Lecture 6 Part 2 Flashcards
Nature and characteristics of the genetic code
- Triplet Code
- It is continuous, comma free.
- Non-overlapping (It is read in successive groups of three nucleotides)
- Universal (all organisms share the same genetic code)
- code is degenerate (Crick & et al) (amino acids may have more than 1 codon) (exc. AUG- met and UGG- trp)
- has start and stop (AUG – met, GUG -val) and (UAG UGA UUA)
- Wobble occurs in anticodon (degeneracy)
- Genetic code is unambiguous (rare that 1 codon specifies more than 1 a.a) (specific codon = same amino acid)
linear correspondence between DNA sequence and the order of amino acids
Colinearity of a gene and protein
who proposed the colinearity of a gene and protein
Yanofsky et al in 1964
refers to the molecular analysis of the entire genome of species
Genomics
a type of genomic research where there is direct analysis of the DNA itself and
-determination of complete DNA sequence
-done in the human genome two decades ago
structural genomics
-a type of genomic research which identifies which genes are turned on and off
-Determine gene functions and interactions in relation to phenotype
Functional Genomics
-systematic study of all the proteins in a cell or tissue
-the amounts of the different proteins, modifications, interactions, localization, and functions
-all or subsets of all proteins in biological systems, in the whole organisms, tissue, cellular, and sub-cellular levels
Proteomics
it aims to identify and study groups of proteins
-it also determine the role of cellular proteins and how they interact to express the trait
Proteomics
they identified the 21st amino acid - selenocysteine
-encoded by UGA
-found in Archaea, Eubacteria, and Animals
Atkins, J.F and Gestleland in 2002
21st amino acid
-encoded by UGA
-found in Archaea, Eubacteria, and Animals
selenocysteine
22nd amino acid
-encoded by UAG,
-found in Archaea,
-Methnosarcina barkeri
pyrolysine
pyrolysine- encoded by what amino acid
UAG
selenocysteine - encoded by what amino acid
UGA
In _____ cell, after the transcription mRNA undergoes the process of Eukaryotic pre-mRNA processing in order to be converted into a matured mRNA unlike in the prokaryotic cell which does not involve this
Eukaryotic
refers to the RNA transcript prior to any processing
Eukaryotic nuclear gene
TUR - it does not translated into amino acids; only from the first exon to the __ exon would you have the code for the amino acids
third
first process of pre-mRNA processing
1. addition of 5 prime cap
-Addition of 7-methyl guanosine triphosphate on
5’
-Protects from degradation (especially in 5’ end)
-Assists the ribosome binding during translation
second process of pre-mRNA processing
2. SPLICING OF INTRONS
- Removal of introns (intervening sequences)
- Found between region that codes between amino acids (exons)
- Facilitated by spliceosome
- protein complex composed of snRNPs (small nuclear ribonucleic proteins) and other proteins
- takes out introns
these are intervening DNA sequences found in between exons
intron
these are sequences in a gene that code for amino acids
exons
______ have to be take out so that there will continuous series of exons that will be read during transcription in pre-mRNA eukaryotic transcription
introns (they are intervening sequences)
third process of pre mRNA processing:
ADDITION OF POLY A TAIL AT END OF 3’
- addition of multiple adenine residues
- protects from degradation in cytoplasm
- assists in termination of transcription
- helps recognition of mRNA for export to the ribosomes
responsible for taking out the introns and the joining together of exons
spliceosomes
they do not occur in organisms; but these occur in viruses and other particular types
special transfers
In a special transfer, the RNA replication process involves the use of the RNA as template to produce another
RNA
the enzyme involved in the special transfer of RNA replication in the process of using RNA as template to produce RNA
RNA replicase
another type of special transfer where RNA is used to produce a DNA
-found in tumor causing viruses
Reverse Transcription
in reverse transcription, RNA is used to make _
DNA
enzyme involved in reverse transcription where RNA is used to make DNA
reverse transcriptase
this implies that organisms adjust to new environment
-alter gene activity
-synthesis of gene products appropriate to the new condition
Regulation of Gene Action
In ________ ability of the cells to determine:
-which genes should be expressed
-when are those genes should be expressed
-how much of each gene product should be expressed
Gene regulation
activity is controlled in response to the needs of a cell or the organism
-there are times that there will be a large amount of genes, while there are times that this is not the case
regulated genes
-genes that are constantly being transcribed
-expressed all the time
-gene products are essential for maintenance
consitutive or housekeeping genes
group of functionally related genes
-when expressed, they produce polycistronic mRNA
-encodes several proteins
Operon
when operon is expressed it produces
polycistronic mRNA
two types of transcriptional control
negative and positive transcriptional control
with transcriptional control, if a gene is needed then transcription is _, then if the gene is not needed, then trasncription will be _
ON; OFF
a type of transcriptional control which uses repressor protein to turn off transcription which inhibits gene expression
negative transcriptional control
a type of transcriptional control which uses expressor or an activator protein to turn on transcription which triggers gene expression
positive transcriptional control
two operons in prokaryores
Lactose Operon
Tryptophan Operon
group of genes encoding enzymes for lactose utilization
-lactose as source of energy
-system is normally off
Lac Operon
Lac Operon is normally ____ (off or on)
off; which causes small amount of enzymes
LAC Operon in the presence of an inducer (on or off)
on; which is why it is called inducible system
-increased levels of enzymes
Lac operon in the absence of the inducer (on or off)
off
-low level of enzymes
components of the Lac operon
- Regulator gene (lac l)
- Promoter (P)
- Operator (O)
- Structural Genes
a component of the Lac Operon where it produces an active repressor
regular gene (lac l)
a component of the Lac Operon where RNA polymerase binds
Promoter (P)
a component of the Lac Operon where active repressor binds
Operator (O)
permease is encoded by the gene
lac
a structural gene which facilitates the entrance of lactose into the cell
permease
this codes for beta-galactosidase
lac z
a structural gene which splits lactose into glucose + galactose
-converts lactose into an allolactose (inducer)
b-galactosidase
___________ encodes for transacetylase
lac a
this transfer an acetyl group from acetyl-CoA to B-galactosidase
-not involved in lactose utilization
transacetylase
group of genes encoding enzymes for tryptophan synthesis
Trp Operon
Trp Operon is normally turn ___ but it must be turned _____
on; off
what kind of system is lac operon
inducible system
what kind of system is trp operon
repressible system
component of the trp operon which produces an inactive repressor
regulator gene (trpR)
component of the Trp Operon where RNA Polymerase binds
Promoter (P)
component of the Trp Operon where active repressor binds
-formed from the aproprepressor + excess trp
operator (O)
structural genes in trp operon which encodes enzyme for the synthesis of trytophan
trp E, trpD, trpC, trpB, A
a type of eukaryotic gene regulation in which
-genes are quickly turned on and off
-purpose: rapid adjustment to local environment or physiological changes
short term regulation
a type of eukaryotic gene regulation in which events are required for an organism to develop and differentiate
long term regulation
