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Alex's Genetics > Lecture 11a > Flashcards

Lecture 11a Flashcards

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Biology 101 flashcards
1
Q

What cells prevent us from attacking our own immune system?

A

Dendritic cells

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2
Q

What are dendritic cells?

A

Immune system cells present in tissues that are in contact with the body’s external environment (skin, inner lining of the nose, lungs, stomach, and intestines) and our blood.

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3
Q

What is important about the dentrites on dendritic cells?

A

Dentrites are the petal-like projections that maximize surface area and interaction with the environment.

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4
Q

What do dendritic cells ingest?

A

They ingest things that do not belong near the external environment like bacteria and viruses.

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5
Q

What is phagocytosis?

A

When dendritic cells ingest things that do not belong.

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6
Q

After phagocytosis, what do dendritic cells do with the pathogen?

A

Dendritic cells digest the antigen, then use MHC proteins to present little bits of the antigen’s proteins on the surface of the dendritic cell.

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7
Q

What else resides in the cell membrane of the dendritic cell besides MHC proteins?

A

CLR proteins are also placed in their membranes.

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8
Q

What do dendritic cells have to do to get to the spleen?

A

They express a protein called CCR7 which makes the cell migrate to the spleen after it has presented the antigen using the MHC proteins.

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9
Q

If it is actually a pathogen, what do dendritic cells in the spleen do?

A

They will active B and T cells that come to the MHC proteins and fight the pathogen.

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10
Q

What do CLRs do on dendritic cells?

A

Dendritic cells use CLRs to recognize cells that belong to the same individual.

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11
Q

What is a CLR-CLR interaction?

A

This is when the CLRs on separate dendritic cells come into contact. When this occurs, the dendritic cell knows that the proteins (antigens) are ‘self’. The dendritic cell will then acquire the antigen by ingesting a small amount of membrane.

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12
Q

What is nibbling?

A

This is when a dendritic cell recognizes an antigen/proteins as being from the body and so it acquires them by ingesting a small amount of membrane from the dendritic cell it is in contact with.

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13
Q

What occurs after a dendritic cell has ingested self-antigens?

A

The dendritic cell then presents the ingested antigen on its outer cell membrane and puts NEW CLR proteins on its surface.

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14
Q

After ingestion of the self-antigen, why does a dendritic cell put new CLR proteins in its membrane?

A

This is to show that the dendritic cell interacted with ‘self’, that being another cell in the same individual.

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15
Q

If we are a dendritic cell with an antigen on our surface, what area of the body do we wanna get to and why?

A

We wanna migrate to the spleen, because that is where the B and T cells reside.

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16
Q

If we had new CLRs on the cell surface due to recognition of a ‘self’ protein/antigen, what occurs in the spleen?

A

Dendritic cells will interact with B and T cells recognizing the self antigen. The CLR proteins also interact to signal T and B cells that the antigen is NOT foreign, thus, they will NOT attack.

17
Q

Besides antibodies, what else do B and T cells have on their surface that is important in the spleen?

A

They also have CLRs present on their surface, so that the CLRs can interact between cells. This is important for the dendritic cell to signal to B and T cells not to attack.

18
Q

What is a double interaction?

A

When the CLR and presented antigen interact.

19
Q

When we have a ‘self’ antigen, what does interaction between the CLR and presented antigen (double interaction) cause?

A

This makes the B and T cells commit suicide by apoptosis. This is because they are not needed right now due to the antigen coming from our own bodies.

20
Q

T/F: Prokaryotes have several RNA polymerase.

A

False! Prokaryotes have one RNA polymerase which does RNA synthesis.

21
Q

How are bacterial promotors generally organized form the 5’ to 3’ direction?

A

At the 5’ end, there is a -35 position sequence. Then comes a -10 position sequence. More in the 3’ direction, there is the +1 position which is the transcriptional start site.

22
Q

What is the Transitional start site?

A

+1 position

23
Q

What is the promoter region?

A

From -35 position sequence to the -10 position sequence.

24
Q

T/F: Bacterial promotors show no variation.

A

False! The sequences for bacterial promotors are not always the same.

25
Q

What is the consensus sequence?

A

The most common nucleotide sequence in bacterial promotors.

26
Q

What is the relationship between consensus sequence and promotor strength?

A

The closer the nucleotide sequence to the consensus sequence, the stronger the promotor will be.

If you use the consensus sequence for a promoter, the promotor will be VERY STRONG.

27
Q

What is the name for the -10 position sequence?

A

Pribnow Box

28
Q

Is core transcription used in bacteria or eukaryotes?

A

Bacterial transcription

29
Q

What is a closed complex?

A

This is when the sigma factor binds to the -35 and -10 position sequence at the promoter, which stops the movement of RNA polymerase along DNA. Strands are NOT separated.

30
Q

What makes up the complex in the initiation of bacterial transcription?

A

RNA polymerase and sigma factor form a complex.

31
Q

What is an open complex?

A

RNA polymerase changes its shape, which releases sigma factor. RNA polymerase can now separate DNA on its own. RNA polymerase will then move along the gene to make an RNA copy of the template strand.

32
Q

How many RNA polymerases do eukaryotes have? Which produces mrNA?

A

Pol I, Pol II, and Pol III.

Pol II makes mRNA.

33
Q

What is the transcription called that occurs in eukaryotes?

A

Basale transcription

34
Q

What does TFIID initially do during the initiation of RNA transcription?

A

TFIID bings to the TATA box, which recruits other proteins tethering the RNA polymerase to the TATA box.

Another protein and TFIIH bind to RNA polymerase II.

35
Q

What is a kinase?

A

A protein that recognizes and phosphorylates another molecule, often a protein.

36
Q

What does phosphorylation do?

A

Causes activation of the protein.

37
Q

What 2 things does TFIIH do in eukaryotic RNA transcription initiation?

A

1) Acts as a helicase to separate DNA strands (forming an open complex)
2) Acts as a kinase by also phosphorylating RNA poly II

38
Q

What does phosphorylation of RNA poly II do?

A

It causes a change in shape that releases RNA polymerase from the tether created by the transcription factors. This causes the tether to fall apart and now RNA pol II is free to transcribe.

Alex's Genetics (38 decks)

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