Week 4 Lecture Flashcards
DNA was first discovered by
Frederick Miescher
discovered that DNA contained phosphates, five- carbon sugars (cyclic pentose), and nitrogen- containing bases
Phoebus Aaron Theodore Levine
discovered the helical structure by x-ray crystallography
Rosalind Franklin
who described the three-dimensional structure of the DNA molecule in the 1950s.
James Watson and Francis Crick
is a double helical chain of deoxynucleotide.
DNA (deoxyribonucleic acid)
is a double strand twisted together, which many
scientists refer to as a “spiral staircase” (resembling the handrail, sides, and steps of a spiral staircase)
Helix
A phosphate group (PO4)
Nucleotides
(the carbons in the pentose are
numbered 1′ through 5′) sugar (deoxyribose), which makes up the “handrails and sides”
Cyclic five-carbon pentose
A nitrogen-containing base, or the “steps,” either a
Purine and pyrimidine
The two complementary sugar phosphate strands run in opposite directions (antiparallel)
3 to 5 or 5 to 3
basic building blocks of DNA
Nucleotide
attaches to the 5′ carbon of the sugar,
Phospate
is attached to the 3′ carbon of the sugar.
Hydroxyl group
are held together by hydrogen bonds.
Base
Information contained in DNA is determined primarily by the pyrimidine sequence of letters along the
Staircase
consists of a fused ring of nine carbon atoms and nitrogen
Purine
What is two purines
Adenine (A) and guanine (G)
Consists of a single ring of six atoms of carbon and nitrogen.
Pyrimidine
What is the Three pyrimidines
Thymine (T), cytosine (C) and uracil (U)
is also involved in the production of RNA.
DNA (deoxyribonucleic acid)
In RNA, the nitrogenous base is
Thymine (T)
Thymine is replaced by
Uracil (U)
Single-stranded and short, not double stranded and long, and contains the sugar ribose, not deoxyribose
RNA (ribonucleic acid)
means of amplifying specific DNA sequences and detecting very small numbers of bacteria present in a specimen.
Polymerase chain reaction technique
are silent genes, expressed only under certain conditions.
Gene
are always expressed are constitutive.
Gene
are expressed only under certain conditions are inducible
Gene
The duplication of chromosomal DNA for insertion into a daughter cell.
Replication
The synthesis of ssRNA, by the enzyme RNA polymerase, using one strand of the DNA as a template.
Transcription
The actual synthesis of a specific protein from the mRNA code.
Translation
Refers to the synthesis of a protein
Protein expression
are polypeptides composed of amino acids.
Protein
A group of three nucleotides in an mRNA molecule that signifies a specific amino acid.
Codon
The triplet of bases on the tRNA that bind the triplet of bases (codon) on the mRNA
Anticodon
consists of a single, closed, circular piece of dsDNA that is supercoiled to fit inside the cell
Bacterial genome
Contains all the information needed for cell growth and replication
Bacterial genome
genes are specific DNA sequences that code for the amino acid sequence in one protein
One gene equals one polypeptide
Are self-replicating extrachromosomal dsDNA molecules.
Plasmid
pieces of DNA that are mobile and may jump from one place mobile and may jump from one place in the chromosome to another place in the chromosome to another place
Jumping gene
Simplest mobile piece of DNA is an
insertion sequence (IS) element.
It is approximately ______ base pairs long with inverted repeats on each end
1000 base pairs
that allows the element to pop into and out of DNA
transposase enzyme
Which contain many IS elements.
Bacterial genome
are related mobile elements that contain additional genes.
Transposons
often carry drug-resistance genes and are usually located in plasmids
Transposons
Changes that occur in the DNA code and often result in a change in the coded protein or in the prevention of its synthesis
Mutations
occur in bacteria at a rate of about 1 in 109 cells
Spontaneous mutations
Occur as the result of error during DNA replication at a rate of about
1 to 107 cells
Give a type of mutagens that is physical agents
UV rays, Ionizing radiation, X-rays, Visible light, and Heat
What type of mutagen is chemical agents
Alkylating agents, aCridine dyes, 5-Bromouracil, 2-aminopurine and Nitrous acid.
A method by which genes are transferred or exchanged between homologous (similar) regions on two DNA molecules, forming new combinations of genes on a chromosome
Genetic recombination
Uptake and incorporation of free or naked DNA into a bacterial cell
Transformation
Can be incorporated into the bacterial genome by recombination.
Transformation
Cells that take up naked DNA are referred to as
Being competent
The recipient bacterium must be competent to absorb the exogenous fragments of bacterial DNA.
Transformation
Transfer of bacterial genes by a bacteriophage from one cell to another.
Transduction
consists of a chromosome (DNA or RNA) surrounded by a protein coat.
Bacteriophage
When a phage infects a bacterial cell, it injects its genome into the bacterial cell, leaving the protein coat outside.
Transduction
The phage may then take a lytic pathway, in which the bacteriophage DNA directs the bacterial cell to synthesize phage DNA and phage protein and package it into new phage particles
Transduction
What phase Cell eventually lyses , releasing a new phage that can infect other bacterial cells.
Lytic phase
In some instances, the phage DNA instead becomes incorporated into the bacterial genome, where it is replicated along with the bacterial chromosomal DNA; in this state is known as
Lysogeny
the phage is referred to as
being temperate.
Transfer of genetic material from a donor bacterial strain to a recipient strain
Conjugation
Close contact is required between the two cells.
Conjugation
possesses a fertility factor (F factor) on a
plasmid that carries the genes for conjugative transfer
Donor strain (F+)
The donor strain produces a hollow surface appendage called
Sex or conjugation pilus
Transfer of DNA then occurs
Conjugation
which binds to the recipient F− cell and
brings the two cells in close contact.
Sex or conjugation pilus
Bacteria have evolved a system to restrict the incorporation of foreign DNA into their genomes.
Restriction enzymes
produced that cut incoming, foreign DNA at specific DNA sequences
Restriction enzymes
The main effect of is elements in bacteria is that when an is element inserts itself into the middle of a gene,
It disrupt and inactives the gene
Some mutations are silent because
Redundancy of protein synthesis
May be the result of a change in one
nucleotide base (a point mutation)
that leads to a
Change single amino acid within protein
May be the result of insertions or deletions in the genome that lead to
Disruption of gene and frameshift mutation
variations in the nucleotide sequence of a genome
Mutation
are those that result from an exposure to chemicals, UV rays, x-rays, or some other environmental agent.
Induced mutation
occur without any exposure to any environmental agent
Spontaneous mutation
Substitutions, also known as
Point mutation
are those mutations that affect a single base pair. One base is replaced by another
Substitution
refers to a purine or pyrimidine being replaced by a base of the same kind; for example, a purine such as adenine may be replaced by the purine guanine.
Transition substitution
refers to a purine being replaced by a pyrimidine, or vice versa; for example, cytosine, a pyrimidine, is replaced by adenine, a purine.
Transversion substitution
is when the substitution results in a codon for a different amino acid.
Missense mutation
occurs when the substitution results in the formation of a stop codon (UAA, UAG, UGA)
Nonsense mutation
result of the addition of a base
Insertion
removal of a base, also known as
Deletion
only one nucleotide is inserted or deleted. They shift the reading frame of the codons
Frameshift mutation
