Regulation of Gene Expression Flashcards
It contains MEMBRANE-BOUND intracellular structures such as a nucleus, mitochondria, and for photosynthetic eukaryotes, chloroplasts.
Eukaryotes
It is composed of ONE OR MORE LINEAR DNA chromosomes.
Eukaryotic Genome
It helps the genome organization be more COMPLEX and PROTEINS help with COILING.
Histones
Is GENE REGULATION more elaborate due to the?
Larger genome, cell differentiation
It is made up of DNA wound twice around 8 histones (2 of each of 4 main types) with “LINKER” DNA between the beads.
1st Level: Nucleosomes or “Beads on a String”
It is made up of a tightly wound coil of nucleosomes held in position by a FIRST HISTONE (H1).
2nd Level: 30nm Chromatin Fiber
It is made up of loops held in place by scaffolding (NONHISTONE) proteins.
3rd Level: Looped Domains
It is made up of HIGHLY CONDENSED, compact domains.
4th Level: Chromosomes are visible during mitosis
The cells must continually turn genes on and off in response to INTERNAL & EXTERNAL SIGNALS.
Gene regulation
Expression of specific genes is most COMMONLY REGULATED at the?
Transcription
The proteins can BIND DNA and either inhibit or facilitate the BINDING OF RNA POLYMERASE.
Transcription Initiation Regulation
It provides binding sites for regulatory proteins that AFFECT RNA POLYMERASE activity.
Enhancer sequence
The cells can REGULATE GENE EXPRESSION even after a gene is transcribed to rapidly respond to environmental changes.
Post-Transcriptional Regulation
POST-TRANSCRIPTIONAL REGULATION rapidly responds to environmental changes by?
- RNA processing: alternate splicing
- mRNA Degradation: rate
- Translation Initiation: can be blocked by regulatory proteins.
- Protein Processing & Degradation: regulation can occur during any of these final
steps.
It is known as the “JUMIPING GENE”
Transposons
He discovered the “INDIAN CORN”
Barbara McClintock
What are the 2 main parts of GENOME AND PROTEIN CAPSID?
Host range varies and narrow
There is usually a LARGE NUMBER OF PROTEINS, but the number of different kinds of proteins is usually small.
Viral Structures
Capsid is formed from a REPEATING single type of protein with the overall shape
of a rigid rod.
Helical Structures
Capsid is formed from 252 IDENTICAL PROTEIN MOLECULES arranged in a polyhedron with 20 triangular facets and an icosahedron.
Icosahedral Viruses
What is an example of ICOSAHEDRAL?
Adenoviruses - which cause
respiratory infections in animals.
Capsid is surrounded by a membranous envelope derived from the MEMBRANES OF THE HOST (Such membranes prevent detection by the immune system).
Influenza Viruses
The (Viruses that infect bacteria) COMPLEX CASPIDS. The first seven studied were
nicknamed T1 – T7. They have an elongated icosahedral head and an elaborate protein tail.
Bacteriophages
It RAPID DESTRUCTION of host cell
Lytic
Viral DNA INTEGRATES INTO HOST CHROMOSOMES (via crossing over), becomes a prophage, and can reproduce (when a cell divides) WITHOUT DESTROYING the cell.
Lysogenic
It can become lytic in response to ENVIRONMENTAL TRIGGERS.
Lysogenic Viruses
PHAGES that CAN REPLICATE in both ways is called?
Temperate
Types of Baltimore that usually must ENTER THE HOST NUCLEUS BEFORE it is able to replicate.
Examples:
- ADENOVIRUSES, HERPESVIRUSES, AND POXVIRUSES
Class 1: dsDNA virus
Types of Baltimore that they REPLICATE WITHIN NUCLEUS and form a ds DNA intermediate during replication
Examples:
- PARVOVIRUS
Class 2: ss DNA virus
Types of Baltimore that DO NOT RELY ON HOST POLYMERASES for replication to the extent that viruses with DNA genomes do.
Examples:
- REOVIRUSES & BIRNAVIRUSES
Class 3: dsRNA
Types of Baltimore that can be DIRECTLY ACCESSED BY THE HOST RIBOSOMES to immediately form proteins
Examples:
- PICORNAVIRUSES & TOGAVIRUSES
Class 4: Positive sense: ssRNA virus
Viruses containing NON-SEGMENTED GENOME for which the genes CANNOT
be directly accessed by host ribosomes.
Examples:
- ORTHOMYXOVIRUSES & RHABDOVIRUSES
Class 5: Negative sense: ss RNA
It reverse transcriptase and integrase.
Examples:
- RETROVIRUSES
Class 6: Positive sense: ss RNA
It replicates through an ss RNA intermediate.
Examples:
- HEPADNAVIRUSES
Class 7: ds DNA
Viral activity causes the CELL TO RELEASE:
Toxins
UPTAKE OF NAKED, foreign DNA
Transformation
Bacteriophages TRANSFER bacterial genes between hosts accidentally.
Transduction
It direct transfer of genes via a pilus or “MATING BRIDGE”.
Conjugation
It carries resistance genes that code for enzymes that specifically DESTROYS ANTIBIOTICS. Many also carry genes that code for pili to allow conjugation.
R-Plasmids
