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Bio SL > Topic 2- molecular biology > Flashcards

Topic 2- molecular biology Flashcards

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Biology 101 flashcards
1
Q

Draw water molecule

A

Labels and clear arrow showing hydrogen bond

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2
Q

Polar

A

Uneven distribution of molecule charge

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3
Q

Hydrogen bond

A

Bond formed between the - charge from the oxygen of one water molecule and the + from the hydrogen atom of another water molecule

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4
Q

3 properties of water

A
  1. Water is liquid
  2. Water is a solvent
  3. Specific heat capacity of water is very high & remains relatively stable

Water also has high heat of vaporisation and fusion

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5
Q

Cohesion

A

Water molecules ‘sticking’ together

Result of the polarity of a water molecule and its ability to form hydrogen bonds

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6
Q

Adhesión

A

‘Sticking’ to other molecules that are charged or polar, ex) water molecules sticking to beaker surface

(Result of the polarity of a water molecule and its ability to form hydrogen bonds)

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7
Q

Monosaccharide

A

= one sugar unit

  • fructose, glucose, galactose (found in milk)
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8
Q

B glucose diagram

A

OH on top

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9
Q

A glucose

A

OH on the bottom

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10
Q

Disaccharide

A

= two sugar units

-maltose, lactose, sucrose
Ex) glucose+glucose—(condensation)>maltose + water

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11
Q

Polysaccharide

A
  • starch, glycogen, cellulose
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12
Q

Cellulose

A
  • high tensile strength
  • unbranched
  • condensation reaction links carbon 1 and carbon 4, (1,4) glycosidic bond
  • made by linking B glucose molecules
  • subunits oriented alternatively upwards and downwards
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13
Q

Starch

A
  • made by linking a glucose molecules
  • all the glucose molecules can be oriented in the same way, curved rather than straight
  • (1,4) glycosidic bond

Amylose & amylopectin
Amylose: unbranched, forms helix
Amylopectin: chain is branched, globular shape

  • starch is only made by plants
  • too large to be soluble in water (useful in cells where large amount of glucose needs to be stored as starch in seeds and storage organs, ex) potato cells)
  • doesn’t affect osmotic balance
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14
Q

Glycogen

A
  • branches many times, making the molecule more compact
  • made by animals and also some fungi’s
    -stored in the liver and some muscles in humans
  • same function as starch in plants
    (Acts as a store of energy in the form of glucose), because it is insoluble, large amounts can be stored
  • like starch, it is easy to add or remove extra glucose molecules
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15
Q

Lipids

A

= fats (solid at room temp) and oils (liquid at room temp)
- used for long term energy storage
General formula:
H3C—(CH2)n—C=0, -OH

Label general formula as chain of carbon and hydrogen atoms, carboxyl group

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16
Q

Triglycerides

A

Formed by condensation from 3 fatty acids and one glycerol

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17
Q

Cis-isomers

A
  • more loosely packed, hence lower melting point
  • found in nature
  • double bond causes a kink, curve in the chain
  • hydrogen atoms are on the same side of the two carbon atoms
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18
Q

Trans-isomers

A
  • rare to be found in nature, artificially made
  • hydrogen atoms on different sides of the two carbon atoms
  • double bond does not cause kink, thus more compact with higher melting point
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19
Q

Saturated

A

Draw as ^^^^^, all single bonds

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20
Q

Monounsaturated

A

Draw as ^—-^^^^^, one double bond

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21
Q

Polyunsaturated

A

Draw as ^——^—^, contains more than 1 double bond

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22
Q

BMI formula

A

Mass (kg)/ height (m)^2

Units= kgm ^-2

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23
Q

Draw protein diagram

A

Label with amino group, variable (20 different types), carboxylate group

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24
Q

Anabolic reaction

A

Getting more complex molecules from simple molecules

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25
Q

Draw formation of peptide bond

A

Clearly label peptide bond

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26
Q

Amino acid

A

Monomers of protein

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27
Q

Primary structure

A
  • the order/unique sequence of the amino acids in a polypeptide
  • controls all subsequent levels of structure
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28
Q

Secondary structure

A
  • chain of amino acids fold in different structures; a helix and B pleated sheets
  • structures are held by hydrogen bonds for structural stability
    B pleated sheets: two or more segments of a polypeptide chain line up next to each other
    A helix: backbone follow helical structure, R groups stick outwards (free to interact)
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29
Q

Tertiary structure

A

-polypeptides folds and coils to form a 3D shape, held by ionic bonds
- caused by interaction between R groups
Ex) disulphide bridges, caused by interactions between sulfur atoms

30
Q

Quaternary structure

A
  • single peptide chain has only 3 levels of structure unlike proteins made from multiple polypeptide chains
31
Q

Fibrous proteins

A
  • have a structural (strength and support) role
  • long and narrow in shape
  • insoluble in water
  • less sensitive to changes in PH, heat
    Ex) collagen, keratin, myosin
  • repetitive amino acid sequence
32
Q

Globular protein

A
  • functional role
  • rounded/spherical in shape
    -soluble in water
    -irregular amino acid sequence
  • more sensitive to changes in PH and heat
    Ex) insulin, haemoglobin
33
Q

Rubisco (enzyme)

A

Catalysts the photosynthesis reaction that fixes carbon dioxide from the atmosphere

34
Q

Insulin (hormone)

A

Produced by the pancreas, triggers a reduction in blood glucose

35
Q

Immunoglobulins (antibodies)

A

Produced by plasma cells that are capable of targeting specific antigens

36
Q

Collagen (structural)

A

Used in skin to prevent tearing, in bones to prevent fracturing, tendons and ligaments to give high tensile strength

37
Q

Spider silk (structural)

A

High tensile strength, becomes stronger when stretched

38
Q

Enzyme

A
  • biological catalyst
  • globular protein

Diagram with labels:
- active site + substrate, enzyme substrate complex, product, enzyme remains unchanged

  • enzymes are specific to their substrates
39
Q

Lock and key hypothesis

A
  • structurally, substrates that don’t fit wont react

- functionally, substraes that are not chemically attracted wont react

40
Q

Desaturation

A

Permanent change of active site so that the substrate cannot bind/bond

  • affected by temp, PH level, substrate concentration
41
Q

Temp enzyme affecting diagram

A

Optimum temp labelled as 37*

  • increase in temp increases kinetic energy, meaning there’s more successful collisions
  • due to heat, active site changes shape meaning substrate cannot bind as easily
42
Q

PH level enzyme affecting diagram

A

Label optimum PH level as 7

- change in PH can alter shape resulting in a diminished rate of reaction

43
Q

Induced fit model hypothesis

A
  • as substrate approaches the enzyme, it induces a conformational change in the active site/changes shape to fit the substrate. This stresses the substrate, reducing the activation energy of the reaction

Draw labelled diagram; attraction, reaction/conformation change, enzyme reverts to original shape/release

44
Q

Advantages of enzyme immobilisation

A
  • enzymes can be resumed, saving money
  • products are not contaminated with enzymes
  • enzymes are resistant to desaturation over greater ranges of PH and temp
  • concentration of substrate can be increased as the enzyme isn’t dissolved
45
Q

Collision

A
  • the coming together of a substrate molecule and active site
  • successful collisions only happen when substrae and active sites are correctly aligned
46
Q

Methods of enzyme immobilisation

A
  • attachment to surface such as glass (adsorption)
  • entrapment in a membrane or a gel
  • aggregations of enzymes bonded together
47
Q

Substrate concentration enzyme effect diagram

A

Correctly drawn diagram

  • as substrate concentration increases, there is more chance of collision, hence rate of reaction increases
  • at high substrate concentration, many active sites are ‘occupied’ so raising the substrate concentration has little to no effect on enzyme activity
48
Q

Making lactose free milk

A

Lactos—> glucose+galactose

  • lactase is bound to the surface of alginate beads
  • milk is passed repeatedly over beads
  • the lactose is broken down into glucose and galactose
  • the immobilised enzyme remains to be used again and doesn’t affect milk quality
49
Q

DNA 4 bases

A

Adenine with thymine

Guanine complementary with cytosine

50
Q

DNA nucleotide

A

Single unit of a nucleic acid

51
Q

Draw a DNA nucleotide

A

Clearly labelled with; phosphate (negatively charged), deoxyribose sugar base (5 carbon atoms, pensase sugar), base (contains nitrogen)

52
Q

DNA key points/structure wise

A
  • Is a double helix
  • has a sugar phosphate backbone
  • bases join the two strands by hydrogen bonds
  • two strands run in opposite directions/anti parallel
  • nucleotides are linked into a single strand via a condensation reaction
53
Q

Purines and pyrimidines

A

Adenine and guanine are purines

Thymine and cytosine are pyrimidines

54
Q

Draw a DNA sequence diagram

A

Clearly labelled; covalent bond ( phosphodiester bond), sugar phosphate backbone, 5’ (5-prime) on the left top corner, 3’ (3-prime) on top right corner, hydrogen bonds, phosphate, base, deoxyribose sugar base

55
Q

Watson and Crick

A
  • stick and ball models
  • first model (triple helix) was rejected:
    Ratio of adenine to thymine was not 1:1 and it required too much magnesium
    From their setbacks they realised
  • DNA must be a double helix
  • strands must be anti parallel to allow base pairing to happen
  • relationship between the based and base pairing
56
Q

Rosalind Franklin and Maurice Wilkins

A

Used x ray diffraction to understand the physical structure of the DNA molecule

57
Q

DNA helicase

A
  • unwinds the DNA helix (ATP is needed)
  • separates the two polynucleotide strands by breaking the hydrogen bonds between complementary base pairs, two separated strands become the parent/template strands
58
Q

DNA polymerase

A
  • always moves in a 5’ to 3’ direction

- creates complementary strands

59
Q

Polymerase chain reaction (PCR)

A
  • used to amplify small samples of DNA (segment)
    Occurs in thermal cycles:
    1. Denaturation: DNA sample is heated to separate it into 2 strands
    2. Annealing: DNA primers attach to opposite ends of the target sequence
    3. Elongation: a heat tolerant DNA polymerase (TAS) copies the strands
60
Q

Meselson and Stahl

A
  • two theories of DNA replication was suggested, conservative and semi conservative
  1. DNA from bacteria E.coli that had been grown in medium containing N15 was cultured and appeared as a single band
  2. It was then transferred to a medium with the less dense N14, where it then replicated
  3. After a second round of replication, DNA appeared as two bands (one as half N15 and half N14)

Draw clear diagram as example

61
Q

Protein synthesis

A

Creation of proteins by cells that uses DNA, RNA etc..

62
Q

Transcription

A

-occurs in the nucleus
(Process by which an RNA sequence is produced from a DNA template)

RNA polymerase binds to a site on the DNA at the start of the gene and separated it into two strands, RNA polymerase assembles the free nucleotides and links them to form a single strand of mRNA.
The completed strand of mRNA detaches from the DNA and RNA polymerase ‘zips’ up the two strands of DNA again.
(In mRNA, the base Uracil, U, replaces Thymine, T)

63
Q

Translation

A

-takes place in the cytoplasm on ribosome
(Process that uses the coded information in mRNA to construct polypeptide chains/mRNA translated into a sequence of amino acids in a polypeptide chain)

  • each triplet of bases on the mRNA= codon
  • each triplet of bases on the tRNA= anticodon

Ribosome is composed of two halves, large subunit (binding site for tRNA) and small subunit (binds to mRNA)

  1. MRNA binds to a site on the small subunit of the ribosome
  2. The larger subunit binds to the smaller subunit/come together
  3. There are 3 binding sites for tRNA molecules on the large subunit but only two bind at once, the bases on the codon and anticodon link together by forming hydrogen bonds.
  4. The amino acids carried by the tRNA molecules are bonded together by a peptide linkage and released/detached. As the ribosome moves along it form a growing peptide chain.

Draw clearly labelled diagram

64
Q

Start codon

A

The coding region starts with a start codon, AUG

65
Q

Stop codon

A

The coding region terminates with a stop codon, it does not add an amino acid, instead it causes the release of the polypeptide

66
Q

Cell respiration

A

The controlled release of energy from organic compounds in cells (to form ATP)

67
Q

Aerobic respiration equation

A

C6H12O6+6O2—> 6H2O+6CO2 + energy

68
Q

ATP

A

(Adenosine triphosphate) is the immediately available energy source for a cell, made in the mitochondria
- broken down to ADP (adenosine di phosphate) and inorganic phosphate, this conversion releases energy

69
Q

Glucose—> 2 pyruvates diagram

A

Clearly label with;

  • glycolysis (occurs in the cytoplasm)
  • small ATP yield
  • occurs in mitochondria
  • high ATP yield
70
Q

Respirometer

A

Device used to measure the rate of respiration by measuring the rate of oxygen consumption

71
Q

Aerobic VS Anaerobic

A

Aerobic:

  • occurs in cytoplasm and mitochondria
  • requires oxygen
  • produces CO2 and H2O
  • produces around 38 ATP molecules

Anaerobic:

  • occurs in cytoplasm
  • produces a small yield of ATP
  • no oxygen is used
  • produces lactate, ethanol and CO2

Bio SL (3 decks)

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