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binghamton university bio 113 > Lec 18-19 > Flashcards

Lec 18-19 Flashcards

1
Q

Do all cells in the body have identical DNA?

A

Yes

The difference between cells in the stomach vs cells in the liver is what genes are expressed

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2
Q

Operon

A

bacteria puts genes that function in a related way in the same region of their chromosome, control them all with the same promoter

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3
Q

How does the lac operon work?

A

LacI (repressor of lacZ and lacY) is always on

Lactose absent in cell: repressor binds to DNA, transcription of the operon is blocked

Lactose present in cell: lactose binds to repressor, repressor releases from DNA, transcription occurs

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4
Q

CAP and cAMP

A

CAP: binds to DNA in presence of cAMP, enhances ability of RNA polymerase to bind to promoter when operon transcribes frequently (lactose only no glucose)

cAMP: high levels when operon is frequently transcribed (lactose only no glucose)

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5
Q

What happens when there is high glucose and lactose? (lac operon)

A

Glucose will be used and operon will not be transcribed

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6
Q

Imagine that the following conditions occur:
1. lacI gene is mutated such that it is not transcribed.
2. High level of glucose.
3. High level of lactose.
How will the bacteria E Coli Lac operon system
respond?

a) Repressor will be active. CAP will be inactive. Transcription will not occur.
b) Repressor will be present but inactive. CAP will be active. Transcription will not occur.
c) Repressor will be present but inactive. CAP will be inactive. Transcription will not occur.
d) Repressor will be absent. CAP will be active. Transcription will occur.
e) Repressor will be absent. CAP will be inactive.
Transcription will occur

A

E

Mutation= no repressor

High glucose= CAP will be inhibited

No repressor= transcription occurring

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7
Q

Transcription control in eukaryotes - chromatin modification

A

Condensed chromatin: increased coiling, increased condensation, decreased expression, methylation based

Decondensed chromatin: decreased coiling, decreased condensation, increased expression, acetylation based

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8
Q

Epigenic inhertitance

A

Chromatin modifications are inherited when cells divide, they are also inherited across generations

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9
Q

Transcriptional control in eukaryotes - TFs and sequences

A

Genes regulated together are bound by the same transcription factor, have the same regulatory sequences near the promoter and where TFs bind

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10
Q

Transcriptional control in eukaryotes - Alternative splicing

A

Introns are spliced out of pre mRNA normally but alternative splicing also cuts some exons to make different mRNA

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11
Q

Translational control in eukaryotes - RNA interference

A

Single stranded RNA binds to complementary sequence on mRNA and prevents it from being transcribed

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12
Q

Post transcriptional control in eukaryotes - Folding, cutting, and destroying

A

Amino acids can get folded incorrectly, cut up, or destroyed to make proteins not functional

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13
Q

Post transcriptional control in eukaryotes - Activation

A

Proteins can be deactivated by inhibitory molecules

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14
Q

Ribosome structure - translation

A

Active site: peptide bonds between amino acids form

Large subunit: amino acids are brought together

Small subunit: holds the mRNA

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15
Q

tRNA

A

One end holds amino acid, other end has an anticodon (complementary bases to mRNA)

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16
Q

Translation process (amino acid formation)

A
  1. mRNA binds to small subunit
  2. tRNA anticodon binds to mRNA start codon
  3. Large subunit assembles to small subunit, tRNA goes to middle (P) spot
  4. New tRNA move in first (A) spot, anticodon binds with mRNA
  5. Peptide bond forms between amino acids A&P
  6. Each one moves over and new one comes, one on the end (E) site gets ejected
  7. Cycle continues until stop codon, tRNAs released, ribosomes subunits separate
17
Q

mRNA vs tRNA vs rRNA

A
  1. A brain cell and a liver cell would have the same sequence of: rRNA, tRNA
  2. Translated into a protein: mRNA
  3. Required for the process of translation: mRNA, tRNA, rRNA
  4. Transports amino acids: tRNA
  5. Catalyzes the peptide bond between amino acids: rRNA
18
Q

HoxD is also transcribed in some cells that are unrelated to its function, but in those cells translation of HoxD never occurs. Which mechanism of gene expression control is responsible for this?

a) Different transcription factors
b) Alternative splicing
c) RNA interference
d) Folding, cutting, destroying
e) Inactivation

A

C

Translation doesn’t occur meaning mRNA is destroyed

binghamton university bio 113 (10 decks)

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