Random facts Flashcards
Carrier vs channel proteins in FD
Carrier: Integral glycoproteins. Undergo conformational change when specific molecule binds –> translocating molecule across membrane. Can be used for active transport in presence of atp.
Channel: Integral lipoprotein. Have a pore through which ions pass. ion-selective and may be voltage gated to control ions passing in response to particular stimuli. can’t be used for active transport. much faster than carriers
Explain Na+ / K+ pumps
Used in nerve cell electrical impulse transmission that creates a potential difference across the membrane when impulse transmitted.
- At rest, the Na+ ions removed from the cell and the K+ ions accumulated inside. When axon fires electrical impulse, these 2 swap positions.
FD of K+:
- Integral protein w the hyphil inner pore so k+ which is charged can pass through
- 4 subunits and a selectivity filter at the end so only K+ can pass through
- Potassium channels are typically voltage-gated and cycle between an opened and closed conformation depending on the transmembrane voltage
AT of NA+:
Three sodium ions bind to intracellular sites on the sodium-potassium pump
A phosphate group is transferred to the pump via the hydrolysis of ATP
The pump undergoes a conformational change, translocating sodium across the membrane
The conformational change exposes two potassium binding sites on the extracellular surface of the pump
The phosphate group is released which causes the pump to return to its original conformation
This translocates the potassium across the membrane, completing the ion exchange
Centriole v centrosome v centromere
centromere: part of the chromosome that links sister chromatids
centrosome: 2 centrioles are held together by a protein mass called centrosome in animal cells
centriole: structures that organise spindle fibres
Cyclin D
Triggers cells to move from G0 to G1 and from G1 into S phase.
Cyclin E
prepares the cell for DNA replication in S phase.
Cyclin A
activates DNA replication inside the nucleus in S phase.
Cyclin B
promotes the assembly of the mitotic spindle and other tasks in the cytoplasm to prepare for mitosis.
Sense v Antisense
AS: the template strand
SS: coding strand
direction of transcription and dna replication on the strand being created
5’ to 3’
the end at which DNA Poly 3/RNA Poly attach on the template strand
3’
Effect of Histone tail methylation v acetylation
Histone tails are +, DNA is -
- Acetyl –> the histone tails neutralised –> dna loosely wrapped
- Methyl –> histone tails more + –> dna tightly bound
DNA methylation
- increased methylation –> tighter wrapping around histone –> reduced exp
- genes with reduced expression also have higher methylation in them
Functions of the different tRNA arms (clockwise order, from top arm)
- 3’- ACC acceptor stem: carries amino acid
- T arm - associates with the ribosome (A,P,E sites)
- Anticodon - associates with codons on mRNA
- D arm - associates with tRNA activating enzyme
Gene definition
a heritable factor that consists of a length of dna and influences a specific trait
locus
position of a gene on a particular chromosome
