CH 17 Gene Expression Flashcards
1
Q
Gene expression
A
- The process by which information encoded in DNA directs the synthesis of proteins, or, in some cases, RNAs that are not translated into proteins, and instead function as RNAs
-Transcription
-Translation
2
Q
Transcrition
A
- the synthesis of RNA using a DNA template
-RNA polymerase - Consists of three stages
- Initiation
- Promoter-start point
- “Upstream” of actual start of transcription (before actual start point)
- TATA box (eukaryotes)
- All different sequences/lengths w/ TATA repeat
- Transcription Factors
- Bound to RNA polymerase=transcription
- Initiation complex
- Promoter-start point
- Elongation
- RNA polymerase unwinds double helix
- Nucleotides added to 3’ end of growing RNA
- Genes can be transcribed simultaneously
- Amplification of gene expression
- Termination
- RNA polymerase transcribes polyadenylation signal sequence
- The RNA transcript is release 10-35 nucleotides later
- RNA polymerase transcribes polyadenylation signal sequence
- Initiation
- “rewritten”
3
Q
Messenger RNA (mRNA)
A
- a type of RNA, synthesized using a DNA template that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein (in eukaryotes, the primary RNA transcript must undergo RNA processing to become mRNA)
- carries a genetic message from the DNA to the protein synthesizing machinery of the cell
4
Q
Translation
A
- the synthesis of a polypeptide using the genetic information encoded in an mRNA molecule
- there is a change of “language” from nucleotides to amino acids
-occurs in the ribosomes
5
Q
Triplet Code
A
- a genetic information system in which a series of three nucleotide-long words specifies a sequence of amino acids for a polypeptide chain
6
Q
Template Strand
A
- the DNA strand that provides the pattern, or template, for ordering, by complementary base pairing, the sequence of nucleotides in an RNA transcript
-for any given gene, the same strand is used as the template every time that gene is transcribed- further along on the same chromosomal DNA molecule, the opposite strand may function as the template for a different gene
7
Q
Codon
A
- a three nucleotide sequence of DNA or RNA that specifies a particular amino acid or termination signal
- the basic unit of the genetic code
8
Q
Coding Strand
A
- nontemplate strand of DNA, which has the same sequence as the mRNA except it has Thymine (T) instead of Uracil (U)
9
Q
Reading Frame
A
- on an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis (translation)
10
Q
RNA polymerase
A
- an enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complementary binding to nucleotides on a DNA template strand
- assemble a polynucleotide only in 5’ to 3’ direction (adding to its 3’ end)
- able to start a chain from scratch; doesn’t need to add the first nucleotide onto a pre-existing primer (DNA polymerase cannot do this)
11
Q
Promoter
A
- a specific nucleotide sequence in the DNA of a gene that bind RNA polymerase, positioning it to start transcribing RNA at the appropriate place
- initiate transcrption
12
Q
Terminator
A
- in bacteria, a sequence of nucleotides that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detach from the DNA
13
Q
Transcription Unit
A
- a region of DNA that is transcribed into and RNA molecule
14
Q
Start Point
A
- in transcription, the nucleotide position on the promoter where RNA polymerase begins synthesis of RNA
15
Q
Transcrption Factors
A
- a regulatory protein that bind to DNA and affect transcription of specific genes
- help guide the binding of RNA polymerase and the initiation of transcription
16
Q
Transcription Initiation Complex
A
- the completed assembly of transcription factors and RNA polymerase bound to a promoter
17
Q
TATA Box
A
- a DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
18
Q
RNA Processing
A
- modification of RNA in primary transcripts including splicing out of introns, joining together of exons, and alteration of the 5’ and 3’ ends
19
Q
5’ Cap
A
- a modified form of guanine nucleotide added onto the 5’ end of a pre-mRNA nucleotide
20
Q
Poly-A-Tail
A
- a sequence of 50-250 adenine nucleotides added onto the 5’end of a pre-mRNA molecule
21
Q
RNA Splicing
A
- after synthesis of a eukaryotic primary RNA transcript, the removal of portions of the transcript (introns) that will not be included in the mRNA and the joining together of the remaining portions (exons)
22
Q
Introns
A
- a noncoding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing; which also refers to the region of DNA from which this sequence was transcribed
23
Q
Exons
A
- a sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed
24
Q
Spliceosome
A
- a large complex made up of proteins and RNA molecules that splices up RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons
25
Q
Ribozyme
A
- an RNA molecule that functions as an enzyme, such as an intron that catalyzed its own removal during RNA splicing
26
Q
Alternative RNA Splicing
A
- a type of eukaryotic gene regulation at the RNA processing level in which different mRNA molecules are produces from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
27
Q
Transfer RNA (tRNA)
A
- an RNA molecule that functions as a translator between nucleic acid and protein languages by picking up a specific amino acid and carrying it to the ribosome, where the tRNA recognizes that appropriate codon in the mRNA
28
Q
anticodon
A
- a nucleotide triplet molecule that base pairs with a particular complementary codon on an mRNA molecule
29
Q
point mutation
A
- a change in a single nucleotide pair of a gene
30
Q
nucleotide substitution
A
- a type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced by another pair of nucleotides