Nt1310 Unit 1 Exercise 1
Chapter 12
Cyclins and cyclin-dependent kinases are regulatory proteins that assist in the cell cycle. Particular protein kinases give the go-ahead signals at G1 and G2 checkpoints. These protein kinases are present at a constant concentration in the cell but are inactive unless in the presence of cyclin, these are cyclin dependent kinases. The activity of a cdk rises and falls with the concentration of cyclin. Cyclin levels rise during the S and G2 phases then fall abruptly in the M phase.
MPF – maturation-programming factor – cyclin cdk complex that triggers a cells passage past the G2 checkpoint into the M phase (m-phase promoting factor). May assist in the fragmentation of the nuclear envelope during prometaphase. Helps to switch itself …show more content…
Skin color in humans, many genes determine the skin color and offspring is expected to express an intermediate phenotype
When products of many genes influence a trait, individuals of a population show a range of continuous variation.
Environmental Impact on Phenotype The environment has an impact on the phenotype of an individual.
e.g. tanning makes skin darker, exercise alters build, nutrition influences height.
Genotype is associated with a range of phenotypic possibilities due to environmental influences.
Norm of reaction – the phenotypic range of a genotype influenced by the environment. (generally the broadest range is seen for polygenic characters)
e.g. hydrangea flowers of the same genotype can range from blue-violet to pink depending on the acidity and aluminum content of the soil.
e.g. temperature and rabbit fur color. Coldness will darken the fur.
Multifactorial – characters where genetic and environmental factors collectively influence the phenotype.
** An organisms phenotype includes its physical appearance, internal anatomy, physiology and behavior, and reflects its overall genotype and unique environmental history.
Humans and Mendelian Patterns of Inheritance
Cyclins and cyclin-dependent kinases are regulatory proteins that assist in the cell cycle. Particular protein kinases give the go-ahead signals at G1 and G2 checkpoints. These protein kinases are present at a constant concentration in the cell but are inactive unless in the presence of cyclin, these are cyclin dependent kinases. The activity of a cdk rises and falls with the concentration of cyclin. Cyclin levels rise during the S and G2 phases then fall abruptly in the M phase.
MPF – maturation-programming factor – cyclin cdk complex that triggers a cells passage past the G2 checkpoint into the M phase (m-phase promoting factor). May assist in the fragmentation of the nuclear envelope during prometaphase. Helps to switch itself …show more content…
Skin color in humans, many genes determine the skin color and offspring is expected to express an intermediate phenotype
When products of many genes influence a trait, individuals of a population show a range of continuous variation.
Environmental Impact on Phenotype The environment has an impact on the phenotype of an individual.
e.g. tanning makes skin darker, exercise alters build, nutrition influences height.
Genotype is associated with a range of phenotypic possibilities due to environmental influences.
Norm of reaction – the phenotypic range of a genotype influenced by the environment. (generally the broadest range is seen for polygenic characters)
e.g. hydrangea flowers of the same genotype can range from blue-violet to pink depending on the acidity and aluminum content of the soil.
e.g. temperature and rabbit fur color. Coldness will darken the fur.
Multifactorial – characters where genetic and environmental factors collectively influence the phenotype.
** An organisms phenotype includes its physical appearance, internal anatomy, physiology and behavior, and reflects its overall genotype and unique environmental history.
Humans and Mendelian Patterns of Inheritance