Lecture 6 From DNA to protein Flashcards
What are the nucleotides in DNA?
Adenine, thymine, cytosine, guanine
What makes up proteins?
Amino acids
What makes up proteins?
Amino acids
What does the sequence of amino acids determine of a protein?
Structure and function
What are the two types of proteins that amino acids make up?
Structural proteins, enzymes
What is a genome?
complete set of genetic information
A genome is made of what?
chromosome plus plasmids
All cells have what genome?
DNA
Viruses may have ____ genome
RNA
What are the two tasks that cells must accomplish to multiple?
DNA replication, Gene expression
What is transcription
Information in DNA is copied into RNA
What is translation?
RNA is used to synthesize proteins
How does information flow?
DNA to RNA to protein
in DNA, what is numbered?
carbon atoms of pentose sugar
Nucleotides joined between ____ and ____
5’PO4 and 3’OH
What do nucleotides in DNA form?
sugar phosphate backbone
What ends does a single DNA strand have?
5’ and 3’
Strands are ________ which are held together by ________ bonds between nucleobases
complementary
hydrogen
What are the base pairings?
Adenine to thymine (2 H bonds)
Cytosine to Guanine (3 H bonds)
Strands are ________, oriented in opposite directions
Anti parallel
RNA has ________ instead of deoxyribose
ribose
RNA has ________ instead of thymine
Uracil
What is RNA shape?
Short, single strand
In RNA, what replaces thymine?
Uracil
Uracil pairs with what in RNA?
Adenine
RNA molecules is like the _______
transcript
What are the three types of RNA?
Messenger RNA
Ribosomal RNA
Transfer RNA
Which RNA goes through translation to make a protein?
mRNA
DNA replication usually bidirectional from _______ of replication
Origin
Two _______ meets at terminating site when process is complete
Replication forks
Replication is _______
Semiconservative
In DNA replication, what two things bind to the origin of replication?
DNA gyrase and helicases
What do DNA gyrase and helicases do?
break and unwind DNA helix
expose single stranded region that can act as a template
What RNA enzyme is ABSOLUTELY needed for DNA synthesis?
Primase RNA polymerase
What does Primase RNA polymerase do?
synthesizes short regions of RNA called primers
Many enzymes form assembly lines called _______
Replisomes
What direction does DNA polymerase synthesize in?
5’ to 3’
What powers the DNA polymerase to synthesize?
The hydrolysis of a high energy phosphate bond
DNA polymerase can ONLY _______ nucleotides, not _______
Add, initiate
Why are RNA primers required at the origin of replication?
Gives DNA polymerase a molecules to ADD nucleotides to
When helicases unzip DNA, it reveals _______
Template sequences
in helicase unzipping, _______ strand is synthesized continuously
Leading
Spicing removes segments of _____
Eukoryotic transcript
non coding intervening sequences are what
Introns
in splicing, introns are _____
Removed
Expressed regions called _____ remain after introns are removed
Exons
Eukoaryotic mRNA produced within membrane bound nucleus must be transported to _____
Cytoplasm
Translation cannot _____ during transcription
begin
mRNA is _____
Monocistronic
Translation begins at the first _____
AUG
Ribosomes composed of what subunits?
40s and 60s
A set of regulated genes transcribed as single mRNA along with its control sequences is called
Operon
Lac operon means what
Lactose metabolism
Separate operons controlled by single regulatory mechanism constitute _____
Regulon
_____ is simultaneous regulation of numerous genes
global control
_____ enzymes synthesize constantly
Constitutive
Constitutive enzymes typically have indispensible roles in _____ _____
central metabolism
e.g. enzymes of glycloysis
In helicase unzipping, the ________ is synthesized discontinuosly
Lagging
DNA can only add nucleotides to ________ end
3’
Different DNA polymerase replaces ________
Primers
________ forms covalent bond between adjacent nucleotides
DNA ligase
Lagging strand produces ________
Okazaki fragments
DNA gyrase
Enzyme that temporarily breaks strands of DNA, relieves tension caused by unwinding two strands
DNA ligase
Joins two DNA fragments by formaing COVALENT bond between sugar and phosphate of adjacent nucleotides
DNA polymerase
Synthesizes DNA, uses one strand as template to make the other
Synthesis always occurs in what direction?
5’ to 3’
What are helicases
Enzymes that unwind DNA helix at replication fork
What is okazaki fragment
Nucleic acid fragment produced during discontinuation synthesis of lagging DNA strand
What is origin of replication
Region of DNA where replication is initiated
What is primase
Enzyme that synthesizes small fragments of RNA to serve as primers for DNA synthesis
What is primer
fragment of nucleic acid to which DNA polymerase can add nucleotides
- can only add to existing fragment
What is replisome
Complex of enzymes and other protein that synthesize DNA
Replication produces how many complete copies of DNA?
two
Cell can initiate another round of replication BEFORE
previous round is complete
Each daughter cell inherits how many chromosomes already undergoing replication?
One
What happens in transcription?
RNA polymerase synthesizes single stranded RNA (mRNA) from DNA template
RNA polymerase binds to ________
Promoter
What direction does RNA polymerase synthesize in?
5’ to 3’
(orientation of newly synthesized strand)
Transcription stops at a sequence called
Terminator
What polymerase DOES not need a primer?
RNA polymerase
RNA sequence is ________ and ________ to DNA template strand
Complementary, antiparallel
DNA template is + or - strand
-
Complement is + or - strand
+
RNA has the same sequence as what DNA strand?
+ DNA strand except Uracil instead of thymine
What is the prokaryotic mRNA transcript of one gene?
Monocistronic
What is the prokaryotic mRNA transcript of multiple genes?
Polycistronic
Proteins encoded on polycistronic message generally have ________ functions
Related
What orients the direction of transcription
Promoter
Promoter is found ________ of genes
upstream
Once RNA polymerase has moved beyond promoter, what happens?
another RNA polymerase can bind
When RNA polymerase has moved beyond the promoter, another polymerase can bind
- this allows ________ and ________ transcription
Rapid, repeated
What recognizes promoter?
sigma factor
synthesis of sigma factors controls what?
transcription of sets of genes
what cells use transcription factors to recognize promoters instead of sigma factors?
eukaryotic, archaea
When is transcription initiated?
When RNA polymerase binds to promoter
What are the major components of the process of decoding information in mRNA?
mRNA, ribosomes (rRNA), tRNAs, accessory proteins
mRNA is what?
temporary copy of genetic information
Cell must decode the information imbedded in linear array of ________ nucleotide sequence; translating them into the ________ sequence contained in a protein
Nucleotide, amino acid
Genetic code is how many nucleotides?
3
What is 3 nucleotides also called?
Codon
What is a codon the same as?
amino acid
What are the three stop codons?
UAA, UAG, UGA
What is the start/methionine codon?
AUG
What defines the coding region?
nucleotide sequence
Ribosomes serve as
Translation machines
What do ribosomes do?
aligns and forms peptide bond between amino acids
Ribosomes located ________ sequences on mRNA
begins at start site, moves in 5’ to 3’ direction
punctuation
Prokaryotic comprised of ________ and ________ subunits
30S and 50S
How many reading frames are possible?
3 reading frames AKA ways in which triplets of nucleotides can be grouped
What do tRNAs do?
deliver correct amino acid
Each tRNA has a specific ________ sequence, base-pairs with codon
- each carries appropriate amino acid specified by codon
- after delivering amino acid, tRNA can be ________
anticodon
recycled
Which direction does the anticodon of tRNA go in?
3’ to 5’
