Notes II
Chapter 6
Allele one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Homozygous is dominant if it carries two copies of the dominant allele.Homozygous recessive if it carries two copies of the same recessive allele.
Heterozygous means that an organism has two different alleles of a gene.
Genetic analysis is the process of genes interacting in a specific phenotype and then are identified by going on a hunt for all the different kids of mutations that affect that phenotype.
Functional Genomics provides powerful ways of defining the set of genes that participate in any defined system.
Proteomics assays protein interaction.
Regulatory genes are the transcription of one gene that may be turned on and off by other genes.
Genes are responsible for the function of enzymes and each gene controls one specific enzyme.
All proteins, weather or not they are enzymes, are encoded by genes, so the phrase became one-gene - one-protein or one-gene - one-polypeptide.
The type of dominance inferred depends on the phenotypic level at which the assay is made. Either organismal, cellular, or molecular.
Codominance is the relation of two alleles that are both fully expressed.
Double mutant is an organism that is carrying homozygous mutations of two different genes.
Epistasis is the phenomenon of one genes dependance on one or more modifier genes.
Haploinsufficiency is where a diploid organism has only one functional copy of a gene and it does not produce enough gene product to bring about a wild-type condition.
Heterokaryon is a multinucleate cell that contains genetically different nuclei.
Penetrance is the amount a gene or set of genes is expressed in the phenotypes of organisms carrying it.
Pleiotropic effect occurs when one gene influences two or more other phenotypic traits.
Chapter 7
DNA is comprised of phosphate, deoxyribose, and four nitrogenous bases.
Two of the bases, adenine and guanine, have double-ring structure characteristic of a chemical called a purine.
The other two bases, cytosine and thymine, have a single-ring structure called pyrimidine.
Nucleotides are comprised of a phosphate group and a deoxyribose sugar molecule and one of the four bases.
Antiparallel are DNA in opposite orientation.
Major groove and minor groove are single strands of nucleotides and have no helical structure.
Semiconservative replication is the process of the double helix of each daughter DNA molecule contains one strand from the original DNA molecule and one newly synthesized strand.
Conservative replication is the process of the parent DNA molecule is conserved and a single daughter double helix is produced consisting of two newly synthesized strands.
Dispersive replication is the process of daughter molecules consistent of strands each containing segments of both parental DNA and newly synthesized DNA.
Replication fork is the zone where the double helix is unwounded.
Leading strand is the new strand synthesized from the replication fork.
Okazaki fragments are short nucleotide stretches of newly synthesized DNA.
Promises synthesize, by a set of proteins, primers.
DNA ligase joins the 3’ end to the 5’ end of the downstream Okazaki fragment.
Lagging strand is the new strand formed.
Replissme is a molecular machine.
Pol III holoenzyme consists of two catalytic cores and many accessory proteins.
Sliding clamp encircles the DNA and keels the polIII attached to the DNA molecule.
Helices are enzymes that disrupt the hydrogen bonds that hold the two strands of the double helix together.
Nucleosome consists of DNA wrapped in histone proteins.
Daughter molecules are two identical versions of DNA.
Telomerase handles the addition of noncoding sequence.
Chapter 8
Pulse-chase experiment is performed by injecting infected bacteria with radioactive uracil. Any RNA synthesized int he bacteria from then on is labeled with the readily detectable radioactive uracil. After incubation the radioactive uracil is washed away and replaced by uracil that is not radioactive. The RNA recovered shortly after the pulse is labeled recovered somewhat longer after the chase is unlaced indicating that the RNA has a very short lifetime.
Transfer RNA, molecules are responsible for bringing the correct amino acid to the mRNA in the process of translation
Ribosomal RNAs, are the major components of ribosomes, which are large macromolecular machines that guide the assembly of the amino acid chain by the mRNA and tRNA.
Small nuclear RNAs, are part of a system that further processes RNA transcripts in eukaryotic cells.
RNA polymerase is attached to the DNA and moves along it linking the aligned ribonucleotides together to make a growing RNA molecule.
Three steps in transcription are initiation, elongation and termination.
Initiation is the binding of RNA polymerase to double stranded DNA.
Elongation is the addition of nucleotides to the 3’ end of the chain.
Termination is the recognition of the transcription termination sequence.
Chapter 9
Tertiary structure is produced by the folding of the secondary structure.
Quarternary structure is composed of two or more separated folded polypeptides.
Globular proteins are made of compact structures.
Fibrous protein are proteins with a linear shape.
Collinearity is the correspondence between the linear sequence of the gene and that of the polypeptide.
Degenerate genetic code means that each of the 64 triplets must have some meaning within the code. For this to be true some of the amino acids have to be specified by atlas two different triplets.
When a tRNA is attached by a amino acid it is charged.
Most amino acid can be brought to the ribosome by several tRNA types. Each having a different anticodon base pair.
Certain charged tRNA species can bring their specific amino acids to any one of the several codons. These tRNAs recognize and bind to several alternative codons through a loose kind of base paring at the 3’ end of the codon and the 5’ end of the anticodon. This is called a wobble.
Biological Machine is a multisubunit complex that performs cellular functions.
Decoding center ensures that only tRNAs carrying antics that match the codon will be accepted into the A site.
Peptidyl transferase center is where peptide-bond formation is catalyzed.
Chaperones help fold proteins.
Chapter 10
Gene regulation is the regulation of the synthesis of a genes transcript and of its protein product.
Cells need mechanisms that can recognize environmental conditions in which they should activate or repress transcription of the relevant genes. They also must be able to toggle on or off the transcription of each specific gene or group of genes.
The allosteric site acts as a toggle switch that sets the DNA-binding domain in either functional or nonfuncitional mode. The allosteric effector binds to the allosteric site of the regulatory protein such that it changes the structure of the DNA-binding domain. An allosteric transition is a change in shape.
A trans-acting gene can regulate all structural lac operon genes.
In prokaryotes all genes are transcribed into RNA by the same RNA polymerase. In eukaryotes only three RNA polymerases function.
RNA transcripts are extesively processed during transcrition in eukaryotes. The 5’ and the 3’ ends are modified and introns are spliced out.
RNA polymerase II is much larger that its prokaryotic counterpart. It must synthesize RNA and coordinate the special processing events unique to eukaryotes.
Activated transcription requires the binding of regulatory proteins to cis-acting elements in the DNA around the gene.
Combinatorial interaction is where complex patterns require many binding sites for different regulatory proteins to interact with each other.
A dosage imbalance is corrected by dosage compensation which makes the amount of most gene products from two copies of X chromosomes in females equivalent to the single dose of X chromosome in males.
