Gene Function and Pathways Flashcards
What is a gene
What is a gene
- Mendel - a gene controlls a trait
- Because a gene encodes for proteins - and how musch protein is made
- The protein is the Functional part of a cell
- Therefore genes control how the cell functions and interacts with other cells
Proteins as Machines
Proteins as Machines
proteins can be thought of as machines that do all of the functions
Machines that:
* Build the cell
* Enzymes that make necessary molecules
* Antibodies that protect from foregin
* Regulate the cell cycle, cell growth, division
* Carry molecules
Alkaptonuria
Alkaptonuria
- Human disease that turns uran black when exposed to air
- Pedigree analysis on a large number of families suggested autosomal recesive
- To devlop disease, must receive two copies of the recessive allele:
- one from each parent
- Phenotype only seen in homozygotes
Alkaptonuria
Alkaptonuria
People with alkaptonuria excrete HA
* That is what turns urine black
Everyone else breaks down HA
* Metabolize HA into CO2 and H20
People with alkaptonuria are mising an enzyme necessary to metaboliza HA
* Inborn error of metabolism
Proves that genes encode for enzymes
* Lack both copies of gene, lack the enzyme
Alkaptonuria
Alkaptonuria
People with alkaptonuria excrete HA
* That is what turns urine black
Everyone else breaks down HA
* Metabolize HA into CO2 and H20
People with alkaptonuria are mising an enzyme necessary to metaboliza HA
* Inborn error of metabolism
Proves that genes encode for enzymes
* Lack both copies of gene, lack the enzyme
PKU
PKU
Phenylketonuria (PKU) is a recessive disorder that causes people to be unable to metabolize phenylalanine
* Autosomal Recessive mutation
* Gene is Phenylalanine Hydroxylase
* Without this gene phenylalanine accumulates and causes severe mental retardation and early death
* Lacking this enzyme also affects other traits
* Since people with this trait can not make tyrosine they also lack melanin
* Pleiotropy
Albinism
Albinism
- Multiple types of albinism can cause humans to be able to produce melanin
- Most common mutation is an autosomal recessive mutation in the gene Tyrosinase
- Melanin not only provides pigment, but it also protects skin from UV damage
- There are a number of steps in the biochemical pathway between tyrosine and melanin
- Therfore a number of diferent genes can be mutated and cause exact smae trait
- Genetic Heterogeneity
Tay-Sachs Disease
Tay-Sachs Disease
- Autosomal Recessive mutation that blocks the production of an enzyme in lysosomes
- Lysosomes are organelles that contain multiple digestive enzymes
- Responisble for the breakdown of nucleic acids, proteins, sugars, and fats
- The enzyme HexA breaks down a lipid that is used in a nuerons membrane
- Without HexA this type of lipid accumulates in neurons and they cannot function properly
- Neurological Degeneration occurs as neurons lose ability to function
Sickle Cell Anermia
Sickle Cell Anermia
- Anemia is a decrease in red blood cells
- Sickle cell anemia is caused by a mutation in the hemoglobin protein
- Hemoglobin is the protein that carries oxygen in red blood cells
- Caused by a single mutation in DNA
- Changes amino acid in hemoglobin protein, which changes the shape
- Homozygous for mutation
- Sicle cell anemia and early death
- Heterozygous
- Sickel cell trait
- Very few red blood cells are sickle shaped
- Very mild phenotype, nomral life span
- Incomplete dominance
Cystic Fibrosis
Cystic Fibrosis
- Autosomal Recessive mutation in humans causing hughly viscous mucus
- Causes pancreatic, pulmonary, and digestive disfunction and shortend life
- Peliotropy
- Gene: Cystic Fibrosis Transmembrane Regulator (CFTR)
- The protein controls the active transport of chloride ions across the membrane
- Osmosis tries to blanace out the different concentration on each side of the membrane producing a thickend mucus
