Protien Synthesis, Technologies Flashcards
Nucleotide
-building blocks of DNA -strands held together by hydrogen bonds -a,t 2 bonds -c,g 3 bonds Phosphate group, deoxyribonucleic acid, nitrogenous base
Nitrogenous bass
Form a genetic code for a protein -2 types -purines :double ringed a,g -pyrimidines : single ringed c,t
DNA vs rna
DNA -double strand -large -double helix -deoxyribose sugar -g,c,t,a Rna - single strand -single helix -ribose sugar -g,c,a,uracil
Genetics
Study of mechanisms and the pattern of inheritance through the transmission of coded chemical instructions from one generation to the next
Central dogma
DNA - rna = transcription Rna - protein = translation DNA - DNA = replication
DNA replication
-semi conservative (little change) -3 stages 1. Unwinding 2. Elongation 3.termination / rewinding -materials needed : DNA , helicase,DNA polymerase, rna polymerase, free nucleotides, ligase
Unwinding of replication
- helicase unzips the long molecule by breaking the hydrogen bonds (uncoils the DNA ) - junction between unwound single strands and double helix is replication fork - replication fork moves along the parental DNA strand so there is a continuous unwinding of DNA
- Elongation of replication
-nucleoside triphosohates add energy to add nucleotides -in nucleus free nucleotides attach to exposed base with the help of rna polymerase -form new identical chains -enzymes only bind in 5 to 3 direction Leading and lagging strand
Leading strand replication
Synthesised continuously in the 5 to 3 direction by DNA polymerase
Lagging strand
-constructed in fragments and then joined -rna polymerase synthesises a short rna primer which is later removed -DNA polymerase 3 extends rna primer with short lengths of complimentary DNA to make Okazaki fragments -DNA polymerase 1 removes rna primer by digesting it and replaces it with DNA -Ligase seals the gaps between nucleotides and fragments into continuous strand that can now rewind
- Termination /rewinding of replication
-2 new strands rewind into their double helix shape -one parental and one new strand -one strand is conserved from one generation to another
Genes in eukaryotic cells
-nucleus -mitochondria -chloroplasts
Genes in prokaryotic cells
-large circular chromosomes -plasmids (replicate independently)
Karyotype
-picture of chromosomes from humans cell arranged in pairs by size -first 22 pairs called autosomes -last pair sex chromosomes -xx female -Xy male
Centromere
Constriction in a chromosome required for movement during cell division
Chromatid
Daughter strands of a duplicated chromosome that are joined by a centromere
protein synthesis
process in which dan is transcribed into mrna and then translate int amino acid sequences that make up proteins
genetic code
- code is read in a sequence of 3 bases - tripler on dna - codons on mrna - anticodon on trna
transcription
- first stage - occurs in the nucleus - helices unzips the dna strand breaking the h bond exposing the triplet on a single template strand - mrna is synthesised by rna polymerase - rna polymerase attaches to the start of the gene (promoter) to initiate transcription - mrna forms from free nucleotides by complementary base pairing, replacing T with a U - proceeds the 5 to 3 direction until it reaches the stop sequence
post transcriptional modification
- each gene use produce more then one protein - introns are removed after transcription - the way the eons are spliced and number varied creating variation - this allows for a diverse range of proteins
translation
- second stage - determines the order in which amino acids are joined to make proteins - occurs in cytoplasm - 3 stages 1. initiation 2. elongation 3. termination
imitation translation
- 2 ribosomal sub units attach to a specific nucleotide sequence on the mrna strand next to the start codon aug where translation will start
elongation translation
- amino acids are added 1 by 1 by trna as the ribosome moves along the mrna a polypeptide chain forms between adjacent amino acids
termination translation
- occurs when the ribosome reaches a stop codon - binds to the stop codon releasing the polypeptide chain - ribosomal unit falls off so they can be recycled - many ribosomes can work on one mrna (polyribose)
polyribose
- speeds up rate of reaction - multiple ribosomes are working on the one piece of mrna
protein structure
- 4 levels 1. primary : the sequence of amino acids in 1 linear polypeptide chain 2. secondary : the shape of the polypeptide chain 3. tertiary : the overall 3d shape caused by folding 4. quaternary : 2-4 polypeptide chains joined as a functional unit
denaturation of proteins
- loss of proteins 3d structure - bonds in the protein structure break - result in loss of function - irreversible
mrna
- messenger rna - copies and transfers the dna code from the nucleus to cytoplasm - complementary to the dana code
trna
- transfer rna - carries amino acids to the growing peptide chain - one end carries the anticodon
comparing transcription and dna replication
similar - dna unwinds free floating nucleotides bind to the strand transcription: only small part of dna used - enzymes involved in joining rna nucleotides - single stranded rna produced replication: whole dna used - dna polymerase not rna - double stranded produced
ribosomes
- made up of 2 sub units, small and large - can be free in the cytoplasm of associated with the endoplasmic reticulum
protein synthesis in prokaryotic cells
- no nucleus - transcription and translation occur in cytoplasm - rna polymerase binds directly to a promoter region on the dna to begin transcription - mrna synthesis continues until the rna polymerase encounters a termination sequence at which it stops
epigenetics
the study of chemical modifications to gene function that are not due to dna sequence changes, eg methylation and acetylation
epigenome
- chemical tags on genes that turn them on and off
histones
- proteins in which dna coils around to avoid detangling
methylation
- silences gene expression off - addition of methyl groups to DNA - compacts dna, winding onto histones - stops transcription meaning that certain genes aren’t expressed and are turned off
acetylation
- activate gene expression on - addition of acetyl groups to DNA - loosens dna on the histones - makes transcription easier
cause of modifications (methylation and acetylation)
- can be inherited (nature) - accumulate through a persons life - result of environment /lifestyle e.g. smoking (nurture)
genomic imprinting
- an imprinted allele is activated only if it is inherited from 1 parent and other allele is inactivated
identical twins
- as they get older they look less alike - identical genotypes - accumulate phenotype differences as they get older - due to epigenetics
dna technologies
the use of living things to make new products or systems
genetic engineering
- artificially adding gene or changing the way genes wor
restriction enzymes
- act as molecular scissors cutting dna molecules into restriction fragments - different enzymes have different sites - cuts form sticky or blunt ends sticky: leave some nucleotide exposed blunt: no overlapping strands
ligation
- joining dna ends using dna ligase 1. 2 pieces are cut using the same restriction enzymes 2. dna fragments are attached to each other 3. sticky ends are attached to each other annealing - dna ligase joins them together recombinant dna: joined dna of two different origins
str
- short tandem repeats - found throughout genome - 2-5 base pairs e.g. ca or catga - used in gel electrophoresis, more accurate then using restriction enzymes
pcr
multiplys copies of dna - Polymerase chain reaction 1. denaturing:seperates dna strands by heating to 95 for one min, breaking the hydrogen bonds 2. annealing: primers bond to dna cooled to 55 3. extension: thermally stable dna binds to the primers on each side of the dna strand making complementary strands using free nucleotides 70
benefits of transferring genes
- nutritional benefit - improved crop yield - make herbicide resistant plants (more environmentally sustainable - new products
- ethical and doesnt require killing
- inexpensive easy to produce
- fast to produce large amounts
- decrease use of pesticide
-
concerns of transferring genes
- lack of testing - irreversible - reduce lifespan - unnatural - uncontrolled spread of transgenes
VNTRs
- variable nucleotide tandem repeats, more then 5 base sequences
gene therapy
- replace defective genes in the sufferer delivering normal genes
transgenic organisms
- moving genes from 1 species to another
virus
- hijack the cell - shoot their dna into the nucleus or the cell
vector
used to copy genes or transfer to target cells
examples of gene engineering
- bt cotton, kills caterpillers - golden rice, produces vitamin A
dna sequencing - Sanger method
- finds the exact order of bases in dna - uses premature termination dna synthesis by adding labeled modified nucleotides (ddNTPs) - oxygen to stop further synthesis of complementary dna 5 ingredients: single strand dna, dna primer, dna polymerase, free nucleotides, modified nucleotides 1. dna undergoes pcr steps 2. dna primer is annealed to the single stranded dna 3. dna samples are divided into 4 separate tubes 4.dna fragments of possible lengths form 5. fragments sorted by size using gel electrophoresis 6. dna bands visualised by computer systems 7.dna sequence can then be read 8.sequence of original dna is formed
transferring genes
- plasmid vector - liposome vector - viral vector
liposome vector
- liposomes are small spheres that surround the membrane composed of phospholipid bilayers - liposomes join to organisms and a gene of interest can be inserted inside the liposome - used to insert foreign dna into cells cultured in petri dishes
plasmid vector
- isolate the gene, cut genes from cell with restriction enzymes 2.remove plasmid from bacterium 3.cut plasmid with some restriction enzyme to produce sticky ends 4. insert gene in plasmid and place the plasmid in the bacteria 6. bacterium multiplys in broth and produces human proteinsmkaing multiple copies of the desired gene
viral vector
- outside the body - steps 1-4 of plasmid vector but virus not bacteria 5. recombinant dna is packaged into virus 6.assembeled virus injects recombinant dna into human cell 7.virus replicate spreading virus genes 8.put into inhaler, consumed into the lungs which invade the cells dropping off the virus
prokaryotes
- no nucleus
- pili, capsule, plasmid, cytoplasm, ribosome
eukaryotes
- membrane bound organelles
- nucleus present
- cell membrane, nucleus, cytoplasm, ribosomes, mitochondria
comparison of prokaryote ad eukaryote
p:
- less dna
- in the cytoplasm
- circular dna
- plasmids
- dna consists of exons
E:
- more dna
- in the nucleus
- linear dna
- no plasmids
- dna consists of exons and introns
recombinant dna steps
- the foreign dna and plasmid are cut with the same restriction enzyme
- restrictino enzyme creates sticky ends that allows the foreign dna and plasmid to anneal
- ligase glues the annealed fragments together
- the recombinant plasmid is then placed back into the bacterial cell
- bacteria are then grown to replicate and produce the desired protein
- protein is extracted and isolated for use
gene cloning
- plasmids are extended from the bacteria by rupturing their cell walls
- the same restriction enzyme is used to cut the plasmid dna and the dna gene is inserted
- dna liage binds the foreign dna fragemtn / target gene into the plasmid dna
- recombinant plasmids are added to a bacteria culture
- the plasmids replicate in the process of growth and division numerous copies are made
golden rice
- vitamin A
- beleived it could solve vitamin A deficiencies
- the plasmid is inserted into a bacteria which is mixed with the rice plant embryos
- plant embryos are transformed
bt cotton
- modified to produce a pesticide
- cotton plants are susceptible to caterpillars
- bt is a soil bacterium that produces a gene that is topic to caterpillars
- the cotton plants grow and a protein is produced which kills the caterpillars that eat the cotton plant
