Micro Exam 2

• 10-100 um
• Nucleus with linear chromosomes, surrounded by 2 lipid bilayer membranes
• Nuclear membranes have pore complexes and are contiguous with rough ER

varies greatly, from 2.9 million BP to 2,800 million BP

3 to 50

• 3 to 50 linear chromosomes
• Basic unit of chromosomes is DNA coiled around histones
• Visible by electron microscopy
• reside in nucleus
• get replicated every time the cell divides

2.9 million BP to 2,800 million BP

Tandom-Repeated DNA

• Chloroplasts
• Mitochondria

• rRNA, in nucleolus, amanitin - resistant
• mRNA, amanitin - very sensitive
• tRNA, aminitin - somewhat resistant

Introns

• Basket
• Inner Ring
• Outer Ring
• Anchor Protein
• Active Trasporter

sensitive to diptheria toxin and cycloheximide, not sensitive to tetracycline or chloroamphenicol

Denaturation

• Most have a single circular chromosome
• few thousand genes located on it
• single origin of replication

• Chromosome circular, haploid
• Genome Size: 0.5 to 5.8*10^6 BP
• Most DNA are supercoiling
• DNA Gyrase is like bacteria
• 1-3 origins of replication

• No introns in most genes
• mRNAs not spliced, but translated directly
• Promoter- TATA-Box, TATA-Binding Protein like Eukarya
• RNA Polymerase: 1, like Eukaryotic RNA Poly II
• Rifamipin-Insensitive, Like Eukarya

• Ribosomes 70S
• sensitive to diphtheria toxin
• resistant to most antibacterial inhibitors of protein synthesis (tetracyclines, chloroamphenicol)
• AUG start codons use methionine

• Ribsosmes are 80S
• Large subunit has 3 rRNAs, not just 2
• Ribosomes not inhibited by most bacterial inhibitors of protein sysnthesis
• are sensitive to diphtheria toxin
• No shine Delgarno site by start codon (AUG)
• first amino acid is methionine

• replicate independently of the chromosome
• may be present in several copies
• typically have genes which are not essential for the cell under basic conditions, however may assist in resistance to antibiotics, etc (these are specialized genes)

• In a circle/star shape
• Super coils are tangled together and held together by proteins
• Few million BP long

• Attach 5-Methylguanosine Cap
• Attach Poly-Adenosine Tail
• Splice out Introns

Folding/ FunctionalDomains of Polypeptide

• Primer
• Template Strand
• dATP, dCTP, dGTP, dTTP
• Enzyme: DNA Polymerase

• Cleave DNA at specific 4-6 ntsequences.
• Methylation canprotect from them.

• 70S
• Some antibiotics block protein synthesis only in bacterial ribosomes

tRNAs with amino acids enter

tRNAs with amino acid form peptide bond

empty tRNAs leave

Bacteria has a slightly greater range than archaea

Eukaryotes usually have a greater chromosome number. In bacteria it is usually one circular chromosome

Only present in eukaryotes.

Bacteria does not have true histones, but Eukaya and some Archaea do.

• Bacteria has one polymerase with two sub unit parts
• Many sub units in Eukarya
• Archaea have one polymerase but the one polymerase has 8-12 sub units (so is more similar in structure to eukaryotic polymerase)

Eukarya and bacteria have genes in operons

Only in Eukarya

Eukarya 80S; Archaea 70S; Bacteria 70S

• Eukaryotic insensitive to cycloheximide, sensitive to tetracycline.
• Archaea are sensitive to cycloheximide and not tetracycline.

• Generally starts with a material being acted on by an enzyme converting it to an intermediate.
• Process continues until an end product is reach.
• Process can be regulated at various steps.

• Allosteric molecule binds to an allosteric site.
• Catabolic pathways: starting material may be allosteric activator of enzymes, may activate transcription of genes.
• Anabolic pathway: end-product mat act as allosteric inhibitor, decrease transcription of genes.

• 1. Sensor kinase in plasma membrane.
• 2. Response regulator acts as transcriptional activator when phosphorylated.

A repressor protein can bind operator, blocking binding of RNA polymerase to promoter-blocks transcription.

A transcription activator protein must bind near promoter, and assist RNA poly binding at promoter.

• E. Coli prefers glucose as energy source
• Glucose used up, cAMP produced
• Signals to switch to other sugars (like lactose)
• cAMP binds Catabolite Activator Protein
• Stimulates transcription

another mechanism of regulating transcription of the trp operon

• Mainly similar to Bacteria
• Repressor proteins bind TATA box and nearby BRE regions near promoter
• Block access of (TBP) and TFB general transcription factors
• Transcriptional activator proteins enhance binding of TBP at promoter

Most mRNAs in bacteria have a short half-life, and are degraded by ribonucleases, some of which target secondary structures.

Archaea

Archaea

• mRNAs degraded by RNAases
• Antisense RNAs bind to mRNAs

Total size from less than 2 kBP to over 200 kBP (3-100 genes)

• protein coat
• may be helical, Icosahedral, or complex

• consists of host membrane lipids and viral proteins
• may have role in binding and infection of host cells

• virus binds to a host cell
• viral Genome is replicated
• viral proteins are made on host cell ribosomes
• new virions are assembled
• mature virions are released from the host cell

• Viruses of bacteria
• have virions binding to cell wall of host
• inject DNA genome into host cytoplasm
• capsid remains outside

entire virion taken into the host cell by endocytosis or membrane fusion

• Includes many bacterial viruses (bacteriophages)
• (–) strand DNA is template for making mRNA by RNA polymerase
• Genome of dsDNA replicated by DNA polymerase

• must first make complementary DNA
• then DNA can replicate
• (–) strand serves as template for making viral mRNA

May involve 2 kinds of RNA dependent RNA polymerases (Transcriptase & Replicase)

transcribes (-)strand RNA into mRNA

transcribes (+) strand RNA into ds replicative form (RF) RNA

• Have a RNA genome which is made into a DNA copy.
• The DNA copy is then made back into an RNA copy. An example is HIV.

Can replicate - move to new location in chromosome or plasmid

kills host cell

DNA integrates

bacterial DNA carried alongin phage from cell to cell.

Replicating, infectiousRNAs, encode no proteins.

Misfolded proteins, infectious, catalyse misfolding of intact proteins

• DNA Polymerase has a mechanism where it
• changes mutations – RNA does not check.

• type of nucleic acid
• capsid and envelope characteristics
• genome size and sequence
• host infected

Genome RNA → + RNA / - RNA → - RNA

• has a genome that is moderatly large (~160k base pairs)
• icosahedral head, a stalk, and a base plate
• has a linear genome
• has a unique base in to prevent destruction of phage by host restriction endonucleases

• About 48k base pairs long
• one of the earliest genomes to be sequenced
• looks like the other phages, but does not have the base plate
• rolling-circle replication mechanism

• single strand of DNA genome
• cylindrical virus that binds to the sex phylos that are produced to do conjugation
• viral DNA is transcribed to produce viral proteins
• host cell survives the entire process

• Have 3600 base pairs
• RNA can be translated directly by the host cell
• To replicate, replicase must be used.
• Takes single-stranded RNA and makes a (-) copy to make more (+) strand genomes.
• Kills host

Change in Physical Structure of DNA- such as changes in nucleotidesequence.

Errors in DNA polymerase but DNA poly. can proofread

• UV light, X-rays, Ionizing Radiation, Chemicals.
• Excision-repair enzymes can fix some damage

can grow on minimal, defined media with minerals (N, P, S sources) and C-source (glucose)

• Can’t grow on minimal media
• Mutation in a biosynthetic pathway, require amino acid, vitamin, ect.

• (-) stranded RNA genome
• The virus binds to receptors and is brought into the host cell by endocytosis.
• genomes then get into the nucleus of the host cell
• negative strands of RNA are transcribed by Transcriptase and assembled by Replicase
• Replicase does not proofread.

• Host anitbodies no longer protect against virus.
• surface proteins will change

is a prokaryotic transcription initiation factor that enables specific binding of RNA polymerase to gene promoters.

Initiates transcription