6.1.1 gene mutations 6.1.2 regulation of gene expression
- G ene mutation:the change in sequence of DNA base pair and may - R egulatory gene:codes for protein that control theexpression of
result in an altered polypeptide structure gene
- Chromosomal mutation:a change in chromosomal structure/ - Transcription factors:a protein that bind to DNAto switch on or
number off by increasing or decreasing the rate of transcription
- Operon:a section of DNA that contains structuralgenes
- Gene expression at the transcriptional level is controlled by
Indel mutation transcription factors
Insertion
-> Anucleotide is insertedinto the DNA sequence Lac operon
- Base sequence is shifted and the triplets and amino acid are changed - It is used for gene expression in prokaryotes
deletion
-> a nucleotide is deleted from the DNA sequence
- Base sequence is shifted and the triplets and amino acid are changed
Point mutation
-> a base is swapped for a different base
Silent mutation
- A
base is changed but some codons are degenerate codes, so that the
polypeptide is not affected
Missense mutation
- A
change in base causing the amino acid to change, and the amino
acid sequence is changed, so that there will be a change in tertiary
structure of protein
Nonsense mutation
- A
change in base produced a premature stop codon, so that the
polypeptide chain is incomplete, and affects the function and
structure of protein
,Eukaryotes .1.3 Genetic control of body plan
6
- G
ene expression is controlled at transcription, post- transcriptional,
post- translational level development
Post- transcriptional level - B ody plan:a general structure of an organism thatare arranged in
- I ntrons:DNA sections that do not code for amino acid particular ways
- Extrons:DNA section that codes for amino acid - Hox genes:genes that code for proteins that controlbody plan
development
1. Introns and exons are transcribed into primary mRNA transcripts - Homeobox sequences:regions in hox genes that arehighly
2. Introns are removed from the mRNA strand through splicing, and the conserved and changed little during evolution, it is code for
exons joined together homeodomain (protein)
- Homeodomain:it acts as a transcription factor andbinds to DNA to
activate or repress transcription, and alter the production of proteins
- Apoptosis:programmed cell death, e.g. separationof fingers/ toes
undergoes apoptosis
Apoptosis process
. E
1 nzymes inside cell break down cell components
2. Cell starts to shrink and breaks up into fragments
3. Cell fragments are engulfed by phagocytes and digested
Post- translational level
- To activate the proteins after they are synthesised
- Protein activation is controlled by molecules
When cAMP activates protein kinase A
1. Molecules bind to cell surface receptor
2. G protein is activated, which activates adenylyl cyclase
3. Adenylyl cyclase catalyses the conversion of ATP to cAMP
4. cAMP then binds to two subunits of protein kinase A
5. Binding of cAMP causes a change in protein structure, active
subunits of protein kinase A is then released and activated
, 6.2.1 Genetic variation 6.2.2 monogenic inheritance
- G enotype:the alleles of a gene possessed by an individual
- Phenotype:the observable characteristic of an organism Monohybrid cross
- Continuous variation:individuals in a populationvaries within a
range without distinct categories
- Discontinuous variation:individuals in a populationare categorise
into distinct categories
- Variation and environment can influence genes
- Crossing over and independent assortment in cells can cause
variation between individuals
- Dominant alleles are always expressed, recessive alleles are only
expressed when no dominant allele is present
- M onogenic inheritance:the inheritance of a characteristic
controlled by a single gene
- Phenotypic ratio of dominant: recessive = 3:1
- F1 generation: homozygous dominant crosses with a homozygous
recessive to produce the heterozygous offspring
- G ene mutation:the change in sequence of DNA base pair and may - R egulatory gene:codes for protein that control theexpression of
result in an altered polypeptide structure gene
- Chromosomal mutation:a change in chromosomal structure/ - Transcription factors:a protein that bind to DNAto switch on or
number off by increasing or decreasing the rate of transcription
- Operon:a section of DNA that contains structuralgenes
- Gene expression at the transcriptional level is controlled by
Indel mutation transcription factors
Insertion
-> Anucleotide is insertedinto the DNA sequence Lac operon
- Base sequence is shifted and the triplets and amino acid are changed - It is used for gene expression in prokaryotes
deletion
-> a nucleotide is deleted from the DNA sequence
- Base sequence is shifted and the triplets and amino acid are changed
Point mutation
-> a base is swapped for a different base
Silent mutation
- A
base is changed but some codons are degenerate codes, so that the
polypeptide is not affected
Missense mutation
- A
change in base causing the amino acid to change, and the amino
acid sequence is changed, so that there will be a change in tertiary
structure of protein
Nonsense mutation
- A
change in base produced a premature stop codon, so that the
polypeptide chain is incomplete, and affects the function and
structure of protein
,Eukaryotes .1.3 Genetic control of body plan
6
- G
ene expression is controlled at transcription, post- transcriptional,
post- translational level development
Post- transcriptional level - B ody plan:a general structure of an organism thatare arranged in
- I ntrons:DNA sections that do not code for amino acid particular ways
- Extrons:DNA section that codes for amino acid - Hox genes:genes that code for proteins that controlbody plan
development
1. Introns and exons are transcribed into primary mRNA transcripts - Homeobox sequences:regions in hox genes that arehighly
2. Introns are removed from the mRNA strand through splicing, and the conserved and changed little during evolution, it is code for
exons joined together homeodomain (protein)
- Homeodomain:it acts as a transcription factor andbinds to DNA to
activate or repress transcription, and alter the production of proteins
- Apoptosis:programmed cell death, e.g. separationof fingers/ toes
undergoes apoptosis
Apoptosis process
. E
1 nzymes inside cell break down cell components
2. Cell starts to shrink and breaks up into fragments
3. Cell fragments are engulfed by phagocytes and digested
Post- translational level
- To activate the proteins after they are synthesised
- Protein activation is controlled by molecules
When cAMP activates protein kinase A
1. Molecules bind to cell surface receptor
2. G protein is activated, which activates adenylyl cyclase
3. Adenylyl cyclase catalyses the conversion of ATP to cAMP
4. cAMP then binds to two subunits of protein kinase A
5. Binding of cAMP causes a change in protein structure, active
subunits of protein kinase A is then released and activated
, 6.2.1 Genetic variation 6.2.2 monogenic inheritance
- G enotype:the alleles of a gene possessed by an individual
- Phenotype:the observable characteristic of an organism Monohybrid cross
- Continuous variation:individuals in a populationvaries within a
range without distinct categories
- Discontinuous variation:individuals in a populationare categorise
into distinct categories
- Variation and environment can influence genes
- Crossing over and independent assortment in cells can cause
variation between individuals
- Dominant alleles are always expressed, recessive alleles are only
expressed when no dominant allele is present
- M onogenic inheritance:the inheritance of a characteristic
controlled by a single gene
- Phenotypic ratio of dominant: recessive = 3:1
- F1 generation: homozygous dominant crosses with a homozygous
recessive to produce the heterozygous offspring
