Cellular Control Flashcards
Define mutation
Change in the sequence of bases in DNA
Define insertion mutation
A mutation where one or more extra nucleotides are inserted into a DNA strand
Define insertion mutation
A mutation where one or more extra nucleotides are inserted into a DNA
Define substitution mutation
A mutation where one or more nucleotides are substituted for another in a DNA strand
Define deletion mutations
A mutation where one or more nucleotides are deleted and lost from the DNA strand
Define mutagen
Chemical or physical agent which causes mutation
Define Amorph
Mutation that results in the loss of function of a protein
Define Hypomorph
Mutation that results in a reduction of a function of a protein
Define hypermorph
Mutation that results in a gain in function of a protein
Define nonsense mutation
Coding becomes a stop codon, so protein is shorter and usually non-functional
Define missense mutation
Incorporation of incorrect amino acid into the primary structure of a protein, resulting in silent, beneficial, or harmful effects to the functioning of the protein
Define chromosomal deletion
Section of the chromosome breaks off and is lost
Define chromosomal translocation
Section of chromosome breaks off and joins non-homologous chromosome
Define chromosomal inversion
Section of chromosome breaks off, is reversed and joins back on
Define frameshift mutation
A genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read
Physical mutagens
Ionising radiations - break one or both DNA strands
Some breaks can be repaired but mutations can occur in the process
Chemical mutagens
Deaminating agents - Chemically alter bases in DNA
Transcription factors in eukaryotes
Proteins move into the nucleus from the cytoplasm and bind to DNA
Allows/ blocks RNA polymerase attaching
Starts / stops transcription
○ Can be in every cell
○ Present at certain times of development
○ Only present in certain types of cells
○ Most inhibited or activated, e.g, growth factors or hormones
Transcription factors in prokaryotes
Define operon
A length of DNA containing a cluster of structural genes under the control of one promoter region
Define promoter
A sequence that enables the gene to be transcribed - recognised by RNA polymerase
Define operator
A segment of DNA that a regressor or activator binds to
Define operator
A segment of DNA that a regressor or activator binds to
Define intron
Non coding DNA
Define intron
Non coding DNA
Define exon
Coding DNA
Define pre mRNA
The product of transcription is a precursor molecule
Define mature mRNA
Modified pre mRNA
No introns
Define mature mRNA
Modified pre mRNA
No introns
Splicing
○ Spliceosome causes the intron to form a loop shape
○ the intron is excised, and the exons are then spliced together
○ The mRNA may leave the nucleus into the cytoplasm for the next stage of protein synthesis
Splicing
○ Spliceosome causes the intron to form a loop shape
○ the intron is excised, and the exons are then spliced together
○ The mRNA may leave the nucleus into the cytoplasm for the next stage of protein synthesis
Post-translational control
Hormone binds to cell surface membrane
Triggers production of cAMP (signalling molecule)
cAMP binds to regulatory subunit of the enzyme
Regulatory subunit releases catalytic subunit of the enzyme, changing its 3D shape to allow the enzyme to become active
What modifications happen to proteins during post-tranalational control?
○ Folding or shortening of proteins
○ Modifying amino acids and the formation of bonds
○ Addition of non-protein groups
○ Modificatioj by cAMP
