BSCI330 Exam 1 Study Guide-The Cell TheoryAll living organisms are composed of nucleated cells.All cells store their hereditary information in the same linear chemical code (DNA)All DNA is composed of the same four monomers- A, T, C, G, regardless of whether the DNA is in a human cell or a bacterium.All cells replicate their hereditary information by Templated PolymerizationEach nucleotide consists of two parts: A sugar (deoxyribose) with a phosphate group attached and a base (A, G, C, T). The backbones of DNA are created by alternating sugars and phosphates.New DNA is created on a template formed by a strand of preexisting DNA.Base Pairs are held together by hydrogen bonds.All cells transcribe portions of their hereditary information into the same intermediary form (RNA)Templated polymerization is called transcription, in which segments of the DNA sequence are used as templates for the synthesis of RNA. Translation is the process in which RNA directs the synthesis of protein polymersmRNA guides the synthesis of proteins from instructions on the DNAAll cells use proteins as catalystsThere are 20 types of amino acids-the monomers of a protein/polypeptide.These amino acids bind with high specificity to other molecules and act as enzymes to catalyze reactions that make or break covalent bonds. All cells translate RNA into proteins the same wayInfo from mRNA is segmented into codons (3 nucleotides) that are read out by the anticodons on tRNA. Molecules are linked together to form proteins.The fragment of genetic information corresponding to one protein is One GeneIndividual segments of the entire DNA sequence are transcribed into separate RNA molecules- each such DNA segment represents one geneA gene is the segment of a DNA sequence corresponding to a single protein In All Cells, the expression of individual genes is regulatedThe genome of a cell dictates the nature of the cell proteins, and when and where they areto be made.Life requires free energy ∆GATP is a carrier of free energy and phosphate groups to drive DNA and RNA synthesisand many other reactionsAll cells function as biochemical factories dealing with the same basic molecular buildingblocks All cells made DNA, RNA, and proteins.All cells require ATP as a building block for DNA and RNAAll cells are enclosed in a plasma membrane across which nutrients and waste materials must pass.A selective barrier that enables the cell to concentrate nutrients gathered from its environment.It is amphiphilic meaning it has one part hydrophobic and one part hydrophilic. Both sides form a lipid bilayer.A living cell can exist with fewer than 500 genesThe bacterium Mycoplasma genitalium has to make DNA, RNA, and proteins, yet functions with only 480 genes.There are about 60 core genes that are shared by all species with no known exceptionCells can be powered by a variety of free energy sourcesLight- phototropic organisms; mostly bacteria, algae, and plants that produce oxygen as aside-product. Organic chemicals- organotropic – energy comes from other living things or organic molecules they produce.Inorganic chemicals- Lithotropic; They get energy from aerobic reactions (which requiresthe use of oxygen) and some get energy from anaerobic reactionsSome cells fix nitrogen and carbon dioxide for othersDNA, RNA, and proteins are composed of just 6 elements: H, C, N, O, S, P.Plants fix CO2 and create oxygen as a by-product, while bacteria fix nitrogen (Also someplants of the pea family harbor symbiotic nitrogen-fixing bacteria in their roots)The greatest biochemical diversity exists among prokaryotic cells. Eukaryotes keep their DNA in nuclei, where as prokaryotes have no nuclear compartmentThe tree of life has three primary branches: Bacteria, Archea, and EukaryotesEukaryotes: Protists, fungi, plants, animalsArchea: Inhabit areas that humans do notBacteriaSome genes evolve rapidly; others are highly conservedMutations occur and can cause good, bad, or no change in a nucleotide sequenceThrough mutation and natural selection, organisms evolve. Segments of DNA that code for no real genetic information can change a lot very often, whereas genes that code for an important regulatory protein do not alter very often and are Highly Conserved.Most bacteria and archea have 1000-6000 genesMost prokaryotic cells carry very little superfluous baggage and have very small genomes. New genes are generated from preexisting genes by way of:1. Intragenic Mutation: an existing gene can be modified by changes in its DNA sequence,through various types of error that occur mainly in the process of DNA replication; occur within a particular gene2. Gene Duplication: An existing gene can be duplicated to create a pair of initially identical genes in a cell.3. DNA Segment Shuffling: Two of more existing genes can be broken and rejoined to make a hybrid gene consisting of DNA segments that originally belonged to separate genes4. Horizontal (Intercellular) Transfer: A piece of DNA can be transferred from the genome of one cell to that of another- sometimes to that of another species. Gene duplications give rise to families of related genes within a single cellOrthologs: Genes in two separate species that derive from the same ancestral gene in the last common ancestor of those two speciesParalogs: Related genes that have resulted from a gene duplication event within a single genome-and are likely to have diverged from their original function.Homologs: A general term to cover both types of relationship above.Genes can be transferred between organisms, both in the laboratory and in natureViruses act as vectors for gene transfer- they are not living organisms but they are small packets of genetic material that have evolved as parasites on the reproductive and biosynthetic machinery of host cells. They replicate in one cell and infect another cell in the same or different species.Sex results in horizontal exchanges of genetic information within a speciesSex causes a vertical exchange (parent to offspring) but also a large horizontal exchange between two initially separate cell lineages. Normally limited to individuals of the same species. Nearly all eukaryotes and even some bacteriaThe function of a gene can often be deduced from its sequenceMany gene functions have been mappedMore than 200 gene families are common to all three primary branches of the tree of lifeThere are homologies among eukaryotes, bacteria, and archeaHorizontal transfer of genes is largely
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