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Biology Exam Review > Protein Synthesis > Flashcards

Protein Synthesis Flashcards

1
Q

What are proteins?

A
  • made of 20+ amino acids linked together in specific pattern
  • 3 nucleotides code for 1 amino acid (codon)
  • linked to form long chains –> polypeptide
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2
Q

What are the steps (protein synthesis)

A

DNA Replication: nucleus, new strand of DNA synthesized
Transcription: DNA molecule unzips partically and mRNA is transcriped from DNA, once completed mRNA unzips and DNA zips back together
Translation: cytoplasm, ribosome attaches to mRNA and translated into an amino acid sequence to form a protein

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3
Q

What is the Central Dogma?

A

Transcription and Translation

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4
Q

Define 3 types of RNA

A

mRNA - synthesized from DNA molecule
rRNA - provides site on ribosome for translation
tRNA - smallest, 60 diff kinds in cytoplasm, Acceptor End: Amino acid interacts
Anticodon End: mRNA interacts
-brings amino acids to ribosome to be sythesized

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5
Q

Describe the parts of a ribosome

A

-made of proteins and rRNA
-two subunits: small and large which bind to mRNA when leaves nucleus
-on small subunit two active binding sites
A site: amino acid site
P site: peptide site
-each site size of one codon

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6
Q

Explain Transcription

A
  • RNA polymerase binds to promoter region of gene and moves along DNA unzipping it (5’ to 3’)
  • using base pairing rules, new molecule of RNA synthesized
  • when terminator region reached RNA polymerase stops transcriping and detaches, mRNA unzips from DNA and leaves through nuclear pore
  • DNA zips back up
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7
Q

What are the modifications made to mRNA after transcription?

A

5’ guanosine cap added: protect mRNA from digestion in cytoplasm
3’ poly-A tail added: protect mRNA from degration
Eukaryotes: introns removed and exons spliced together by splicosomes

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8
Q

What is the difference btw. prokaryotes and eukaryotes?

A
  • prokaryotes have no nucleas transcription and translation can occur at same time
  • prokaryotes have no introns so entire mRNA molecule translated
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9
Q

What happens in initiation of translation?

A
  • ribosome binds to 5’ end of gene and recognizes start codon (AUG)
  • met occupies A site, tRNA with complementary anticodon base pairs with it and ribosome moves down so it occupies the P site and new codon enters A site
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10
Q

What happens in elongation of translation?

A
  • new codon occupies A site and tRNA with anicodon binds to it
  • peptide bond formed between two amino acids in small subunit and first tRNA is released into P site
  • continues and other amino acids added to growing polypeptide until STOP codon reached
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11
Q

Explain the process of termination.

A
  • STOP codon recognized in A site by release factors and ribosome dissociates from mRNA molecule
  • last tRNA is released
  • no further elongation
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12
Q

What modifications happen after translation?

A
  • start codon removed from protein
  • foiling and coiling
  • addition of cofactors
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13
Q

What is a substitution mutation?

A

-one base is substitued for another base
-changes one codon and can affect amino acid sequence
nonsense- substitution caues stop codon, results in disfunctional protein–chain termination

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14
Q

What is a silent mutation?

A
  • when a substitution mutation has no affect on final protein
  • due to genetic code redundancy, although different codon, codes for same amino acid
  • -wobble hypothesis
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15
Q

What is a frameshift mutation?

A
  • addition or deletion of base

- affects all codons downstream of mutation

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16
Q

Describe the operon region is?

A

-prokaryotes have region btw structural gene and promotor known as operator

17
Q

What is a repressor?

A
  • a molecule that binds to the operator region inhibiting transcription as RNA polymerase cannot bind to promoter
  • gene turned “off”
18
Q

What are inducers?

A
  • some genes always off
  • inducer is a molecule that binds to repressor changing its shape and removing it from the operator region
  • turns gene “on”
    ie. lac operon
19
Q

What is a corepressor?

A
  • some genes always on – house keeping genes used to maintain regular cell functions
  • corepressors bind to repressors to allow them to bind to the operator to turn the gene “off”
    ie. trp operon
20
Q

How is eukaryotice gene expression regulated?

A
  1. Regulating RNA processing
  2. Regulating Transcription
  3. Regulating Translation
  4. Regulating RNA longevity
21
Q

What are the 4 aspects that regulate transcription?

A
  • enhancers and silencers
  • promoters
  • methylation
  • transcription factors
22
Q

What are promoters?

A

-found before structural gene
basal/core promoter: same for all genes
upstream promoter: different for genes
-allow transcription enzymes to bind to transcribe gene

23
Q

What are enhancers and silencers?

A

enhancers- promote transcription
silencers- suppress transcription
-located away from promoter not fully understand how work

24
Q

What is methylation?

A
  • DNA can be chemically modified
  • methy group (CH3) by enzyme called methytransferase
  • suppresses gene expression
25
Q

What are transcription factors?

A
  • decrease/increase gene expression depending on transcription factors
  • proteins that switch on genes by binding to DNA and helping RNA polymerase to bind
    ie. hormones
26
Q

Explain regulating RNA processing.

A
  • addition of 5’ cap and 3’ tail
  • intron removal
  • regulates when mRNA can leave nucleas
27
Q

Describe regulating RNA longetivity.

A
  • removal of 5’cap and 3’ tail
  • nibbling away molecule 5’ to 3’
  • regulate lifespan of mRNA and how many times it can be translated
28
Q

What is regulating translation of RNA?

A
  • control # of times mRNA translated

- control # of ribosomes that bind the mRNA

29
Q

What is reverse transcriptase?

A
  • enzyme that turns RNA into DNA

- converts genetic msg in RNA into complementary copy of ssDNA, then DNA polymerase converts into DNA (dbl stranded)

30
Q

Describe retrovirues.

A
  • genetic material RNA
  • structural gene that codes for reverse transcriptase
  • invade host cell and use machinary to change RNA into DNA
  • allows viruse to encorporate genetic info into cell’s DNA
31
Q

What technology can reverse transcriptase be used it?

A
  • scientists can use enzyme to synthesize DNA from any mRNA molecule
  • now have to find gene, only mRNA from cells that normally produce protein
32
Q

What are stem cells and what are their properties?

A

Stem cells: unspecialized cell

Properties- can divided and reproduce over long periods of time, become specialized, unspecialized

33
Q

Define potency.

A

-# of cells a stem cell can become

34
Q

What is totipotent, pluripotent, and multipotent?

A

totipotent- can become any cell, first few cell divisions after fertilization
pluripotent- can become any cell except extra-embryonic cells, from inner blastocyst 5-7 days after fertilization
totipotent- taken from body after birth can only become specific cells

35
Q

What are the potential uses for stem cells?

A
  • test medicines
  • develope new organs
  • gather information how cells become specialized

Biology Exam Review (8 decks)

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