BIOLEC UH TEST RIGHT NOW 2ND Q

Transcription

A new RNA strand is synthesized from a template DNA strand

Anti-sense strand / Template strand / (-) strand

DNA strand that is used as template for RNA synthesis

Sense strand / Coding strand / (+) strand

DNA strand with the similar sequence as the synthesized RNA

RNA polymerase

Similar to DNA Pol, synthesis of new RNA by the - is always 5' → 3

Core, 2a beta beta prime horseshoe

- enzyme consists of five subunits (-,-,-,-)

2a

for enzyme assembly

Beta prime

template binding

Beta

5-3 RNA polymerase activity

Fancy o

Dissociable & enables RNA polymerase to recognize promoter region on DNA strand

Ó subunit + core enzyme

-+-= Holoenzyme

Idk?? Rna polymerase or something

Synthesizes all of the RNA (mRNA, rRNA & tRNA) PREVIOUS ARE ALL PROKARYOTES

1. RNA POLY 1

2. RNA POLY 2

3. RNA POLY 3

There are three different RNA polymerases in EUKARYOTES

RNA poly 1

Synthesizes rRNA (45S rRNA), cleaved into 285, 185 & 5.8S rRNA

RNA poly 2

Synthesizes mRNA (processed into mature mRNA. snRNA & miRNA

RNA poly 3

Synthesizes small RNAs such as tRNA, SS rRNA. SARNA & SCRNA

1. Initiator complex

2. Synthesis and elongation

3. Termination sequence

RNA Polymerase

Major functions include:

Formation of the - which is responsible for unwinding the double helix structure of DNA.

-of the RNA transcript by adding nucleotide bases

Formation of the - that stops transcription.

upstream, downstream

Promoter, transcribed region

Regions in Initiation of transcription

Recognition sequence

Dito nag aattach and RNA polymerase pag nakita nya ay DITO ako mag attach

Upstream, downstream

At - nahahati and - stream and - stream

Promoter,

Upstream is the - region kung saan nandun recognition sequence makapag attach and RNA polymerase

Promoter,

Eventually mag tra transcript na to the downstream or the - region

-10 -35

Parts of RNA polymerase that specifically bind to - and - elements

ONLY IN PROKARYOTES

Pribnowax, at rich sya, madali ma unwind

- is also called -10 ano tawag other

TATA box (eukaryotes) -75 -25

Acts as a binding site for transcription factors which recruit the RNA Polymerase to the correct start site

TATA BOX, hogness box

-25 is also called

CAAT box

-75 is sometimes present and is called -

Basal transcripion factor

Helps the RNA Polymerase attach to the DNA

Basal transcripion factor

helper protein

Euchromatin

Loosely packed & easily accessible chromatin loop

Heterochromatin

Tightly packed & Condensed chromatin loop

Histone acetyltransferase

Histone deacetylases

For bead of string model to loosen up for transcription w o chromatin modelling using the -

To package naman ulit we use -

Heterochromatin to euchromatin

So dalat from - to - na transcriptionally active

Elongation

The RNA Polymerase travels across the 3' -

5' template strand

Elongation

Synthesis is 5' 3' and follows proper base pairing

Terminator

Transcription stops when RNA polymerase transcribes a sequence called the -

1. Rho dependent

2. Rho independent (intrinsic)

Termination can be

Rho dependent termination

RNA strand has a binding site for rho factor which then pulls the RNA polymerase away from the template strand

Rho independent termination

When RNA polymerase approaches the end of the gene, it enters a region rich in cytosine and guanine

Rho independent termination

This causes the transcribed RNA to fold on itself to create a hairpin structure.

Termination

RNA Polymerase is detached from template DNA through a certain mechanism

Polycistronic, prokaryotes

May product which is the mrna na na transcript mo, pag prokaryotes the encoded mrna is diretcho for translationz, so mrna, invokved in translation the transcript has certain portions that codes for the diff kind of proteins which we finally call - which means maraming ma e encode na protein dun lang sa isang mrna. This is for - only

Exon and intron, intron, exon, monocistronic, eukaryotes

In eukaryotes we have what we call - and - , in here wee remove the -. Then - is expressed to get a specific protein. Now that's - which is only for -

Pre MRNA, post transcriptional modif.

The immediate product of an mRNA transcript is a - which needs to be modified to form the mature mRNA

Modification of mrna

Helps prevent degradation

Increases efficiency of protein synthesis

Expands complexity of proteome

Prokaryotic modification

No processing is involved

Protein synthesis can happen during transcription

Eukaryotic modification

Addition of 5' cap

Addition of poly (A) tail

Splicing introns

Degradation

Addition of 5 prime cap and addition of poly a tail prevents -

Splicing introns

-helps us code protein properly

Addition of 5 primecap

A methylated cap is added to the 5' end to protect against degradation by exonucleases

5 prime end, GTP guanosine triphosphate , 1, 2

We're synthesizing mrna it has a 5 prime portion and 3 prime end. The only thing we're protecting here is the -. We put a cap called the -. 5 prime to 5 prime mag attach. Then you'll see a portion of triphosphate.

Triphosphate is usually - phosphate from the gtp - phosphate from the 5 prime end. Then we'll have triphosphate linkage which is basically the cap preventing degradation

Addition of poly (A) tail

A poly (A) tail is added to the 3' end for further protection and to help the transcript exit the nucleus

Poly a tail, polyadenylation

Tuloy tuloy na nilalagay lang sa 3 prime end yung - na tinatawag na -

Introns

SPLICING

- do not code for proteins and are removed

Exons

- code for proteins and are linked

Splicesosome, lariat formation

- will only happen if - is involved, na magpuputol. Yung intron is papaloop nya para ma enclosedm - is the also one involded para pagkatanggal ng intron pagdudutgtungin na ang extron which will then lead to mature mrna that w ecan use for coding or translation offfff protein

Alternative splicing

A particular exon may or may not be incorporated into the final mature mRNA

Alternative splicing

Increase complexity of proteome d na maraming mrna i transcribe iba ibang exons lang kukunin para ma ano ng protein

Trna modification

Ensure structural stability and efficient, accurate protein translation

Trna, anti codon loop, increases, cca sequence

_ is involved later on in translation, trna are not yet matured when transcribed, in the - may need pa tanggalin to get the anti codon necessary. One thing it also does is it - the stability of the rna, also in the 3 prime end napapalitan sya into - which is important for amino acids to hold

Activator transcriptioj factors

bind to enhancer DNA sequences to promote gene expression

BOTH ARE FOR PROKARYOTES ONLY

Represseor transcription factor

bind to silencer DNA sequences to inhibit gene expression

Operon Prokaryotic

Cluster of genes that work as a single unit to give a single mRNA molecule, which then encodes multiple proteins

Inducible operon

Normally turned off but can be switched on

Inducer, lac operon

_ binds to the oppressor, which causes the oppresor to not be attached to the operator maa tu turn on ang transcription process

Allolactose

Inducer other name is

Resd

If lactose is present mah b bind yung allolactose sa oppresor

Camp, gene expression

Higher - means higher

Trp operon

- repressible, normally on but can be turn off.

Tryptophan

- binds to the trp repressor to stop the expression of structural genes na

Genetic code

Defines how the four-letter nucleotide bases in DNA and RNA are translated into the 20 amino acids that build proteins

The genetic code

This code uses three-letter combinations called codons and is universal, continuous, non-overlapping, and exhibits degeneracy

AUG, methionine

- start codon it codes for -

UUA UGA UAG

-,-,-, are the stop codons

Translation

requires the input of an mRNA template, ribosomes, tRNAs, and various enzymatic factors

Ribosomes, translation

Each mRNA molecule is simultaneously translated by many - all synthesizing protein in the same direction

Transfer rnas

Serving as adaptors, each tRNA type binds to a specific codon on the mRNA template and adds the corresponding amino acid to the polypeptide chain

Exit site

The site where the empty tRNA (unloaded or deacylated tRNA) occupies prior to exiting the ribosome

Peptidyl site parking site

Occupied by the peptidyl-tRNA, the tRNA carrying the growing polypeptide chain

Acceptor a

Attachment site for an incoming aminoacyl-tRNAS

EPA

Ribosome has - sites

A site, P site, e site

- site must be complementary to the mrna

Then move to - site na hawak ang growing polypeptide chain then goes to the - site where kung saan wala na syang hawak na polypeptide

Initiation

Transitional Complex forms, and IRNA brings first amino acid in polypeptide chain to bind to start codon on mRNA.

Elongation

tRNAS bring amino acids one by one to add to polypeptide chain

Termination

Release factor recognizes stop codon, translational complex dissociates, and completed polypeptide is released.

Wobble base pairing, 3rd

tRNAs may have a flexible base pairing at the wobble positionm happens only at the - position

Posstransational modification

Addition of sugar units (glycoproteins

Posstransational modification

Binding of coenzymes or prosthetic groups

Posstransational modification

Cleavage of polypeptide

Posstransational modification

Modification of side chains (methylation, phosphorylation, etc.

Mutation

Changes the DNA sequence, which could alter the amino acid sequence of the protein during translation

Point mutation

Only one base is changed

Frameshift mutation

Insertion or deletion of a base results to a shift in reading of genetic code

Leftz right

Deletion -, insertion -

Transversion and transition

Kinds of point mutation

Transition

Transition

Adenine to guanine=

Thymine to cytosine=

Transversion

Adenine to Cytosine =

Silent point mutation

There's a change in dna level but it's still the same na inaano na protein

Nonsense

Maaga na stop ang mutation nagawa agad yung uaa uga uah

Missense

Kapah iba na nacocode mong keneme

Conservative missense

Nagiba kung san sya nakagrupo and eskale same group nagkaiba ornsomething