Level 2 Bio: Epigenetics & Metabolic Pathways Flashcards
Describe what is meant by a ‘metabolic pathway’
A metabolic pathway is a series of enzyme-controlled steps involved in the synthesis or breakdown of a substance. The product of one step becomes the substrate for the next step.
State the end products of the breakdown of phenylalanine
Carbon dioxide (CO₂) & Water (H₂O)
State the end products of the breakdown of tyrosine
Thyroxine or Melanin
Explain how Albinism is caused
Albinism is caused by ‘block 2” where the pigment Melanin which is the end product of Tyrosine is not formed meaning the individual is albino.
Explain how Cretinism is caused
Cretinism is caused by ‘block 3’ where thyroxine the other end product of Tyrosine is not made which results in physical and mental retardation as it is needed to control metabolism.
Name the products that accumulate to cause Alkaptonuria
Homogentisic acid accumulates in the urine and causes connective tissue to turn black and leads to arthritis.
Name the products that accumulate to cause Tyrosinosis
Hydroxyphenolpyruvic acid accumulates in the urine and can cause liver & kidney failure or damage.
Name the products that accumulate to cause Phenylketonuria
Phenylalanine & Phenylpyruvic acid to accumulate, damaging the nervous system, light skin pigmentation, & causes physical and mental retardation.
Explain the term ‘autosomal recessive condition’
Autosomal recessive condition means the mutation has occurred in the gene on an autosome (#15) & not on a sex chromosome & it is recessive as the alleles are recessive.
Describe the relationship between the HEXA gene and hexosaminidase A
The HEXA gene has the base sequence that codes for hexosaminidase A.
Discuss the way DNA controls the function of the cell
DNA contains the genetic information needed to carry out all of the functions & essential processes of the cell.
Discuss the role of enzymes in metabolic pathways
Enzymes control each step of the pathway by catalysation. Therefore metabolic pathways depend on enzymes for the pathway to work.
What is a Metabolic pathway (IMPORTANT)
A metabolic pathway is a series of enzyme catalyzed reactions in which the product of one reaction becomes the substrate for another.
How does Metabolism occur
Metabolism occurs as a series of enzyme-controlled chemical reactions, known as metabolic pathways.
What controls the chemical reactions of metabolism
Specific proteins (enzymes) in the body, control the chemical reactions of metabolism.
What determines what proteins (enzymes) are made in Metabolic pathways
The DNA code
What does a metabolic pathway look like?
Gene A Gene B
↓ ↓
Enzyme A Enzyme B
↓ ↓
Substrate—————>Intermediate————->Product
How does a Metabolic pathway work
A metabolic pathway is when the product of 1 enzyme reaction is the substrate for the next enzyme reaction.
What happens in PKU (Phenylketonuria)
In PKU the body lacks an enzyme called phenylalanine hydroxylase. This means that the body is unable to break down an amino acid called phenylalanine. As a result, levels of phenylalanine build up in the blood & brain.
What happens in Albinism
Albinism is caused by a defect in one of several genes that produce or distribute melanin pigment. The defect also may result in the absence of melanin production or a reduced amount of production. Albinism symptoms are an absence of colour or lighter than normal colour in hair, skin or eyes (light skin pigmentation).
What are needed for each step of a metabolic pathway
Specific enzymes are needed for each step of a metabolic pathway.
What codes for each enzyme in a metabolic pathway?
Each enzyme is coded for by an expressed gene
What can stop an enzyme being made & therefore stop a metabolic pathway
Mutations can stop an enzyme being made & therefore stop a metabolic pathway & this can affect the phenotype of an individual e.g PKU (Phenylketonuria) & Albinism.
What is epigenetics?
Epigenetics is changes in organisms caused by the modification of gene expression (Phenotype) rather than alteration of the genetic code itself.
What 3 things are part of the Nature side of Epigenetics
1) Genetics
2) Physical appearance
3) Biological appearance
What 3 things are part of the Nurture side of Epigenetics
1) Environment
2) Upbringing
3) Social influences
What is the genotype
Genotypes are the genetic makeup of an individual
What is the phenotype
Phenotypes are the set of observable characteristics of an individual resulting from the interaction of it’s genotype with the environment.