Gene Expression - Stem Cells Flashcards
(37 cards)
Gene
Stretch of DNA that codes for a protein
How does mRNA become translated into a protein
1) Codons (3 nucleotides)
2) Codons are complementary to specific tRNA’s
3) tRNA attaches to teh codon thats complementary
4) tRNA delivers a specific amino acid
5) Ribosome joining together the amino acids
6) Forming a peptide bond between each nucleotide
What do we do because we cant use embryonic stem cells or adult stem cells
IPSC’s
Induced pluripotent stem cells
Make adult stem cell totipotent again
Epigenetics
How does the environment influence our DNA
How does epigenetics affect histomes
Whether they are wrapped or not
What changes how histomes are wrapped
Wrapped = methylation attaches onto histome
Unwrapped = acetylation
Whats a gene mutatin
Change in sequence if base pairs in a DNA molecule that may result in an altered plypeptide
Types of mutations
Continously
Spntaneously
What des degenerate mean
Single amin acid may be coded by more than one triplet code
Why might mutations not not alter the polypeptide
Code is degenerate
Codes fro mre than one
What can mutations in DNA base sequences result in
Insertion, Deletion, Substitution of a nucleotide
OR
Inversion, duplication or translocation of a section of a gene
What does an insertion of nucleotides do
Changes original amino acid and creates different triplet of bases
Frame shift
Can change the polypeptides function
Deletion of nuleotides
Nucleotide deleted randomly from DNA sequence mutation
Changes original amino acid, changing the grup of three bases, sometimes frameshift
Changing plypeptides functin
Whats a substitution of nucleotides
Mutation when a base in DNA sequence randomly swapped for a different base
Difference between substitution and insertion and deletion
Substituion only changes amino acid for the triplet in which the mutation occurs, will not have a knock on effect
Three types of substitution mutations
Silent mutations - mutation does nto alter amino aciid sequence, degenerate code
Missense - alters single amino acid in polypeptide, changing single amino acid sequence
Nonsense -mutation creates a premature stop codon, causing plypeptide produced to be incomplete, affecting final protein structure and function
WHats duplication of a gene
Gene or section of gene duplicated so there are two cpies of the gene on the same chromosome
Original version intact = mutation isnt harmful
If second copy is duplicated, can develop new functions
Why are duplication mutations important
Evolutionary change
What is translocation of a gene section
Gene cut in two pieces and attaches to a separate gene
Cut gene is non functioning as it has a section missing
Gene gained the translocation section is also likelly to be non functioning
WHat happenbs if a proto-oncogene is translocated
Boost expression and lead to tumour
What happens ia. Sectionof a tumour suppressor gene is translocated
Faulty tumour suppressor gene
Leads to cell continuoing to replicate when it contains faulty dna
Cuases of mutations
Rate that mutations occur
Exposure to mutagenic agents = high energy ionising radiation (alpha, beta gamma radiation) OR chemicals (NO2, tobacco smoke)
WHat happens as a result of gene mutations on polypeptides
Most mutations do not alter the polypeptide
Small number of mutations alter polyeptide with a different shape
May affect the ability of the protein to perform its funciton
Effect of gene mutations on phenotype
Cellular mechanisms affect phenotype of an organism
Mutation causes major alteration, could affect cellular mechanisms whihc impact the phenotype of an organism
