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Biology Paper 1 > TOPIC 1 : BIOLOGICAL MOLECULES > Flashcards

TOPIC 1 : BIOLOGICAL MOLECULES Flashcards

1
Q

State the definition of a Monosaccharide

A

Simple sugar monomer

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2
Q

State the definition of a Disaccharide

A

Two monosaccharides joined together by a glycosidic bond

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3
Q

State the definition of a Polysaccharide

A

Many monosaccharides joined together (more than 2)

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4
Q

Draw the structure of alpha and beta glucose

A

Beta: Hydroxyl group facing up
Alpha: Hydroxyl group facing down

check image

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5
Q

Draw the structure of ribose

A

check image

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6
Q

State the monosaccharides that make up sucrose

A

Alpha glucose and fructose

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7
Q

State the monosaccharides that make up Lactose

A

Alpha glucose and beta galactose

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8
Q

State the monosaccharides that make up Maltose

A

Two alpha glucose

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9
Q

Draw and label the condensation reaction between two alpha glucose molecules.

A

see image

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10
Q

Define Hydrolysis

A

Using water to break glycosidic bonds between subunits

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11
Q

Describe the structure of cellulose

A
  1. Long straight chains that don’t spiral (cellulose is unbrached)
  2. Made up of beta glucose with 1-4 glycosidic bonds where every other beta glucose is inverted for hydrogen bonding to take place.(cross-linking)
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12
Q

Describe the structure of starch

A
  1. Chain of alpha glucose monomers
  2. Made up of two Polysaccharides: Amylose and Amylopectin
  3. Amylopectin is branched with 1-4 and 1-6 glycosidic bonds it is compact with branches so can be hydrolysed quickly so energy can be released quickly
  4. Amylose is an unbrached molecule so is very compact with 1-4 Glycosidic bonds it is coiled and compact so it can store lots of energy in a small amount of space
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13
Q

Describe the structure of Glycogen

A
  1. Made up of alpha glucose monomers
  2. Has both 1-4 and 1-6 glycosidic bonds so it is branched
  3. It is a compact molecule so can store lots of energy but also can be hydrolyzed quicker as it has branches
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14
Q

State the difference between saturated and unsaturated fatty acids.

A
  1. In saturated fatty acids all carbons form single covalent bonds with hydrogen.
  2. In unsaturated fatty acids one or more carbon atoms is linked by a double bond (C=C)
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15
Q

Describe the properties of Saturated lipids

A
  1. Do not have double carbon bonds
  2. Higher melting point
  3. Solid at room temperature
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16
Q

Describe the properties of Unsaturated lipids

A
  1. Do have carbon double bonds
  2. Weaker intermolecular forces
  3. Lower melting pint
  4. Liquid at room temperature
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17
Q

Describe the structure and properties of Fibrous proteins

A
  1. Long straight chain polypeptides
  2. Very little tertiary/quarternary structure mainly secondary structure
  3. Occasional cross-linkages which form microfibres for tensile strength
  4. Insoluble in water
  5. Large molecules
  6. Repeated amino acid sequences
  7. Structural proteins
  8. Hydrophobic on the outside
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18
Q

Describe the structure and properties of Globular proteins

A
  1. Complex tertiary/quaternary structures
  2. Form colloids in water
  3. Uses include hormones, antibodies
  4. Soluble
  5. small molecules
  6. Hydrophillic on the outside
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19
Q

State how the structure of lipids relates to their role in Energy Storage

A

energy is released when triglycerides are oxidised in respiration (mass for mass they release twice as much energy as carbohydrates)

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20
Q

State how the structure of lipids relates to their role in Waterproofing

A

Lipids are hydrophobic therefore they repel water.

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21
Q

State how the structure of lipids relates to their role in Insulation

A

Lipids are poor thermal and ion conductors. Lipids found in adipose tissue under the skin to reduce heat loss. Myelin is a lipid found on neurones to insulate the neurone and speed up neurotransmission

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22
Q

State the difference between a phospholipid and triglyceride.

A

Phospholipids and triglycerides are very similar but for phospholipids one of the fatty acids is replaced with a phosphate group.

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23
Q

State how the structure of a phospholipid related to its function in the cell membrane.

A

The cell membrane is a phospholipid bilayer with hydrophilic head facing out and hydrophobic tails in the middle controlling the exchange of substances

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24
Q

Draw the basic structure of an amino acid.

A

see image

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25
Q

Draw and label the condensation reaction between neighbouring amino acids.

A

see image

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26
Q

Primary structure of protein

A

The order and number sequence of amino acids

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27
Q

secondary structure of protein

A
  1. Shape of the protein.
  2. can either be alpha helix or a beta-pleated sheet
  3. Hydrogen bonds, ionic bonds between charged R groups and disulphide bridges.
28
Q

Tertiary structure of protein

A
  1. 3D folding of secondary structure into a complex shape.

2. Hydrogen bonding, Disulfide bonds and Ionic bonds between amino acids hold these shapes in place

29
Q

Quartenary structure of protein

A

3D arrangement of more than one polypeptide

30
Q

Pyrimadine bases

A

Thymine, Uracil and Cytosine

31
Q

Purine bases

A

Adenine and Guanine

32
Q

Define gene

A

Sequence of bases on a DNA molecule coding for a sequence of amino acids

33
Q

Describe the structure of collagen

A
  1. Collagen is an example of a fibrous protein.
  2. Collagen molecules are made up of three polypeptides which form an alpha triple helix which forms fibrils and strong collagen fibres.
  3. Both hydrogen and covalent bonding occur causing high tensile strength
34
Q

Describe the structure of haemoglobin

A
  1. Haemoglobin is water soluble
  2. It is a globular protein which consists of four polypeptide chains ( two alpha chains and 2 beta chains) and each chain has a prosthetic haem group.
35
Q

What are the three types of point mutations

A

Substitution, insertion, deletion

36
Q

What does it mean by the genetic code being universal

A

all living organisms made up of the same genetic code

37
Q

Non-overlapping

A

Each triplet is discrete/ each base is only used once in a triplet

38
Q

Degenerate

A

More than one triplet can be used for a particular amino acid/stop codes.

39
Q

Triplet code

A

Each amino acid is coded for by three bases

40
Q

Explain how a gene mutation can result in an enzyme unable to break down substances

A
  1. A gene mutation changes the base sequence of the DNA.
  2. Change in amino acid/primary structure of enzyme
  3. Different R groups and different position of bonds
  4. The enzyme folds differently changing the shape of the active site and substrate does not bind
41
Q

Nitrate ions

A

Important in making DNA and amino acids

42
Q

Phosphate ions

A

Important in making ATP and ADP

43
Q

Calcium ions

A

important in making calcium pectate for the middle lamellae

44
Q

Magnesium ions

A

Important in production of chlorophyll

45
Q

Competitive inhibition

A

The inhibitor binds to the active site of the enzyme therefore the substrate can no longer bind - can be overcome by increasing substrate concentration

46
Q

Non-competitive inhibition

A

The inhibitor binds to the allosteric site permanently changing the shape of the active site to the substrate no longer binds

47
Q

End product inhibition

A

When the final product of a series of reactions goes back to inhibit one of the earlier reactions in the series.

48
Q

Describe the structure of an enzyme

A
  1. Globular proteins
  2. Active site
  3. Has charged R groups
49
Q

Properties of Water

A
  1. Polar molecule-as it is polar ionic substances can dissolve in it making water an excellent transport mechanism.
  2. Cohesive-strong hydrogen bonds between water molecules-important for movement of water in xylem
  3. Incompressible-can be used in hydraulic mechanisms
  4. Large latent heat of vaporisation- Evaporation provides cooling effect
  5. High specific heat capacity-Lots of energy needed to raise temperature of water so little temperature fluctuations occur
  6. Maximum density at 4 degrees.This means that ice is less dense than water and floats this creates an insulating layer increasing survival of organisms in water.
50
Q

Name 4 greenhouse gases

A
  1. Methane
  2. Water Vapour
  3. Nitrous Oxide
  4. Carbon Dioxide
51
Q

Describe the structure of Lipids

A
  1. Contains ONLY carbon ,hydrogen and oxygen

2. Made up of fatty acids and glycerol joined together by ester bonds.

52
Q

Describe the structure of a cell membrane.

A
  1. Cell membrane is made up of a phosphate lipid bilayer
  2. The phosphate head faces outwards with the fatty tails inwards as the phosphate head is hydrophilic and the tails are hydrophobic
  3. The cell membrane also has carrier proteins which are integral proteins found intrinsically
  4. The cell membrane also has glycoproteins which has the function of cell identification
53
Q

Explain the term recessive allele

A
  1. Both alleles have to be present in order for the recessive phenotype to be expressed.
  2. Alleles are different forms of a gene with the same locus
54
Q

Describe the function of a neutrophile in defence

A

They engulf and breakdown bacteria and microbes (phagocytosis)

55
Q

Explain how the structure of the membrane controls the transport of polar molecules

A
  1. The cell membrane is a phospholipid bilayer
  2. Phosphate head is hydrophilic whereas the fatty tails are hydrophobic
  3. Polar molecules are charged and are hydrophilic and water soluble so they do not pass through the hydrophobic centre
  4. They pass the membrane through channel carrier proteins
56
Q

Draw and label the structure of DNA

A

See Image

57
Q

Describe the process of semi-conservative replication.

A
  1. Helicase breaks H bonds between nucleotides separating the two strands
  2. Free complimentary nucleotides form H bonds with exposed nucleotides on leading and lagging strand
  3. DNA polymerase catalyses the condensation reaction between adjacent nucleotides (5’ to 3’ direction) forming phosphodiester bonds
  4. Leading strand is continuous and lagging strand forms Ogazaki fragments which are joined with ligase as DNA polymerase catalyses the reactions between nucelotides in the 3’ to 5’ direction.
  5. DNA ligase joins ogazaki fragments
  6. Each molecule contains a new strand and one from the original parents strand
58
Q

Describe the difference between a DNA and RNA molecule.

A
  1. DNA has Thymine; RNA has uracil
  2. DNA has a deoxyribose sugar; RNA has a ribose sugar
  3. DNA is a double helix; RNA is usually a single strand
59
Q

Draw and label the structure of tRNA

A

See Image

60
Q

Describe the process of transcription.

A
  1. H bond between are broken and DNA is partially separated
  2. Free complimentary RNA nucleotides form H bonds with exposed nucleotides on the antisense strand
  3. RNA polymerase catalyses the condensation reaction between RNA nucleotides forming phosphodiester bonds
  4. The complete mRNA stand becomes detached from the antisense strand and the RNA leave the nucleus through nuclear pores.
61
Q

Describe the process of translation.

A
  1. mRNA binds to the ribosomes in the cytoplasm and is read codon at a time (each codon codes for 1 amino acid)
  2. tRNA is activated in the cytoplasm where is binds to amino acid

· Activated tRNA with complimentary anticodon forms temporary H bonds with codon

  1. Next tRNA binds at ribosome and peptide bonds form between adjacent amino acids
  2. Free tRNA released into the cytoplasm to be re-used
  3. Process continues until a stop codon is reached then polypeptide chain is released from the ribosome
62
Q

Explain the nature of the genetic code.

A

Degenerate – some amino acids are coded for by more than one codon

· Non-Overlapping – each nucleotide is included in only 1 codon

· Universal – all living organisms made up of the same genetic code

63
Q

Explain the effects of point mutations

A
  1. Deletion and substitution result in frame shift – each nucleotide moved up/down by 1
  2. Frameshift moves the stop codon to produce shorter or longer polypeptide chain.
  3. Substitution may or may not affect the protein due to the genetic code being degenerate
64
Q

Describe the induced fit model of enzyme activity

A
  1. Active site is roughly complimentary to the substrate shape
  2. Only once substrate binds to the active site does it becoming truly complimentary
65
Q

Define the term denature

A

Bonds holding the enzyme protein together break, proteins unfold, active site changes shape, substrate no longer binds

Biology Paper 1 (17 decks)

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