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Biology Year 12 > Bio Chem (not Carbohydrates, Lipids) ✅ > Flashcards

Bio Chem (not Carbohydrates, Lipids) ✅ Flashcards

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1
Q

What are hydrogen bonds

A

Eg H20, Oxygen atom has a partial negative charge and hydrogen has a partial positive charge, the oxygen atom in a water molecule is attracted to hydrogen atoms in a neighboring molecules

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2
Q

What are properties of water

A

Good solvent
High specific heat capacity
High heat of vaporization
Cohesion
Low density solid (ice)

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3
Q

Why is water a good solvent, why is it important

A

Polar water molecules attract (and dissolve) other polar molecules and ions

Water transports dissolved solutes (eg in blood and phloem)
Chemical reactions occur in water

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4
Q

Why does water have a high specific heat capacity, why is it important

A

A relatively large amount of energy is required to increase water temperature

Thermal stability in aquatic environments and inside organisms

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5
Q

Why does water have a high heat of vaporization, why is it important

A

Additional energy is needed to change water from liquid to gas

Thermoregulation- sweating and panting can cool an organism when water on body is evaporated

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6
Q

Why does water have cohesion, what is importance

A

Hydrogen bonds cause water molecules to be attracted to each other and flow together

Water movement up xylem vessels
Surface tension- small organisms can move on the water surface

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7
Q

Why does water have a low density solid, why is it important

A

The crystalline structure in ice is less dense than liquid water

Provides an insulating layer of aquatic habitats in cold climates
The ice surface provides a habitat for some organisms (eg polar bears)

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8
Q

How do you test for reducing sugars (eg monosaccharides, lactose, maltose)

A

Mix with Benedict’s Reagent in a boiling tube and heat, negative result is blue, positive result is green for low oranje for medium brick red for high

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9
Q

How do you test for non reducing sugars (eg sucrose)

A

After a negative result with the Benedict’s test, boil with dilute HCl, conduct the Benedict’s test a second time, blue is negative, green is low medium is oranje and brick red is high

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10
Q

How to test for starch

A

Mix iodine/ potassium iodide solution with sample, negative result is yellow/ brown, positive result is blue/ black

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11
Q

What are the properties and roles of triglycerides and phospholipids

A

Triglycerides: compact and soluble, role is for energy storage and insulation

Phospholipid : hydrophilic head and hydrophobic tail, role is for membrane structure

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12
Q

What do amino acids contain

A

A central carbon atom, an amine group, a carboxyl group, and a hydrogen atom. Amino acid determined by a R group

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13
Q

What is a polypeptide bond how is it formed

A

A polypeptide is formed when many amino acid bonds together, this occurs at ribosomes during translation. Peptide bonds broken in hydrolysis

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14
Q

What happens when amino acids are joined together

A

Amino acid monomers joined together by condensation reaction, a peptide bond is formed between 2 amino acids, producing a dipeptide

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15
Q

What is the primary structure of a protein

A

Amino acid sequence in a peptide

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16
Q

What are the secondary and tertiary structure

A

Secondary: hydrogen bond between amino acid (alpha helix coiled or beta pleated sheet)

Tertiary:
ionic bond between NH3 and O (aspartic acid),
Disulfide bridges; between S-S (cysteine)
Hydrophobic interactions between hexagon carbon shape and CH3 between (tyrosine and valine)

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17
Q

What is a quaternary structure

A

Produced when 2 or more polypeptides associate
Eg hemoglobin consists of 4 polypeptide subunits and collagen has 3 polypeptides. Prosthetic groups can be present in quaternary structures

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18
Q

State what would be seen when an emulsion test gives a positive result (2 marks)

A

White/ creamy (1) emulsion (1)

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19
Q

Explain why the structure of a phospholipid is suited for its role in membranes (4 marks)

A

Hydrophilic phosphate (1)
Faces/ interacts with water (in tissue fluid and cytosal [1]
Hydrophobic fatty acids [1]
Form a partially permeable barrier [1]

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20
Q

Outline the similarities and differences between the synthesis of polypeptide L’s and the synthesis of triglycerides (4 marks)

A

Similarities:
Condensation reactions [1]
Water produced [1]
Enzymes catalyse the reactions [1]

Differences:
Polypeptides are polymers, but triglycerides are not [1]
Peptide bonds formed in polypeptides, but ester bonds formed in triglycerides [1]
Triglycerides always consist of glycerol and 3 fatty acids, whereas polypeptides vary in number of amino acids they contain [1]

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21
Q

Suggest how the biuret test can be used to assess the concentration of proteins (4 marks)

A

Prepare a range of protein solutions of known concentration [1]
Add a specific volume of biuret solution to each protein solution [1]
Use a colorimetry to plot a calibration curve (protein concentration againt absorption) [1]
Test unknown sample and calculate protein concentration from calibration curve [1]

22
Q

What is shape, structure/ binding, water solubility, conjugation (presence of prosthetic group), functions of globular proteins

A

Shape: compact and spherical

Bonding/structure: hydrophilic R groups on outside, hydrophobic R groups inside

Water solubility: soluble

Conjugation: sometimes

Functions: enzyme (eg catalase), hormones (eg insulin), membrane proteins, antibodies, transport proteins (eg haemoglobin)

23
Q

What is shape, structure/ binding, water solubility, conjugation (presence of prosthetic group), functions of fibrous proteins

A

Shape: long and linear

Bonding/structure: limited range of amino acids, often with a repetitive sequence, organized and strong structures

Water solubility: insoluble

Conjugation: no

Functions: structural roles (eg keratin, collagen)

24
Q

In which organelle are prosthetic groups added to polypeptides (1 mark)

A

Golgi apparatus

25
Q

Explain, in terms of their functions, why it is important for globular proteins to be soluble and for fibrous proteins to be insoluble (2 marks)

A

Globular proteins often need to be transported (eg in blood) and therefore need to be water soluble [1]
Fibrous proteins tend to have structural roles and should not dissolve in water [1]

26
Q

Keratin contains many disulfide bonds, keratin in hair contains fewer disulfide bonds then keratin in nails, suggest why (2 marks)

A

Keratins flexibility increases when number of disulfide bonds decreases [1]
Hair is more flexible then nails [1]

27
Q

What does a nucleotide structure contain

A

A Pentose (5-carbon) sugar, a phosphate group, organic nitrogenous base

28
Q

Deoxyribonucleic acid (DNA) and ribonucleic acids (RNA) are both what, how are they formed

A

Polynucleotides
By condensation reactions between nucleotides, which form phosphodiester bonds broken by hydrolysis

29
Q

DNA NOT IN TEST
NEED TO COMPLETE FLASHCARDS LATER

A
30
Q

What is metabolism

A

Sun of all chemical reactions occurring in an organism, either anabolic (formation of molecules) or catabolic (breaking down of molecules)

31
Q

How do enzymes work

A

Substrate collide with active site of enzyme

Shape of active site complementary to substrate

Substrate binds to active site to form enzyme- substrate complex (ESC)

Bonds in substrates are placed under strain and break; enzyme provides and alternative reaction pathway that reduces activation energy required for reaction

An extension product complex is formed snd products released

32
Q

What is the induced-fit hypothesis

A

Suggests that initially weak binding by the substrate will a later enzymes tertiary structure, this strengthens the temporary bonds between substrate and enzyme, and weakens bonds within the substrate

33
Q

State 3 structural features that are common to all enzymes (3 marks)

A

All enzymes are proteins/ polymers of amino acids [1]
All enzymes have a globular structure [1]
Folded [1]
Contain active sites [1]

34
Q

Explain how enzymes are able to lower the activation energy of reactions (4 marks)

A

Alternative reaction pathway/ AW [1]
Temporary bonds between substrate and active site [1]
Substrate bonds are strained/stretched [1]
Less energy required to break bonds in the substrate [1]

35
Q

How does temp effect enzyme activity

A

Temp: rise increases enzyme activity to an optimum temp, past optimum decreases till it stops

Enzyme and substrate molecules gain kinetic energy and move faster, thereby increasing the change of successful collisions

Weak bonds eg H2 ions in active site vibrate more, strain and break (enzyme denature)

36
Q

How does PH affect enzyme activity

A

Decreases when PH moves away from optimum, a further change stops all enzyme activity

Change to H+ion concentration alter charges on amino acids in active site which can prevent substrate molecules from binding
Hydrogen and ionic bonds in active site broken which causes permanent change in enzyme tertiary structure

37
Q

How does substrate and enzyme concentration affect enzyme activity

A

Substrate increases: reaction rates increases as substrate concentration rises but eventually plateaus

Enzyme increases: raise reaction to a higher Vmax

38
Q

Explain how high temp and changes in pH can prevent enzymes from functioning (5 marks)

A

Denaturation [1]
Secondary/ tertiary structure of enzyme is changed [1]
Active site is altered [1]
Active site no longer a complementary shape to substrate [1]
High temp cause weak bonds in enzyme to vibrate and break [1]
pH changes result of n hydrogen and ionic bonds breaking [1]

39
Q

Suggest why microorganism ms that inhabit alkaline lakes are unlikely to cause infections in humans (2 marks)

A

The pH in human body will be lower than the pH in lakes [1]
Enzymes in microorganisms will not function at an optimal rate/ may be denatures [1]

40
Q

Psychrophiles are organisms that inhabit environments where temp can drop below 0, suggest how structure of psychrophiles enzymes might differ from those found in humans (2 marks)

A

Psychrophiles enzyme structure are more flexible [1]
Different bonds in tertiary structure [1]
Fewer hydrogen bonds/ more disulfide bonds [1]

41
Q

Draw Ribose, deoxyribose, alpha glucose, beta glucose

A
42
Q

Competeibe inhibition binding site, mechanism, reversible or irreversible, examples, effect on reaction rate

A

Binding sit: active site

Mechanism: competes with substrate for enzymes active site and blocks the substrate form entering

Reversible

Examples: penicillin, statins

Effect on reaction rate: slows rate, max rate can still be reached if substrate concentration is increased

43
Q

Non- competitive inhibition binding site, mechanism, reversible or irreversible, examples, effect on reaction rate

A

Binding site: allosteric site

Mechanism: tertiary structure of enzyme changes shape, meaning active site no longer a complementary shape to substrate

Sometimes reversible, sometimes not

Examples: cyanide ions, organophosphates

Effect on reaction rate: slows rate and lowers Vmax

44
Q

What is end-product inhibition

A

Occurs at conclusion of metabolic reaction pathways, regulates fats at which product is made can be competitive and non competitive

45
Q

What are cofactors

A

Non proteins substances required for enzymes to functions

46
Q

Coenzyme, are they organic, how do they interact with enzymes, examples

A

Are they organic: organic
How do they interact: form temporary bonds with enzyme but leave following the reaction
Examples: coenzyme A, NAD+

47
Q

Inorganic cofactor, are they organic, how do they interact with enzymes, examples

A

Are they organic: inorganic
How do they interact with enzymes: form temporary bonds with the enzyme but leave following the reaction
Examples: Cl- ions, Mg2+

48
Q

Prosthetic group, are they organic, how do they interact with enzymes, examples

A

Are they organic or inorganic: can be either
How do they interact with enzymes: permanently bound to the enzyme
Enzymes: Zn2+, FAD

49
Q

Outline the differences between coenzymes and prosthetic groups (2 marks)

A

Prosthetic groups bind permanently/ tightly (whereas coenzymes bind temporarily/ loosely [1]
All coenzymes are organic (whereas prosthetic groups can be organic or inorganic [1]

50
Q

Suggest why some digestive enzymes are produced as inactive proteins (2 marks)

A

Otherwise digestive enzymes would cause damage to cells [1]
The enzymes are activated in the digestive tract [1]

51
Q

Using your knowledge from earlier chapters, suggest how polypeptides are modified to produce enzymes with prosthetic groups (4 marks)

A

Translated polypeptide [1]
Moves in vesicles [1]
To Golgi apparatus [1]
Where prosthetic group is added [1]

Biology Year 12 (8 decks)

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