Elastin Metabolism and Composition

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Questions and Answers

What does the ATP7A gene provide instructions for making?

Elastin cutis laxa forms

Supravalvular aortic stenosis (SVAS)

A protein important for regulating copper levels in the body (correct)

A protein involved in the formation and function of elastic fibers

How are autosomal recessive forms of cutis laxa generally compared to the autosomal dominant form?

They have a different pattern of inheritance

They have similar severity levels

They tend to be more severe (correct)

They are less severe

What is the X-linked form of cutis laxa often referred to as?

Supravalvular aortic stenosis (SVAS)

Occipital horn syndrome (correct)

Acquired cutis laxa

Menkes syndrome

Which gene is associated with causing Supravalvular aortic stenosis (SVAS)?

ELN gene Signup and view all the answers

What effect can aortic narrowing, caused by SVAS, have on the heart?

Lead to shortness of breath, chest pain, and heart failure Signup and view all the answers

Which condition is considered a mild type of Menkes syndrome?

Occipital horn syndrome Signup and view all the answers

Which pigment found in the skin resembles melanin but is diffusely present throughout the epidermis?

Melanoid Signup and view all the answers

What polymer is eumelanin composed of?

Dihydroxyindole carboxylic acids and benzothiazine units Signup and view all the answers

Which pigment is largely responsible for red hair and freckles?

Pheomelanin Signup and view all the answers

What is the precursor of melanin synthesis?

L-tyrosine Signup and view all the answers

Which organ of the human body is affected by melanin synthesis?

Skin Signup and view all the answers

What is the characteristic color of Hemoglobin?

Purple Signup and view all the answers

What is the half-life of elastin in the human body?

74 years Signup and view all the answers

How many tropoelastin gene(s) exist in humans?

One Signup and view all the answers

What enzyme catalyzes the reaction of linking soluble tropoelastin protein molecules to form elastin?

Lysyl oxidase Signup and view all the answers

Which disease is characterized by loose, sagging skin, aneurysm risk, and emphysema?

Cutis laxa Signup and view all the answers

What is the main role of lysyl oxidase in elastin metabolism?

Catalyzing cross-linking in elastin formation Signup and view all the answers

What type of genetic pattern is associated with Williams syndrome?

Autosomal dominant Signup and view all the answers

Which gene is associated with Williams syndrome?

ELN Signup and view all the answers

Why do people with Williams syndrome have connective tissue abnormalities?

Loss of ELN gene Signup and view all the answers

Which gene is responsible for encoding fibrillin-1 protein in Marfan syndrome?

FBN1 Signup and view all the answers

What is the main role of the Fibrillin-1 protein in Marfan syndrome?

Proper formation of extracellular matrix Signup and view all the answers

Which genetic disorder is characterized by being unusually tall with long limbs and thin fingers?

Marfan syndrome Signup and view all the answers

What is the likelihood that the replacement base in the excision repair process is the same as the base that was removed?

1 in 4 Signup and view all the answers

How does excision repair impact the risk of developing skin cancer?

Introduces DNA mutations Signup and view all the answers

What role does melanin play in protecting the skin from UV rays?

Absorbing UV rays Signup and view all the answers

What is the photochemical process that converts UV-photon energy into heat called?

Internal conversion Signup and view all the answers

What harmful outcomes can result if UV-photon energy is not converted into heat?

Generation of free radicals Signup and view all the answers

How does natural skin color impact photoprotection?

Darker skin provides more photoprotection due to increased melanin Signup and view all the answers

Study Notes

ATP7A gene provides instructions for making a copper-transporting ATPase, essential for copper homeostasis.
Autosomal recessive forms of cutis laxa often present with more severe manifestations compared to the milder autosomal dominant forms.
The X-linked form of cutis laxa is often referred to as "X-linked cutis laxa."

Supravalvular Aortic Stenosis (SVAS)

The gene associated with causing Supravalvular aortic stenosis is ELN (elastin gene).
Aortic narrowing due to SVAS can lead to increased pressure in the heart, potentially causing heart failure.

Menkes Syndrome and Melanin

A mild type of Menkes syndrome is known as "occipital horn syndrome."
Pheomelanin is a pigment in the skin that resembles melanin and is diffusely located throughout the epidermis.
Eumelanin is composed of a polymer of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA).

Hair and Freckles

Pheomelanin is largely responsible for red hair and freckles.
The precursor of melanin synthesis is tyrosine.
The organ affected by melanin synthesis is primarily the skin.

Hemoglobin and Elastin

Hemoglobin has a characteristic red color.
Elastin has an estimated half-life of about 70 years in the human body.
There are two tropoelastin genes in humans which encode the precursor of elastin.

Elastin and Connective Tissue Disorders

The enzyme lysyl oxidase catalyzes the reaction that links soluble tropoelastin proteins to form elastin.
Ehlers-Danlos syndrome is characterized by loose, sagging skin, a risk of aneurysm, and emphysema.
Lysyl oxidase's main role in elastin metabolism is to facilitate the cross-linking of collagen and elastin fibers.

Genetic Disorders and Connective Tissue Abnormalities

Williams syndrome is associated with a genetic pattern of deletion in the 7q11.23 region.
The gene associated with Williams syndrome is the ELN gene (elastin).
Connective tissue abnormalities in Williams syndrome are due to the disruption of elastin production.

Marfan Syndrome

The gene responsible for encoding fibrillin-1 protein in Marfan syndrome is the FBN1 gene.
The Fibrillin-1 protein plays a crucial role in maintaining connective tissue integrity and elasticity.
Marfan syndrome is characterized by unusual tall stature, long limbs, and thin fingers.

DNA Repair and Skin Cancer

In the excision repair process, the likelihood that the replacement base is the same as the removed base is quite low.
Excision repair can significantly lower the risk of developing skin cancer by repairing DNA damage caused by UV radiation.
Melanin's role includes protecting the skin from UV rays by absorbing and dissipating harmful radiation.

UV Radiation and Natural Skin Color

The photochemical process that converts UV-photon energy into heat is known as "thermalization."
If UV-photon energy is not converted into heat, it can result in DNA damage, leading to skin aging or cancer.
Individuals with darker natural skin color have enhanced photoprotection due to higher melanin concentrations, which absorb more UV radiation.

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Description

Learn about the metabolism and composition of elastin, the longest lasting protein in the human body. Discover interesting facts about elastin production and its composition.