Quiz 2: Lecture 6 Videos

Question 1

Prion protein characteristics:
What do all mammalian cells contain?

Answer 1

A gene that codes for the primary sequence of amino acids for the prion protein PrP

Question 2

How does PrP normally fold?
What is the normal function of the prion protein?

Answer 2

Normally, PrP folds into a functional form with several a-helices, called cellular PrP
The normal function of the prion protein is not well understood, but it is believed to be Important in Normal Synaptic Development and Function and May be Involved in Stabilizing the Structure of the Synapses and in Establishing Memory

Question 3

What is the prion protein also capable of folding into a form with?

Answer 3

b- pleated sheets (beta)

Question 4

How do prions reproduce?

Answer 4

Prions do not reproduce like bacteria or viruses
Instead, infectious prions convert normal prions into more infectious prions by folding them into beta-pleated sheets

Question 5

What does an infectious prion look like?
How does the number of infectious prions increase?

Answer 5

beta-pleated sheets
By conversion rather than traditional reproduction

Question 6

What can prion proteins in the infectious conformation group into?
Over time, what happens?

Answer 6

Multimers, which are very stable and resistant to protease
These multimers probably lead to some of the damage seen in prion-infected tissues

Question 7

R Fineman video:
Jiggling Atoms

Answer 7

Hot and cold is the speed that the atom’s jiggling
If the atoms jiggle more, it corresponds to hotter- colder is jiggling less

Question 8

What do atoms have unlike balls that jiggle then stop?

Answer 8

Perfect elasticity, they never lose any energy (keep bouncing, perpetually moving)

Question 9

Scrapie video:
What do we know about scrapie?

Answer 9

We know that scrapie is an infectious disease that has affected sheep and goats for more than 250 years
It is a degenerative disease that affects the central nervous system and first found in US in 1947
Its means of natural transmission are not fully understood

Question 10

How is scrapie believed to be transmitted?

Answer 10

From you to offspring at birth or to other lambs born in close proximity
(Younger lambs are considered particularly vulnerable to infection)

Question 11

What is a factor that makes early diagnosis of scrapie difficult?

Answer 11

Involves subtle changes in normal reflexes, behavior, and temperament and thus often go unnoticed

Question 12

Advanced stages of scrapie:

Other clinical signs:

Answer 12

Animals experience progressive incoordination, and in severe cases may not be able to stand
High stepping of the forelegs, bunny hop movement of the rear legs, swaying of the rear end, stumbling or falling

Biting of the feet and limbs, tremors of the head and neck

Question 13

The Central Dogma of Biology video:
What does the DNA double helix contain?

Answer 13

Two linear sequences of the letters A, C, G, and T which carry coded instructions

Question 14

How does transcription of DNA begin?

What is the blue molecule doing?
What about the yellow chain?

Answer 14

With a bundle of factors assembling at the start of a gene to read off the information that will be needed to make a protein

The blue molecule is unzipping the double helix and copying one of the two strands
The yellow chain speaking out of the top is a close chemical cousin of DNA called RNA

Question 15

What are the building blocks to make the RNA enter through an intake hole?

Answer 15

They are matched to the DNA letter by letter to copy the gene

Question 16

What needs to happen to the RNA before it can be translated into a protein?
What is the editing process called?

Answer 16

RNA needs to be edited
Splicing, which involves removing the green noncoding regions called Introns, leaving only the yellow protein coding Exons

Question 17

What does splicing begin with?

What does the spliceosome do? After that?

Answer 17

Assembly of factors at the Intron-Exon borders which act as beacons to guide small proteins to form a splicing machine called the Spliceosome

The spliceosome then brings the Exons on either side of the Intron very close together ready to be cut
One end of the Intron is cut and folded back on itself to join and form a loop

The spliceosome the RNA to release the loop and join the two Exons together
The edited RNA and Intron are released and the spliceosome disassembles
(This process is repeated for every intron in the RNA)

Question 18

What do numerous sliceosomes do?

Answer 18

Remove all introns so that the edited RNA contains only Exons, which are the complete instructions for the protein

Question 19

What happens when the RNA copy is complete?

What does the ribosome do?

Answer 19

It snakes out into the outer part of the cell
Then all the components of a molecular factory called a Ribosome lock together around the RNA

It translates the genetic information in the RNA into a string of amino acids that will become a protein

Question 20

What do special transfer molecules do?

Answer 20

Bring each amino acid to the ribosome

Question 21

What happens inside the ribosome?

Answer 21

The RNA is pulled through like a tape
There are different transfer molecules for each of the 20 amino acids shown as small red tips
The code for each amino acid is read off the RNA, Three letters at a time and matched to three corresponding letters on the transfer molecules

The amino acid is added to the growing protein chain and after a few seconds, the protein starts to emerge from the ribosome

Question 22

What can ribosomes do?

Answer 22

Make many proteins, it just depends what genetic message you feed into the RNA