Lecture 13 - Control of Gene Expression (CH 8)

Question 1

What happens once the trp operon is removed in E coli? This means that …

Answer 1

The cell and its babies wont remember that; future cells won’t maintain their on or off state (that was done by a trp operon)

Question 2

What’s different or the same between e coli and human (or other multicell) organisms regarding operons?

Answer 2

We have to maintain the on or off state

Question 3

The maintainance of gene expression and transcription regulation is called

Answer 3

cell memory

Question 4

What is it called when groups of transcriptional regulators work together to express one gene?

Answer 4

It is called combinatory control

Question 5

How do we determine if a gene is on or off?

Answer 5

Signal integration

Question 6

Seven stripes along the fly embryo correspond to what along thw fly? And what gene creates this?

Answer 6

7-14 segments; Even skipped (Eve) gene

Question 7

How can we find how a gene (i.e. Eve) shows or does not show? Where do they get placed

Answer 7

Reporter Genes! Behind an upstream sequence

Question 8

Give 2 examples of reporter genes

Answer 8

They tell us what to look for (i.e. lac z finds color and fluorenscents do filters)

Question 9

Eve can expand transcription if either of which repressors are gone in stripe 2?

Answer 9

giant and krupel

Question 10

What two activators need to be there for eve to expand transcription?

Answer 10

bicoid and hunchback

Question 11

Presence of cortisol in the ___ activates ___ protein

Answer 11

Liver; cortisol receptor protein

Question 12

Undifferentiated stem cells are in which state

Answer 12

Pluripotency

Question 13

How many genes can be controlled by 1000 transcriptional regulators?

Answer 13

24,000 human genes

Question 14

What does Ey regulate?if you put that gene in the wrong spot, what would happen?

Answer 14

The growth of an eye on fly. ectopic structures can form (i.e eye on a leg)

Question 15

Give an example of reprogramming cells

Answer 15

You can reprogram a liver to a neuronal cell

Question 16

Reprogramming cells uses de differentiating that creates ___ cells in order to remake them

Answer 16

Induced pluripotent cells (iPS)

Question 17

How can we maintain cell memory

Answer 17

We can use positive feedback loops to keep transcription keep going on

Question 18

How do cells maintain DNA methylation?

Answer 18

An enzyme called maintainance methyltransferase continues to inherit methylation after cell division happens. It does this by methylating the sites opposite the template strand.

Question 19

Where does DNA methylation happen on a strand of DNA?

Answer 19

Methylation happens on CYTOSINE bases in 5 prime C G to 3 prime combinations

Question 20

Cell memory mechanisms are forms of ___. Give three examples of how its done!

Answer 20

Epigenetic inheritance; methylation, histone modification, and positive feedback loops

Question 21

How is listeria able to infect cells?

Answer 21

It is a thermosensor that detects 98 degrees on the hairpin mRNA structure in order to infect.

Question 22

How do mRNA sequences control their translation?

Answer 22

RNA binding proteins can stop specific mRNAs from translating. i.e they stop ribosomes from binding to their site in mRNA

Question 23

What is the job of miRNAs? What are they processed by?

Answer 23

microRNAs target mRNAs and destroy them mwahhahahaha; Dicer protein

Question 24

miRNA becomes part of a ____.; what happens?

Answer 24

RNA induced silencing complex (RISC); the complex searches for mRNA match to kill and that mRNA cant make protein

Question 25

What is the job of siRNA? Give an example

Answer 25

These get rid of foreign RNA, like double stranded RNA (VIRUS) but they target ONE specific mRNA

Question 26

siRNAs can also join RISC complexes, true or false? What kind of response happens

Answer 26

TRUE; adaptive immune response

Question 27

What protects cells from their own transposons; what are these a part of?

Answer 27

siRNAs; RITS complex (RNA induced transcriptional silencing complex)

Question 28

How long are lncRNAs; how many of these are there in the human genome

Answer 28

more than 200 nucleotides; 5000 lnc in the genome

Question 29

Which long noncoding RNA is involved in X inactivation? How long; what else can it do?

Answer 29

Xist; 17000 nucleotdes; form scaffolds

Question 30

What piece of RNA has the hairpin structure?

Answer 30

miRNA

Question 31

Which one is double stranded, miRNA or siRNA?

Answer 31

siRNA, which is how it can recognize ds RNA viruses