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A Level Biology > Chapter 3.1 (biological Molecules) > Flashcards

Chapter 3.1 (biological Molecules) Flashcards

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1
Q

Monosaccharides

A

The monomers from which learner carbs are made

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2
Q

Disaccharides

A

Two monosaccharides joined together by a glycosidic bond

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3
Q

Polysaccharides

A

A chain of monosaccharides joined together by glycosidic bonds

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4
Q

Glycosidic bonds

A

Covalent bonds formed between monosaccharides

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5
Q

Condensation reaction

A

A reaction were water is removed to form a bond

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6
Q

Hydrolysis reaction

A

A reaction where water is added to break a bond

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7
Q

Give some examples of monosaccharides?

A

Glucose (alpha & beta), galactose, fructose

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8
Q

Give some examples of diasaccharides?

A

Sucrose, (fructose + glucose)
lactose, (Galactose + glucose)
maltose (Glucose + glucose)

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9
Q

What are monomers?

A

Smaller units fro which larger molecules are made

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10
Q

What are polymers?

A

Molecules made from a large number of monomers joined together

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11
Q

What are some examples of monomers?

A

Monosaccharides
Amino acids
Nucleoitides

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12
Q

Draw an alpha and beta glucose

A

See notes

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13
Q

What are types of polysaccharides?

A

Glycogen
Starch (amylose & amylopectin)
Cellulose

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14
Q

What is the structure of glycogen?

A

-alpha glucose
- 1,4 and 1,6 glycosidic bonds
- branched chains
- coils into a helix (held by H bonds)

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15
Q

What is the structure of amylose (starch)

A
  • alpha glucose
  • 1,4 glycosidic bonds
  • coils into a helix (held by H bonds)
  • unbranched
  • straight
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16
Q

What is the structure of amylopectin (starch)

A
  • alpha glucose
  • 1,4 and 1,6 glycosidic bonds
  • branched
  • coils into a helix (held by H bonds)
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17
Q

What is the structure of cellulose?

A
  • beta glucose
  • 1,4 glycosidic bonds (alternate B glucose flipped)
  • straight
  • unbranched chain
  • individual chains held by H bonds adjacently (to from microfibrils which bind to form fibres)
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18
Q

What properties of starch and glucose make them good storage molecules?

A

Compact
- don’t take up a lot of space
Insoluble
- no water potential change
No osmotic effect
Easily hydrolysed
- releases glucose

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19
Q

What properties of cellulose give them structural function?

A

High tensile strength
- resistant to pull force
Insoluble
- no water potential change
Flexible
- resistant to turgor pressure
Resistant to digestion

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20
Q

What is the biochemical test for carbs ?

A

Use Benedict solution (reducing/ non reducing sugars)
Use iodine (for starch )

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21
Q

Bond between amino acids for protein formation?

A

Peptide bonds
(Formed during condensation reactions between amino acids)

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22
Q

Def of dipeptide?

A

2 amino acids covalently joined by a peptide bond (formed during condensation reaction of two amino acids)

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23
Q

Def of polypeptide?

A

A long chain of amino acids
(joined during condensation reactions)

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24
Q

Primary structure of proteins defines?

A

The order of amino acids in polypeptide chains

E.g.
A-x-g-n Is different from. X-g-a-n

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25
Q

Secondary structure of proteins defines?

A

The type of folding with the hydrogen (H) bonds

It will be determined by the different R groups

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26
Q

Two types of hydrogen bond folding in proteins?

A

Alpha- helix. Or. Beta- pleated sheets
[coil]. [zig zags on top of each other]

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27
Q

Names of the stages of protein structure?

A
  • primary
  • secondary
  • tertiary
  • quaternary
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28
Q

Types of bonds in Tertiary and Quaternary structure of proteins?

A

1) Disulfide Bridges
2) ionic bonds
3) hydrophobic interaction
4) H bonds

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29
Q

Describe disulfide bridges (protein structure)?

A

Strong covalent bonds form between two sulfur atoms
(E.g. between 2 cysteines - type of amino acids with sulfur)

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30
Q

Describe ionic bond (protein structure)?

A

Form between oppositely charged R groups

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31
Q

Describe Hydrophobic interactions (protein structure)?

A

Form between non-polar R groups on inside of molecule (to shield them from water)

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32
Q

difference between tertiary structure and Quaternary structure (proteins)?

A

Tertiary
> final 3D shape of folded polypeptide chain (involving the 4 types of bonding)

Quaternary
> final 3D shape of the folded proteins formed from MORE THAN ONE polypeptide chain

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33
Q

Test for proteins?

A

Add biuret solution (blue) [sodium hydroxide and copper sulphate]
Leave for 2 minutes
Observe sample if protein present it will turn lilac

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34
Q

2 types of lipids?

A

Triglycerides & phospholipids

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35
Q

Function of lipids in the body?

A

Water proofing
Energy store
Thermal insulation
Protection
Membrane structure (phospholipids)
Electrical insulation
Steroid hormones

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36
Q

Structure of triglycerides?

A

1 glycerol joined to 3 fatty acids through condensation reactions to form ester bonds

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37
Q

Type of bonds in lipids?

A

Ester bonds

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38
Q

Difference between unsaturated and saturate triglycerides?

A

Saturated
-no double bond
- longer
- high melting points as shape can pack the close together

Unsaturated
- double bonds present
- shorter
- low melting points as shape makes them not closely pack together

39
Q

Structure and function of phospholipid?

A

1 phosphate group (head), 1 glycerol (body), 2 fatty acid (tails)

They double up to form a bilayer to make plasma membranes

With the phosphate groups( - charge) being water soluble on the outside and the fatty acids (non-polar) water repelling being inside.

40
Q

Test for sucrose (non-reducing sugar)?

A
  1. Test for reducing sugar by adding 3cm^3 of Benedict solution and heat in water bath set above 90oc
  2. If this is negative boil the sample in HCl (acid) to hydrolyse the glycosidic bond
  3. Neutralise with NaHCo2)
  4. Boil in Benedict solution again
41
Q

Food Test for lipids?

A
  1. Dissolve sample in ethanol (alcohol) and Mix well
  2. Pour the alcohol mixture into water
  3. If lipids present water turns cloudy (emulsion formed)
    If lipids absent water stays clear (no emulsion)
42
Q

Globular proteins vs fibrous proteins

A

Globular proteins
- roughly spherical in shape
- functional roles
- wide range of R groups
E.g. haemoglobin, enzymes, insulin

Fibrous proteins
- long strand shape
- structural roles
- limited R groups
E.g collagen, fibrin, keratin

43
Q

Why are enzymes specific (protein structure)?

A

The active site of enzymes has a unique shape which is complementary to a specific substrate allowing it to bind and form a enzyme-substrate complex.
The active site is created by R groups of amino acids brought together when the polypeptide folds into its secondary/tertiary structure.
Each polypeptide will fold into a specific shape because of its primary structure so other molecules don’t have the correct shape to fit into the active site

44
Q

Describe 2 enzyme action models?

A

1) lock and Key model
- shape of substrate and enzyme’s active site are complementary

2) Induced fit
- substrate binds to the enzyme’s active site, then the active site changes shape to accommodate the substrate

45
Q

Factors that effect enzyme activity?
+draw graphs for each

A

Enzyme concentration
Substrate concentration
Temperature
pH
(For graphs see notes)

46
Q

Names of the 3 additional non-protein molecules/ions required for some enzymes to catalysis?

A

Coenzymes
Cofactors
Prosthetic groups

47
Q

Describe coenzymes? (Enzymes)

A
  • are organic molecules required by certain enzymes to carry out catalysis

Coenzymes bind to active site & participate in catalysis (not the substrate though)
(See notes for photo)

48
Q

Describe cofactors? (Enzymes)

A

-cofactors are inorganic ions needed to increase the rate of catalysis

  • cofactors interact with substrate at active site but aren’t permanently attached
    (See notes for photo)
49
Q

Describe prosthetic groups? (Enzymes)

A
  • organic ( vitamins, sugars,etc) or inorganic (ions)
  • in enzymes prosthetic groups are needed to catalysis by being involved in active site
    (Alway attached)
    (See notes for photo)
50
Q

Describe role and effect of competitive inhibitors on enzymes?
(Draw graph to show)

A

Competitive inhibitors have similar shape to substrate, bind to active site preventing formation of enzyme-substrate complexes

(Effect is reversible by adding more substrates)
(See notes for graph)

51
Q

Describe role and effect of non-competitive inhibitors on enzymes?
(Draw graph to show)

A

Non-competitive inhibitors bind to a different part of enzyme (allosteric site)
Causes its shape of active site to change

(Irreversible effect)
(See notes for graph)

52
Q

structural differences of phospholipids and triglycerides

A
  • phospholipids contain a phosphate group
  • phospholipids contain only 2 fatty acid chains compared with 3
53
Q

Def of pentose sugar & hexose sugar

A

Pentose
- a sugar molecule that contains 5 carbon atoms
(E.g deoxyribose, ribose)

Hexose
- a sugar molecule that contains 6 carbon atoms
(Glucose, galactose, fructose

54
Q

Factors that effect enzyme activity?

A

Concentration of:
- enzymes
-substrates
- competitive/ non competitive inhibitors

-pH
- temperatraure

55
Q

Def of nucleotide?

A

A monomer used to build DNA & RNA (also ATP)

56
Q

Structure of ATP?

A

ATP- a nucleotide derivative formed of:
Adenine (nitrogenous base)
Ribose (pentose sugar)
3 phosphate groups

57
Q

How is ATP formed?

A

phosphorylation
ATP is synthesised by adding inorganic phosphate group to ADP

ADP is like ATP but with only 2 phosphate groups

(This reaction is catalysed by the enzyme ATP synthase during photosynthesis or respiration)

58
Q

Cellular processes that require energy

A
  • synthesis of macromolecules
  • growth/cell division
  • active transport
  • generation of nerve impulses/ muscle contractions
59
Q

Enzyme that catalyse formation of ATP

A

ATP synthases

60
Q

Where is ATP synthesised?
(In animal and plants)

A

Animal
- inner membrane of mitochondria (cristae)
Plant
- thylakoid membrane of chloroplast

61
Q

Enzyme involved in hydrolysis of ATP

A

ATP hydrolase

62
Q

Role of DNA and RNA?

A

In cells
DNA holds genetic information
RNA transfers this info from DNA to ribosomes to synthesise proteins

63
Q

Ribosomes formed from?

A

RNA and Proteins

64
Q

General structure of a nucleotide?

A

A pentose sugar
A nitrogenous organic base
A phosphate group

65
Q

4 possible bases of DNA?

A

Adenine (A)
Guanine (G)
Thymine (T)
Cytosine (C)

66
Q

Structure of DNA molecule?

A

A phosphate group
A deoxyribose (pentose sugar)
Nitrogenous base (A/C/T/G)

67
Q

4 possible bases of RNA?

A

Adenine (A)
Guanine (G)
Uracil (U)
Cytosine (C)

68
Q

Structure of RNA molecule?

A

A phosphate group
Ribose sugar (pentose)
Nitrogenous base (A/C/G/U)

69
Q

Bond between 2 nucleotides?

A

A phosphodiester bond forms between nucleotides during condensation reaction

70
Q

In DNA double helix how are polynucleotide chains held together?

A

By Hydrogen bonds between complementary base pairs

A - T. (2 bonds )
G-C. (3 bonds)

71
Q

Hydrolysis of ATP forms?

A

ADP and inorganic phosphate group

(The hydrolysis is catalysed by the enzyme ATP hydrolase and can be coupled to energy-requiring reactions within the cell)

72
Q

What happens to inorganic phosphate released during hydrolysis of ATP?

A

Either
- recycled back into a molecule of ATP
- used to phosphorylate other compounds (often making them more reactive)

73
Q

Features of ATP that make it great at its function?

A

-Releases enough energy to be useful but not too much to damage cells/ tissue
- exists as a stable molecule
- can be recycled
- hydrolysed easily and quickly
- soluble and moves easily within cell

74
Q

Role of enzyme DNA helicase?

A

In DNA replication it
Breaks H bonds between complemetary bases (unzips DNA molecule)

75
Q

Role of DNA polymerase?

A

In DNA replication
It forms phosphodiester bonds between phosphate group and deoxyribose in condensation reactions

76
Q

Process of DNA replication?

A

1) ** DNA helicase ** unzips DNA molecule breaks H bonds between the 2 strands
2) each strand acts as a template for the synthesis of new DNA strands
3) ‘free’ DNA nucleotides hydrogen bond with complementary nucleotides on both strands (following base paring rules)
4) ** DNA polymerase ** condenses nucleotides together by forming phosphodiester bonds to from polynucleotide strand (containing 1 old chain and 1 parent chain)

77
Q

Why is DNA replication semi-conservative?

A

After DNA replication each DNA helix consists of one of original ‘parent’ strands and one newly synthesised ‘daughter’ strands.

78
Q

mRNA
(Formed where)
(Structure)
(Involved in?)

A

Formed: nucleus
Single chain helix
Short life

Involved in protein synthesis (transcription & translation)

79
Q

tRNA
(Formed where)
(Structure)
(Involved in?)

A

Formed: nucleolus
Single chain folded in clover shape
Different types - anticodon three bases determine amino acid

Involved in protein synthesis (translation )

80
Q

Def of cohesion

A

Water molecules ‘sticking together’ due to H bonds between molecules

81
Q

Def of adhesion

A

Water molecules ‘sticking’ to other molecules on the surface due to H bonds

82
Q

Draw water molecules with bonds between molecules

A

See notes

83
Q

Role of water due to high specific heat capacity

A

Water acts as buffer against temperatures variations on aquatic environments

84
Q

Role of water as a thermoregulation

A

Due to high latent heat of vaporisation
Plants and animals can lose excess heat by evaporating water from their body surface

85
Q

Function of water

A
  • hydrolysis reactions
  • solvents to remove waste/ dissolve substances
  • all for thermoregualtion
  • creates habitat
  • controls aquatic environments temperature
86
Q

Other than being smaller, give two ways in which prokaryotic DNA is different from eukaryotic DNA.

A
  1. Circular rather than linear
  2. Not associated with proteins
  3. No non-coding regions
87
Q
  • Humans and grasshoppers have very similar percentages of each base in their DNA but they are very different organisms.
    Use your knowledge of DNA structure and function to explain how this is possible.*
A

Different genes are in different order so different proteins are produced

88
Q

The events that take place during interphase and mitosis lead to the production of two genetically identical cells. Explain how.

A
  1. In interphase DNA is replicated
  2. Complementary base parings means
  3. 2 identical chromatids are produced
  4. Chromatids are separated to opposite poles of cell
89
Q
  • during dna replication DNA polymerase molecules work in opposite directions reforming stands explain why the arrows point in opposite directions.*
A
  1. DNA strands run antiparallel
    2.shape of the nucleotides is different
  2. Enzymes have specific shaped active sites
  3. Only the 3’ end can bind to the enzymes active site
90
Q

HSV infects nerve cells in the face (line 1). Explain why it infects only nerve cells.

A

Outside if virus has proteins with complementary shapes to receptors found only on membrane of nerve cells

91
Q

HSV can remain inactive inside the body for years (lines 2–3). Explain why this virus can be described as inactive.

A

No more nerve cells are infected
Virus isn’t actively replicating

92
Q

The scientists concluded that production of this microRNA allows HSV to remain in the body for years (lines 10–12).
Explain how this microRNA allows HSV to remain in the body for years.

A

MicroRNA binds by specific base paring to mRNA
so prevents mRNA being read by ribosome so prevents production of proteins
leading to cell death

93
Q

Describe how substances move across cell surface membranes by facilitated diffusion

A

1) substances bind to carrier proteins
2) proteins specific to the substance
3) substances move down contraction gradient

94
Q

describe how the result from colorimeter can identify the fruit juice containing the higher sugar content

A

Higher absorbable means more sugar is present in juice

A Level Biology (10 decks)

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