all Flashcards
The process of transcription
The DNA strands are separated by DNA helicase
Transcription factors bind at promoter region
RNA polymerase binds around promoter region
RNA polymerase produces a strand of mRNA in the 5’ to 3’ direction, complementary to the template strand
A stop codon is reached and the enzyme falls off
Capping, tailing and splicing may occur
What enzymes are involved in transcription
DNA helicase
RNA polymerase
The process of DNA replication
DNA helicase unravels the helix at the origin of replication
Primase adds primers to each end of the molecule
DNA polymerase adds nucleotides to the primers to form two new strands. The lead strand is created in the 5’ to 3’ direction, whereas the lag strand is created in the 3’ to 5’ direction. This produces okizaki fragments, which are later joined up by DNA ligase
Each replication fork proceeds towards each other until they join up
What enzymes are involved in DNA replication
DNA helicase
Primase
DNA polymerase
DNA ligase
The process of translation
The small (40S) subunit of the ribosome with a methionine tRNA binds to the 5' cap of the mRNA molecule They move along the mRNA until an AUG start codon is found, at which point the large (60S) subunit of the ribosome will bind Translation then proceeds: a tRNA molecule with an anticodon complementary to the next codon of mRNA binds at the A site, using energy from GTP the amino acid of this tRNA forms a peptide bond with the methionine at the P site, using peptidyl transferase This process continues, with the A site accepting and the P site holding the protein until a stop codon is reached
The process of mitosis
Prophase - nuclear membrane breaks down, spindle fibres form, chromosomes condense
Prometaphase - Chromosomes attach to spindle fibres at centromere
Metaphase - Chromosomes align at metaphase plate
Anaphase - Sister chromatids are pulled towards opposite poles
Telophase - Chromosomes decondense, spindle fibres break down, nuclear membrane reforms and cleavage occurs
The process of meiosis
As in mitosis, but two rounds of division occur
Bivalents form so that maternal/paternal chromsomes are pulled in opposite directions
Crossing over occurs at prophase I
Independant assortment occurs at metaphase
Remember: meiosis occurs before sexual intercourse - all gametes come from one body!
How is the secretion of insulin controlled
An increased concentration of glucose in the ECF allows glucose to enter the beta cells via the GLT2 receptor
Increased glucose within the cell causes depolarization
Calcium ions flood in
Causes vesicles containing insulin to be exocytosed
How does insulin act on its target tissues?
Binds to an insulin receptor
Each insulin receptor is made up of two subunits, each containing an alpha and a beta chain. The alpha chain is outside the cell and the beta within
When insulin binds, the alpha chains move closer together, activating the beta globins
Through a cascade of reactions this increases the expression of GLT4 receptors in the target tissues
What are the glucose receptors in the pancreas called?
GLT2
What are the glucose receptors in the target tissues called?
GLT4
The process of PCR
DNA heated to 95 degrees to denature the strands
cooled to 50-65 degrees and primers added
DNA (taq) polymerase added at 72 degrees
Free nucleotides added
What is a point mutation?
Single base substitution
What is a missense mutation?
a mutation which cause an amino acid to be replaced by another
What is a nonsense mutation?
a mutation which introduces an early stop codon - producing truncated proteins
