Biochem Chapter 11 Flashcards by Sanjene Sidhu

Dietary fat consists mainly of which type of fat

Triacylglycerols

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Where does lipid emulsification occur in body

Duodenum

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Emulsification of fat si done with what 2 things(where)

Bile from liver
Gallbladder

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Pancreatic enzymes break lipids into what 3 things so they can be absorbed across intestinal walls

2-monoacylglycerols
Free fatty acids
Cholesterol

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What 3 things secreted from pancreas help digest lipid

Pancreatic lipase
Colipase
Cholesterol esterase

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Fatty acid, cholesterol and monoglycerides bind with wheat to become micelles

What are they

Bile salts

Water soluble spheres with a lipid soluble interior to allow fats to go through aqueous environment of intestine

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Bile salts do not go with micelles where do they get reuptaken

Ileum

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Lipids during absorption go through what process and to become what

Re esterficiation

Become triacylglycerols and cholesterol esters

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When lipids are packaged with proteins and vitamins a they are calle

Chylomicrons

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How do chylomicrons enter lymphatic system

Through all teals and then the blood stream via the thoracic duct

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How do short chain fatty acids get absorbed by body where they go

Go directly into blood

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Lipid metabolism happens at what state

Postabsorptive state
When food is done, when nutrients form digestion are no longer entering bloodstream

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Lipid mobilization stage

Glucose levels
Insulin
Epinephrine
Cortisol
Glucagon

Levels increase or decrease

Glucose decreases, insulin decreases, the hormones increase

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How does hormones sensitive lipase get activated during lipid mobilization

What does it do, break triglycerides into which 2 things

Hormones like epinephrine, cortisol and glucagon increase, when activates the lipase in adipose tissue

Breaks triglycerides into glycerol and free fatty acids

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Where glycerol broken down in lipid mobilization go after

Travels to liver for glycolysis and Gluconeogenesis to become glucose

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Where does free fatty acids broken down by lipid mobilization go

What is it used for (2) , what type of oxidation and what body production to generate energy

Goes to tissues for beta oxidation and ketone body production to generate energy

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Insulin
Epinephrine
Cortisol

What increase or decrease leads to hormone sensitive lipase to get activated

Insulin drop, other 2 increase

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What is beta oxidation with fatty acids during fat moblibization like waht does it make

Fatty acids to acetyl coA

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Ketone bodies travel to where to be converted back to acetyl co A

Brain (muscle )

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A patient who has diabetes begins insulin injections for management of blood glucose levels. Waht is expected impact on patients weight

Increase in insulin levels will increase lipid storage and decrease lipid mobilization

Weight gain

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What is the ratio of free fatty acids to glycerol produced through lipid mobilization

Ratio of fatty acids to glycerol is 3:1

One glycerol and 3 fatty acids make one molecule

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Triacylglycerols and cholesterols are packaged into what to transport into blood

Lipoproteins

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What determines if lipoproteins are more dense than others

More protein in the particle , more dense

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Lipoproteins are made of what proteins

Apolipoprotein

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Chylomicrons main function is what Where do they travel from and to

Transport dietary lipids from intestine to lymph to blood to tissue

What breaks down triglycerides in chylomicrons in blood

Lipoproteins lipase

After lipoprotein lipase breaks down chylomicrons what do they become

They become chylomicrons remnants

What do chylomicrons main functions

Deliver the remaining lipids to liver

Where are VLDL made

Liver

What do VLDL do

Transport newly made triglycerides from liver to tissues

VLDL gets broken down by what to become what

Lipoproteins lipase Become IDL

If ILD loses more triglycerides, what is it become

LDL

LDL is rich in what

Cholesterol

What does LDL do

Deliver cholesterol to body cells

Waht 2 organs make HDL

Liver and intestine

Waht does HDL

Picks up excess cholesterol and return it to liver

ApoA-I is a type of what

Apolipoproteins, they form the protein component of lipoproteins

Waht does apoA-I do Activates what What is its purpose

Activates LCAT that is an enzyme that is catalyzing cholesterol esterificaiton

Which apoprotein mediates chylomicrons secretion

ApoB-48

Chylomicrons VLDL IDL LDL HDL Which ones transport and carry what

Chylomicrons - triacylglycerols VLDL - triacylglycerols IDL - intermediate LDL - cholesterol HDL- cholesterol

Free fatty acids what is their primary method for transporting free fatty acids in blood

Binding with albumin and remaingin the blood

When phyciscnas order a lipid panel to evaluate a patient, which value do they prefer to see over a minimum threshold rather than below a maximum

HDL It is considered good cholesterol because it picks up excess cholesterol to extreme from tissues

Cholesterol is synthesized mainly by what organ

Liber

Cholesterols is synthesized from ))__________ using ________

Acetyl co A NADPH

The rate limiting step in synthesizing cholesterol is catalyzed by what enzyme,

HMG-CoA reductase

What does HMG-CoA reductase do

Controls how fast choelsterol is made Does Feedback inhibitions and insulin signalling

Cholesterol is carried wiht lipoproteins and 2 enzymes called

LCAT and CETP

What does LCAT and CETP do in cholesterol mobilization They have diff functions

LCAT is packaging cholesterols into esterfirication so HDL can collect choelstrol CETP transfers choelstrol esters between diffeerent lipoproteins dos redistributing to where cells need choelstrol adn the ones that dont

Under waht conditions is HMG-COA reductase most active In what cellular region does it exist

Most stimulated in absence of choelstrol It converts into mevalonate which helps produce cholesterol in cell Cholesterol reduces its activity In endoplasmic reticulum

Fatty acids are what type of compounds chemically Which carboxyl carbon is the alpha carbon

Carboxylic acid Carbon 1 and carbon 2

Saturated fatty acids have or don’t have double bonds

If fatty acid is written as 18:0 , what that mean

18 carbons and no double bonds

Unsaturated fatty acids use which of either notation to show location of double bonds

Delta or omega

Difference between saturated fatty acids and unsaturated fatty acids (1)

Saturated will only have single bonds at room temperature Unsaturated would have one or more double bonds liquid at room temperature

Delta notation (triangle) with unsaturated fatty acids means what Counts from which end and indicates what

Counts from carboxylic end, and indicates the carbon number where the first double bonds begins

Omega notation (w) with unsaturated fatty acids means what Counts from which end and indicates what

Counts from methyl end and indicates how far the first double bonds is from the end

Which are 2 unsaturated fatty acids that humans need but cannot synthesize them so have to get them form diet

Linoleic and linolenic acid

Why does lipid and carbohydrate synthesis called nontemplate syntehsis

Because they do not rely on the coding of nucleic acid like protein does

With adding ester linkages to glycerol to make triglycerides, what type of reaction is that, and what is added to it

3 water molecules condensation

What are the 2 opposing processes in fatty acids metabolism What do they each do Do they happen at the same time

Fatty acids syntehsis and beta-oxidation Stores energy, releases energy Don’t happen at same time

When does fatty acid occurs And where does it occur

After a big meal when insulin is high and you have lots of energy Converts excess glucose into fatty acids for long term energy storage In liver cytoplasm

Why is fatty acid complicated in terms of its building block WHAT SHUTTLE DOES IT USE

Building block of fatty acid is acetyl coA That is found in the mitochondria, and fatty acids syntehsis happens in cytoplasm Acetyl coA can’t cross mitochondrial membrane directly So the cell needs to use transport mechanism called CITRATE SHUTTLE

PRIMARY END PRODUCT OF FATTY ACID SYNTHEISS

PALMITIC ACID

Rate limiting step in lipid syntehsis is

Malonyl coA formation

What are the 3 molecules required for malonyl CoA formation

ATP Co2 Biotin

Malonyl CoA formation is done by which enzyme

Acetyl coA caboxylase

What happens after malonyl CoA is formed

Goes through palmitate syntehsis Fatty acid syntehsis adds two carbons per cycle using Malonyl CoA and NADPH to produce palmitate

Wha are the 4 reactions that happen to malonyl group to palmitate

Condensation Reduction Dehydration Reducetion

In palmitate syntehsis, we go through condensation, reduction, hydration and reduction Waht is added ore removed in all this

Condensation, CO2 removed Reduction , NADPH becomes NADP Dehydration , H2O removed Reduction, NADPH becomes NADP

How many carbon molecule is palmitate

What protein is used in palmitate synthesis

Acyl carrier protein

Palmitate has double bonds or no

No its a saturated fatty acids

What is highly needed in fatty acid syntehsis for power

NADPH

What is palmitate modification done (2 ways) Where does it occur

Endomplastmic reticulum Elongation, additional 2 carbon units added to it Desaturated : introduces double bonds into fatty acid chain

Desaturation of palmitate is done with which enzyme What is needed for this reaction to occur

Fatty acyl coA desaturase Oxygen and NADPh

Fatty acids are stores as what

Triacylglycerols

Where do fatty acids get transported to after palmitate modificationto

liver in VLDL to adipose tissuse

Where doles beta oxidation occur

Mitochondria

When does beta oxidation occur

When you’re fasting Insulin is low, hormones are high Lower energy conditions when glucagon and Epinephrine are high

What is purpose of beta oxidation

To break down fatty acids to produce ATP

First set- of beta oxidation to get it actiated is done how Where are they tryna go from and to

They get attached to coenzyme A by fatty acyl coA synthetase They get activated in cytoplasm to enter mitochondria

The first step of beta oxidation of activating fatty acids Does it require energy Is it reversible

Irreversible ATP is used

WHAT TRANSPORT SYSTEM DOES FATTY ACIDS USE IN BETA OXIDATION

CARNITINE SHUTTLE

WHAT IS THE ENZYME FACILITATING CARTNITINE SHUTTLE

CARNITINE ACYLTRANSFERASE I

When molecule is inside mitochondria for beta oxidation, what transfers fatty acid back onto coqneyme A

FA-coA

What is produced in beta oxidation steps

Acetyl coA NADH FADH 2

Beta oxidation removes how many carbons at a time

What is the rate limiting step of beta oxidation

Carnitine acyltransferase I

What are the 4 reactions that happen to beta oxidation

Oxidation to form double bond Hydration to form hydroxyl group Oxidation to form a. Carbonyl Splitting into shorter acyl coA adn acetyl coA

Each cycle of beta oxidation produces 3 things

Acetyl coA for citric acid cycle NADH for atp syntehsis FADH2 for energy too

How are the yields of odd chain fatty acid chains different that’s even chain fatty acids

Odd : yield 1 acetyl coA and 1 propionyl-coA Even: 2 acetyl coA

Since propionyl-coA can’t enter citric acid cycle, what usable intermediate is it converted into what through what molecule

propionyl-coA -> methylmalonyl coA using propironyl -using coA carboxlyase Then lastly succinyl coA to enter citric acid cycle

Why do unsaturated fatty acids require 2 additional enzymes for beta oxidation

Because they have double bonds and tht disturbs stereochemistry and they need oxidative e nay mess to act on teh fatty acids

For monounsaturated, what enzyme is needed for beta oxidation

Only enoyl coA isomerase

For polyunsaturated fatty acids, what enzymes is needed for beta oxidation Why is there 2

Enoyl-coA isomerase and 2,4 dienoyl-coA Because 2 double bonds turn into 1, and then the last one can be broken down by the enoyl one

When do ketone bodies get formed

When there is prolonged starvation state due to excess acetyl coA in the liver

How does ketogenesis occurs

Acetyl coA -> HMG CoA -> Acetylacetate -> 3-hydroxybutarate

What are the 2 enzymes used in ketogenesis

HMG synthase and HMG CoA lyase

Ketolysis regenerates acetyl coA for use as an energy source in peripheral tissues using what enzyme

Succinyl coA acetoacetyl coA transferasw, thiophrase basically

When ketones are metabolized into acetyl coA in brain, what is inhibited

Pyruvate dehydrogenase So lesss glycolysis and glucose uptake

How does ketogenesis differ from ketolysis (location and what stimulates) How are they the same (1)

Ketogenesis and ketolysis are both activated by prolonged fasting Ketogenesis is in liver and is stimulated by high amounts of acetyl coA Ketolysis is triggered by low energy state in muscles and brain tissues and does not occur in liver

What is proteolysis

Breakdown of proteins into amino acids after prolonged fasting

proteolysis begins where and continues till where

Starts by pepsin in stomach Then pancreatic enzymes, trypsin, chemo trypsin adn carboxxypeptiases A and B continue in small intestine

Amino acids in proteolysis are absorbed into the small intestine through

Active transport to enter blood stream for energy use

proteolysis transporters rely on either which 2 things

Sodium or hydrogen ion gradients

Amino acids are metabolized primarily in which 2 things

Muscles and liver

Amino group of amino acids need to be removed by either one of 2 processes to be used as energy source What group are they trying to remove

Transamination Delamination Nitrogen removal

What happens to the removed nitrogen from carbon Skeleton in amino acids in proteolysis

Removed nitrogen is toxic and is converted into urea in the liver

Glucogenic amino acids go through waht process

Produce glucose through glycogenesis

What happens to ketogenic amino acids after proteolysis

They become acetyl coA or ketone bodies

Which 2 are not glucogenic amino acids

Anything but leucine and lysine

Waht are ketogenic amino acids 7

Leucine lysine tyrosine Tryptophan Phenylalanine Isoleucine Threonine

Bulk of protein digestion occurs in

Small intestine

Carbon skeleton Amino group Side chain What is the eventual fate of these during protein processing

Carbon skeleton : transported into liver to become glucose or ketone bodies Amino group: go into urea cycle for excretion by kidneys Side chain: basic side chains will go into urea cycle, other

Biochem Chapter 11 Flashcards

(114 cards)