LECTURE 5 - Central Dogma Flashcards
refers to the copying DNA to make 2 DNA molecules
replication
3 general processes of central dogma
- replication (dna synthesis)
- transcription (rna synthesis)
- translation (protein synthesis)
DNA are templates for?
synthesis of complementary strands
ENZYME
unwinds the dna
helicase
ENZYME
prevents DNA from reannealing
single strand binding proteins
ENZYME
relaxes twisting tension experienced by DNA after unwinding
DNA gyrase
ENZYME
synthesizes short segments of RNA after unwinding
in what direction?
primase
5’ to 3’
ENZYME
add nucleotide triphosphates
DNA polymerase 3
DIRECTION OF:
- leading strand
- lagging strand
+ how many primers are used for each?
LEADING: newly synthesized 5’ to 3’ (only 1 primer)
- towards replication fork
LAGGING: newly synthesized 3’ to 5’ (multiple primers)
- away the replication fork
discontinuous segments of complementary DNA
okazaki fragments
ENZYME
proofreads DNA molecule
DNA polymerase 1
ENZYME
removers primers in DNA after replication
+ what is replaced in those removed primers?
DNA polymerase 1
new DNA nucleotides
DNA Polymerase 1, after replacing primers, leaves a ____ or a _____ in the _______ of the _____ DNA segments
which are later joined by the enzyme ____
- break/nick
- sugar-phosphate backbone
- replicated
LIGASE
when does replication end?
when all the parent DNA nucleotides have been complemented
DIFFERENCE between the central dogma of EUKARYOTES and PROKARYOTES
EU:
- transcription occurs in nucleus
- RNA products are transported to cytoplasm for translation
PRO:
- transcription and translation occurs in cytoplasm
TRANSCRIPTION
_____ attaches to a specific sequence in the DNA called a ____ through the help of ____ ____ which recognizes the promoter sequence and later on ____
- RNA polymerase
- promoter
- sigma factor
- dissociates
site where transcription starts
initiation site
what is the DNA strand that mRNA uses as a template to start transcription?
+ what is its direction?
anticoding (anti-sense) strand
3’ to 5’
what separates the dsDNA in TRANSCRIPTION in order to elongate the mRNA?
RNA polymerase
separates the 2 strands while adding complementary nucleotide bases
TRANSCRIPTION
As soon as a segment is complemented for the mRNA, the dsDNA template starts to ____
reanneal
TERMINATION OF TRANSCRIPTION
elongation of mRNA ends upon reaching the ____ ____, where the ___ ____ ____ binds to the RNA polymerase and dissociates it from the DNA
- termination point
- protein factor rho
3 types of RNA and function
- mRNA - template with codons for amino acid sequence
- tRNA - carries the anticodon that dictates the amino acid for protein synthesis
- rRNA - made of ribosomal proteins that form the ribosomes
how many different tRNAs are there?
20 for the 20 different amino acids
protein synthesizing organelles in cell
ribosomes
RIBOSOME IN PROKARYOTES
densities of its:
- small subunit
- large subunit
both of which form the _____ complex
+ 2 sites found in the ribosome
+ which of the subunits can be found on the sites
SMALL: 30S
LARGE: 50S
70S complex
2 sites:
A site (amino-acyl/acceptor site) - 50S
P site (peptidyl-binding/donor site)
chart that shows what amino acids are coded for
genetic code chart
formylated met vs met
+ in TRANSLATION INITIAITON, what site of big ribosome subunit do they enter first?
fmet: prokaryotes
met: eukaryotes + archaea
P-site
one codon = ____ amino acid/s
one amino acid = ____ codon/s
- one
- many
a ribosomal binding site in bacterial and archaeal mRNA during TRANSLATION
Shine-Dalgarno sequence
3 PREVIOUSLY PROPOSED MODELS of DNA REPLICATION
- CONSERVATIVE model
- the parental double helix remains intact
- a second all new copy is made
* basically 1 parent = 1 copy of parent + 1 new different copy - SEMI-CONSERVATIVE MODEL
- the model as we know today - DISPERSIVE MODEL
- each strand of the daughter dna strands contains a mixture of the genes of old and newly synthesized parts
DNA REPLICATION
what do you call complex molecular machine or group of enzymes that replicates DNA?
+ composition (2)
+ what DNA replication model is this found?
REPLISOME (basically all enzymes in DNA replication)
- DNA Polymerase III with 2 catalytic cores
- Primosome (helicase + primase)
- trombone model
DNA REPLICATION - INITIATION
How many origins of replication can DNA have during initiation process in:
- eukaryotes
- prokaryotes
EU - can have several replication bubbles
PRO - only 1
DNA REPLICATION - INITATION
- the Origin of Replication becomes a _____ _____ upon being opened up
- replication bubble
DNA REPLICATION
- 2 significance
- faithfully copying of DNA to produce 2 DNA molecules that are identical to each other and to the parents
- aids in the transmission of biological info from parent cell to daughter cells
DNA REPLICATION
length of RNA primer in PROKARYOTES & EUKARYOTES
11 ± 1 nucleotides - prokaryotes
10-60 nucleotides - eukaryotes
IS prokaryotic dna linear?
no, it’s circular (ang eukaryotic ang linear)
8 MAIN evidences that show that DNA is the genetic material
- Constancy of DNA in all diploid tissues (in starvation, DNA is undamaged)
- Haploid cells have half the amount of DNA in diploid cell
- Doubling of DNA content at S phase
- Cells with extra sets of chromosomes have a proportional increase in DNA content
- Parallelism of UV absorption with mutation rates
- Transformation and Transduction in bacteria
- Production of new viral particles in bacterial cells
- RNA content of TMV caused infection and not the protein coat
MECHANISMS of HIGH PRECISION REPLICATION (3)
- Specifity of base pairing
- Proof reading ability of DNA polymerases
- Excision repair mechanisms
MECHANISMS of HIGH PRECISION REPLICATION - EXCISION REPAITR MECHANISMS
- 2 types
- repair of thymine dimer (endonuclease)
- N glycosidase activity
- hydrolyzes bond between damaged base and sugar
6 CHARACTERISTICS of a GENETIC MATERIAL
- Can duplicate with extra fidelity
- stable molecular structure
- mutation is duplicated faithfully
- can carry all necessary biological information
- can transmit info from generation to generation
- stored info must be decoded and translated into action
WHAT can be CODED by 1 PROTEIN but 4 with POLYPEPTIDE SUBUNITS
hemoglobin
what amino acids can be coded by only 1 codon
methionine and tryptophan
what steps are repeated during TRANSLATION - elongation (3)?
codon recognition
peptide bond formation
translocation
