Unit 1 : DNA Flashcards
4 stages of hypothesis for the formation of the 1st cell
- abiotic (non living) synthesis of small organic molecules
- small molecules into macromolecules
- packaging of molecules into protocells (prokaryotic cells)
- origin of self replicating molecules
Describe the Miller - Urey Experiment
they created an experiment to see if water vapor cooled our oceans and wanted to see what was in it and to see if it was possible that macromolecules could be formed
What is a protocell?
(lipids and other molecules?)
May have been fluid filled vesicle
- they lipids and other molecules can form vesicles formation
What can increase the rate of vesicle formation? What substrate?
adding clay can increase the rate of vesicle
What properties of life vesicles can exhibit?
- simple growth
- reproduction
- metabolism
- maintenance of internal environment
Why is RNA the 1st genetic material and not DNA?
Due to hypothesis protocells were able to form on earth and they grew and split and passed RNA to their “daughters” and RNA can replicate itself and not DNA
What catalyzes different reaction?
ribozymes
Why is it important that earth has a reducing atmosphere?
due to the lack of oxygen and other gases and vapors, which prevents oxidation,
What did morgans group showed ?
showed genes are located on chromosomes and made of DNA and held together by proteins.
How was the role of DNA 1st discovered?
discovered by studying bacteria and viruses that can infect them.
Griffith Experiment
- worked with two strains of bacteria (pathogenic, harmless)
- transformation: the strains could change it self
What did Avery, Mccarty, and MacLeod established?
20 years later they affirmed griffith experiment
- you can transform cells with just DNA and change behavior
Pathogenic vs. Harmless strains of bacteria
(Griffith Experiment)
(S strain) Pathogenic: smooth - body doesn’t recognize it (deadly) pneumonia
(R starin) Harmless: rough - body attacks it (not deadly)
Hershey - Chase
- they used viruses to see if it was protein or DNA, which has sulfur
- showed that DNA is the genetic material of the T2 phage (virus)
Double Helix
- franklin and wilkins discovered that DNA was a double helix
- franklin concluded that 2 sugar phosphate backbones with nitrogenous bases
Franklin, Watson, Cricket,
- franklin discovered double helix in DNA
- watson and cricket formed a model of double helix (leaked info from franklin)
Translation
mRNA
in cytoplasm
process in which the information encoded in a strand of mRNA is used to construct a protein
- where tRNA & mRNA work together to make polypeptide
happens in the cytoplasm and ribosomes are involved (eukaryotic cells)
Transcription
tRNA
in nucleous
making mRNA using info in DNA
- (DNA directed synthesis of RNA)
- strand of DNA is used as a template for the manufacture of a strand of pre-mRNA
Polypeptide
1 small bead from translation = 1 amino acids
tRNA vs mRNA
definition
tRNA - transfer (role in protein synthesis, translation)
mRNA - messenger
Primary transpict
initial RNA transcript from any gene prior to processing (pre mRNA)
Promoter, TATA Box
TATA box - a lot of thymine & adenine
- tata box must bind to DNA before RNA polymerase can bind in the right position
Promoter - DNA of a gene that binds to RNA polymerase
RNA polymerase
breaks DNA strands apart and join together the RNA nucleotides
- the promoter starts transcribing a gene for RNA polymerase
DNA template strand
read it from 3 prime to 5 prime
- nucleotides in RNA sequence
Codon Strand
mRNA
read it from 5 prime to 3 prime
- same sequence as mRNA but T instead of U
- codon
RNA processing
definition
pre mRNA to mRNA
- enzymes modify pre mRNA before its sent off to cytoplasm
- slicing
- happening in nucleus
5’ cap
sequence of nucleotides that are going to get added to the 5 prime end of mRNA
- where ribosome is going to attach
poly-A-tail
- added on 3 prime end (adenine)
- poly-A-tail protects mRNA
modifications for 5’ cap & poly-A-tail
export of mRNA to cytoplasm
- enzymes can break the bond between nucleotides
- helps ribosomes attach to the 5’ end.
- we need mRNA out
- protect RNA
- ribosome to bind to RNA to start translation
Exons & Intron
exons - exit the nucleus
intron - stay in nucleus will not be apart of the final translation process
Spliceosome
- proteins make spliceosomes
- cut out introns
Ribozymes
RNA molecules that function as enzymes and can splice RNA
alternative RNA splicing
some genes can encode more than one kind of polypeptide
Transfer RNA
(tRNA)
translating mRNA into protein
- tRNAS transfer amino acids to polypeptides in a ribosomes
Anticodons
tRNA
base-pairs with codon on mRNA
A site / P site / E site
A site - holds tRNA that carries to the next animo acid (do i fit in with the codons)
P site - tRNA carries the polypeptide chain
E site - exit site tRNAs leave the ribosomes
operon model
- bacteria
type of regulation of groups of genes
operator
switch is a segment of DNA
operon
bacteria
includes operator, promoter, and genes they control
- it can be switched off by a protein called repressor
repressor
bound to tryptophan, then binds to dna to turn off and blocks RNA polymerase transcription
if repressor is binded RNA polymerase cant transcript
regulatory gene
located some distance from the operan
tryptophan
(trp)
is an amino acids, operon is on
- trp is turned off by REPRESSOR if tryptophan is making too much
lac
bacteria breaks down lactose because bacteria likes glucose (sugar)
- catabolic
- wont turn on unless lactose is around
breaks things down
cyclic AMP
(cAMP)
cAMP activates protein CRP
- CRP binds to promoter of lac operon which increases RNA polymerase accelerating transcription
- when glucose starts to leave cAMP and CRP increases the rate of trancription and translation to make more enzyme and break down lactose at a faster rate
positive gene regulation turning up the volume
Chromatic modification
1st step in gene expression in eukaryotic cells
histone acetylation, DNA methylation
histone acetylation - loosens chromatin structure promoting the start of transcription
DNA methylation - with reduced transcription, causes long term inactivation of genes in cellular differiation
nucleosomes
Transcription Regulation
2nd step in gene expression in eukaryotic cells
transcription factors - needs help from RNA polymerase to start transcription
some bind to tata box (promoter region)
- when the start is complete RNA polymerase can begin to move along the templagte strand
- activators (protein) bind to enhancers (DNA)
RNA proccesing
3rd step in gene expression in eukaryotic cells
- alternative RNA splicing (introns)
- RNA segmants treated as exons
Protein degration (protesomes)
4th step in gene expression in eukaryotic cells
- once protein made in cytoplasm gets tagged by ubiqutin
- protein enters proteosomes
- when non more needed ubiqutin gets recycled
