central dogma of molecular biology

dna replication

bidirectional 5’ to 3’; semiconservative

semiconservative replication

dna consists of one original strand and one newly synthesized strand

dna

antiparallel double strand, complementary base pairing

prokaryotes

single origin of replication, circular dna

eukaryotes

multiple origin of replications, linear chromosomes, telomere replication

replisome

team of enzymes and proteins that accomplish dna replication

initiation

ORI is recognized, initiators move along dna to encounter start of repli and makes opening

helicase

unzip dna by breaking whb and forms replication bubble

y-shape

replication fork where dna is cop

single strand binding proteins

prevents reannealing

gyrase

prevents coiling in prokaryotes

topoisomerase

prevents coiling on eukaryotes

primase

lays down rna primers at each repli fork

dna polymerase

synthesize new dna strands, add dntps and build new dna

reiji okazaki

okazaki fragments is named after

dna ligase

joings okazaki and fill the gaps

mismatch repair

correct errors using dna polymerase

exonuclease activity

cuts incorrect base

dna polymerase III

adds nucleotides

dna polymerase I

replace rna primers with dna

dna polymerase II, IV, V

repair

telomeres

non coding dna at ends of chromosomes

telomerase

extends telomeres to prevent dna loss

apoptosis

programmed cell death

nucleosomes

dna wound around histones to form

histone chaperones

nuclosomes disassemble during dna repli and reassemble after dna is copied using

transcription

genotype to phenotype starts with

ribose sugars, one of the 4 nucleotide bases, phosphate

rna is composed of

pentose sugar

used by both rna and dna

OH groups

reactive groups; oxygen aggresive attacks atoms

mrna

carries message out of nucleus

trna

carries amino acids

rrna

organizes process of translation

microrna (miRNA)

small rna control gene expression

small nuclear rna (snrna)

finishing touches during splicing

thymine

protects dna better than uracil as it make methyl ch3 less obvious to nucleases

nucleases

chew dna and rna

secondary structure

rna forms bonds with itself and gets twisted and folded up

nuclear pores

mrna exits nucleus through

promoters

start of transcription region

terminator

stop transcribing

gene, promoter, terminator

transcription unit is composed of

tata box

eukaryotes promoter sequence, indicates where a gene is, and tell s enzyme which strand holds the genetic info

30 bases away going in the 3’ direction (downstream)

tata box is located

consencus sequence

sequences agree or mean the same thing

non template strand

tata is on the ___ and indicates that the other strand is to be used as template for transcription

ribonuleotides

building blocks of rna

holoenzyme

rna polymerase consist of multiple subunits that combine to form a complete complex called

rna polymerase I

takes care of long rna molecules

rna polymerase II

carries out synthesis of most mrna and some tiny specialized types of rna molecules that are used in rna editing after transcription is over

rna polymerase III

transcribes trna genes and other small rnas used in rna editing

initiation

includes finding the gene and opening the dna molecule so that enzymes can get to work

enhancers

dna sequences sometimes distantly located from transcription unit, control how often a particular gene is transcribed

transcription bubble

the opening created by rna polymerase when it wedges its way between two strands of the helix is called

rntps

rna polymerase strings together ___ to form rna

20 bases of dna

the transcription bubble itself is very small and only about __ are exposed at a time

terminator

when rna polymerase encounters the ___, it transcrive the terminator sequence and stops the transcription

terminator factor

aids rna in finding the right stopping place

5’ cap

a guanine triphosphate is modified and attached to the 5’ end of the transcript

poly-a-tail

a long tail of adenine bases is tacked on the 3’ end of the transcript to further protect the mrna from natural nuclease activity

unmodified rntp

rna polymerase starts the process of transcription by using an

methyl groups at the 5’ end of the mrna

protects it from decomposition and allow the ribosome to recognize mrna as ready for translation

length

the __ of poly a tail determines how long the message last and how many times it can be translated before nucleases eat the tail and destroy the message

introns

non coding sequences; intervening presence

exons

coding sequences; expressed nature

splicing

specialized type of rna work to find the start and end of introns, pull exons together, and snip out extra rna (intron)

spliceosome

splicing is don by a little cellular machine called ____; recognizes consensus sequences

alternative splicing

vary the way initial transcript is edited to make diff versions of a protein from the same gene

translation

converts genetic message from dna to protein

polypeptides

long chains of amino acids that are folded into complex shape and hooked tgt

codon

combination of 3 nucleotides in a row

degenerate

18 to 20 amino acids are specified by 2 or more codons

triplet

bases are read 3 at a time in codons

orderly

each codon is read only one way and in only one direction just as english is read left to right

nearly universal

every organism on earth interprets the language of the code in exactly the same way

triplet, degenerare, orderly, nearly universal

features of genetic code

wobble

the flexibility of the third position

cytoplasm

translation takes place in the

ribosomes

large protein making factory organizes entire translation process and contains the enzyme that catalyzes bond formation between amino acids in the growing polypeptide chain

amino acids

complex chem compounds which contain nitrogen and carbon and strung tgt in thousands of unique combinations to make polypeptide chains that form proteins

ribozyme

enzyme made of rna instead of protein

charging

trna molecules must be hooked up with the right amino acids in a process called

anticodon

a three base sequence on one loop of each trna which is complementary to one of the codons spelled out by the mrna sequence

acceptor arm

signle stranded tail of the trna where amino acid corresponding to the codon is attached to the trna

aminoacyl-trna-synthetases

trnas get charged with the help of a special group of enzymes called

a-site

charged trna molecules enter the ribosome at this site, matching their anticodons with the codons of the mrna; aminoacyl

p-site

the trna holding the growing polypeptide chain is in this site; peptidyl

e-site

trnas that are no longer carrying anything are released from the ribosome from this site; exit

initiation factors

at the start of translation, smaller subunit attached near the 5’ cap of the mrna with the help of proteins called

ribosome binding sequence

small subunit recognizes and attaches to a special sequence in the mrna called the

translocation

porcess of the ribosome and mrna shifting relative to each other

release factors

special proteins move in and bind to the ribosome and recognizes stop codon and sparks the reaction that cleaves the polyopeptide chain from the last trna