GENE EXPRESSION L15 Flashcards
I. Relationship between Genes and Proteins - SEQ information flow in cells - CC RNA types - APPLY genetic code II. Transcription - SEQ, HD eukaryotic transcription III. Translation - SEQ, HD eukaryotic translation
1
Q
ribose
A
- RNA
- has extra OH (only difference from DNA)
2
Q
uracil (U)
A
- pyrimidine base
- used instead of T in RNA
- T = U-CH3
- complementary to A
- 2 H bonds
3
Q
3 main kinds of RNA
A
- mRNA: messenger RNA - encodes amino acid sequence
- rRNA: ribosomal RNA - part of ribosome structure
- tRNA: transfer RNA - carries amino acids to ribosome during translation
4
Q
codons
A
- sequence of 3 bases – information for 1 amino acid
- 1 start codon
- 3 stop codons
5
Q
transcription
A
- first part of gene expression
- synthesis of RNA, complementary to DNA
6
Q
initiation
A
- DNA serves as template for RNA synthesis
- 1 DNA strand is transcribed
- DNA read in 3’ – 5’ direction
- RNA synthesized in 5’ – 3’ direction
- other strand not transcribed
7
Q
promoter
A
- specific DNA sequence on transcribed strand
- designates start site of transcription
- not transcribed
- RNA polymerase binds promotor, unwinds helix, begins transcription
8
Q
elongation
A
- RNA synthesis
- anti-parallel to template strand
- uses RNA nucleoside triphosphates
9
Q
termination
A
- specific DNA sequence signals RNA polymerase to stop
- RNA transcript dissociates from DNA template
- can be helped by a protein
10
Q
mRNA modification
A
- only in eukaryotes
- transcription – pre mRNA - not useful for protein synthesis
- add 5’ cap, 3’ poly-A tail – export from nucleus, protection, ribosome recruitment
11
Q
RNA splicing
A
- two regions in pre-mRNA
- introns and exons
- removes introns from pre-mRNA
- occurs in nucleus
12
Q
exons
A
coding regions
13
Q
introns
A
non-coding regions
14
Q
transcription summary
A
- DNA – RNA
- initiation – elongation – termination – mRNA processing
15
Q
translation
A
- mRNA – polypeptide
- occurs in ribosomes - cytoplasm or surface of ER
16
Q
components of translation
A
- tRNA
- small RNA molecule
- 3D structure
- intramolecular base pairing
17
Q
tRNA function
A
- binds specific amino acid
- brings into ribosome
- bind correct codon in mRNA
- amino acid can be added to polypeptide
18
Q
anticodon
A
- 3 specific bases on loop of tRNA
- complementary to codon on mRNA
19
Q
ribosomes
A
- structures that carry out translation
- protein and rRNA
20
Q
rRNA
A
- ribosomal RNA
- transcribed from DNA - not translated into protein
- catalytic function
- ribozyme
21
Q
ribosome function
A
- works as an enormous enzyme complex
- catalyzes reaction between mRNA, changed tRNAs, polypeptide
22
Q
translation initiation
A
- small ribosomal subunit binds mRNA and tRNA
- move along mRNA until reaches AUG
- initiation factors bring in large subunit – translation initiation complex
23
Q
translation elongation
A
- repeating cycle
- peptide bond formation by ribozyme
- translocation
- each cycle adds single amino acid
24
Q
translation termination
A
- stop codons not recognized by tRNAs
- recognized by release factors (proteins) - bind stop codon in A site
- cannot form new peptide bond
- polypeptide released
