module 4 Flashcards

Question

what is a gene

Answer 1

unit of heredity affecting 1+ traits of an organism; DNA sequence that corresponds to a specific protein

Answer 2

production of a functional gene product, such as a protein regulated

Answer 3

dna is transcribed into rna which is then translated into protein

Answer 4

generation of rna from dna -> dna is the template dna and rna use the same "language" of nucleic acids

Answer 5

"code" carried on a molecule of messenger rna (mRNA) term "translation" is used since this indicates a change in the language used from nucleic acids to amino acids

Answer 6

different places between prokaryotes and eukaryotes prokaryotes do NOT have a nucleus -> transcription and translation occur in the cytoplasm eukaryotes HAVE a nucleus -> transcription occurs in nucleus and translation occurs in the cytoplasm

Answer 7

similar in polarity -> one end has 5'-phosphate grp and the other has 3'-hydroxyl (makes RNA less stable molecule than DNA)

Answer 8

1. sugar in RNA -> ribose - hydroxyl at 2' carbon 2. nitrogenous base -> uracil - replaces thymine found in DNA, A pairs with U in RNA 3. 5' end of RNA is typically a triphosphate - 5' end of DNA is typically a monophosphate 4. RNA is often of shorter length than DNA and most RNA molecules are single stranded 5. RNA can fold

Answer 9

create a complementary copy a DNA sequence into an RNA sequence DNA serves as a template for RNA production in the cell despite differences in transcriptional location, processes are similar in prokaryotes (cytoplasm) and eukaryotes (nucleus)

Answer 10

1. DNA template 2. RNA polymerase -> enzyme needed for transcription 3. polymerase moves in 3' to 5' direction along template DNA strand -> RNA grows in 5' to 3' direction 4. ribonucleotide triphosphates -> ATP, GTP, CTP, UTP - provides energy to drive the anabolic/synthetic reaction

Answer 11

a region of DNA unwinds, and one strand will be used as a template for the RNA transcript T's are replaced with U's new RNA strand grows in the 5' -> 3' direction template DNA strand is read in the 3' -> 5' direction by RNA polymerase transcription takes place in 3 stages -> initiation, elongation and termination

Answer 12

adding nucleotides to the 3' end

Answer 13

initiated at a specific region of DNA -> promoter double stranded DNA sequence that proteins known as transcription factors and RNA polymerase bind - promoter sequence are conserved DNA sequences - one very common base pair sequence in eukaryotes is 5'-TATAAA -3' -> TATA box - first nucleotide to be transcribed is usually found ~25 base pairs away from TATA box - transcription proceeds until RNA polymerase gets to a terminator

Answer 14

prokaryotes: in bacteria, promotor recognition is mediated by a protein -> sigma factor protein associates with RNA polymerase (RNA pol) and RNA pol's binding to specific promoters

Answer 15

eukaryotes: at least 6 proteins must work together to initiate transcription -> general transcription factors bind to the promoter region transcriptional activator proteins will bind to enhancer sequences on the DNA recruits RNA polymerase complex ii (RNA pol ii) mediator complex associates with the general transcription factors and RNA pol ii looping of RNA brings activator proteins into contact with the proteins bound at the promoter region -> initiates transcription forms a "bubbles" that is about 14 pairs in length - RNA-DNA duplex in the bubble is about 8 base pairs in length

Answer 16

in prokaryotes, all transcription is performed by a single type of RNA polymerase in eukaryotes there are 3 distinct RNA polymerases RNA pol ii to makes mRNA

Answer 17

RNA pol (prokary) and RNA pol ii (eukary) allows for unwinding of DNA -> allows complementary nucleotides to be added to growing mRNA transcript

Answer 18

thru channels

Answer 19

1. dna double helix to enter/exit 2. an exit of growing mRNA 3. release of mRNA when transcription is terminated

Answer 20

1. RNA pol detects incoming ribonucleoside triphosphate and, if it base pairs appropriately, joins it to the expanding transcript 2. RNA pol orients the oxygen in the hydroxyl grp at the 3' end of the growing strand into a position from which it can attack the innermost phosphate of the triphosphate -> provides energy for reaction 3. pyrophosphate grp P-P is then released 4. creates a permanent attachment of the ribonucleotide and allows next nucleotide to be linked

Answer 21

the primary transcript contains info of the gene using an RNA code

Answer 22

the primary transcript has the info to direct the ribosome to translate the protein transcription in prokaryotes is simpler bc primary transcript is mRNA both transcription and translation occur in cytoplasm no nuclear envelope to separate transcription from translation primary transcripts may contain info for more than one gene, if this is the case then the mRNA is called polycistronic mRNA

Answer 23

if in prokaryotes, the primary transcripts contain info for more than one gene

Answer 24

added layer of complexity in eukaryotes between transcription and translation -> presence of nuclear membrane

Answer 25

due to nuclear membrane, there is added complexity between transcription and translation primary transcript needs to be modified so message can move from nucleus to cytoplasm -> chemical modifications = RNA processing

Answer 26

chemical modifications done to primary transcript in eukaryotic transcription 1. addition of a 5' cap 2. addition of the poly A tail 3. removal of introns

Answer 27

addition of a 5' cap of 7-methylguanosine to the 5' end of the primary transcript 1. unique 5'-5' bond 2. helps protext mRNA from exonucleases and provide stability 3. addition is needed since ribosome would not recognize the mRNA -> translation could not occur

Answer 28

polyadenylation: addition of about 250 consec adenines to the 3' end of the mRNA -> poly(A) tail important role in: 1. transcription termination 2. export of mRNA to cytoplasm 3. protection from degradation by exonucleases

Answer 29

excision of introns (certain sequences) leaves intact exons also known as RNA splicing

Answer 30

some genes can produce primary transcripts that are spliced in different ways a single gene may produce different but related protein products in different cells -> splicing results in different mRNAs

module 4 Flashcards

nucleic acids and information (54 cards)