2e AND 2F Flashcards
exocytosis
the cells excrete waste and large molecules from the cytoplasm to the exteriorenvironment via vesicle
differnece between golgi body and RER
golgi body packages proteins inot vesciles, whislt RER modifies protiens
Once proteins are produced and modified, what happens to the proteins
the proteins are packaged into a vesicle and released out of the cell via exocyotisis
What type of transport is exocytosis and is ATP required
exocystosis is a form of bulk transport and requires ATP
Process of exocytosis
- Vesicle is transported to the plasma membrane
- Vesicle fuses with the plasma membrane
- contents of the plasma membrane is released from the cell into the extracelluar environment
Whatt triplet base sequence repersents tryptophan
UGG codes for tryptophan
What is the process of attenuation when tryptophan is present on the tRNA molecule
- transcription and translation occurs at the same same
- when ribsokmes reach the UGG code for tripytophan, tryptophan attaches to polypeptide chain,tRNA
- Ribsoomes reach STOP codon, RNA polyermase continues to read the DNA, however ribosomes stop translating the mRNA
4.but at the same time domain 3&4 pull away and form a hairpin
- Thereofre RNA polyermase stops reading dna after the attenuated region
How is bacteira, E.Coli responsible for transcribing genres involved in making tryptophan
In E. coli, the trp operon regulates the transcription of genes involved in tryptophan synthesis. When tryptophan levels are low, the operon is activated, allowing for gene transcription and subsequent tryptophan production.
Process of attenuation when tryptophan is absent on the tRNA molecule
- transcription and translation happen at the same time
2.ribosomes pause at the two tryptophan codons because its waiting for tryptophan
- During that pause domain 2 and domain 3 form a loop, which stops domain 3 & 4 from pairing.
- This allows RNA polyermase to still attach to the 4th domain, and continue to transcribe the trp operon genes, thus making more trytophan, which is known as attenuation.
between what domains is there a pause of trp production
between domain 2 and 3, hwoever there is no pause betewen seciton 3 and 4
thisis because the pause between domain 2 and 3 allows for the attenutation mechanism to occur. However, there is no pause between domain 3 and 4 because they are not involved in attenutation mechanism because they have the genes for tryptophan production.
complete process of transcription in gene expression
- Inititation:
Transcription factors bind to the promotor region to intitate transcription
RNA polymerase binds to the promotor region whihc signals to the weak hydrogen bonds between the DNA to break
This results in the bases of DNA to be exposed
- Elongation:
RNA polymerase moves along the template strand of the DNA in a 3’ to 5’ end direction
As it moves along, the complemenatry RNA nucleotides are added to produce a pre-mRNA molecule
Termination:
Transcription ends when RNA polymerase reaches the termination sequence
This signals to the premRNA molecule to be released for processing
DNA winds up and hydrogen bonds form between the strands
full process of translation in gene expression
- Initation:
the 5’ end of the mRNA molecule attaches to the ribosomes
The start codon(AUG) is read then the tRNA molecule with complementary anticodon(UAC) binds to the ribsoomes to deliever the amino acid to methione
- Elongation:
The next codon is read and the complementary tRNA molecule delivers a specific amino acid to the ribosomes
This amino acid will bind to the adjacent amino acid from the peptide bond
This process continues and a growing polypeptide chain of amino acids are produced.
- Termination:
Once the stop codon is read, this signals the end of translation
Since there is no tRNA moleucle that corresponds to the STOP codon,
instead, A release factor binds to release the polypeptide chain of amino acids for modification
attenuation mechanism
attenuation mechanisms can refer to processes by which gene expression is regulated, often involving the repression of transcription or translation, leading to a decrease in the production of tryptophan.
trp operon
seriesof genes responsible for the production of the amino acid tryptophan,
examples of each of the structures
hydroge n onds
attrction etween ocxygen and hydrohgen and form between the complementary nitrongoeus basess of DNA
open reading frame
section of the gene that is being coded into mRNA
tata box is
sequenceof the promtor region that indicates where a genetic sequence can be read and decoded
sequence of a gene
promotor –> operator –> leader –> trp genes (coding region)
function of coding genes and non coding regions
Coding genes contain instructions for making proteins, while non-coding regions regulate gene expression and maintain genome stability.
in the trp opern, there is 1 coding region, with 5 structural genes, what are they and what do they do
collecitvley these trp structural genes make up parts of the enzyme and involved in the production tryptophan
where is trp opern produced
E.coli which is a prokaryote
why does attenutation more likely to occur E.coli/prokaryotes
since the prokaryotes dont have a nucleus, the transcription and translation occurs occur simulataneously and close together
unlike the eukaryotes in which transcription occurs inside the nucleus whereas translation occurs outside the nucleus
compare attenuation and repression
in trp operon repression transcription does not occur, but in trp opern attenuation transcription begins but stops before a protein is produced.
in trp operon repression, the operator region is the most importat secitionbc its where the repressor bind to, but in trp operon attenutation is the leader region isthe most importnat because its where the leader sequence is
leader sequence is important because
, the leader sequence helps control how much tryptophan the cell makes by stopping the production of trp structueal genes when it’s not needed.
protein secretorty pathway- what isexplain
The protein secretory pathway is a cellular process responsible for synthesizing, modifying, and transporting proteins to their final destinations within or outside the cell.
why does transcription and tranlsation occur at the sametime
, in prokaryoteslike some cells like bacteria, transcription (making RNA from DNA) and translation (making proteins from RNA) happen at the same time because the cell doesn’t have a separate compartment for these processes.
what does RNA polyemerse do
bindto DNA tomakes mRNA
process of protein secretorty pathway
The protein secretory pathway involves proteis being produced in the ribosomes. These proteins, either stay in the cytoplasm or being directed to the Rough endoplasmic reticulum (ER) for folding and modification before being transported to the Golgi apparatus for further be packaged into vesicles, which deliver proteins to be transported out of the cell via exoctyosis.
compare transcirption vs translation
transcription isthe process wherbey DNA is made into RNA
Translation isthe process where by RNA is made into proteins
outline the process of transcription
Transcription begins with the unwinding of DNA at the promoter region. RNA polymerase catalyzes the synthesis of a complementary RNA strand, using the DNA template strand. This newly synthesized RNA, called pre-mRNA, is complementary to the DNA template and includes adenine pairing with uracil instead of thymine. Transcription terminates when RNA polymerase reaches thetermination sequence in DNA.
3 main steps of gene expression state
transcription
RNA processing
Translation
outline the process of tranlsation
Translation begins with initiation where the5’ end of the mRNA binding to ribosomes. Then followed by the complemeanatrytRNA molecule attaches to the start codon. During elongation, the ribosome moves along the mRNA,by matching tRNA anticodons with mRNA codons and forming peptide bonds between amino acids. Termination occurs when the stop codon is read, polypeptide chain of amino acids is released.
repressor gene and represosr protein.
premRNA is characterised by
introns and exons
where is RNA found
free in ribosomes or cytoplasm
comparing the bonds between Adenine and thymine and cytosine and guianaien
adenine and thymine has weaker bonds bceause it has 2 hydrogen bonds, whereas cytosine andguanine are stronger because they have 3 hydrogenbonds
how is DNA and RNA associated to nucleotides
DNA and RNA are polymers of nucleic acids.
how are nucleic acids built
by DNA/RNA polyermease in a 3’ to 5’ direction.
how many base pairs of a double helix form per twise
10.5 bp base pairs per twist
where is the promotor region found
at the 5’ end of the gene.
what does RNA polyermease do at the templatestrand/non coding region
RNA polyermase pairs RNA nucloetides with complemmenatry bases on the non coding strand of the DNA.
genetic code is said to be degenerate means
amino acids are encoded by more than one mRNA codon
cargo proteins
Any protein that is carried within the vesicles of a cell’s secretory system
