AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011

ok so the ends of the gene arent important???

Hi people!

Was just wondering... haven't really thought much about the synoptic essay question so wanted to ask what main topics you'd recommend to read up on/ revise?

??

the t-tubules connect the membrane to a protein complex

this protein complex is connected to a sarcoplasmic reticulum

when an action potential passes down the t-tubule and reaches the protein complex it stiumulates the protein complex to signal the release of calcium ions from the sarcoplasmic reticulum

alos does tha mean that restriction endonucleases are ususally used on dna isolated by reverse trancriptase so they are intron free?

ok so the ends of the gene arent important???

I believe that they can be used on DNA containing exons and introns as restriction endonucleases are specific-its just DNA with only exons is shorter so procedure takes shorter amount of time to carry out

red blood cells...?

"Thus, the t-tubules are an important determinant of cardiac cell function, especially as the main site of excitation-contraction coupling, ensuring spatially and temporally synchronous Ca2+ release throughout the cell"
Brette and Orchard, Circulation Research. 2003;92:1182

I think different books have slightly different versions of this.

In the histology of skeletal muscle, a triad is the structure formed by a T tubule with a sarcoplasmic reticulum (SR) known as the terminal cisterna on either side.[1] Each skeletal muscle fiber has many thousands of triads, visible in muscle fibers that have been sectioned longitudinally. (This property holds because T tubules run perpendicular to the longitudinal axis of the muscle fiber.) In mammals, triads are typically located at the A-I junction;[1] that is, the junction between the A and I bands of the sarcomere, which is the smallest unit of a muscle fiber.

Triads form the anatomical basis of excitation-contraction coupling, whereby a stimulus excites the muscle and causes it to contract. A stimulus, in the form of positively charged current, is transmitted from the neuromuscular junction down the length of the T tubules, activating dihydropyridine receptors (DHPRs). Their activation causes 1) a negligible influx of calcium and 2) a mechanical interaction with calcium-conducting ryanodine receptors (RyRs) on the adjacent SR membrane. Activation of RyRs causes the release of calcium from the SR, which subsequently initiates a cascade of events leading to muscle contraction. These muscle contractions are caused by calcium unmasking the t-t complex on the actin myofilament and allowing the myosin cross-bridges to connect with the actin.

red blood cells...?

Left-hand side of gene will have promoter, operator regions

Right-hand side of the gene will have stop codons, usually more than one.

You can cut out the gene in such a way, that when it is reattached to the vector, it will be flanked by promoter on one side (provided by vector) and stop codons on the other side (provided by vector)

But they don't contain a nucleus...

red blood cells lack any DNA - hence they cannot replicated by mitosis.

DNA in blood comes from white blood cells.

I believe that they can be used on DNA containing exons and introns as restriction endonucleases are specific-its just DNA with only exons is shorter so procedure takes shorter amount of time to carry out

oh ok so the vector will techincally make up part of the gene,, clever thankyou

hey yh i understand that but when isolating a gene for insertion into a plasmid you would want it to be intron free, so in these cases i was asking?

I'm confused. Where is the DNA in the blood found?