Chapter 12

Double stranded
-Nucleotide made of the sugar deoxyribose, a phosphate group, and a nitrogen-containing base (A, G, C, or T)

-Single stranded
-Nucleotide made of the sugar ribose, a phosphate group, and a nitrogen-containing base (A, G, C, or U)

-When making a copy of the gene, the RNA nucleotides base pair with the DNA:
-DNA T pairs with RNA A
-DNA C pairs with RNA G
-DNA G pairs with RNA C
-DNA A pairs with RNA U
-The RNA copy is the blueprint that tells the cell which amino acids to join together to produce a protein
-Genetic information flow: DNA à RNA à protein

involves producing the copy of the required gene

involves decoding the copied RNA sequence and producing the protein for which it codes

binds to the promoter and makes a messenger RNA (mRNA)complementary to the DNA gene

carries amino acids, which bind to three-letter nucleotide sequences on the mRNA

Code sequences

The sequence from DNA dictates the order of amino acids in the proteins
-Scientists have figured out the genetic code and made a chart that tells what amino acid is coded for by what codon
-There are 64 codon combinations
-There are 3 codons (stop condons) that do not code for an amino acid
-There is one start codon – AUG
-All proteins are built starting at the start codon, so all proteins begin with the same amino acid – Methionine (met)

There are some codons that code for the same amino acids

No effect occurs when the mutation in the DNA does not change the amino acid that is called for

If one base is added or deleted

-All cells in all organisms undergo protein synthesis, but different cell types have somewhat different experiences:
-In eukaryotic cells, transcription occurs in the nucleus and translation in the cytoplasm… -Since prokaryotic cells have no nuclei, prokaryotic cell transcription and translation occur in the same location…

proteins that help RNA polymerase bind to the promoter

Step 1:  remove the gene from the cow chromosome
Step 2:  insert the BGH Gene into the bacterial plasmid
Step 3:  insert the recombinant plasmid into a bacterial cell

-The cow gene is sliced out using restriction enzymes
-Restriction enzymes cut DNA only at specific sequences, called palindromes…
-The bottom middle sequence is the reverse of the top sequence Restriction enzymes cut the DNA in a staggered pattern, leaving “sticky ends”…

-The bacterial plasmid is also cut with the restriction enzyme, leaving sticky ends
-A plasmid is DNA that is separate from the bacterial genome
-This is now recombinant DNA
-The BGH gene is referred to as the rBGH gene, with the r indicating that this product is genetically engineered

-The recombinant gene is then placed into bacterial cells
-Large numbers of these rBGH genes are copied
-The bacteria produce the BGH protein
-This works, because bacteria use the same genetic code as cows (and all living things) -Other proteins are made in this way:
-Insulin  for diabetics
-Clotting factors for hemophiliacs

-Manufactures must get FDA approval for an food not generally recognized as safe (GRAS), including new genetically engineered food substances
-The FDA declared milk from rBGH cows safe for consumption in 1993

seeks to answer questions for which there is no profit motive or direct commercial application – generally government funded

seeks to answer questions that will have an immediate and profitable application – generally privately funded

  can be used to insert a particular gene into plant cells

  inserts pellets covered with foreign DNA into the cells of such crop plants as corn, barley, and rice

produced when a gene from one organism is incorporated into the genome of another

The more popular term for transgenic organisms

-Much of the national debate on GMOs has centered on calls for labeling laws
-Proponents say labels will enable consumers to make better decisions
-Opponents counter that labeling is unnecessary in the absence of any proven health risk posed by GMOs

-Genetic manipulation could lead to decreasing variation within a species
-GM varieties of most corn and soybean crops are nearly identical genetically
-An unforeseen disease or pest could sweep through these crops, devastating them and those who rely on them

Sequenced the entire human genome

contain genes that are the same as human genes

Scientists used overlapping fragments to figure out the entire chromosomes

Can be researched by replacing defective genes with functional ones

the making of entire organisms using genetic engineering

Done instead of cloning entire organisms

are induced to turn into specific tissue cells

more able to become any other cell