Chapter 8 Pt. 1: Microbial Genetics

genetics

The study of genes, how they carry information, how information is expressed

chromosomes

Structures containing DNA that physically carry hereditary information; the chromosomes contain genes

genes

segments of DNA that encode functional products, usually proteins

genome

all the genetic information in a cell

genetic code

set of rules that determines how a nucleotide sequence is converted to an amino acid sequence of a protein

central dogma

DNA replication and protein synthesis

genotype

the genetic makeup of an organism

phenotype

expression of the genes

vertical gene transfer

flow of genetic information from one generation of the next

horizontal gene transfer

flow of genetic information within the same generation

gene expression

genetic information is used within a cell to produce the proteins needed for the cell to function

recombination

genetic information can be transferred vertically to the next generation of cells

DNA structure

DNA forms a double helix, backbone of deoxyribose-phosphate, nucleotides A-T, C-G, run antiparallel

topoisomerase and gyrase

relax the strands

helicase

separates the strands

replication fork

 one “parent” double-stranded DNA molecules is converted to two identical offspring molecules

DNA polymerase

adds nucleotides to the growing DNA strand

DNA replication

runs 5’ to 3’

leading strand

synthesized continuously

lagging strand

synthesised discontinuously, created Okazaki fragments

Bidirectional DNA replication

most bacterial DNA replication

RNA

ribonucleic acid, single-stranded nucleotide, 5-carbon ribose sugar, contains U instead of T

rRNA

integral part of ribosome

tRNA

transports amino acids during protein synthesis, have anticodons that pair with bases

mRNA

carries coded information from DNA to ribosomes

promoter

begins transcription by binding to RNA polymerase on DNA

terminator

stops transcription when reached on the DNA sequence

codons

group of three mRNA nucleotides that code for a particular amino acid

sense codon

61 codons that encode the 20 amino acids

degeneracy

each amino acid is coded by several codons

translation

begins at start codon ends at UAA, UAG, UGA, require amino acids to be transported to the ribosome

peptide bonds

join amino acids

cytoplasm

where translation and transcription occur in bacteria