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Biology > Gene expression > Flashcards

Gene expression Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Who worked on the haploid neurospora? What was the experiment on neurospora (bread mould), and what was concluded?

A
  1. George Beadle and Edward Tatum
  2. The cells were subjected to x-rays to induce a mutation in one gene per cell. They found that some couldn’t make an essential nutrient…they couldn’t grow on minimal media, but could on enriched media.
  3. They concluded that the gene that makes the nutrient was disabled so they couldn’t grow on media without it…they lacked an enzyme to make the nutrient
    They concluded that there is one gene for one enzyme (One gene-one polypeptide)
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2
Q

What is transcription?

A

RNA is made from a copy of a strand of DNA

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3
Q

How is DNA vs RNA read/synthesised?

A

DNA: 3’ to 5’
RNA is synthesised 5’ to 3’

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4
Q

What can be used to determine the amino acid sequence in the RNA?

A

The non-template strand

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5
Q

What does being out of frame result in?

A

Different amino acids

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6
Q

What is the start point of transcription called?

A

The promoter

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7
Q

What is the end point of transcription called?

A

Termination

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8
Q

What do transcription factors do?

A

Bind to the DNA at specific locations

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9
Q

What does RNA polymerase ll do in transcription?

A

Unwinds the DNA strands

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10
Q

What is a terminator sequence?

A

When RNA polymerase reads a sequence that tells it to stop

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11
Q

What is the pre-mRNA process?

A

Both ends of the transcript get altered. Introns get split, exons get stitched together

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11
Q

What does a 5’ cap do?

A

Protects the 5’ end and helps in translation

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12
Q

What do poly-A tails do?

A

Gives the mRNA stability in the cytosol and helps in translation

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13
Q

What are protein domains?

A

The place where stuff happens (active sites)

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14
Q

How are introns able to facilitate evolution?

A

Exon shuffling

The crossing over of the exons of an allele during meiosis

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15
Q

Do prokaryotic mRNAs have introns?

A

No, they are directly translated

16
Q

How do tRNAs recognize codons of the mRNA?

A

Anticodons on the tRNA

17
Q

Translation occurs via?

A

tRNAs which transfer amino acids from the cytoplasm to the polypeptide chain in the ribosome

18
Q

What do anticodons recognize?

A

Codons to code for amino acids via aminoacyl-tRNA synthetase

19
Q

What are the functions of ribosomes?

A
  1. Facilitate codon-anticodon matching
  2. Form peptide bonds
20
Q

What are ribosomes composed of and what are the tRNA sites? (APE)

A

rRNA and proteins

A=aminoacyl (where tRNAs attach)
P= peptidyl (holding space)
E= exit (where tRNAs are ejected)

21
Q

What are the steps to build a polypeptide?

A
  1. A ribosome is made from rRNA and proteins
  2. The ribosome binds an mRNA at the 5’ end and finds the first AUG codon to start
  3. It reads the triplet codons, matching codons with the anticodon from the tRNA
  4. The new and old amino acids are attached together to form a polypeptide
21
Q

What are examples of post-translation modifications?

A

The attachment of sugars, lipids, phosphate groups, etc.

Enzymes that remove amino acids

Enzymes attach two or more polypeptides into a chain

22
Q

Where do free ribosomes roam?

A

The cytosol

22
Q

Where are bound ribosomes?

A

The rough ER/nuclear envelope

23
Q

What is the name of the thing that tags a polypeptide?

A

A signal-recognition particle

24
Q

What do poly-A tails act as in eukaryotes?

A

A timer. If it gets too short the mRNA can no longer be translated. Longer tails yields more protein product

25
Q

Is there mRNA processing in prokaryotes?

A

No

26
Q

What are point mutations?

A

Changing one single nucleotide

27
Q

What is nucleotide-pair substitution?

A

Replacements of nucleotide pairs

28
Q

What are silent mutations?

A

No change in the amino acid produced

29
Q

What are missense mutations?

A

One amino acid is changed

30
Q

What are nonsense mutations?

A

A point change resulting in a stop codon

31
Q

How do insertions and deletions affect the polypeptide sequence?

A

They shift everything over (frameshift mutations may occur)

32
Q

What are mutagens?

A

Chemical or physical agents that alter DNA

Biology (23 decks)

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