen

    • 4 possible base types: Adenine, Guanine, Cytosine, and Thymine

      • Pairing: Good Cats : Annihilate Tacos! GC, AT

      • Purines: Good Angels are pure (G and A)

      • Pyrimidines: Thebes the Cat's pyramid (T and C)

  • Nucleotides bond by connecting phosphate and deoxyribose molecules.

• Important people in DNA discovery:

  • Watson

  • Crick

  • Franklin

  • Chargaff

• The sequence of nucleotides is the genetic code of an organism.

• DNA replication is the process of copying DNA.

  • Steps

    • 1. DNA is seperated with DNA Polymerase (an enzyme)

    • 2. Nucleotides in the nucleoplasm bond with the separated DNA strands.

    • 3. Another enzyme joins the nucleotides and already constructed strand together.

    • 
      

11.2

• DNA codes for all the proteins your body makes.

• RNA makes the protines

  • Differences between RNA and DNA

    • RNA is single stranded.

    • The sugar in RNA is ribose (DNA has deoxyribose)

    • RNA has uracil instead of thymine.

• Three types of RNA

  • messenger RNA (mRNA)

    • contains information for making proteins

    • is made via transcription (process like DNA replications, but instead RNA is formed and breaks off into a single strand instead of a double)

  • transfer RNA (tRNA)

    • has anti-codons

    • chains together amino acids with peptide bonds

  • ribosomeal RNA (rRNA)

    • RNA on the ribosome for translation

• Codon – 3 nitrogen bases that get made into an amino acid

• All organisms have the same genetic code for amino acids.

• The process of converting RNA to proteins is called translation.

  • Step 1: tRNA's anti-codon temporarily bonds with a corresponding mRNA codon.

  • Step 2:

• REMEMBER: Things must be transcripted before they can be translated.

11.3

• Changes in DNA sequences are called mutations

• Mutated organisms are called mutants

• Mutation can occur

  • as a result of changes in the DNA of sex cells

  • from environmental sources (radiation, mutagens)

• Cancer can result from mutations

• Point mutations are mutations where a single base pair is changed in DNA.

• Frameshift mutations are mutations in which a single base is added or deleted from DNA.

• Chromosomal mutations are changes in chromosomes, such as nondisjunction.

  • These changes occur frequently in plants.

  • Few chromosomal mutations are passed on to the future generations.

    • Most CM organisms are either sterile (cannot reproduce) or die at birth.

  • 4 chromosomal mutations:

    • deletion: part of chromosome is left out

    • insertion: part of a sister chromatid attaches itself to the other sister chromatid

    • inversion: parts in the chromosome are exchanged

    • translocation: parts of a chromosome are attached to a completely different chromosome

• Any agent that causes a change in DNA is called a mutagen.

  • Radiation, chemicals, and sometimes high temperatures are all mutations.

    • Radiation can delete bases.

    • Chemical mutagens usually result in a substitution mutations.

• DNA can repair itself with special enzymes.

Section 10.2

• Diploid – Normal cell with 2n number of chromosomes from either parent organism

• Haploid – only one kind of chromosome (n). These cells are gametes usually.

• Homologous chromosomes – chromosomes that determine the phenotype of an organism's cells that will have the same genes for a trait but not in the same order, necessarily.

• If sex cells had the number of chromosomes that a normal cell has, the amount of chromosomes would increase over time. This is why meiosis occurs.

• Meiosis Cycle, easy way to remember:

  • Prophase (Please) – Spindle fibers form, tetrads form, crossing over may occur

  • Metaphase (Make) – Tetrads attach to spindle fibers, move to equator

  • Anaphase (Another) – Tetrads split into double stranded chromosomes and move to opposite ends

  • Telephase (Taco) – Spindle breaks down, chromosomes uncoil, cytoplasm divides

• Meiosis II = EXACTLY THE SAME EXCEPT: It yields 4 gametes instead of two normal cells.

• 70 TRILLIAN different combinations, excluding genetic crossover.

• Genetic recombination – basically, genetic crossover

• Nondisjunction – failure of chromosomes to separate during meiosis

• Trisomy – when an gamete with an extra chromosome fuses with a normal gamete

  • Many organisms with extra chromosomes will survive

• Monosomy – when a gamete misisng a chromosome fuses with a normal gamete

  • Organisms will not survive monosomy most of the time, but Turner syndrome, where females have only one X chromosome, is one non-lethal example

• Triploid – organism has three sets of chromosomes

• Tetraploid – organisms has four sets of chromosomes

• Polyploids – organisms with more than the usual number of chromosome sets

  • Animals that are polyploidal almost always die

  • Polyploidal plants usually will survive with unique characteristics, such as enlarged size and greater health.

  • Plant breeders have learned how to cause polyploidal conditions in plants using chemicals