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Fundamentals Of Biology > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Carbohydrates are made of?

A

Carbon, hydrogen and oxygen

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2
Q

Main groups of carbohydrates?

A

Monosaccharides
Disaccharides
Polysaccharides

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3
Q

General formula of a monosaccharide?

A

(CH2O)n

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4
Q

Monosaccharide structure?

A

(CH2O)n formula
Contain carbonyl group (C=O)
Classified by number of carbons in carbon skeleton (triose, pentose)

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5
Q

Structure of glucose?

A

C6H12O6
Hexose sugar
Straight line or ring structure
In aqueous solution a cylindrical ring is formed, more stable

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6
Q

Difference between Alfa glucose and beta glucose?

A

Alfa has hydroxyl group on bottom

Beta has hydroxyl group on top

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7
Q

Examples of monosaccharide?

A 
Glucose 
Fructose
Galactose
Ribose
Deoxyribose
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8
Q

Maltose is made up of?

A

Two Alfa glucose molecules

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9
Q

Sucrose is made up of?

A

One alfa glucose and one beta fructose

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10
Q

Lactose is made up of?

A

One beta galactose and one Alfa glucose

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11
Q

How do monosaccharides form disaccharides?

A

Condensation reaction forming a glycosidic bond between a hydroxyl group from each molecule

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12
Q

Main polysaccharides?

A

Starch
Cellulose in plants
Glycogen in animals

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13
Q

Structure of starch?

A

Made of many Alfa glucose molecules
Either amylose and amylopectin
Amylose forms helix structure only 1,4 bonds
Amylopectin forms branch structure has 1,4 and 1,6 bonds

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14
Q

How to test for starch?

A

Use iodine
Positive is blue/black blue to iodine molecules fitting down helix structure of amylose forming a polyiodide-starch complex

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15
Q

Structure of glycogen?

A

Similar to amylopectin but more branches
1,6 bonds to form branches
Compact structure
Stored in muscles and liver cells

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16
Q

Structure of cellulose?

A

Made up of beta glucose molecules
1,4 bonds
Molecules have to rotate 180 to bond leading to long chain, hydrogen bonds form between parallel chains giving it strength

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17
Q

How to test for reducing sugars?

A 
Benedicts test 
Reducing sugars donate an electron to copper and become oxidised to a carboxylic acid 
Blue= zero
Green= low
Orange= medium 
Red= high
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18
Q

Reducing vs non- reducing sugar?

A

Reducing contain an aldehyde or ketone group whereas non reducing do not

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19
Q

How to test for non-reducing sugars?

A

Heat with HCL to hydrolyse then as sodium bicarbonate to neutralise before performing benedicts test

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20
Q

Structure of lipids?

A

Contain carbon, hydrogen and oxygen
Insoluble in water, hydrophobic, non-polar, covalent bonds
Triglycerides, cholesterol, steroid, wax and phospholipids
Not true polymers

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21
Q

Structure of triglyceride?

A

Glycerol backbone joined to three fatty acid chains joined together by ester bond formed in a condensation reaction between OH group of glycerol and COOH of fatty acid

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22
Q

Structure of glycerol?

A

An alcohol
Formula of C3H8O3
Contains three hydroxyl groups

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23
Q

Structure of fatty acids?

A

Long chain hydrocarbons contain a carboxylic group (COOH) at one end
General formula is CH3(CH2)nCOOH

24
Q

What is a saturated fatty acid?

A

Contain maximum number of hydrogen atoms so no double bonds
Straight chains
Tend to be solid at room temperature

25
What is an unsaturated fatty acid?
Contain some double carbon bonds as not all spaces are taken by hydrogens Not a straight chain Tend to be liquid at room temperature
26
Phospholipid structure?
Contain glycerol and two fatty acid chains Phosphate group joined to third hydroxyl group and an alcohol group is usually bound to the phosphate group affecting the properties of the phospholipid
27
Why is the phospholipid head hydrophilic?
Contains a polar phosphate group
28
Why is the phospholipid tail hydrophobic?
Fatty acid chains repel water
29
Amphipathic meaning?
A molecule with both hydrophilic and hydrophobic sections
30
Test for lipids?
Emulsion test Add ethanol to sample and shake to dissolve Add to pure water after where a white cloudy emulsion forms Lipids are non-polar so dissolve in ethanol but not water
31
Structure of amino acids?
``` Central alpha carbon An amino group (NH2) A carboxyl group (COOH) A hydrogen atom And an R group (20 different varieties which determines properties) Empirical formula of C2H4NO2+R group Tetrahedral The carbon in the middle is known as a chiral centre ```
32
Types of amino acids?
Polar Non-polar Electrically charged
33
Amino acids in relation to acid/bases?
They can act as both as the NH2 group can gain a hydrogen ion to become positively charged The carboxyl group can lose a hydrogen ion to become negatively charged This means they are amphoteric
34
What is it called when two amino acids join together?
An amide
35
How do amino acids bond together?
By a condensation reaction to form a peptide bond Forms between carboxylic group on one molecule and the amino acid on the other molecule producing water OH and H bond together Peptide bond between the carbon and nitrogen atoms
36
How break a dipeptide to two amino acids?
A hydrolysis reaction | Water is added
37
What are the four levels of protein structure?
Primary Secondary Tertiary Quaternary
38
What is primary structure of proteins?
Sequence of amino acids in polypeptide chain, held by peptide bonds Determined by DNA sequence R groups alternate sides of chain so they do not get in the way of each other
39
What is secondary structure of proteins?
Coiling or pleating of polypeptide chain Hydrogen bonds form between amino acid backbones (H to O) Bonds are individually weak but collectively strong
40
What is tertiary structure of proteins?
Secondary structure folded into a 3D shape Precise 3D shape due to interactions between R-groups (hydrophobic interactions, van der Waal forces, ionic bonds, hydrogen bonds, disulfide bridges) Shape determines function
41
What is quaternary structure of proteins?
Multiple protein subunits held together by weak forces | Arrangement of two or more polypeptide chains held by the same bonds as tertiary structure
42
How to determine protein structure experimentally?
X-ray crystallography | Magnetic resonance spectroscopy
43
Two types of secondary structure?
Alpha helix or beta pleated sheet
44
What is the alpha helix?
Secondary structure Hydrogen bonds between the NH group of one amino acid and the CO group of an amino acid four places ahead Helix is tightly packed therefore van der Waal forces are present R-groups point outwards from helix
45
What is the beta pleated sheet?
Secondary structure Hydrogen bonds form between H and O between neighbouring polypeptide chains Either parallel or non-parallel depending on the directions the polypeptide chains run Anti-parallel structure is more stable as the hydrogen bonds are straight not angled
46
Structure of haemoglobin?
``` 4 polypeptide chains 2 alpha subunits 2 beta subunits 4 haem groups (non-polypeptide) Haem groups contain Fe ions that binds oxygen and a histidine amino acid ```
47
What are enzymes?
Proteins | Biological catalyst that speed up reactions
48
What is the molecule that an enzyme acts in?
Substrate
49
What is the region where substrate bonds called?
Active site
50
Catabolic reactions of enzymes?
Larger substrates into smaller products with the release of energy (exergonic) Chemical bonds of substrate are broken Such as digestion, cellular respiration and detoxification
51
Anabolic reactions of enzymes?
Smaller substrates joined to form larger products, requires energy (endergonic) New chemical bonds formed Such as protein synthesis and polysaccharide synthesis
52
Lock and key model?
1894 Proposed substrates and active sites are complementary Determined by tertiary structure
53
Induced fit model?
Active site not rigid shape but modified by reactions between R group and substrate Increases rate of catalysis Active shape returns to resting shape when product formed
54
How do enzyme speed up reactions?
Lower the activation energy needed allowing reactions to take place at lower temperatures as they are held under stress and in the correct position
55
What is an enzyme cofactors?
Non-protein components that are required to make the enzyme work Can be a permanent prosthetic group or temporarily bound, for example ions, ATP, vitamins or NAD

Fundamentals Of Biology (8 decks)

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