Chemistry Exam 3: Lipids
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organic substances not soluble in H2O
usually less dense than H20
What are the three main functions of lipids:
1. energy storage - long term energy
2. membrane components - controls entry and exit
- 3. messengers (primary - steriods)
- (secondary - protaglandins and thromboxanes)
What are the four main gropus lipids are classified into?
1. simple (fats and waxes)
4. secondary messengers (Prostaglandins, thromboxanes, leukotrienes)
What is a triglyceride?
Triester of glycerol and long chain carboxylic acids called fatty acids.
inculdes alchohol, fatty acid, ester
Understand the physical state of a triglyceride
Animal Fats - solid at room temp....saturated fat....only single bonds
Plant/Fish - liquid at room temp...unsaturated fat....double bonds...don't stack well...reactive
How are fats hydrogenated?
A carbon-carbon double bond cn be reduced by treating them with H2
and a metal catalyst.
- **Unsaturated fats can be converted to saturated fats by this method**
What does it mean when a fat goes rancid, and what causes it?
When an unsaturated fat goes bad due to exposure of the double bond to O2
Turning some molecules into aldehydes, causing foul smell and taste.
Keep oils refridgerated, in dark bottles, limit time open to air.
What are the two main tpes of complex lipids and how do they differ?
1. Phospholipids - alcohol, fatty acid, phosphate
2. Glycolipids - alcohol, fatty acid, carbohydrate
Know the dynamics of a cell (diagram)
- 1. cholesterol
- 2. Proteins
- 3. Carbohydrate chain
- 4. Glycoprotein
- 5. Glycolipid
How are things transported into the cell?
Think 3 types
Remember....membranes are not static structures.
1. Gap Junction - allows control of passive transport
2. Facilitated transport - a transporter (protein) assists in crossing
3. Active transports - ions through a gradient.
Facilitated and Active are more selective.
Usually controlled by Ca, Na, K
What is the Myelin sheath, and how does it relate to Multiple Sclerosis?
Myelin sheath - lipid coating around the nerve axons.
MS - overtime, the myelin sheath deteriates.
Symptoms - muscle weariness, lack of coordination, vision loss....death
**Demyelinated axons cannot conduct nerve impulses**
Describe what makes a molecule a steriod?
its ring structure.
What is lipid storage diseases?
When some of the enzymes needed to decompose the complex carbs are defective or missing.
Complex carbs accumulate and cause enlarged liver and spleen, mental retardation, blindness, early death.
Ex: Gucher's disease, Krabbe's leukodystrophy, Fabry's disease, Tay-Sachs disease, Niemann-Pick disease.
What is cholesterol?
The most abundant and most important steriod in the human body
How is cholesterol used?
-plasma membrane component (RBC)
-raw material for synthesis of other steriod hormones (sex, adrenolcorticoid) and bile salts
How is cholesterol transported?
LDL - transport of cholesterl starts out as very large VLDL particles...VLDL becomes LDL.
HDL - these transport cholesterol from peripheral tissues to the liver and transfer cholesterol to LDL.
Compare and contrast LDL and HDL
LDL - low density lipoprotein - bad cholesterol - contains 25% protein, 50% cholesterol, larger in diameter
HDL - high density lipoprotein - good cholesterol - contains 33% protein, 30% cholesterol
What is the role of hormones?
What are anabolic steroids? Why are they used? What are the dangers?
-Used to build muscle
-Side effects - acne, liver tumors, facial hair, baldness, deepening of voice, menstrual irregularities.
How does oral contraceptive work?
Tricks the body into thinking its pregnant by using progesterone-like compounds.
Synthetic progesterone + Estradiol compounds (prevents irregularity) = Birth control
What are bile salts and how do they work?
Oxidation products of cholesterol.
Main function: Remove excess cholesterol by breaking it down
Think bile salts is to cholesterol in the sm intestines as detergent is to dirty clothes - form EMULSIONS, which is essential for digestion of fats.
List and Define the 3 Secondary messengers:
- 1. Prostaglandin:
- -stimulates uterine contractions, induces labor, lowers BP, treat asthma, decongestent
- 2. Thromboxanes:
- -induce platelet aggregation
- 3. Leukotrienes:
- -occur in WBC, produce long muscle contractions, can cause asthma attacks and inflammation and fever
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