Table of Contents:
I. DNA and RNA Structure and Function
II. Structure and Function of RNA
III. Gene Expression
IV. Genomics
V. DNA Technology
I. DNA and RNA Structure and Function
A. DNA (deoxyribonucleic acid)- genetic material largely found in the chromosomes.
(Insert chromosome picture/ Frolich PowerPoint slide 14)
1a. DNA Must be able to replicate, store information, and undergo mutations to provide changes in genetics. (Mader 444)2a. DNA is transcribed to make proteins that run cell metabolism. (Frolich PowerPoint Slide 13)
3a. REVIEW: Each chromosome is a single DNA molecule wrapped up within a special group of proteins giving it a particular shape. (Frolich PowerPoint Slide 14)
4a. Structured to replicate: DNA is “double helix”—two complementary strands wound in a spiral.
(Insert DNA structure picture / Frolich PowerPoint Slide 15)
5a. Each strand is a polynecleotide. The phosphate and sugar molecules create a backbone and the bases go out to one side. Two strands together, DNA looks like a ladder. (Mader 444)
6a. Strands separate and DNA replicates by filling in other half of each separated strand. (Frolich PowerPoint Slide 15)
(Insert DNA replication picture / Frolich PowerPoint Slide 16)
7a. Complementary paired bases: Hydrogen bonding between particular bases; in DNA, (T) pairs with (A), and (G) pairs with (C). (Mader Glossary G-5)
8a. DNA base purine (2 rings) is always paired with pyrimidine (1 ring). (Mader 444)
B. Replication of DNA
1b. After a cell divides, each new cell gets an exact copy of DNA. (DNA replication)
2b. During this replication, each original strand serves as a template for the new strand. "Semiconservative"- each new double helix has one brand new strand, and one original.
3b. Mutation- a permanent change in the sequence of bases that results from a replication error that makes the new DNA strand different from the parental strand. Repair enzymes usually fix this error. (Mader 445)
II. Structure and Function of RNA
A. RNA (riconucleic acid): Consists of nucleotides that contain the sugar ribose. Single-stranded. B. RNA molecule is made up of 4 nucleotides with the following bases: adenine (A), uracil (U), cystosine (C), and guanine (G).
C. RNA is a helper to DNA, allowing protein synthesis to occur according to the genetic information in DNA.
(Insert dna and rna picture / http://www.acmecompany.com/stock_thumbnails/13217.dna_&_rna_helixes.jpg)
D. 3 types of RNA: Ribosomal, Messenger, and Transfer
1d. Ribosomal: produced in the nucleolis of nucleus where DNA serves as a template for it's formation. Joins with the proteins made in the cytoplasm and forms ribosomes. These then leave the nucleus, rejoin in the cytoplasm, and protein synthesis can begin. Synthesized in the ribosomes. (Mader 446)
2d. Messenger: Produced in nucleus, DNA is template. Carries genetic info. from DNA to ribosomes in cytoplasm where protein synthesis occurs. 3d. Transfer: Produced in nucleus. Transfers amino acids to ribosomes, where amino acids join to form a protein. (Mader 446)
E. Similarities and Differences between DNA and RNA:
1e. Similarities: both are nucleic acids, composed of nucleotides, have a sugar-phosphate backbone, 4 different types of bases.
2e. Differences: DNA found in nucleus, RNA in nucleus and cytoplasm. DNA is the genetic material itself, RNA is the helper to DNA. DNA's sugar is deoxyribose, RNA's sugar is ribose. DNA bases are A,T,C,G, and RNA bases are A,U,C,G. DNA is double-stranded, RNA is single. DNA is transcribed (given to messenger rna), RNA is translated to give to proteins. (Mader 446)
III. Gene Expression
A. Structure and function of proteins:
1a. Proteins are composed of subunits called amino acids. There are 20 of these acids that are commonly located in proteins. Synthesized at the ribosomes in the cytoplasm. The sequence of amino acids in the protein give it it's shape.
2a. Proteins are responsible for determining the structure and function of the cells in the body.
3a. Enzymes: organic catalysts that speed reactions in cells. (Mader 447)
(Insert enzyme picture / http://www.staff.brookings.k12.sd.us/ http://www.staff.brookings.k12.sd.us/Reidell/images)
B. Gene expression: Step 1: Transcription: a strand of mRNA forms that compliments a portion of DNA. The mRNA molecule that forms is a transcript ("faithful copy") of a gene. (Mader 448) Simplified terms: DNA is read to make a mRNA in the nucleus of our cells. (Frolich PowerPoint Slide 18) Occurs in nucleus. Double-helix "opens up" and the mRNA transcript is made from the DNA template. (Frolich PowerPoint slide 19)
1b. Translation: sequenc of nucleotides is tranlated into the sequence of amino acids. (Mader 448) Simplified terms: Reading the mRNA to make a protein in the cytoplasm. (Frolich PowerPoint Slide 18) Happens outside of nucleus. Translated by ribosomes. They stick to mRNA and line up the amino acids. (Frolich PowerPoint slide 20)
C. The Genetic Code: Triplet Code: Every three RNA bases codes for one amino acid. (Frolich PowerPoint slide 21)
1c. Codon: three-letter base unit of mRNA molecule.
D. Gene expression, summarized: DNA is transcribed to make proteins that run cell metabolism. •DNA is transcribed to mRNA
•mRNA is translated to amino acid sequence
•Amino acid sequence folds up into protein
•Proteins catalyze reactions of cell metabolism
•This process is called “gene expression”—the information in one region of the DNA—a “gene”—is being expressed so that the cell’s metabolism can function (Frolich PowerPoint slide 17)
(Insert overview of transcription and translation picture / PowerPoint slide 22)
E. Regulation of Gene Expression:
•Gene expression is regulated—not all genes are constantly active and having their protein produced.
•The regulation or feedback on gene expression is how the cell’s metabolism is controlled. (Frolich PowerPoint slide 24)
1e. 4 primary levels of control: a. Transcriptional control: In nucleus, several things regulate which genes are transcribed and teh rate of that transcription. ie. organization of chromatin and the use of transcription factors to being transcription. b. Posttranscriptional control: In nucleus, occurs after DNA is transcribed to mRNA. c. Translational control: In cytoplasm, occurs after mRNA leaves the nucleus and before protein synthesis. d. Posttranslational control: In cytoplasm, occurs after protein synthesis. (Mader 453) When this regulation doesn't work right, the result is cancer! (Frolich PowerPoint slide 24)
2e. In order for a gene to be transcribed in human cells, the chromosome in that region must first decondense (unpackage and uncoil) before it can be transcribed to mRNA. (Mader 453) and (Frolich PowerPoint slide 23)
(Insert Lampbrush chromosomes picture / Frolich PowerPoint slide 23)
3e. Lampbrush chromosome shows loops of DNA that are being transcribed. When mRNA is being synthesized, chromosomes decondense and each chromosome has numerous loops protruding from its axis. (Mader 453)
4e. Transcription factors: DNA-binding proteins. Each cell has many different types, and they regulate the activity of genes. (Mader 453)
IV. Genomics
A. Genomics is the study of genomes (our genes and those from other organisms).
B. The Human Genome Project lasted 13 years and resulted in the discovery of the order of the 3 billion bases A, T, C, and G in our genome.
1b. First, investigators deciphered a short sequence of base pairs. Sperm DNA was used becuase it has a much higher ratio of DNA to protein than other types of cells. White blood cells from femals were also used. Many polymorphisms (small regions of DNA that vary between individuals). "Also found that genome size is not proportionate to the number of genes and does not correspond to the complexity of the organism." Another discovery was that the base sequence of humans is very similar to animals. Approx. 25000 human genes. Comparing genomes is one way to figure out how species have evolved. Next, researchers hope to find out how our 25000 genes funcion in cells and how human base sequence differences are linked to illnesses. (Mader 455)
C. Proteomics: Study of the structure, function, and interaction of cellular proteins.
1c. Human proteome: collection of proteins. These are harder to analyze than genomes because protein concentrations differ widely in cells, and researchers must analyze all proteins, even when there are thousands of copies of a protein in a cell. The study of these proteins is important to the development of better drugs. Most drugs are proteins or molecules that affect the function of proteins.
2c. Bioinformatics: the application of computer technologies to the study of the genome. (Mader 455)
D. Gene Therapy: The insertion of genetic material into human cells for the treatment of a disorder.
1d. Ex Vivo Gene Therapy: Treats children sith SCID. They lack the enzyme ADA. Therefore, bone marrow stem cells are removed from one marrow and are injected with an RNA retrovirus that carries a "normal" gene for the enzyme. Cells are then returned to patient.
2d. In Vivo Gene Therapy: Cystic fibrosis patiens lack a gene that codes for the transmembrane carrier of the chloride ion. The gene needed to cure cystic fibrosis is sprayed into the nose of delivered by adeno viruses or by lipoproteins in a solution.
3d. Gene therapy is increasinly used for cancer treatments. (Mader 456)
V. DNA Technology
A. Cloning: The production of genetically identical copies of DNA, cells or organisms through asexual means.B. Gene Cloning: Produces many identical copies of the same gene. This can happen because of the recombinant DNA, which has DNA from two or more different sources.
(Insert gene cloning picture / jan.ucc.nau.edu http://rds.yahoo.com/_ylt=A0S0200iK1RIRAcBa2ijzbkF/SIG=12ji44otd/EXP=1213562018/**http%3A//jan.ucc.nau.edu/~lrm22/bio300/lecture_notes/lectures.htm )
1b. Cloning Process, summarized: 1. Restriction enzyme used to cleave human DNA and plasmid DNA. This enzyme creates a gap in plasmid DNA in which foreign DNA can be placed if it ends in complementary bases. 2. Enzyme called DNA ligase is used to seal foreign DNA into the opening created in the plasmid. 3. Some of the bacterial cells take up a recombinant plasmid. 4a. Gene cloning occurs as the plasmid replicates on its own. 4b. Bacterium is also transoremed and can make a product that it couldn't before. (Mader 458)
C. Specific DNA sequences can be cloned.
1c. If only small pieces of identical DNA are required, the polymerase chain reaction can create copies of a segment of DNA quikcly in a test tube. DNA polymerase, the enzyme that carries out DNA replication is needed, along with more nucleotides. (Mader 459)
D. Biotechnology Products
1d. Transgenic organisms: those that have had a foreign gene inserted into them. Many, many uses: produce medicines, increase food supply, etc. (Mader 460)
2d. Although many believe that genetically engineered foods offer benefits, they also worry about the unknown long-term affects. (Mader 462)
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