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Biology > Biochemistry UNIT 1 > Flashcards

Biochemistry UNIT 1 Flashcards

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0
Q

What are carbohydrates made from

A

Monosaccharides

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1
Q

Carbohydrates are present in foods like….

A

Pasta
Potato
Bread
Cakes

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2
Q

Name the elements that make up carbohydrates

A

Carbon
Hydrogen
Oxygen

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3
Q

Most carbohydrates are…

A

Polymers

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4
Q

The monomers that carbohydrates are made from are….

A

Monosaccharides for example glucose, fructose, galactose

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5
Q

What type of sugar is glucose

A

Hexose sugar, so it contains 6 carbon atoms in each molecule

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6
Q

How many forms of glucose are there

A

2- alpha and beta

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7
Q

Monosaccharides join together to form….

A

Disaccharides and polysaccharides

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8
Q

What are disaccharides made from

A

2 monosaccharides

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9
Q

What are polysaccharides made from

A

More than 2 monosaccharides

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10
Q

Monosaccharides are joint together by what process

A

Condensation reaction/ dehydration synthesis

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11
Q

How do monosaccharides break apart

A

Hydrolysis

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12
Q

Explain condensation reaction

A

A molecule of water is realised and a glycosidic bond forms between the 2 monosaccharides

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13
Q

What happens to disaccharides and polysaccharides during digestion

A

They are broken down

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14
Q

Luckily we have…….realised by the…….that ……. Disaccharides and polysaccharides

A

Enzymes
Intestinal epithelium
That hydrolyse

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15
Q

What does hydrolyse mean

A

Breaking down

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16
Q

What enzyme is needed to hydrolyse maltose

…..sucrose
…….lactose

A

Maltase. Into glucose and glucose
Sucrase. Into glucose and fructose
Lactase. Into glucose and galactose

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17
Q

What causes lactose intolerance

A

The lack of lactase

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18
Q

Lactose is a sugar found in…

A

Milk

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19
Q

Lactose is digested by an enzyme called….

A

Lactase

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20
Q

Where do you find lactase

A

In the intestine

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21
Q

What happens if you don’t have enough of the enzyme lactase

A

You won’t be able to break down the lactose in milk properly, a condition called lactose intolerance

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22
Q

What happens to undigested lactose

A

It’s fermented by bacteria, and causes a host of intestinal complaints such as stomach cramp, excessive flatulence and diarrhoea

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23
Q

What is done to milk to make it suitable for lactose intolerance people

A

Artificially treated with purified lactase

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24
Q

Sugar is the general term for….

A

Monosaccharides and disaccharides

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25
Q

All sugar can be classified as…..

A

Reducing or non reducing sugars

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26
Q

What is the test for sugars

A

Benedicts reagent

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27
Q

The benedicts reagent test differs on what?

A

Whether the sugar is reducing or non reducing

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28
Q

Reducing sugars include

A

Monosaccharides and some disaccharides including maltose

29
Q

What colour is benedicts reagent

A

Blue

30
Q

How do you test for reducing sugars

A

Benedicts reagent is added and heated. If the sample contains reducing sugars, it will gradually turn brick red( orange) due to the formation of a red precipitate

31
Q

Name a non reducing sugar

A

Sucrose

32
Q

How do you test for non reducing sugar

A

Carry out reducing sugars test. Result should remain blue. Heat mixture with dilute hydrochloric acid to hydrolyse any remaining disaccharides. Add sodium hydrogencarbonate to neutralise solution as benedicts reagent won’t work in acidic conditions. Test again with benedicts, solution should change to orange

33
Q

Starch is made up from how many polysaccharides?

A

2- amylose and amylopectin

34
Q

Amylose and amylopectin are composed of what

A

Long chains of alpha glucose linked together by glycosidic bond formed in condensation reaction

35
Q

How is starch digested

A

Is first broken down into maltose by amylase, which is an enzyme released from the salivary glands and the pancreas, then the maltose is broken down into an alpha glucose molecule by the maltase which is released from the intestinal epithelium

36
Q

What is amylase

A

An enzyme realised from the salivary glands and the pancreas

37
Q

Where is the body is amylase realised from

A

Salivary glands and pancreas

38
Q

What releases maltase

A

The intestinal epithelium

39
Q

What test is used for starch

A

Iodine

40
Q

How is the starch test carried out

A

Iodine is dissolved in potassium iodide solution. This is added to the test sample and if there is starch present it changes from a browny orange to blue/ black

41
Q

The monomers of proteins are….

A

Amino acids

42
Q

What is a dipeptide

A

Formed when two amino acids join together

43
Q

What is a polypeptide

A

When two or more amino acids join together

44
Q

All amino acids have the same general structure. Explain this.

A

They have a carboxyl group and an amino group, attached to a carbon. The difference between different amino acids is the variable group they contain

45
Q

What is the name of the bond formed between amino acids

A

Peptide bonds

46
Q

A proteins shape determines its……

A

FUNCTION

haemoglobin is a compact, soluble protein, which makes it easy to transport. This makes it great for carrying oxygen around the body. Collagen has 3 polypeptide chains tightly coiled together, which makes it strong. This makes it a great supportive tissue in animals

47
Q

4 examples of proteins

A

Enzymes, antibodies, transport proteins, structural proteins

48
Q

Explain enzymes in terms of how they are a specialised protein

A

They are usually roughly spherical in shape due to tight folding of the polypeptide chains. they’re soluble and often have roles in metabolism, either digesting or synthesising large food molecules

49
Q

Explain antibodies in terms of how they are a specialised protein

A

Involved in immune response. Made up of 2 light polypeptide chains and 2 heavy polypeptide chains bonded together. Antibodies have variable regions- the amino acid sequences in these vary greatly

50
Q

Explain transport proteins in terms of a specialised protein

A

Present in cell membranes. Contain hydrophobic and hydrophilic amino acids, which cause the protein to fold up and form a channel. These proteins transport molecules and ions across membranes

51
Q

Explain structural proteins in terms of being a specialised protein

A

Physically strong. Consist of long polypeptide chains lying parallel to each other with cross links between them. Structural proteins include keratin and collagen

52
Q

What test is used for detecting proteins

A

Biuret test….. 2 stages to this test

1) the test solution needs to be alkaline, so first add few drops of sodium hydroxide solution.
2) then you add some copper sulphate solution

If protein is present a purple layer forms.
If no protein, the solution remains blue. The colours are pale so you need to look carefully

53
Q

Enzymes are ………. catalysts

A

BIOLOGICAL

54
Q

How do enzymes act as biological catalysts

A

They speed up chemical reactions….
They catalyse metabolic reactions in body (digestion, respiration). Even your phenotype is due to enzymes that catalyse the reactions that cause growth and development. Enzymes are proteins, they have an active site which has a specific shape. This is where the substrate molecules bind. Enzymes are highly specific due to their tertiary structure.

55
Q

What part of a reaction does an enzyme lower?

A

The activation energy. It does this when forming the enzyme-substrate complexes
Makes reactions happen at a lower temperature, speeds up the rate of reaction.

56
Q

2 reasons why the enzyme-substrate complex formations lower activation energy

A

1) if 2 substrate molecules need to be joined, being attached to the enzyme holds them closer together, reducing any repulsion between molecules so they can bond more easily.
2) if enzyme is catalysing a breakdown reaction, fitting into the active site puts strain on bonds in substrate, so substrate molecules break up more easily

57
Q

What is the lock and key model

A

Explains how the enzyme and it’s substrate are complimentary shapes so are able to bind

58
Q

Problems with lock and key model

A

New evidence showed that the enzyme-substrate complex changed shape slightly to complete the fit. This locks the substrate even more tightly to the enzyme

59
Q

What is the induced fit theory

A

Helps explain why enzymes are so specific and only bond to one particular substrate. The substrate has to be right shape to fit active site and also has to make the active site change shape in the right way aswell. The active site undergoes a conformational change which reveals an alternative reaction pathway with a lower activation energy.

60
Q

What are the properties of enzymes, relating to their tertiary structure

A

Enzymes very specific - usually only catalyse one reaction because only one substrate will fit into the active site. The active sites shape is determined by the enzymes tertiary structure. Each different enzyme has a different tertiary structure and so a different shaped active site.if the tertiary structure of a protein is altered in any way the shape of the active site will change. Means substrate won’t fit into active site and enzyme will no longer bad able to carry out its function. The tertiary structure of an enzyme may be altered by changes in pH or temp. The primary structure (amino acid sequence) of a protein is determined by a gene. If a mutation occurs in that gene it could change the tertiary structure of the enzyme produced

61
Q

Explain properties of enzymes due to lock and key model

A

They are very specific, as they can usually only catalyse one reaction due to only only substrate being a complimentary shape.

62
Q

Why is induced fit better than lock and key

A

Induced fit explains how enzyme substrate complexes don’t just have to form through specificity, they can form through a confor,atonal change within the active site which allows the substrate to bind. If also reveals the alternative pathway with the lower activation energy, which makes the catalysed reaction more successful

63
Q

How does temp effect enzyme activity

A

The rise in temp gives enzymes more kinetic energy so they vibrate more, so they are moving faster so more likely to find its complimentary substrate, the energy of the collisions also increase so that means each collision is more likely to result in a reaction. If the temp goes above a certain level, this vibration breaks some of the bonds that hold the enzyme in shape. The active site changes shape and the enzyme and substrate can no longer fit together, enzyme is denatured

64
Q

How does pH affect enzyme activity

A

All enzymes have an optimum pH. Above and below this optimum, the H+ and OH- ions found in acids and alkalis can disrupt the ionic and hydrogen bonds that hold the enzymes tertiary structure in place. This makes the active site change shape so enzyme is denatured

65
Q

How does substrate concentration affect enzyme activity

A

The higher the substrate concentration, the faster the reaction -more substrate molecules means a collision between substrate and enzyme is more likely and so more active sites will be used. This is only tire up until ‘saturation’ point, after that there are so many substrate molecules that the enzymes have as many as they can cope with as all the active sites are full, so adding more makes no difference

66
Q

Enzyme activity can be prevented by…..

A

Enzyme inhibitors

67
Q

What are enzyme inhibitors

A

Molecules that bind to the enzyme that they inhibit. Can be competitive or non competitive

68
Q

Affect of competitive inhibitor on enzyme activity

A

Competitive inhibitor molecules have similar shape to that of substrate molecules, they compete with the substrate molecules to bind to the active site but no reaction takes place. Instead they block the active site so no substrate molecules can fit in it. How much the enzyme is inhibited depends on the relative concentrations of the inhibitor and substrate. If there’s a high concentration of the inhibitor, it will take up nearly all the active sites and hardly any of the substrate will get to the enzyme

69
Q

Affect on non competitive inhibitor on enzyme activity

A

Non competitive inhibitor molecules bind to the enzyme away from The active site, this causes the active site to change shape so the substrate molecules can no longer bind to it. They don’t ‘compete’ with the substrate molecules to bind to the active site because they are a different shape. Increasing the concentration of substrate won’t make any difference as enzyme activity is still inhibited

Biology (13 decks)

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