- DNA to RNA mRNA "copies" of genes are made by RNA polymerase

ch 17: transcription Flashcards by Jiya Patel

when does protein synthesis occur?

almost all the time in almost all cells

How well did you know this?

Not at all

Perfectly

what do proteins determine?

how a cell or organism functions and looks

How well did you know this?

Not at all

Perfectly

DNA

stores RNA and protein-encoding information
- transfers information to daughter cells

How well did you know this?

Not at all

Perfectly

RNA

carries protein-encoding information
- helps make proteins and catalyze some reactions

How well did you know this?

Not at all

Perfectly

transcription

DNA to RNA
mRNA “copies” of genes are made by RNA polymerase

How well did you know this?

Not at all

Perfectly

where does transcription occur?

nucleus

How well did you know this?

Not at all

Perfectly

translation

mRNA to proteins

How well did you know this?

Not at all

Perfectly

where does translation occur?

cytosol

How well did you know this?

Not at all

Perfectly

what four steps are needed for transcription?

initiation
elongation
termination
processing

How well did you know this?

Not at all

Perfectly

what is needed for transcription initiation?

open chromatin

How well did you know this?

Not at all

Perfectly

chromatin

DNA + histones

How well did you know this?

Not at all

Perfectly

histones

protein complexes responsible for packing DNA

How well did you know this?

Not at all

Perfectly

what do histones do?

determine open or closed state of DNA

How well did you know this?

Not at all

Perfectly

euchromatin

copied or used region of DNA
- open

How well did you know this?

Not at all

Perfectly

heterochromatin

not copied or used
- closed

How well did you know this?

Not at all

Perfectly

transcription factors

proteins that bind to DNA and regulate gene expression

How well did you know this?

Not at all

Perfectly

what are types of transcription factors?

activators and repressors

How well did you know this?

Not at all

Perfectly

what do activators do?

promote transcription by helping general transcription factors and RNA polymerase assemble

How well did you know this?

Not at all

Perfectly

what do repressors do?

stop transcription by blocking general transcription factors and RNA polymerase

How well did you know this?

Not at all

Perfectly

general transcription factors

proteins that bind upstream of EVERY gene that needs transcribed at a region called the TATAA box

How well did you know this?

Not at all

Perfectly

promoter

determines the start site and direction of transcription

How well did you know this?

Not at all

Perfectly

what does RNA polymerase do during initiation of transcription?

it binds DNA

How well did you know this?

Not at all

Perfectly

how does RNA polymerase read DNA?

3 to 5 direction

how does RNA polymerase build mRNA?

5 to 3 direction
- antiparallel

what does RNA polymerase not need?

does not need a primer

where does RNA polymerase begin transcribing?

at the initiation site - first capital letter

transcription termination

1. RNA polymerase encounters termination sequence encoded in the DNA 2. RNA polymerase falls off DNA and releases mRNA transcript

transcription in bacteria

instead of GTFs, sigma factors bind to promotor DNA region to guide RNA polymerase to the correct location - once transcription starts, the sigma factor is released and RNA polymerase continues transcribing

what forms during transcription in bacteria?

a hairpin loop in mRNA due to sequence of transcribed bases that hydrogen bond together

what are hairpin structures followed by?

a long stretch of uracil bases leading to RNA polymerase separation, terminating transcription

how many transcripts can be made at the same time?

many

what 3 things need to happen to make pre-mRNA into mature mRNA?

1. alternative splicing 2. add a 5' cap 3. add a polyA tail

splicing

introns are removed and exons join together on mRNA strand

do introns stay in or leave the nucleus?

stay in the nucleus

do exons leave or stay in the nucleus?

leave the nucleus

why do eukaryotes do alternative splicing?

protein variation: can have multiple protein variations from 1 gene

what protein removes the introns?

snRNP binds to the ends of the intron and creates a loop to remove it

do all transcripts have the same initiation site?

no, and they do not have the same exon/intron structure

capping

adding a Guanine base to the 5' end of the strand

tailing

3' side gets a string of adenine nucleotides added to it

what is the purpose of capping and tailing?

stabilizes mRNA transcript and helpful for translation machinery

are all parts of the gene translated?

no, there is a 5' untranslated region and 3' untranslated region

what does the genetic code do?

allow ribosomes from any organism to produce specific proteins from any mRNA molecule

properties of the genetic code

1. triplet 2. non-overlapping 3. redundant 4. unambiguous 5. punctuated 6. universal

triplet

all words of the genetic language are 3 RNA nucleotides long

non-overlapping

once a codon is read, it does not get read again

punctuated

- always begins at AUG (methionine) - 3 stop codons (UAA, UAG, UGA)

redundant

most amino acids are represented by more than 1 codon example: multiple codes represent valine

unambiguous

each codon specifies only 1 amino acid

universal

the same codons specify the same amino acids and stop codons in all organisms

mRNA

translates into an amino acid sequence in the cytoplasm or rough ER

tRNA

links the codon on mRNA with the correct amino acid based on hydrogen bonding of complementary bases

what are tRNAs charged with?

amino acids

tRNA synthetases

they attach the amino acid to the tRNA with the corresponding anticodon

rRNA

the ribosome: builds proteins

what does rRNA do?

- mediates tRNA binding to mRNA strand - catalyzes bond between amino acids

how does translation and transcription occur in prokaryotes?

together because they do not have a nucleus, so there is no splicing