MICROBIO CH. 10 DR. Brookins TCC SOUTHEAST

Central Dogma of molecular biology

concept established with contribution from Francis Crick describing how genetic information flows from DNA to RNA to protein

Genetic material criteria

genetic material must meet four essential criteria which are information (storing instructions for cell functions) transmission (being inherited across generations) replication (being copied accurately) and variation (allowing genetic diversity and evolution)

Griffith's transformation experiment (1928)

experiment showing that genetic material can transform Streptococcus pneumoniae; live mice injected with the live smooth (S) virulent strain died while mice injected with the live rough (R) nonvirulent strain or heat-killed S strain survived; mice injected with a mixture of live R strain and heat-killed S strain died and only live S strain bacteria were recovered from them showing that something from the heat-killed S strain transformed the R strain into the pathogenic S strain

Rough colony (pneumococcus)

nonvirulent colony type of Streptococcus pneumoniae lacking a polysaccharide capsule

Smooth colony (pneumococcus)

virulent colony type of Streptococcus pneumoniae possessing a polysaccharide capsule

Transforming principle

term coined by Griffith for the substance passed from heat-killed virulent bacteria that transformed nonvirulent bacteria into virulent bacteria

Genetics

the study of inherited variation and traits

Levels at which genetic information is transmitted

DNA genes chromosomes genome individual/organism family and population

Nucleotide

building block of nucleic acids composed of a phosphate group a pentose sugar (deoxyribose or ribose) and a nitrogenous base

Purines

nitrogenous bases with a two-ring structure including adenine and guanine

Pyrimidines

nitrogenous bases with a single-ring structure including cytosine thymine and uracil

Adenine

purine nitrogenous base found in both DNA and RNA

Guanine

purine nitrogenous base found in both DNA and RNA

Cytosine

pyrimidine nitrogenous base found in both DNA and RNA

Thymine

pyrimidine nitrogenous base unique to DNA

Uracil

pyrimidine nitrogenous base unique to RNA

RNA vs DNA

RNA is typically single-stranded uses ribose sugar and contains uracil instead of thymine while DNA is typically double-stranded uses deoxyribose sugar and contains thymine; RNA can fold upon itself with folds stabilized by short areas of complementary base pairing forming a three-dimensional structure

Phosphodiester bond

covalent bond formed between the phosphate group attached to the 5' carbon of one nucleotide and the hydroxyl group of the 3' carbon of the next nucleotide linking nucleotides together into a polynucleotide strand

Sugar-phosphate backbone

alternating sugar and phosphate structure that forms the framework of a nucleic acid strand

DNA double helix

structure proposed by Watson and Crick in which two DNA strands are twisted around each other to form a right-handed helix with the strands arranged antiparallel to each other; the sugar and phosphate form the backbone on the outside while nitrogenous bases stack inside and pair with each other; there are approximately 10 bases per turn

Antiparallel strands

arrangement of DNA strands in which the 3' end of one strand faces the 5' end of the other strand

Major groove (DNA)

wider space in the DNA double helix where the sugar-phosphate backbones are farther apart allowing proteins to bind

Minor groove (DNA)

narrower space in the DNA double helix where the sugar-phosphate backbones are close together

Complementary base pairing

pairing of nitrogenous bases in DNA held together by hydrogen bonds in which adenine pairs with thymine and guanine pairs with cytosine

DNA denaturation

process in which high temperatures or certain chemicals break the hydrogen bonds between complementary bases separating the double helix into two single strands of DNA

DNA renaturation (reannealing)

process in which single-stranded DNA is put back together as double-stranded DNA through cooling or removing chemical denaturants allowing hydrogen bonds to reform

GC content effect on denaturation

DNA with a high GC content is more difficult to denature than DNA with a lower GC content due to the additional hydrogen bond in the C-G base pair

Gene

a segment of DNA that encodes a protein

Genome

the complete set of genetic instructions of an organism

Allele

different versions of a gene

Genotype

the genetic makeup of an organism such as BB Bb or bb

Phenotype

the observable trait of an organism such as brown or blue eyes

Gene locus

the specific location of a gene on a chromosome

Homologous chromosomes

pair of chromosomes containing the same genes at the same loci one inherited from each parent

Sister chromatids

identical copies of a chromosome joined together after DNA replication

Eukaryotic genome

found in diploid (2n) somatic cells with chromosomes housed in the nucleus and extrachromosomal DNA found in mitochondria (all cells) and chloroplasts (plants and algae)

Bacterial and archaeal genome

found in haploid (n) cells often with additional plasmids

Bacillus anthracis pathogenicity

due to the maintenance of two plasmids called pX01 and pX02 which encode virulence factors

Human genome size

approximately 3 times 10 to the 9th base pairs

Saccharomyces cerevisiae (yeast) genome size

approximately 1.2 times 10 to the 7th base pairs

Escherichia coli genome size

approximately 4.6 to 5.6 times 10 to the 6th base pairs

Deltavirus genome size

approximately 1.7 times 10 to the 3rd base pairs

Pandoravirus genome size

approximately 2.5 times 10 to the 6th base pairs

Nucleoid

region of a bacterial cell that houses the bacterial chromosome

Plasmid

extrachromosomal independent replicon of DNA that carries nonessential genes such as those for drug resistance

Eukaryotic chromosome characteristics

located in the nucleus linear in shape diploid and accompanied by extranuclear DNA in mitochondria and chloroplasts

Tremblaya princeps genome

endosymbiont of mealybugs with a circular chromosome of 139 kb and no plasmids for a total genome size of 139 kb

Mycoplasma genitalium genome

found in normal flora of human skin with a circular chromosome of 580 kb and no plasmids for a total genome size of 580 kb

Vibrio cholerae (El Tor N16961) genome

causes cholera with two circular chromosomes totaling 2961 plus 1072 kb and no plasmids for a total genome size of 4033 kb

Mycobacterium tuberculosis genome

causes tuberculosis with a circular chromosome of 4400 kb and no plasmids for a total genome size of 4400 kb

Escherichia coli K-12 (W3110) genome

model strain for E. coli research with a circular chromosome of 4600 kb and no plasmids for a total genome size of 4600 kb

Agrobacterium tumefaciens genome

causes tumors in plants and is used as a genetic engineering vector with two chromosomes totaling 2840 plus 2070 kb and circular plasmids totaling 214 plus 542 kb for a total genome size of 5666 kb

Anabaena species (PCC 7120) genome

cyanobacteria that is a major photosynthetic producer of carbon source for freshwater ecosystems with a circular chromosome of 6370 kb and circular plasmids totaling 110 plus 190 plus 410 kb for a total genome size of 7080 kb

Borrelia burgdorferi genome

causes Lyme disease with a linear chromosome of 911 kb and 21 plasmids ranging in size from 9 to 58 kb for a total genome size of more than 1250 kb

Methanocaldococcus jannaschii genome

a methanogen from a thermal vent with a circular chromosome of 1660 kb and circular plasmids totaling 16 plus 58 kb for a total genome size of 1734 kb

Haloarcula marismortui genome

a halophile from a volcanic vent with two chromosomes totaling 3130 plus 288 kb and circular plasmids totaling 33 plus 33 plus 39 plus 50 plus 155 plus 132 plus 410 kb for a total genome size of 4270 kb

Coding DNA

region of the genome that encodes a gene product such as a protein or RNA

Noncoding DNA

regions of the genome that do not encode proteins or stable RNA products commonly found before the start of coding sequences and in intergenic regions between genes

Intergenic regions

DNA sequences located between genes