Gen Bio (lipids) exam 1

triacylglycerol structure

(also known as fat) triacylglycerol forms when the hydroxyl composed of smaller molecules, specifically a glycerol and three fatty acids. on the carboxyl functional group on the fatty acid combines with a hydrogen ion on one of the hydroxyl functional groups on the glycerol. The hydroxide ion and the hydrogen ion are released from the fatty acid and glycerol molecule and combine to form a water molecule. The fatty acid forms an ester link with the glycerol molecule. Two other fatty acids combine with the two remaining hydroxyl functional groups on the glycerol molecule. The structure of a triacylglycerol molecule makes it hydrophobic: it has no affinity for water. The hydrogen and carbon atoms form nonpolar covalent bonds in the fatty acid

Fat

A fat, also called a triacylglycerol (or a triglyceride), is a lipid composed of smaller molecules, specifically a glycerol and three fatty acids

How many hydrocarbon tails are found in a fat/triglyceride? In a phospholipid? In cholesterol?

A fat/triglyceride has THREE hydrocarbon tails joined by ester bonds to a glycerol. A phospholipid has TWO hydrocarbon tails joined to glycerol by ester bonds. Cholesterol contains just ONE hydrocarbon tail that is bound to a steroid. Correct This answer is correct because a fat/triglyceride has three hydrocarbon tails joined by ester bonds to a glycerol. A phospholipid has two hydrocarbon tails joined to glycerol by ester bonds. Cholesterol contains just one hydrocarbon tail that is bound to a steroid.

fatty acid

A fatty acid is a carboxylic acid with a hydrocarbon chain that is usually 16 to 18 carbon atoms long (three fatty acids in fat +glycerol)

why saturated fatty acid stay solid at room temperature

A fatty acid that is saturated with hydrogen atoms, meaning that hydrogens fill the remaining bond locations instead of double bonds with the carbon skeleton. Single Bond. The LINEAR structure of a saturated fat allows the fatty acid chains to PACK TOGETHER CLOSELY. As a result, a saturated fat is often solid at room temperature. Mammalian fats such as lard and butter have a high content of saturated fats.

phospholipids

A phospholipid is type of lipid composed of TWO fatty acids (triglyceride has three), one glycerol and one PHOSPHATE functional group. The structure of a phospholipid is unique. The fatty acid forms the hydrophobic tail of the phospholipid. The head is the hydrophilic end, and it interacts with water. The two hydrophobic tails composed of long hydrocarbon chains do not interact with water and will spontaneously arrange themselves to minimize their contact with this polar molecule.

saturated fatty acid

A saturated fatty acid is a lipid that does NOT have any Double Bonds between the carbon atoms in the carbon skeleton. This fatty acid is saturated with hydrogen atoms, meaning that hydrogens fill the remaining bond locations instead of double bonds with the carbon skeleton. The linear structure of a saturated fat allows the fatty acid chains to pack together closely. As a result, a saturated fat is often solid at room temperature. Mammalian fats such as lard and butter have a high content of saturated fats.

steroid structure

A steroid is another type of lipid. A steroid is composed of a carbon skeleton arranged in four fused rings

What are the primary ways a triacylglycerol, saturated fatty acid, and unsaturated fatty acid are different?

A triacylglycerol is a lipid molecule composed of smaller molecules — specifically glycerol and three fatty acids. A saturated fatty acid is a fatty acid that contains no double bonds in the hydrocarbon chain (linear structure, packed tightly together). It holds the maximum possible number of hydrogen atoms. An unsaturated fatty acid contains one or more double bonds in the hydrocarbon chain ( kink and liquid at room temp). It does not hold the maximum possible number of hydrogen atoms.

unsaturated fatty acid

An unsaturated fatty acid is a lipid/fatty acid with one or more double bonds between carbon atoms. The Double bonds, which are almost always in a cis formation, produce a KINK in the molecule. This kink prevents fatty acids from packing tightly together. The kink gives it fluidity. As a result, an unsaturated fat — also referred to as an oil — forms a liquid at room temperature. Triacylglycerols from plants and fish such as olive oil and cod liver oil have a high content of unsaturated fatty acids.

adipose cells

Animals require a more compact energy source. Fats are stored in adipose cells that swell and shrink as the reserves are stored and used. In addition to an energy source, fats cushion bodily organs and provide insulation.

Apolipoproteins

Apolipoproteins are proteins that bind lipids to form lipoproteins. They transport the lipids through the lymphatic and circulatory systems.

cholesterol

Cholesterols partly make up the cell membrane of animal cells and has biological functions in it. The liver produces cholesterol, but it can also be obtained from diet.

exception to phospholipid rule

Exceptions to the rule. Unlike most prokaryotes and eukaryotes, which have membranes made up of phospholipids, members of the Domain Archaea have cell membranes made up of isoprenoid lipids. Isoprenoid lipids differ from other prokaryotic and eukaryotic membranes because they have branched tails as compared with long, straight chains. Isoprenoid lipids have a different chemical structure than phospholipids as well, making them more structurally stable in the harsh environments that most archaea reside.

Distinguish among triacylglycerol, saturated fatty acid, and unsaturated fatty acid.

Fats, also known as triacylglycerols, can be constructed of saturated fatty acids and/or unsaturated fatty acids. A triacylglycerol forms when a hydroxyl on the carboxyl functional group combines with the hydrogen on the hydroxyl functional group on the glycerol. This pairing forms an ester link joining the fatty acid to the glycerol. Two more fatty acids join the glycerol to produce the triacylglycerol. In a saturated fatty acid, the carbons in the hydrocarbon tail are bonded by single covalent bonds, which makes them "saturated" with hydrogen atoms. In an unsaturated fatty acid, the hydrocarbon tail contains one or more double covalent bonds between the carbons. The fatty acid's carbon skeleton is not "saturated" with hydrogen atoms.

types of lipids

Fats, phospholipids, and steroids

LDL

LDL-linked cholesterol ("bad cholesterol") levels to estimate the risk of cardiovascular disease. Stays in the bloodstream (low density liprotein).

lipids are

Lipids are a diverse group of hydrophobic molecules that serve a variety of important biological functions.

lipids polar or non-polar?

Lipids are nonpolar and hydrophobic. The nonpolar covalent bonds, hydrophobic in nature, prevent the hydrocarbon from interacting with water, a polar molecule.

Describe the main characteristics of lipids!!!!

Lipids include fats, phospholipids, and steroids. Most lipids are composed primarily of hydrocarbons held together with single and/or double bonds. They are nonpolar and hydrophobic, and they do not interact with water. Lipids contain FUNCTIONAL GROUPS that are POLAR in nature. These functional groups are hydrophilic and interact with water, however the majority of a lipid is nonpolar and hydrophobic.

lipoproteins

Lipoproteins are categorized into five groups according to their structures and what types of lipids they can transport. Two of these groups are the high-density lipoprotein (HDL) and low-density lipoprotein (LDL). Both HDL and LDL lipoproteins transport cholesterol in the bloodstream, and act as carrier molecules. The amounts of HDL and LDL in the blood determine how much cholesterol is in the blood, and where it ultimately goes in the body. The relative concentration of each of these lipoproteins controls how much cholesterol accumulates within blood vessels, a key component to human diseases.

micelle

Micelles form to aid in the transport and absorption of complex lipids and fat-soluble vitamins such as vitamin A. A micelle is a small object that forms naturally when the hydrophobic phospholipid tail (mostly shorter tails ) points inward protecting the phospholipid tail from the water. The hydrophilic phospholipid head is exposed to the water.

essential fatty acids

Must ingest. example: Omega-3 and omega-6 fatty acids are important compounds and nutrients that living things must acquire. They occur in products like fish, oils from sources such as avocados and pumpkins, and certain nuts. The names of these omega molecules derive from the double bonds between the specific carbon atoms in their carbon skeletons; for omega-3 fatty acids, it is the double bond between the third and fourth carbon.

two ways phospolipds can form

Phospholipids can either form a circular, single-layered micelle or two layers of phospholipids can line up together to form a bilayer. Phospholipids with short tails are more likely to form micelles, whereas those with longer tails are more likely to form bilayers.

which stores more energy fats or polysaccharides?

Plants store energy in polysaccharide molecules. Animals rely on fats for an energy reserve. Fat compounds hold twice as much energy as polysaccharides like starch. A polysaccharide is a bulky molecule that is adequate for plants because plants do not move around. Animals require a more compact energy source. Fats are stored in adipose cells that swell and shrink as the reserves are stored and used. In addition to an energy source, fats cushion bodily organs and provide insulation.

Relate the structure of fat molecules to the function of energy storage.

Plants use polysaccharides, like starch, as energy reserves. These compounds are large. In contrast, lipids are relatively smaller molecules that hold twice as much energy as polysaccharides. Animals need lipids such as triacylglycerols to continue to maintain life functions. Animals store triacylglycerols in adipose tissues that shrink and swell as reserves are used or stored. Adipose tissue has additional benefits of cushioning major organs and providing insulation. Fat is generally synonymous with the term lipid, and the characteristics of fat molecules (triacylgycerols) can be applied to all lipids. Steroids and phospholipids, like fats, are molecules used for energy storage.

How do steroids move around?

Steroids are transported through the bloodstream by special lipoproteins that contain proteins and lipids. These lipoproteins have internal hydrophobic regions that allow fats and fat-soluble compounds to be transported. They also have hydrophilic exteriors that allow them to move through the blood

types of steroids

Steroids include sex hormones and cholesterol. A steroid is defined by the functional groups attached to its carbon rings

In which direction is a polypeptide assembled?

Synthesis of the polypeptide always occurs in the same direction, with the initial methionine at the amino end. This is known as the N-terminus. Each amino acid is added at the carboxyl end, or C-terminus of the previous amino acid. During elongation, amino acids are added to the C-terminus of the growing polypeptide. (remember the structure of an amino acid)

HDL

The cholesterol carried by HDL is commonly called "good cholesterol" because HDLs can transport cholesterol out of the blood to the LIVER where it can be reused by the body. If cholesterol remains in the blood at high levels, then (constriction of blood vessels) may develop

phospholipid bilayer function

The phospholipid bilayer also controls what materials enter or leave the cell. Nonpolar molecules, like oxygen, carbon dioxide, and hydrocarbons, dissolve in the hydrophobic interior of the phospholipid bilayer. These materials easily pass through the cell membrane. Hydrophilic molecules cannot pass through the phospholipids' hydrophobic interior. Other compounds embedded in the cell membrane, like proteins, act like channels moving these materials into and out of the cell.

advantage/disadvanatage of structural formula

The structural formula allows a scientist to visualize the elements arranged in a molecule. However, this model does not show the three-dimensional space that the molecule fills.

is a triacylglycerol molecule hydrophobic/hydrophollic? why?

The structure of a triacylglycerol molecule makes it hydrophobic: it has no affinity for water. The hydrogen and carbon atoms form nonpolar covalent bonds in the fatty acid. A lipid is composed primarily of hydrocarbons. The hydrocarbons form single and double nonpolar covalent bonds. As such, lipids do not react with water, which is a polar molecule.

Trans fat

Trans fat is an UNSATURATED FAT with a trans Double bond. Because this trans bond allows for a more dense arrangement of triacylglycerol molecules, trans unsaturated fats, or just "trans fats," remain solid at room temperature. Although trans fats are produced in nature, most are manmade. Unfortunately, consumption of trans fats leads to negative health effects. These fats are known to increase LDL cholesterol levels more than do other types of fats.

phospholipid bilayer strucure

When placed in water, the hydrophobic ends of the phospholipid align with one another (mostly longer tails ). This arrangement prevents the hydrophobic ends from interacting with water. The hydrophilic heads are in contact with environmental aqueous solutions. This arrangement produces a phospholipid bilayer. The phospholipid bilayer thus provides a boundary that protects the cell from the outside environment

The head of a phospholipid is hydrophilic because it has...

a phosphate group carries negative charges that allow the phospholipid head to interact with water.

phospholipid structure

a) Often, phospholipids are drawn symbolically as a head with one straight tail and one bent tail. b) The structural formula of phospholipids reveals that the choline and phosphate regions contain a positive and a negative charge, respectively. These charges are attracted to the opposite charges on water molecules, and this is known as the hydrophilic head. The fatty acid tails, which have no net charges, have no affinity for water and are described as the hydrophobic tails. c) The space-filling model shows the three-dimensional arrangement of atoms on a typical phospholipid.

triglyceride

also known as fat/triacylglycerol. is a lipid composed of smaller molecules, specifically a glycerol and three fatty acids.

advantage/disadvanatage to space filling model

space-filling model is a three-dimensional representation of the molecule. Spheres represent the different atoms in the molecule. The radius of each sphere is proportional to the other atoms in the molecule. The atoms are color-coded. A space-filling model gives a realistic representation of the size, shape, and space that elements occupy in the molecule. However, this model prevents a clear representation of bonds that form between elements in the molecule.

Complete the following sentence: In humans, steroids are involved in the...

steroids are involved in the production of HDL, LDL, sex hormones, apolipoprotein, and many other molecules in humans.

Prion

strange infectious proteins called prions. These highly unusual pathogens lack genetic material. Modified prion proteins cause fatal neurodegenerative diseases

advantage/disadvanatage symbol

this model does not provide any detailed information about the elements in the molecule or the three-dimensional structure. It is useful for representing the behavior of phospholipids within a membrane or the relationship between phospholipids and other molecules.