Chapter 7 Flashcards
Genetics
study of inheritance and inheritable traits as expressed in an organisms genetic material
genome
entire genetic complement including genes and nucleotide sequences
genes
specific sequences of nucleotides that code for polypeptides or RNA molecules
nucleotides
nucleoside attached to a phosphate group
nucleoside
pentose sugar attached to a nitrogenous base
prokaryotic chromosomes
where prokaryotes package main portion of DNA, associated proteins and RNA
prokaryote DNA molecule size, shape, location
haploid, circular molecule located in the nucleoid
plasmids
small molecules of DNA that replicate independently of the chromosome that is not essential for growth, metabolism, or reproduction but can confer survival advantages
types of plasmids
fertility, resistance, bacteriocin, and virulence factors
fertility factors
carry instructions for conjugation, transferring genes from one bacterial cell to another
resistance factors
carry resistance to one or more antimicrobial drugs or heavy metals
bacteriocin factors
carry genes for proteinaceous toxins called bacteriocins which kill its competitors of the same or similar species
virulence plasmids
carry instructions for structures, enzymes, or toxins that an able the bacterium to become pathogenic
DNA replication
anabolic polymerization process that requires monomers and energy which triphosphate deoxyribonucleotides serve both functions
Semiconservative
DNA replication is semiconservative meaning that each new DNA strand is composed of one original and one daughter strand
examples of triphosphate deoxyribonucleotides
dATP, dGTP, dCTP, dTTP
examples of nucleotides
ATP, GTP, AMP, CMP, GMP, TMP, CTP
genotype
set of genes in the genome
phenotype
physical features and functional traits expressed by genes
transcription
information in DNA is copied as RNA
translation
polypeptides synthesized from RNA
central dogma of genetics
DNA is transcribed to RNA, RNA is translated to form polypeptides
direction of replication
5’ to 3’
types of RNA transcribed from DNA
RNA primers, mRNA, rRNA, tRNA
three steps of transcription
initiation, elongation, termination
names of DNA strands used in transcription
template and coding, template strand is used to code RNA
initiation
RNA polymerase binds to promoter gene sequence
elongation
add RNA nucleotides to template strand 5’ - 3’; reads the gene
termination
DNA strands bind back together after RNA has copied; when RNA polymerase meets termination it falls off
translation
anabolic process where ribosomes use genetic information of nucleotide sequences to synthesize polypeptides
primary structure
string amino acids in chain, peptide bonds
secondary structure
helices and pleats, held by bonds (weak)
participants in translation
mRNA, tRNA, ribosomes, rRNA, amino acids
operon
a promoter and a series of genes regulated together that may be regulated by an operator only found in prokaryotes
inducible operon
always off, must be activated by inducers; lac operon is an example
repressible operon
always on, always transcribed until deactivated by repressors, negative feedback loop; tryptophan operon is an example
mutation
change in the nucleotide base sequence of a genome, rare event and must be at the DNA level to be inherited
types of mutations
point and frameshift mutations
types of point mutations
silent, missense, nonsense; they are insertions, deletions, and substitutions that result in only one base pair being affected
silent mutation
DNA change does not change amino acid
nonsense mutation
inserts stop codon
missense mutation
changes amino acid sequence
frameshift mutations
insertions and deletions that misplace triplets
mutagens
agents that bring about mutations
types of mutagens
radiation and chemical
types of chemical mutagens
nucleotide analogs, nucleotide-altering chemicals, and frameshift mutagens
nucleotide analogs
looks like a regular nucleotide and disrupts DNA and RNA replication
nucleotide-altering chemicals
change nucleotides resulting in base-pair substitutions and missense mutations
pyrimidine dimer
adjacent pyrimidine bases covalently bond to each other distorting the sugar phosphate backbone and preventing proper replication
genetic recombination
exchange of nucleotide sequences between two DNA molecules
horizontal gene transfer
genes donated between two unrelated cells in same generation
three types of horizontal gene transfer
transformation, transduction, conjugation
genetic variability
mulitiple copies of the same gene and crossover during meiosis
transformation
competent cells pick up DNA from environment and express it
types of transduction
generalized and specialized
generalized transduction
mediated by viruses, carries random DNA segment from donor to recipient
specialized transduction
mediated by viruses, only certain donor DNA sequences are transferred
bacterial conjugation
mediated if the cell has fertility (f) plasmid which codes for pili; F+ make F- cells F+
Hfr
F+ inserts in the chromosome of F- and then F- will still be F- but have cool new genes
