PPQ Corrections 2 Flashcards
How Do Hydrophobic Signalling Molecules Work?
Diffuse across phospholipid bilayer.
Bind to intracellular receptors which are transcription factors.
The hormone-receptor complex moves to the nucleus and binds to HRE’s.
The rate of transcription is altered, affecting the gene expression of many genes.
How Do Hydrophilic Signalling Molecules Work?
Bind to transmembrane proteins.
Receptor changes conformation.
This triggers a G-protein or kinase cascade inside the cell.
Cellular response is activated.
Action of Insulin
Bind to transmembrane proteins.
Receptor changes conformation.
This triggers a phosphorylation cascade inside the cell.
Vesicles containing GLUT4 are recruited to the cell membrane.
This allows the entry to glucose into the cell.
Cyclin‑CDK complexes regulate the cell cycle by…
Phosphorylation of specific proteins.
Cell cycle
G1-S-G2-M
G1 checkpoint
Size is checked to see if it is sufficient for cell division to occur.
Checks for DNA damage.
Role of Rb and cyclin-CDK in G1.
Rb acts as a tumor suppressor by inhibiting transcription of genes that code for proteins needed for DNA replication.
Rb is inhibited by being phosphorylated by cyclin-CDK allowing the transcription of genes that code for proteins needed for DNA replication, this needs to happen before S stage can begin.
Meiosis
Chromosomes replicate to form two identical chromatids.
Homologous chromosomes pair up and points of contact form between non-sister chromatids of a homologous pair.
Crossing over takes place to form new combinations of alleles of linked genes.
Chromosomes of each homologous pair attach to spindle fibres and separate to opposite poles.
Cytokinesis occurs and two daughter cells form.
Two daughter cells undergo further division separating sister chromatids of each chromosome.
Absolute Fitness
frequency of a particular genotype before selection
Relative Fitness
number of surviving offspring per individual of the most successful genotype
Repeating readings is useful for checking…
Precision
