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Module 2 > Chapter 3- Biological Molecules > Flashcards

Chapter 3- Biological Molecules Flashcards

(59 cards)

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1
Q

Give the basic bonding rules of the first four elements

A

HONC
Hydrogen (1 bond)
Oxygen (2 bonds)
Nitrogen (3 bonds)
Carbon (4 bonds)

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2
Q

Why is life often referred to as carbon based?

A

Carbon is the backbone of most biological molecules

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3
Q

Define an ion

A

An atom or molecule where the number of electrons is not equal to the number of protons

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4
Q

What are the two forms of ions

A

Cations- Ions with a net positive charge
Anions - Ions with a net negative charge

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5
Q

List the elements present in carbohydrates

A

Carbon, Hydrogen, Oxygen

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6
Q

List the elements present in Lipids

A

carbon, hydrogen and oxygen

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7
Q

List the elements present in proteins

A

Carbon, hydrogen, oxygen nitrogen and sulphur

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8
Q

List the elements present in nucleic acids

A

Carbon, hydrogen, oxygen, nitrogen and phosphorus

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9
Q

What causes polarity in water molecules

A

Although water molecules have no net charge, due to the uneven distribution of electrons, one side (pole) is slightly more negatively charged and the other slightly more positive

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10
Q

If a molecule contains a hydroxyl group, what property is it likely to have?

A

Polarity

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11
Q

List the basic properties of water

A

Cohesive and Adhesive
Solvent
Coolant
Very stable temperature
High boiling point
Less dense in a frozen state

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12
Q

Describe the difference between the two structural variations of glucose

A

Beta glucose has an inverse hydroxyl group compared to alpha glucose

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13
Q

How is a glycosidic bond formed?

A

A condensation reaction

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14
Q

Name three disaccharides and their monomers

A

Two alpha glucose - maltose
fructose and glucose - sucrose
galactose and glucose - lactose

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15
Q

What are the two components of starch and their compositions?

A

Amylose - alpha glucose bonded 1-4 glycosidic bonds
Amylopectin- alpha glucose bonded 1-4 but also branching 1-6 every 25 subunits

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16
Q

What is the difference between amylopectin and glycogen?

A

Glycogen has branching subunits more frequently (every 10 units) than amylopectin (every 25 units) because animals need to conserve more energy than plants

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17
Q

Why do beta glucose form straight chain molecules?

A

Because of the positioning of the hydroxyl group on carbon 1, every other monosaccharide has to be flipped upside down, meaning the angle of the bonds is different to alpha glusose and the molecule is straight

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18
Q

Name the order of sizes of cellulose fibres

A

Cellulose molecules
Microfibrils
Macro fibrils
Cellulose fibres (cell walls, ect)

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19
Q

Describe the test used for reducing sugars

A

Benedict’s test-
Place the sample in a boiling tube, add an equal volume of Benedict’s reagent and heat gently for 5 minutes

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20
Q

What happens in Benedict’s reaction and how do we read the results?

A

Reducing sugars react with copper ions from BR. Adding electrons to these copper ions turns them brick red. The more reducing sugar present the stronger the concentration of brick red precipitate

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21
Q

How do we change Benedict’s test to test for non reducing sugars?

A

Boil the sample first with a dilute hydrochloric acid

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22
Q

What is the test for starch?

A

Iodine changing colour from yellow brown to black

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23
Q

Why are lipids not considered polymers?

A

Because they are not made from repeating units- instead we call them macromolecules

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24
Q

What is the reaction forming bonds between fatty acids and glycerols and what are they called?

Study These Flashcards
A

Ester bonds formed by esterification

25
What is the difference between saturated and unsaturated fatty acids?
Saturated- fully saturated with hydrogen molecules, no double bonds Unsaturated- not fully saturated, double bonds lead to kinks in structure
26
Describe the structure of cholesterol
A small hydrophilic hydroxyl group and a large hydrophobic body
27
What is the test used to identify lipids?
Emulsion test- sample is mixed with ethanol and shaken vigorously. If a white emulsion forms, the test is positive
28
What are trans fats?
Unsaturated lipids that have reversed double bonds commonly linked to health issues like heart disease
29
What is the ratio of different amino acids commonly found in cells?
9 essential- only obtained from diet 5 non essential - our body can make them using other amino acids 6 conditionally essential- only needed by children
30
Where does the bond form on a protein?
between the amine group and the carboxyl group (hydrogen and hydroxyl)
31
How do we calculate the Rf value?
Distance travelled by component/ distance travelled by solvent
32
What are the two types of secondary structure in proteins?
Alpha helix or beta pleated sheets
33
Which test is used to identify proteins?
Biuret test- a mixture of alkali and copper solution turns the solution from blue to violet in the presence of proteins
34
Give an example of a globular protein
Insulin- a hormone involved in blood glucose concentration
35
Give an example of a conjugated protein
Haemoglobin- made from four polypeptides and four haem (Fe2+) groups Catalase- uses prosthetic groups to break down hydrogen peroxide
36
Describe the structure of keratin, elastin and collagen
Keratin- high proportion of disulfide bonds Elastin- links many troposin together to make a large insoluble molecule, stabilised by cross linkage Collagen- three polypeptide chains wound together in a triple helix
37
Name the two pyrimadines
Cytosine and Thymine
38
Name the two purines
Adenine and guanine
39
Which molecule would the ‘3 end of a nucleic acid end in?
A pentose monosaccharide
40
What are the bonds called that form the backbone of a nucleic acid?
Phosphodiester bonds
41
How is DNA arranged?
Antiparallel- each strand has a phosphate group at one end and a hydroxyl at the other, arranged so they run in opposite directions
42
What are the complementary base pairs?
Thymine and Adenine Cytosine and Guanine In RNA molecules uracil replaces thymine
43
How many hydrogen bonds form between each complementary base pair?
Three between cytosine and guanine two between adenine and thymine
44
What is the importance of RNA?
RNA molecules are small enough to leave the nucleus and travel to ribosomes After protein synthesis they are degraded in the cytoplasm
45
What is the name of the enzyme that ‘unzips’ a DNA molecule during semi-conservative replication?
DNA helicase
46
What is the name of the enzyme that forms new phosphodiester bonds during semi conservative replication?
DNA polymerase
47
Describe the difference between continuous and discontinuous replication
Because DNA polymerase can only attach to the hydroxyl group, the strand that is unzipped from the phosphate group has to work backwards across the strand- meaning DNA is produced in fragments (Okazaki fragments)
48
What does one codon produce?
One codon (a triplet of three bases) codes for one amino acid
49
Define a gene
A section of DNA containing all the codons needed to produce a single protein
50
What does degenerate code mean?
When one amino acid can be coded for by many codons
51
What is the name of the start codon?
Methionine
52
Which strand is called the sense strand?
5’ to 3’
53
Which strand is used as a template during transcription?
The antisense strand (3’ to 5’)
54
What are the main types of RNA and where are they used during transcription and translation?
m (messenger) RNA- produced during transcription using the antisense strand as a template r (ribosomal) RNA- the RNA making up the subunits of the ribosome t (transfer) RNA- composed of a strand of RNA folded so that three bases (anticodon) are exposed
55
What are the three reasons cells require energy?
Synthesis Transport Movement
56
What is the difference between ATP and an adenine nucleotide?
ATP has three phosphate groups
57
How does ATP release energy?
A small amount of energy is needed to break the bond holding the last phosphate, however the yield of energy is very high when this phosphate undergoes other reactions
58
Why is ATP not a good long term energy store?
Because of the instability of phosphate bonds
59
What happens during respiration?
The energy released in the breakdown of large stable storage molecules, (carbohydrates, lipids) is used to phosphorylate ADP into ATP

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