Lipids (Part 11 of 11) - Sterols / Steroids

Summary

This video script delves into the world of lipids, focusing on sterols and steroids, which share a common steroid nucleus structure. It explains their roles as membrane components and signaling molecules, with cholesterol being a key player in maintaining membrane fluidity. The script also covers bile acids' role in fat emulsification and the significance of steroid hormones, such as testosterone and estradiol, in the body. It touches on corticosteroids, including cortisol and aldosterone, and their impact on stress response and mineral balance. The video concludes with synthetic corticosteroids like prednisone, highlighting their anti-inflammatory properties and potential risks.

Takeaways

• 🌟 Sterols and steroids are lipids with a basic structure based on a steroid nucleus, which includes four rings: three six-membered rings and one five-membered ring.
• 🔍 Steroids function as membrane components and signaling molecules, such as hormones.
• 🧬 Cholesterol is the major sterol in animals, playing a crucial role in maintaining membrane fluidity and serving as a precursor to other steroid molecules.
• 🔢 The numbering system of cholesterol is important for understanding enzyme names and their functions in converting one steroid molecule to another.
• 🍗 Bile acids, a type of steroid, help emulsify fats from our diet, making them more accessible for lipases to break down further.
• 🚹🚺 Sex steroids, such as testosterone and estradiol, are produced in the reproductive organs and are involved in various physiological processes.
• 🌡 Corticosteroids, including glucocorticoids and mineralocorticoids, are produced in the adrenal cortex and have effects on blood glucose levels and mineral balance in the body.
• 💊 Synthetic corticosteroids, like prednisone, are used to treat anti-inflammatory diseases and have immunosuppressive effects, which can increase susceptibility to infections.
• 🔬 Steroid hormones, including sex steroids and corticosteroids, exert their effects by altering gene transcription within cells.
• 📚 Understanding the structure and function of steroids is essential for studying various biological pathways and their roles in health and disease.
• 📈 The video aims to provide a comprehensive wrap-up of lipids, focusing on the importance of sterols and steroids in biological systems.

Q & A

What is the basic structure of all steroids?

The basic structure of all steroids is based on a steroid nucleus, which consists of four rings: three six-membered rings (A, B, and C rings) and one five-membered ring (D ring). This structure is nearly planar.

What roles do sterols and steroids play in biological membranes?

Sterols and steroids function as membrane components and help maintain membrane fluidity. They prevent the membrane from becoming too rigid or too fluid, thus maintaining optimal fluidity levels.

What is the primary sterol found in animals and what is its main function?

The primary sterol in animals is cholesterol. It plays a crucial role in maintaining membrane fluidity and serves as a precursor to other steroid molecules.

How does cholesterol's amphipathic nature contribute to its function in biological membranes?

Cholesterol's amphipathic nature, with both polar and non-polar portions, allows it to interact with the phospholipids in the membrane, contributing to the membrane's fluidity and stability.

Why is the numbering system of cholesterol important in understanding steroid metabolism?

The numbering system of cholesterol is important because it helps in identifying the carbon atoms involved in enzymatic reactions that convert one steroid molecule to another, which is essential for understanding steroid metabolism pathways.

What is the function of bile acids in the human body?

Bile acids function to emulsify fats from our diet, breaking them down into smaller molecules that lipases can act upon for further digestion.

Can you explain the difference between sex steroids and corticosteroids?

Sex steroids, such as testosterone and estradiol, are produced in the reproductive organs and are involved in sexual development and function. Corticosteroids, on the other hand, are produced in the adrenal cortex and are involved in stress response and regulation of blood glucose and mineral balance.

What is the role of aldosterone in the body?

Aldosterone is a mineralocorticoid that plays a role in regulating sodium levels in the body, which in turn affects blood pressure and fluid balance.

What is the purpose of synthetic corticosteroids like prednisone in medical treatments?

Synthetic corticosteroids like prednisone are used to treat anti-inflammatory diseases and act as immunosuppressants, reducing inflammation and immune responses.

Why might patients taking synthetic corticosteroids be more susceptible to infections?

Patients taking synthetic corticosteroids may be more susceptible to infections because these drugs suppress the immune system, reducing the body's ability to fight off pathogens.

How do steroid hormones exert their effects within the body?

Steroid hormones exert their effects by altering gene transcription within the nucleus of cells, leading to changes in cellular function and response.

Outlines

00:00

🧪 Sterol and Steroid Basics

The first paragraph introduces the basic structure of sterols and steroids, which is based on a steroid nucleus consisting of four rings: three six-membered rings and one five-membered ring. These molecules are nearly planar and are referred to as the A, B, C, and D rings. Steroids function as membrane components and signaling molecules, such as hormones. Cholesterol, the major sterol in animals, is highlighted for its amphipathic nature, with a small polar group and a large non-polar hydrocarbon portion, allowing it to maintain membrane fluidity. The paragraph also discusses the importance of cholesterol's numbering system for understanding enzyme names and functions in steroid pathways, such as the conversion of testosterone to dihydrotestosterone by 5-alpha reductase.

05:03

🌿 Bile Acids and Steroid Hormones

The second paragraph delves into bile acids, which are steroids that emulsify fats from our diet, breaking them into smaller molecules for lipases to further break down. The specific bile acid taurocholic acid is mentioned, highlighting its torine portion that carries the acidic group. The paragraph then transitions to steroid hormones, focusing on sex steroids produced in the reproductive organs: testosterone in the testes and estradiol in the ovaries. The names of these hormones are explained in relation to their structures. Corticosteroids, produced in the adrenal cortex, are also discussed, with cortisol as a stress hormone and aldosterone affecting sodium levels. A synthetic corticosteroid, prednisone, is mentioned for its use in treating anti-inflammatory diseases and its immunosuppressive effects, which can increase susceptibility to infections.

10:03

📚 Conclusion on Steroids and Lipids

The final paragraph wraps up the discussion on lipids by emphasizing the importance of steroid hormones as signaling molecules that can alter gene transcription within cells. It encourages viewers to like, comment, subscribe, and share the video if they found it helpful, and wishes them happy studying.

Keywords

💡Sterols and Steroids

Sterols and steroids are a class of lipids with a characteristic four-ring structure, consisting of three six-membered rings and one five-membered ring. They are nearly planar and are integral to the video's theme of lipids. In the script, the basic structure of these compounds is described as the 'steroid nucleus,' and they are highlighted for their roles in biological membranes and as signaling molecules, such as hormones.

💡Cholesterol

Cholesterol is a major sterol in animals and is described in the script as an amphipathic molecule with both polar and non-polar regions. It plays a critical role in maintaining membrane fluidity, preventing the membrane from becoming too rigid or too fluid. The script also discusses the importance of cholesterol's numbering system for understanding enzymatic reactions involving steroid molecules.

💡Membrane Fluidity

Membrane fluidity refers to the ability of a cell membrane to remain flexible and dynamic, which is essential for its function. In the script, cholesterol is described as a key component that helps regulate membrane fluidity, ensuring that it does not become too rigid in cold conditions or too fluid, which could lead to structural instability.

💡Bile Acids

Bile acids are a type of steroid that function to emulsify fats from our diet, breaking them down into smaller molecules that can be further digested by lipases. The script provides an example of a specific bile acid, 'chenodeoxycholic acid,' highlighting the role of the 'taurine' component in carrying the acidic group.

💡Steroid Hormones

Steroid hormones are signaling molecules derived from cholesterol and are crucial for various physiological processes. The script distinguishes between sex steroids, such as testosterone and estradiol, which are produced in the testes and ovaries, respectively, and corticosteroids, which are produced in the adrenal cortex and include glucocorticoids and mineralocorticoids.

💡Testosterone

Testosterone is the male sex steroid hormone produced in the testes. The script explains its structure and how it is involved in the production of dihydrotestosterone (DHT) through the action of the enzyme 5-alpha reductase, illustrating the importance of the steroid numbering system in understanding such enzymatic reactions.

💡Estradiol

Estradiol is the female sex steroid hormone produced in the ovaries. The script provides its chemical structure and explains the significance of its name, which relates to the presence of two alcohol groups, indicating its role as a female sex steroid.

💡Corticosteroids

Corticosteroids, also known as corticoids, are a class of steroid hormones produced in the adrenal cortex. The script differentiates between glucocorticoids, like cortisol, which affect blood glucose levels, and mineralocorticoids, like aldosterone, which regulate mineral balance, particularly sodium levels.

💡Cortisol

Cortisol is a glucocorticoid hormone that plays a vital role as a stress hormone. The script explains its function in modulating blood glucose levels and its naming convention, which relates to the presence of a ketone group in its structure.

💡Aldosterone

Aldosterone is a mineralocorticoid hormone that regulates sodium levels in the body. The script describes its role in maintaining electrolyte balance and its significance in the context of mineralocorticoids.

💡Prednisone

Prednisone is a synthetic corticosteroid mentioned in the script for its use in treating anti-inflammatory diseases and as an immunosuppressant. The script also cautions about the increased susceptibility to infections due to its immunosuppressive effects, providing a practical example of how steroid hormones can have wide-ranging impacts on the body's physiological responses.

Highlights

Introduction to sterols and steroids, emphasizing their basic structure based on a steroid nucleus with four rings.

All steroids share the same four ring system, with slight variations distinguishing different types.

Steroids function as membrane components and signaling molecules, such as hormones.

Cholesterol is the major sterol in animals, playing a key role in maintaining membrane fluidity.

Cholesterol's amphipathic nature allows it to have both polar and non-polar portions, contributing to its role in membranes.

The importance of cholesterol's numbering system for understanding enzyme actions in steroid molecule conversions.

Bile acids, as steroids, emulsify dietary fats, making them more accessible for lipases to break down.

The role of bile acids in facilitating the digestion of fats through emulsification.

Steroid hormones, including sex steroids and corticosteroids, are produced in reproductive and adrenal organs.

Testosterone and estradiol are the primary male and female sex steroids, respectively.

Corticosteroids, such as cortisol and aldosterone, are involved in stress response and mineral balance.

The naming conventions of steroid hormones can sometimes reflect their chemical structures.

Prednisone, a synthetic corticosteroid, is used for treating anti-inflammatory diseases and as an immunosuppressant.

The potential risks of using immunosuppressant drugs like Prednisone, including increased susceptibility to infections.

Steroid hormones exert their effects by altering gene transcription within the cell nucleus.

The video aims to introduce and summarize the topic of steroids within the broader context of lipids.

Encouragement for viewers to like, comment, subscribe, and share the video for further educational content.

Transcripts

hey folks if you'd like to support me or

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and enjoy the

video I'd like to wrap up the discussion

of lipids by talking about sterols and

steroids um so their basic structure is

based on this idea of a steroid

nucleus steroid nucleus which I've drawn

here it's these this four ring system

three of them are six membered rings and

this last one is a five membered ring

and this whole situation is nearly

planer the Rings are referred to as the

a ring B ring C- ring and D

ring now so all steroids have this basic

structure B this basic four ring system

they vary slightly from one to the other

but they have that same same sort of

situation going on their functions they

function as membrane

components and they can also function as

um signaling

molecules namely

hormones the

major stero in animals is

cholesterol and its structure is like

this

it looks like

that it is a a it is an

amphipathic molecule which means it has

polar and non-polar portions its polar

portion is actually pretty small it's

just this o group here right it's got a

polar o the rest of the molecule though

is just hydrocarbons right carbons and

hydrogen so the rest of it is non-polar

which is why it can actually be a

membrane

component it um specifically in

membranes it plays a role in maintaining

membrane

fluidity so if it gets too cold and a

membrane sort of begins to become more

rigid cholesterol play a role in helping

it become more fluid and if it becomes a

little bit too fluid and might break

apart it becom allows it to become a

little bit more rigid uh to maintain

optimal fluidity levels so cholesterol

plays an important role there it's also

important as a precursor to other

steroid

molecules in fact um something that's

actually pretty important to that is uh

the numbering system of cholesterol it's

27 carbons long and it's numbered like

this starting from carbon number one

right there and we go around 1 2 3 4 5 6

7 8 9 10 then we jump up here to 11 12

13 14 15 16 17 then these two methyl

groups 18 19 and then 20 through 27 are

on this this over

here um this the numbering system might

not seem really important right now but

there are certain enzymes involved in

the in sort of converting one am or what

excuse me not one amino acid one uh

steroid uh molecule to another and the

the names of the enzymes sometimes refer

to where they're actually doing whatever

it is they're doing uh for as an example

there's an enzyme

called there's an enzyme called five

Alpha reductase and what that does that

molecule is actually what takes

testosterone

testosterone and turns it into uh uh di

dihydrotestosterone which or or

DHT and the enzyme name five Alpha

reductase it's action it's it's reducing

the five carbon of testosterone to to

become uh dihydrotestosterone or DHT so

that's just one example there are other

examples but the point is that being

familiar with the numbering system of

the steroids is helpful in understanding

the names of the enzymes in case you're

studying those

Pathways okay next up here bile acids so

there are bile acids uh that are that

are

steroids and their their function really

is to emulsify fats from our diet and

what that means is basically it takes

these these gigantic fats that we're

consuming and breaks them up into little

smaller sort of uh molecules that that

lipases can act on uh and lipases will

go through and and and break down the

fats further from there so I've just

drawn here an example of a specific bile

acid called toolic acid and the reason

the tooro portion of that name comes

from this portion up here called torine

and that torine portion actually carries

the acidic um the acidic group that is

carrying the negative charge after it

has been

[Music]

deprotonated now steroid hormones

steroid hormones so these are the ones

that I think a lot of people study uh

these first two up

here are the sex steroids and they are

made in the reproductive

organs so over here I've drawn the male

sex steroid and over here I've drawn the

female sex

steroid the male sex steroid is made in

the male reproductive organ which is the

testes and the female sex steroid is

made in the ovaries the female

reproductive

organ so which

two steroids are these you may already

have guessed it this one is testosterone

and this one is

estradiol the names can make a little

bit of sense um this this uh test refers

to the fact that these things are made

in the testes uh stair comes from uh the

SD steroid and then o refers to Ketone

so we got a ketone right there so it's

basically saying male sex steroid and it

has a ketone in it

um estradiol estra refers to

estrus um and the the diol refers to two

alcohols there's an alcohol there and an

alcohol there so these names can make a

little bit of sense they're not always

Sure Fire um but they can they can

sometimes make a little bit of

sense um okay next up three and four

three and four are the

corticosteroids because they are made in

the

adrenal cortex so cortex cortico

corticosteroids they're also called

corticoids for

short uh the first one over here to the

left is a

glucocorticoid and this one over here to

the right is a um

mineralocorticoid mineralo

corticoid and you may have guessed the

names of these this one is cortisol and

this one is

aldosterone cortisol is a stress hormone

and the reason it's called a

glucocorticoid is because of its effect

on blood glucose

levels aldosterone is a mineral

corticoid because of its effects on the

minerals in our body specifically uh

sodium right sodium is a mineral and so

aldosterone uh plays a role in uh sodium

levels so so it's a mineralocorticoid

and the own again again here the own

refers to Ketone um cortisol also has a

ketone but ites doesn't have it it

doesn't end in own but up here it does

have some alcohols so that o might refer

to these alcohols up

here um cortisol's name doesn't really

lend too much to its structure um but

cortisol and aldosterone are both

corticoids because they were made and

released from the adrenal

cortex this last one here number five is

uh a synthetic corticoid oh synthetic

corticosteroid synthetic kod Co steroid

and it's actually called uh prazone okay

so prazone is used uh to treat um

anti-inflammatory

diseases anti-inflammatory

diseases um and it is an

immunosuppressant

drug so though it can treat

anti-inflammatory diseases um because of

its

immunosuppressive um effects it can

leave Pat patients susceptible to

infections so um I don't know I'm just

as soon as I I heard that I thought okay

so if someone is taking Prednisone for

some sort of disease we might want to

make sure that you know we make sure

that everything that we give them is

pretty clean and free from infections

because they're especially susceptible

to

infections now all these steroid

hormones can basically are important in

signaling so because they are steroid

hormones they can um they will uh

somehow make their way to the the

nucleus of of

um of a cell and alter Gene

transcription these guys alter they

exert their Effects by altering

transcription

of of

genes okay well I hope that video was

helpful in kind of introducing steroids

and wrapping up lipids thanks for

watching yo if you found that video

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thanks happy studying