pls slay Flashcards
3 stages of transcription
INITIATION:
- RNA polymerase binds to the promoter region
- DNA unwinds
ELONGATION:
- RNA polymerase reads the DNA template strand and uses complementary RNA nucleotides to catalyse the formation of pre-mRNA
- strand of DNA that is not read is called the coding strand
TERMINATION:
- transcription is terminated when the termination sequence is recognised
- pre-mRNA is then processed to become mRNA
3 stages of translation
INITATION:
- mRNA molecule binds to the ribosomes
- tRNA complementary to mRNA deliver corresponding amino acids to the ribosome
ELONGATION:
- adjacent amino acids are joined with peptide bonds via a condensation reaction to form a polypeptide
TERMINATION:
- translation ends when a STOP codon is recognised
repression
LOW LEVEL OF TRYPTOPHAN:
- insufficient tryptophan to bind to repressor protein
- causes repressor protein to detach from operator region
- allowing RNA polymerase to transcribe the trp gene and increase tryptophan levels
HIGH LEVEL OF TRYPTOPHAN:
-sufficent tryptophan to bind to the repressor protein
- causing conformational change and repressor protien to stay attached
- RNA polymerase will not transcribe the trp gene and no tryptophan will be produced
attenuation
- transcription and translation occur simultaneously
LOW LEVEL OF TRYPTOPHAN: - due to no tRNA bound tryptophan in cell ribosomes pause
- causes mRNA molecule to fold and form anti-terminator hairpin loop
- RNA polymerase continues and transcribes genes to synthesise tryptophan
HIGH LEVEL OF TRYPTOPHAN: - tRNA bound tryptophan travels to ribosomes and is added to proteins
- causes mRNA to fold and form terminator hairpin loop
- causes mRNA to seperate and RNA polymerase to detach stop transcription and no new tryptophan to be synthesised
CRISPR-Cas9 in bacteria
EXPOSURE:
- the bacteriophage injects in DNA
- a short section of the DNA is cut out called the protospacer
- the protospacer is introduced into the CRISPR gene becoming a spacer
EXPRESSION:
- CRISPR spacers are transcribed and converted into gRNA
- gRNA binds to Cas9 to create CRISPR-Cas9 which is directed to any viral DNA
EXTERMINATION:
- the CRISPR-Cas9 scans for invading bacteriophage
- Cas9 cleaves
CRISPR-Cas9 in gene editing
STEPS:
- synthetic gRNA is created that matches target DNA
- Cas9 enzyme is obtained with target PAM sequence
- Cas9 and gRNA bind together to make the CRISPR-Cas9 complex
- mixture is injected into specific cells
- Cas9 finds target PAM sequence
- Cas9 cuts the selected sequence
- DNA with blunt end will attempt repair
- when repairing cells may introduce new nucleotides
PCR steps
DENATURATION
- DNA is heated to 90-95 degrees to break hydrogen bonds, forming single stranded DNA
ANNEALING
- DNA is cooled to 50-55 degrees to allow primers to bind to complementary sequences
ELONGATIONS
- DNA is heated to 72 degrees, allowing Taq polymerase to bind to the primer and being synthesising
REPEAT
LIGHT DEPENDENT STAGE: location
thylakoid membranes of the chloroplast
LIGHT DEPENDENT STAGE: inputs
- H2O
- NADP+
- ADP + Pi
LIGHT DEPENDENT STAGE: outputs
- O2
- NADPH
- ATP
LIGHT INDEPENDENT STAGE: location
stroma of the chloroplast
LIGHT INDEPENDENT STAGE: inputs
- CO2
- NADPH
- ATP
LIGHT INDEPENDENT STAGE: outputs
- glucose (C6H12O6)
- H2O
- NADP+
- ADP+Pi
GLYCOLYSIS: location
- Cytosol
GLYCOLYSIS: inputs
- Glucose
- 2 ADP + Pi
- NAD+ + H+
