Unit 6:DNA, RNA, Genetic

EngineeringEssential Concepts and Skills - SOL 2 & 6

1. The genetic code is contained in DNA.a) DNA (deoxyribonucleic acid) is a macromolecule (polymer) made up of repeating

subunits called nucleotides (monomers). b) The genetic code is the sequence of DNA nucleotides in the nucleus of a cell.c) The DNA code controls cell activities by telling the cell which proteins to make

(especially enzymes).d) There are four DNA nucleotides: adenine (A), guanine (G), thymine (T), cytosine (C).e) DNA is a double-stranded molecule. The strands are connected by complementary

base pairs: A-T and C-G, like rungs on a ladder.f) The ladder twists to form a double helix.g) Nitrogen bases that have a double ring of carbon = Purines (A & G).h) Nitrogen bases that have a single ring of carbon = Pyrimidines (C & T).

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2. Cells pass on the genetic code by replicating (copying) their DNA. (DNA replicates during Interphase).a) Enzymes unwind and unzip the double helix.b) Each strand serves as a template for building a new DNA

molecule.c) Free nucleotides bond to the template (A-T and C-G), forming a

complementary strand.d) The final product is two identical DNA molecules.

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3. RNA (ribonucleic acid) is a macromolecule made up of repeating subunits called nucleotides (monomers). a) RNA is a single-stranded polymer of four nucleotide monomers.b) A RNA nucleotide is identified by the base it contains: adenine (A), guanine (G), and cytosine (C) or uracil (U).

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4. RNA comes in 3 forms: a) mRNA – carries the message from DNA in the nucleus to the ribosomes in the cytoplasm (messenger RNA). b) tRNA- carries amino acids to the mRNA (transfer RNA) c) rRNA- found in the ribosomes (ribosomal RNA).

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5. Proteins are synthesized using the genetic code (sequence of DNA nucleotides)- Proteins (enzymes) control the activities of each cell. a) The genetic code is the sequence of DNA nucleotides in the nucleus of each cell.b) The DNA code controls cell activities by telling the cell which proteins to make

(especially enzymes).c) There are 2 steps in protein synthesis: Transcription and Translationd) Transcription: The DNA code is transcribed (copied) to messenger RNA (mRNA)

inside the nucleus.e) The mRNA carries the code from the nucleus to the cytoplasm.f) Translation: In the cytoplasm, at the ribosomes, the mRNA code is translated to a

sequence of amino acids. The amino acids are carried by tRNA).

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g) The amino acids are linked together to form specific proteins.

6. Inserting, deleting, or substituting DNA segments can alter genes and make a new phenotype (mutations).

a) Mutations are changes in the DNA sequenceb) A changed (mutated) gene may be passed on to every cell that develops from it,

causing changes. c) An altered gene (mutation) may be beneficial, detrimental, or have no effect.d) Sometimes entire chromosomes can be added or deleted, resulting in genetic

disorders such as Trisomy 21 (Down syndrome), Turner Syndrome (X0), or Klinefelter’s Syndrome (XXY)

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7. DNA technology: Genetic Engineering and DNA Fingerprintinga) The tools of genetic engineering:

1. Extract DNA; 2. Cut DNA with restriction enzymes; 3. Separate the pieces of DNA using gel electrophoresis; 4. Make copies of the DNA using PCR (Polymerase Chain Reaction).

b) DNA Fingerprinting: DNA is cut and separated using gel electrophoresis. The pattern of bands is unique for each individual. Used in forensics, criminal, and paternity cases.

c) Transgenic Organisms: Insert a piece of foreign DNA into the DNA of an organism. The piece of DNA inserted carries a gene with a desirable trait. Common application: Insert gene for vitamins or production of insecticide in plants; insert gene for insulin or, human growth hormone, into bacteria or other easily raised organisms.

d) Recombinant DNA: DNA made from combining the DNA of 2 different organisms (different species)

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8. The Human Genome Project was a collaborative effort to map the entire gene sequence of organisms.

The goals of the Genome Project were to: 1. Sequence the DNA2. Identify the genes that cause diseases3. Map the location of every gene in the chromosomes

This information will be useful in detection, prevention, and treatment of many genetic diseases, but it raises practical and ethical questions too.

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9. Cloning is the production of genetically identical cells and/or organisms starting with a single cell. Sheep, cows, dogs, cats, mice have already been cloned experimentally. Cloned cattle are available for farming purposes.

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Must Know Vocabulary- DNA- RNA- nucleotide- genetic code-- complementary bases/ strands- Nitrogen bases- Adenine- Thymine- Uracil- Cytosine- Guanine- double helix- messenger RNA- transfer RNA- ribosomal RNA- amino acids

- proteins- gene- translation- transcription- replication- anticodon- codon- chromosome- Rosalind Franklin- Watson & Crick- Protein synthesis- Genetic Engineering- Human Genome Project- DNA fingerprinting

- Clone/Cloning- Transgenic Organism- Polymerase Chain Reaction (PCR)- Plasmid- Restriction Enzymes

- Gel electrophoresis

-Exons

-Introns