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AQA A LEVEL Biology > Section 1 Biological molecules > Flashcards

Section 1 Biological molecules Flashcards

1
Q

What are the biological molecules?g

A

Molecules made by living organisms

  • Proteins
  • Lipids
  • ATP
  • DNA
  • Water
  • Inorganic ions
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2
Q

What are the functions of carbohydrates?

A

energy source (glucose in respiration)

energy store (starch in plants, glycogen in animals)

structure (cellulose in cell wall of plants)

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3
Q

What are the building blocks for carbohydrates called?

A

Monosaccharides

Examples:

glucose (alpha and beta), galactose, fructose

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4
Q

What is the formula for monosaccharides?

A

C6 H12 O6

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5
Q

What is the difference between alpha and beta glucose?

A

on Carbon 1, alpha glucose has a OH group on the bottom and beta glucose has a OH group on the top

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6
Q

How are monosaccharides joined together?

A

Condensation reaction (loss of water) between 2 OH groups

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7
Q

What is the definition of a condensation reaction?

A

Condensation reactionA chemical reaction in which two molecules combine to form a larger molecule with the elimination of a small molecule (H2O in biological systems).

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8
Q

Bond in carbohydrate?

A

Glycosidic bond between carbon 1 and 4

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9
Q

What is a dissaccharide?

A

Two monosaccharides bound together via a glycosidic bond.

Examples:
glucose + glucose = maltose
glucose + galactose = lactose glucose + fructose = sucrose

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10
Q

What is the formula of a dissaccharide?

A

C12 H22 O11

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11
Q

What is a polymer?

A

A groups of 3 or more monosaccharides bound together by glycosidic bonds.

Examples:

Starch (long chain of alpha glucose) which is energy store in plants

Glycogen (long chain of alpha glucose) which is energy store in animals

Cellulose (long chain of beta glucose) which makes cell wall in plants

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12
Q

How are polymers separated?

A

Hydrolysis (addition of water)

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13
Q

What is starch made of and what are their properties?

A

made from Amylose and Amylopectin

Amylose = long straight chain of alpha-glucose which is coiled

Amylopectin = straight chain of alpha-glucose with side branches (1,6-glycosidic bond)

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14
Q

What is the structure of glycogen?

A

straight chain of alpha-glucose (1,4-glycosidic bond) with side branches (1,6-glycosidic bond)

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15
Q

What are the properties of STARCH & GLYCOGEN that make it a good energy store

A

Insoluble = do not affect water potential of the cell, do not diffuse out of the cell

Coiled/Branched = compact, more can fit into a cell

Branched/Chained = glucose removed from the end

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16
Q

What is the structure of cellulose?

A

β-glucose arranged in a straight chain (each alternative β-glucose is rotated 180 degrees) = cellulose straight chain

many cellulose chains are cross linked by hydrogen bonds to form microfibrils

many microfibrils are cross linked to form marcrofibrils

forms structure of cell wall

strong material (prevents plant cell from bursting or shrinking)

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17
Q

What is the test for starch?

A

Iodine

If present turns blue/black

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18
Q

Test for reducing sugar?

A

Heat with Benedict’s solution

If present turns brick red

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19
Q

Test for non-reducing sugar?

A

heat with benedicts – no change

therefore, add dilute hydrochloric acid (hydrolyses glycosidic bond)

then add sodium hydrogencarbonate (neutralises solution)

heat with benedict - turns brick red

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20
Q

What are the 2 types or forms of proteins

A

Globular and fibrous

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21
Q

What are globular proteins?

A

Soluble proteins with a specific 3D shape

e.g. enzymes, hormones

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22
Q

What are fibrous proteins?

A

strong/insoluble/inflexible material

e.g. collagen and keratin

23
Q

What are the “building blocks” for proteins?

A

Amino acids

24
Q

Structure of an amino acid

A

central carbon, carboxyl group to the right (COOH), amine group to left (NH2), hydrogen above and R group below

25
Q

How do amino acids differ?

A

Different R groups

26
Q

How are amino acids joined together?

A

By condensation reaction between the carboxyl groups causing a peptide bond.

27
Q

Define primary, secondary, tertiary and quaternary.

A

Primary = sequence of AA, polypeptide chain (held by peptide bonds)

Secondary = the primary structure (polypeptide chain) coils to form a helix, held by hydrogen bonds

Tertiary = secondary structure folds again to form final 3d shape, held together by hydrogen/ionic/disulfide bonds

Quaternary = made of more then one polypeptide chain

28
Q

What is the test for proteins?

A

Add biuret solution and if present the solution should turn purple

29
Q

What is an enzyme?

A

A biological catalyst that:

Speeds up reaction times
Lowers the activation energy

30
Q

What makes an enzyme specific?

A

It has a specific active site shape which only binds to complementary substrates to form enzyme substrate complexes (ES complexes).

31
Q

What is the lock and key model?

A

In the lock and key model the active site is rigid and only the exact substrate can bind to the active site to form ES complexes.

32
Q

What is the induced fit model?

A

The active site changes its shape when the substrate binds so it fits it exactly forming an ES complex.

33
Q

Factors that affect enzyme activity

A

Enzyme concentration
Heat (optimum)
Concentration of substrate
PH (optimum)

34
Q

What is a competitive inhibitor?

A

A substance with a similar complementary shape to the substrate making it able to bind to the enzymes active site blocking other substrates from binding.

35
Q

What is a non competitive inhibitor?

A

A substance that binds to another site on the enzyme OTHER THAN the active site which causes the active site to lose its specific shape and preventing ES complexes.

36
Q

What are the three types of lipids?

A

Triglycerides
Phospholipids
Cholesterol

37
Q

What is the structure of a triglyceride?

A

One glycerol with 3 fatty acids attached

38
Q

What is saturated fat?

A

Fat that has no double bonds within the R group

39
Q

What is unsaturated fat?

A

Has carbon double bonds in the R group of the fatty acid.

40
Q

What is the structure of phospholipid?

A

1 glycerol, 2 fatty acids, 1 phosphate group

41
Q

What are nucleic acids?

A

Polymers made from nucleotides

Examples: DNA and RNA

42
Q

What are the building blocks of DNA?

A

Adenine with Thymine and Cytosine with Guanine

43
Q

What is the name of the structure of DNA?

A

Double helix structure

44
Q

What are the properties of the Double helix structure?

A

Double stranded (more stable)
Coil into helix (More compact)
Sugar phosphate back bone (Coding for proteins)
Complementary base pairing (ensures identical copies)

45
Q

What is the process of DNA replication?

A

Occurs in inter phase before mitosis and meiosis, also occurs by semi conservative replication

46
Q

Describe Semi conservative DNA replication

A

DNA helicase breaks hydrogen bonds between the complementary bases

Double strands separate leaving two template strands

DNA polymerase joins the sugar phosphate backbone of the new strand

47
Q

What is RNA and what are the various types?

A

Ribo Nucleic Acid

2 types= mRNA and tRNA

mRNA is a messenger RNA
tRNA is a transfer RNA

48
Q

What is ATP?

A

Adenosine triphosphate

49
Q

What is the structure of ATP?

A

Made from 1 adenosine and 3 phosphates

Formation: ADP + Pi= ATP

50
Q

What makes ATP an effective energy deliverer?

A 
Immediate source (only one bond needs to be broken)
Manageable source (small amount of energy released)
51
Q

Uses of ATP

A 
Protein synthesis
Organelle synthesis
DNA replication
Cell division (mitosis)
Active transport 
Metabolic reactions
Movement
Maintaining temperature (Homeostasis)
52
Q

Roles of water in Biology?

A 
Found in living organisms in:
Cytoplasm
Xylem/phloem
Tissue fluid and blood
Also acts as a habitat for some living organisms.
53
Q

Properties of water

A

Water molecules (H20) are dipolar

54
Q

What are inorganic ions?

A

Salts/minerals
Inorganic meaning not containing carbon

Example: Sodium ions and chloride ions

AQA A LEVEL Biology (8 decks)

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