Genome projects and gene technology- Paper 2 Flashcards
what is a genome and what can it include
complete set of genes in a cell. these genes could be arranged on linear DNA, independent chromosomes or on circular DNA in prokaryotes
Can include: gene that codes for a protein
regulatory genes such as those that code for transcription factors
mitochondrial DNA which codes for proteins involved in aerobic respiration, doesn’t have to rely on other cells
chloroplast DNA which codes for proteins involved in protein synthesis
genes that code for antibiotic resistant that are located on plasmids in prokaryotes
viral RNA or DNA such as HIV
define phylogenetics
sequence DNA and amino acid sequence helps classify new species
what is a proteome and what can it be used to determine
the full range of proteins produced by cells, used to target gene therapy and faulty genes so can make them work.
off spec content: Pfizer and BioNTeach
they produce a complementary but shorted mRNA strand to the SARS CoV-2 spike protein. This mRNA strand was the key molecule in the COVID-19 vaccine. When injected into muscle cell in the arm, the mrna was translated into a smaller section of the antigen and this triggered a primary immune response that led to the production of specific antibodies and memory cells that were complementary to part of the antigen.
what is recombinant DNA
when a cell has two or more sources of DNA and can be achieved by isolating fragments of the DNA and then inserting this DNA into another organism or species
universal
the same triplet codes for the same amino acid, important because the process of transcription and translation is universal meaning that it is possible for a bacterial cell to produce human insulin.
degenerative
more than one base triplet for each amino acid
non-overlapping
each base is part of only one triplet
How can reverse transcriptase be used to isolate a copy of a specific DNA fragment
Reverse transcriptase carries out transcription in reverse. It makes cDNA copies from mRNA templates. mRNA is then mixed with free DNA nucleotides and enzyme reverse transcriptase
Free DNA nucleotides bind to a single stranded mRNA template via complementary base pairing. Reverse transcriptase joins DNA nucleotides together to form a single stranded cDNA molecule. DNA polymerase is required to make cDNA double stranded
advantages of using reverse transcriptase
cells contain a maximum of two alleles of each gene (one of each homologous chromosome)
if the cell expressing that gene the cell will contain many mRNA molecules with a complementary base sequence to that gene
mRNA
mRNA is much easier to obtain
using mRNA isolated from cytoplasm means introns have been removed and exons spliced together, whereas gene contains introns and exons
bacterial DNA doesn’t contain introns. Bacteria don’t have enzymes for splicing
DNA fragments produced using mRNA as a template code for functioning protein without the need for splicing
mRNA can be isolated from the cytoplasm of cell types which produce the protein in large amounts
how can restriction endonuclease be used to isolate a copy of a specific DNA fragment
these are enzymes that hydrolyse DNA at specific recognition base sequences. Different restriction endonucleases hydrolyse at different points because the shape of the sequence is complementary to the enzymes active site.
DNA is incubated with the specific enzyme which hydrolyses DNA into fragments wherever the recognition sequence appears. if target gene has recognition sequences before and after the target gene, the fragment will contain the desired gene.
If the recognition sequence for the selected restriction endonuclease occurs within the DNA fragment, you want to isolate it.- this will cut the gene and it will not code for a functional protein
What are recognition sequences
palindromic, reads the same both forwards and backwards
How does the gene machine work
way of manufacturing genes by entering the desired sequence of nucleotide bases into a computer
can also reverse engineer the nucleotide sequence by working out the primary amino acid structure
- single stranded DNA produced
2.PCR machine: ssDNA copied and made double stranded (dsDNA) of the gene of interest - PCR amplifies the target gene
describe the process of the gene machine
desired nucleotide fed into computer, synthesis of short sequence of nucleotides, assembly of gene, these short sequences are overlapped then joined together and made double stranded using the polymerase chain reaction, gene is inserted into bacterial plasmid
advantages of isolating DNA fragments via the gene machine
artificial genes are easily transcribed and translated by prokaryotes, as they have no introns in their DNA.
define a vector
a DNA carrier used to transfer foreign DNA into cells
describe the process of inserting genes into a vector
isolated target DNA fragments inserted into the vector DNA by cutting open the vector using the same restriction endonuclease that was used to isolate the DNA fragment. Use the same to create complementary base pairs
this produces complementary sticky ends between the ends of DNA fragment and cut ends of vector DNA
Target DNA fragment anneals to vector DNA by complementary base pairing between their sticky ends
DNA ligase is used to join the DNA fragment and vector DNA at the sugar phosphate backbone. This process is called ligation and forms phosphodiester bonds.
The new recombined DNA fragment and vector DNA is recombinant DNA.
outline a method for in vivo gene cloning
cut desired gene from the DNA of the desired organism
using restriction endonuclease
make artificial DNA with correct sequence of bases
using DNA polymerase
cut plasmid open
with same restriction endonuclease
sticky ends attach
DNA ligase used to join and return plasmid to bacterial cells
