Chapter (4) Chemical Composition Of Cells Flashcards

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1
Q

What does living organisms consist of?

A

⭐️💛* Living organisms consist of organic compounds that contain 6 elements of life: CHONPS
( they contain carbon atoms covalently bonded to CHONPS)

⭐️💛* All living things are made up of four classes of large biological molecules : Carbohydrates, lipids , proteins , and nucleic acids

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2
Q

Three of four classes of life’s organic molecules are :

A

Polymers

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3
Q

Are lipids polymers ?? 🫒

A

→ the forth class, lipids, are not polymers nor macromolecules.🤍🍰

→ fats & oils are not polymers but contain glycerol and fatty acids. They are repeated units but they are not the same monomers, also not big enough, so they aren’t considered as polymers.🤍🍰

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4
Q

Starch is a polymer of:

A

Glucose.

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5
Q

Proteins are polymers of:

A

Amino acids

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6
Q

What are reagents??

A

Reagents are chemicals that will be used to test for the presence of certain molecules.

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7
Q

Principle of reagents:

A

If a color change is observed, the test is positive, indicating that a particular molecule is present. If color change is not observed, the test is negative and the molecule is not present.

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8
Q

What is the definition of organic compounds?

A

Compounds that contain carbon atoms, covalently bonded to oxygen, nitrogen, hydrogen, sulfur, or phosphorus

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9
Q

What are the large organic molecules or macromolecules or polymers?

A

They are molecules consisting of small molecules (monomers), joined in acid sequence 

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10
Q

What are the monomers of starch or glycogen or cellulose?

A

Glucose

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11
Q

What are the monomers of nucleic acids?

A

Nucleotides

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12
Q

Monomer of carbohydrates

A

monosaccharides

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13
Q

The carbohydrate can be monomers or polymers

A

A) Monosaccharides: consist of simple sugars (the simplest carbohydrate) for example: glucose ,galactose , fructose

B) disaccharide: or double sugars, consisting of two monosaccharides, joined by a covalent bond . For example.: sucrose, lactose ,maltose .

C) polysaccharides : are composed of many sugar building blocks, and they are considered as a macromolecules, for example, starch , cellulose , glycogen.

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14
Q

Depending on the location of the carbonyl group, monosaccharide, classified as:

A

1) Aldose : aldehyde sugar
2) ketose : ketone sugar

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15
Q

General information about lipids:

A

= they are generally not big enough to be considered macromolecules.

= lipids share an important trait.They are hydrophobic.

= they consist mostly of hydrocarbons, which form non-polar covalent bonds.

= there are three types of lipids that are most biologically important : Fats, phospholipids , and steroids.

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16
Q

What are fats phospholipid consist of?

A

1- Fats (triacylglycerol or triglyceride) constructed of one glycerol and three fatty acids.

2- phospholipids are one glycerol and two fatty acid and one phosphate group.

3- steroids are four fused rings.

17
Q

General information about protein

A

**. Proteins are constructed from the same set of 20 amino acids.
**. The bond between amino acids is called bide bond.
**. Polypeptides Range in length from a few amino acid to 1000 or more.
**. Each specific polypeptide has a linear sequence amino acids.

18
Q

What are vitamins :

A

Vitamin are complex chemical compounds of high molecular weight that are essential to normal growth a health maintenance.

For example:
🍋 vitamin C [ascorbic acid ] 🍋

19
Q

Negative tests:

A

If the color change is not observed, the test is negative and the molecule is not present.

20
Q

Positive test:

A

If a color change is observed, the test is positive, indicating that a particular molecule is present.

21
Q

Control sample:

A

A distilled water sample that will go through all the steps of the experiment and give a negative test result.

22
Q

Is there a test for all types of carbohydrates??

A

Carbohydrates comprise a wide variety of monomers and polymers, and no single test can be used as a marker for all of them.

23
Q

Benedict test is used for :

A
  • It’s a blue chemical reagent which is made up of a complex mixture of chemicals including copper (ii) sulfate.
  • it’s used to test the presence of glucose (reducing sugar)
  • when a reaction occurs between reducing sugar & a Benedict reagent it produces red ppt.
24
Q

Write the chemical reaction of Benedict reagent & reducing sugars

A

Guycose+ CuSO4 → gluconic acid+ Cu2O ( red ppt)

25
Q

How can the Benedict test show the amount of reducing sugar present in the solution ??

A

The test shows the amount of reducing sugars present in the solution through the color change :-
🍎 if the color is blue, that means no reaction- there is no reducing sugars due to the not changing in the color.
🍎 A reaction with a small amount of reducing sugar present in the solution will turn the color to green as an indicator of traces of reducing sugar.
🍎 when it’s moderate, the color is orange red ppt.
🍎 when the color is brick red precipitate. There is large amount of reducing sugars.

26
Q

What does it mean when the color of the solution of Benedict turns from blue to green / yellow??

A
  • There is traces of reducing sugar.
27
Q

What does it mean when therefor of Benedict turns to Orange!!!

A

Moderate amount of reducing sugars.

28
Q

What does it mean when the color of the Benedict solution turns to brick-red ppt??

A

It indicates large amount of reducing sugars.

29
Q

What would we do to convert non reducing sugars (sucrose) to a reducing sugars???

A

Breakdown sucrose into glucose and fructose monomers (reducing sugars) by acid hydrolysis (hcl)

—————
Note :
The steps are :
* Add HCl on sucrose and boil it to speed up the hydrolysis of the sucrose into its monomers.

  • Then after boiling for 5 min , we are now sure that the sucrose is converted into its monomers.
  • Now , to perform the Benedict test, it’s better to get rid of the acidic environment by adding NaOH to neutralize the HCl.
  • Now add Benedict solution.
30
Q

What is the lugols test ?

A

The test is used to distinguish certain polysaccharides such as starch,
glycogen, cellulose from other Mono-, di-, and polysacchrides.

The original color of lugols test is yellow

The negative test is brown / yellow color , and the test positive is blue / purple color

31
Q

How does starch interact with lugols test ?

A

*Starch is a polymer of glucose

  • the chains are coiled up in a
    particular way so it can interact with iodine molecules in Lugol’s solution
  • give a distinctive blue- black colour.
32
Q

Do other polymers interact with lugols test as the starch do?

A

**Other polymers even those of glucose, lack the precise coiled structure of starch and do not give the blue colour. (( so they don’t give the same result of starch , but not the negative result also))

** violet-brown to red-brown colour is given by cellulose.

** A red colour is given by glycogen.

33
Q

When potato juice give a positive result that means: -

A

I it contains starch // cellulose but it is impossible to have glycogen

34
Q

Define Emulicification

A

The mechanical breakdown and dispersal of large globules into smaller droplets.

35
Q

What is the emulsifier and how can it perform mechanical breakdown of the fat ?

A

🍓 An emulsifier contains molecules with polar and nonpolar ends.
🍓When the nonpolar ends are attached to the nonpolar fat, the polar ends are exposed.
🍓 Since the polar ends are soluble in water, the fat is dispersed.

36
Q

Why is sucrose considered non reducing sugar?

A

It cannot convert to an open chain form of an aldehyde group.