Unit 1 misc Flashcards
Describe how IEPs can be used in electrophoresis
Soluble proteins can be separated using an electric field and a pH gradient. A protein stops migrating through the gel at its IEP in the pH gradient because it has no charge
What is the name of the technique used to identify thin sections of dissected tissues, entire organisms, individual cells
bright field microscopy
Describe fluorescence microscopy
FM uses specific fluorescent labels to bind and visualise certain molecules or structures within cells or tissues
What is the purpose of aseptic technique
To eliminate unwanted microbial contaminants when culturing micro-organisms and cells (by heat or chemical means)
How can a microbial culture be started
Using an incoculum of microbial cells on an agar medium
What is the purpose of growth factors
They promote cell growth and proliferation
how can the density of cells in the culture be estimated
by plating out of a liquid microbial culture on solid media allowing the number of colony-forming units to be counted
What is the name of the apparatus that estimate the cell numbers in a liquid sample
haemocytometer
What is the role of rRNA, tRNA, RNA etc
They control expression of other genes
Describe the structure of ER
It forms a network of membrane tubules continuous with the nuclear membrane
Describe the structure of the Golgi apparatus
a series of flattened membrane discs
What can the hydrolases of lysosomes digest
proteins, nucleic acids, lipids and carbohydrates
Where are lipids synthesised
In the SER
What happens to the protein once it has been produced in the RER
It is inserted into the membrane of the ER
What happens to proteins that have been inserted into the membrane of the ER
They are transported by vesicles that bud off the ER and fuse with the Golgi apparatus
Describe the movement of proteins through the Golgi apparatus
Molecules move through the Golgi discs in vesicles that bud off from once disc and fuse to the next one in the stack
What structure do vesicles move along
microtubules
Name 2 examples of secreted proteins
Peptide hormones and digestive enzymes
What happens once proteins have gone through PTM
Proteins are packaged into secretory vesicles
What type of secreted protein requires proteolytic cleavage to become activated
digestive enzymes
What is the cause of secondary structure in proteins
hydrogen bonding along the backbone of protein strand
When does quaternary structure occur
When two or more polypeptide subunits are connected
What happens when pH levels are raised/lowers in proteins
The normal ionic interactions are lost between charged groups
What does the addition of phosphate groups add
Adds a negative charge
Some ___ proteins are transmembrane
Integral membrane proteins
What type of protein is a peripheral protein
Hydrophilic/polar
What is facilitated diffusion
The passive transport of substances across the membrane through specific membrane proteins
What are channels
Multi-subunit proteins with the subunits arranged to form water-filled pores that extend across the membrane
What are voltage gated channels opened by
Changes in ion concentration
What enzyme hydrolyses ATP
ATPase
What two things combine to allow electrochemical gradient
Concentration gradient
Electrical potential difference
What is a use of the sodium potassium pump
Accounts for a high proportion of the basal metabolic rate in many organisms
Name 3 examples of extracellular signalling molecules
Peptide hormones, neurotransmitters and steroid hormones
What are transcription factors
Proteins that when bound to DNA either stimulate or inhibit the rate of transcription
2 examples of hydrophobic signalling molecules
oestrogen and testosrerone (both steroid hormones)
Where do G-proteins relay signals from activated receptors to
Target proteins such as enzymes and ion channels
What allows more than one intracellular pathway to be activated
Phosphorylation cascades
Upon binding of insulin what happens to the t.m receptor
changes in conformation and triggers phosphorylation oof it
What is an action wave
A wave electrical excitation along the plasma membrane of a neuron
What is depolarisation
The change in the membrane potential to a less negative value
Describe how an electrical wave is passed through the neuron
Depolarisation of the plasma membrane causes neighbouring regions of membrane to go through the same cycle
Why do Na/K pumps restore the membrane potential after the action potential has been passed through membrane
To allow voltage gated sodium channels can return to a conformation where they can open in response to depolarisation of the membrane
What is the retina
The area of the eye that detects light
What is the effect of cyclic GMP concentration decrease
closes the membrane ion channels in the membrane of rod cells which triggers nerve impulses in neurons the retina
What variation is found in cone cells
Different forms of retinal combine with opsin which have different maximal sensitivity to specific wavelengths
Where do spindle microtubules originate from
centrosome (MTOC)
What gene can mutate to form a tumour promoting gene
proto-oncogene
