Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOSCI 107 > Lecture 9: CSF Gene to Protein > Flashcards

Lecture 9: CSF Gene to Protein Flashcards

1
Q

What is genotype?

A

An organism’s hereditary information

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is phenotype?

A

Actual observable or physiological traits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is gene expression?

A

The process of forming a functional product from DNA

DNA -> RNA -> Protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 steps to gene expression?

A

Transcription
Processing
Translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 3 steps to transcription?

A

Initiation -> polymerase binds to promoter
Elongation -> moves downstream through the gene, transcribing RNA
Termination -> detaches after terminator reached

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the difference in bases in mRNA and DNA?

A

Uracil takes place of thymine in mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the significance of uracil replacing thymine in mRNA?

A

Thymine is more stable -> DNA is the inherited material hence needs to be more stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain how initiation process occurs during transcription

A

Initiation is the assembly of proteins required before transcription can commence

  1. DNA contains a promoter region in which the TATA box can be found
  2. Several transcription factors bind to the promoter region (including TATA box binding protein [TBP])
  3. This changes the shape of the promoter region allowing RNA polymerase II to bind along with more transcription factors to form the transcription initiation complex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the TATA box?

A

A sequence of DNA found in the promoter region which marks where transcription should be initiated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is TBP?

A

TATA box binding protein is a transcription factor that binds to the TATA box of the promoter region forming transcription initiation complex.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain how the elongation process occurs during transcription

A

10 - 20 nucleotides become exposed at a time as DNA unwinds

Complementary RNA nucleotides are added to the 3 to 5 DNA sequence (template strand).

As complementary base pairs form between mRNA and DNA, the 3’ end forms a phosphodiester bond with the 5’ end of incoming nucleotide.

Double helix reforms as transcript leaves the template strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain how the termination process occurs for transcription

A

After transcription of the polyadenylation signal, nuclear enzymes release the pre-mRNA and RNA polymerase then dissociates from the DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the polyadenylation signal?

A

A sequence of nucleotide bases that signal the termination of transcription hence the release of pre-mRNA and RNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 3 steps to processing stage of gene expression?

A

Capping, tailing, splicing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are exons?

A

Coding regions of mRNA strand including untranslated regions (UTR)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are introns?

A

Non-coding regions intervening exons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is UTR?

A

Untranslated regions at 5’ and 3’ ends of the mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is capping?

A

A modified guanine nucleotide is added to the 5’ end (lid on top)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is tailing?

A

50-250 adenine nucleotides are added to the 3’ end (tail on bottom)

20
Q

What is splicing?

A

Introns are removed from the transcript and adjacent exon ends are joined to form mature mRNA

21
Q

Where does splicing occur?

A

At the spliceosome, in the nucleus

22
Q

What is a spliceosome?

A

A large complex of proteins and small RNAs

23
Q

What is alternative splicing?

A

A process in which different combinations of adjacent exons are joined together - this means multiple mRNA molecules can be formed from a single pre-mRNA

24
Q

What is a codon?

A

A base triplet that codes for an amino acid

25
Q

What are the 3 steps of translation?

A

Same as transcription -> initiation, elongation, termination

26
Q

How are mRNA codons translated to tRNA molecules?

A

By attaching to ribosomes

27
Q

Explain the structure of the ribosome

A

Large and small subunit

Large subunit contains E, P, and A sites (where tRNA binds to and exits)

Small subunit contains mRNA binding site

28
Q

What is the A site?

A

A region on the large subunit of ribosomes where the next in line tRNA molecule is bound to

29
Q

What is the P site?

A

A region on the large subunit of ribosomes where the tRNA carrying the growing polypeptide binds to

30
Q

What is the E site?

A

A region on the large subunit of ribosomes where the tRNA that have added its amino acid to the polypeptide chain exit through

31
Q

What is a tRNA molecule?

A

Transfer RNAs are the physical link between the amino acid and the mRNA.

Contains an amino acid attachment site and an anti-codon (3’ to 5’) complementary to the codon (5’ to 3’) on mRNA

32
Q

How does the initiation stage of translation occur?

A
  1. Initiator tRNA (Met) is bound to the small subunit of the ribosome which binds to the 5’ cap of mRNA
  2. The small subunit ribosome scans the mRNA molecule in the downstream direction to find translation start site (AUG codon)
  3. At this start site hydrogen bonds form between the initiator anticodon (UAC) and mRNA (AUG)
  4. Large ribosomal subunit then binds completing the initiation complex (requires energy in the form of GTP)
33
Q

How does the elongation stage of translation occur?

A
  1. Codon recognition - tRNA molecules with anticodon complementary to the codon of mRNA form hydrogen bonds using energy from GTP (these “next in line” tRNA will bind to the A site)
  2. A large subunit rRNA catalyses the peptide bond formation of adjacent amino acids of the P site and A site tRNA molecules -> the P site tRNA amino acid bond is broken (hence polypeptide chain only attached to A site tRNA)
  3. The tRNA from the A site moves into the P site and the tRNA in the P site exits through E site - again energy is required
  4. Emptied tRNA molecules with no amino acid attached are reloaded with the amino acid in the cytoplasm using aminoacyl-tRNA synthetases
34
Q

What are aminoacyl-tRNA synthetases?

A

Enzymes which reload the tRNA molecules with no amino acid attached in the cytoplasm

35
Q

How does the termination stage of translation occur?

A
  1. The ribosome reaches a stop codon on mRNA causing the binding of a release factor into the A site of the large subunit
  2. The release factor promotes breakdown of tRNA in the P site from mRNA. Bond between this tRNA and polypeptide is also broken down causing the release of the polypeptide chain
  3. Ribosomal subunits and other components dissociate - requires energy from two GTP molecules
36
Q

Describe amino acid structure

A

Central carbon atom bonded to amino group, carboxylic group, H atom and R group

20 different R groups forming 20 different amino acids

R group determines amino acid structure and function

37
Q

What is the 5’ end and 3’ end of amino acid chains?

A

N-terminus (amino end) - 5’ end

C-terminus (carboxyl end)- 3’ end

38
Q

What is primary structure?

A

The sequence of amino acids in a polypeptide chain held together by peptide (covalent) bonds

39
Q

What is secondary structure?

A

Held by weak hydrogen bonds to form alpha helix or Beta pleated sheets

40
Q

What is tertiary structure?

A

Further folding and coiling to form complex 3D shape due to various side chain interactions

41
Q

What is quaternary structure?

A

Association of multiple proteins forming a functional protein

42
Q

Where are the ribosomes for translation found?

A

Free in the cytoplasm

43
Q

How are endomembrane proteins translated?

A

The translation begins by ribosomes in the cytoplasm however the process is completed at fixed ribosomes on the RER for packaging.

44
Q

How are ribosomes in the cytoplasm directed to the rough ER for the completion of translation of endomembrane proteins?

A
  1. Polypeptide synthesis begins
  2. Signal recognition particle binds to signal peptide (a part of chain already made)
  3. Signal recognition particle binds to receptor protein on ER membrane
  4. Signal recognition particle detaches and polypeptide synthesis resumes
  5. Signal-cleaving enzyme cuts off signal peptide
  6. Completed polypeptide folds into protein
45
Q

What is signal peptide?

A

A length of polypeptide on the N terminus of protein which the signal recognition particle binds to allowing the complex to bind to the receptor protein of ER and hence move the polypeptide synthesis into the ER.

46
Q

What is the purpose of post translational modifications?

A

Can confer activity (e.g. phosphorylation of enzyme)
Ability to interact with other molecules
Direct to particular locations

BIOSCI 107 (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions