1. Relationship between Genotype and Phenotype
Molecular Basis for
Relationship between Genotype and Phenotype
genotype
DNA
DNA sequence
transcription
RNA
translation
amino acid
sequence
protein
function
phenotype
organism

2. Relationship between Genotype and Phenotype
Molecular Basis for
Relationship between Genotype and Phenotype
genotype
DNA
DNA sequence
transcription
RNA
translation
amino acid
sequence
protein
function
phenotype
organism

3. Alternative Splicing Produces Related but Distinct Protein Isoforms

4. Posttranslational Events
Protein Folding:
Translational product (polypeptide) achieves appropriate folding by aid of chaperone proteins.
Modification of Amino Acids:
* Phosphorylation/dephosphorylation
* Ubiquitination
Protein Targeting:
Directing proteins to specific locations (for example, nucleus, mitochondria, or cell membrane) is accomplished by tagging of proteins (signal sequence for secreted proteins, nuclear localization sequences for nuclear proteins).

5. Posttranslational Events
Protein Folding:
Translational product (polypeptide) achieves appropriate folding by aid of chaperone proteins.
Modification of Amino Acids:
* Phosphorylation/dephosphorylation
* Ubiquitination
Protein Targeting:
Directing proteins to specific locations (for example, nucleus, mitochondria, or cell membrane) is accomplished by tagging of proteins (signal sequence for secreted proteins, nuclear localization sequences for nuclear proteins).

6. Phosphorylation and Dephosphorylation of Proteins
Kinases add phosphate groups to hydroxyl groups of amino acids such as serine and threonine.
Phosphatases remove phosphate groups.

7. Ubiquitinization Targets a Protein for Degradation
Short-lived proteins are ubiquitinated:
cell-cycle regulators
damaged proteins

8. Posttranslational Events
Protein Folding:
Translational product (polypeptide) achieves appropriate folding by aid of chaperone proteins.
Modification of Amino Acids:
* Phosphorylation/dephosphorylation
* Ubiquitination
Protein Targeting:
Directing proteins to specific locations (for example, nucleus, mitochondria, or cell membrane) is accomplished by tagging of proteins (signal sequence for secreted proteins, nuclear localization sequences for nuclear proteins).

9. Signal Sequences Target Proteins for Secretion
Signal sequence at the amino-terminal end of membrane proteins or secretory proteins are recognized by factors and receptors that mediate transmembrane transport. Signal sequence is cleaved by signal peptidase.
Nuclear localization sequences (NLSs) are located in interior of proteins such as DNA and RNA polymerases. They are recognized by nuclear pore proteins for transport into nucleus.

10. Relationship between Genotype and Phenotype
Molecular Basis for
Relationship between Genotype and Phenotype
genotype
DNA
DNA sequence
transcription
RNA
translation
amino acid
sequence
protein
function
phenotype
organism

11. Frameshift Mutations and Suppressor Mutations
frameshift mutations: insertions or deletions of nucleotides that cause a shift in the translational reading frame
suppressor mutations: mutations that counteract or suppress the effects of another mutation
wild-type
CAU CAU CAU CAU CAU
HIS HIS HIS HIS HIS
addition of A
deletion of A
CAU ACA UCA UCA UCA U__
HIS THR SER SER SER
CAU ACU CAU CAU CAU
HIS THR HIS HIS HIS
deletion of U
addition of G
CAU CAC AUC AUC AU__
HIS HIS ILE ILE
CAU CAC GAU CAU CAU
HIS HIS ASP HIS HIS

12. Mutation: Levels of Hereditary Change
Gene (Point) Mutation:
One allele changes to a different allele.
Effects are limited to that locus.
Chromosome Mutation:
Changes occur at the chromosome level.
Multi-locus effects are not unusual.

13. Relationship between Genotype and Phenotype
Molecular Basis for
Relationship between Genotype and Phenotype
genotype
DNA
DNA sequence
transcription
RNA
translation
amino acid
sequence
protein
function
phenotype
organism

14. Base substitution: change in base of nucelotide pair
Point mutations at the molecular level
Base substitution: change in base of nucelotide pair
Base additions: insertion of nucleotide pairs
Base deletions: deletion of nucleotide pairs

15. Point mutations at the molecular level

16. Consequences of Point Mutations within Genes

17. Point Mutations Can Alter mRNA Splicing

18. Point Mutations on Gene Products