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Flashcards in Biological Molecules Deck (65):
1

What do amino acids contain?

Carbon, hydrogen, oxygen and nitrogen, some contain sulfur

2

How many different amino acids are used in proteins?

Twenty

3

What are proteins held together by?

Peptide bonds

4

What is the primary structure in proteins?

The order in which the amino acids are arranged in a protein chain

5

What is the secondary structure in proteins?

Some chains fold into pleats that are held together by weak forces of chemical attraction called hydrogen bonds, the pleats are the secondary structure

6

What is the tertiary structure in proteins?

Some proteins have a tertiary structure, the chain of amino acids is folded into a ball that's held together by a mixture of weak chemical bonds and stronger bonds.

7

What a globular protein?

If the protein has a spherical shape

8

What type of bond holds together the secondary structure of a protein?

Hydrogen bonds

9

What three elements do carbohydrates contain?

Carbon
Hydrogen
Oxygen

10

Give three examples of carbohydrates

Sugars
Starch
Cellulose

11

What are monosaccharides?

Single units from which all the other carbohydrates are built

12

What two forms does glucose have?

Alpha and beta

13

What are disaccharides?

Formed when two monosaccharides are joined together by a chemical reaction, a molecule of water is also formed

14

What is a polysaccharide

It's formed when more than two monosaccharides are joined together by condensation reactions

15

What two polysaccharides are starch molecules made up of?

Amylose and amylopectin

16

Name two monosaccharides

Glucose and fructose

17

Name two polysaccharides

Starch and cellulose

18

What do lipids contain

Carbon
Hydrogen
Oxygen

19

Plant oils and animal fats are mostly made up of a group of lipids called...

Triglycerides

20

What does a triglyceride consist of?

A molecule of glycerol with three fatty acids attached to it

21

What is a fatty acid molecule?

A long chain of carbon atoms with an acid group at one end

22

What are attached to the carbon atoms in a fatty acid molecule?

Hydrogen

23

What does is mean by a fatty acid is saturated?

If every carbon atom in the chain is joined by a single bond

24

What does it mean when a fatty acid is unsaturated

If one or more of the bonds is a double bond

25

A fatty acid with many double bonds is...

Polyunsaturated

26

What are phospholipids

A type of lipid

27

What are cell membranes made from?

A double layer of phospholipids

28

What do enzymes do?

Speed up biochemical reactions

29

What are enzymes?

Biological catalysts

30

What is activation energy?

The input energy in a reaction

31

What do enzymes do to the activation energy?

Reduce it

32

Why are all enzymes globular proteins?

Because they're roughly spherical

33

What determines an enzymes structure?

The order of amino acids

34

Enzymes can be involved in...

Breaking down molecules or building molecules

35

What do digestive enzymes do?

Break down food into smaller molecules

36

A substance that's acted upon by an enzyme is called

It's substrate

37

What is the active site?

A region on the surface of the enzyme molecule where a substrate can attach itself, this is where the catalysed reaction takes place

38

Why are enzymes described as specific?

Is can only catalyse one reaction, the substrate must be the correct shape to fit the active site and only one substrate will fit. Anything that changes the shape will affect how the enzyme works.

39

How does an enzyme denature?

At high temperatures the atoms of the enzyme molecule vibrate more rapidly and break the weak bonds that hold the tertiary structure together. The shape of the active site changes so the substrate will no longer fit.

40

What two things disrupt the weak bonds and change the shape of the active sites in enzymes?

Hydrogen ions in acids and hydroxyl ions in alkalis.

41

What are proteins made up of?

Amino acids

42

What are polymers?

Large complex molecules composed of long chains of monomers joined together

43

What's a monomer?

Small basic molecular units that can form a polymer

44

What is a condensation reaction?

Forms a chemical bond between molecules, releasing a molecule of water

45

How can polymers be broken down?

By hydrolysis

46

What is a hydrolysis reaction?

Breaks the chemical bond between monomers using a water molecule

47

What is the evidence for evolution in different organisms?

They share the same groups of carbon based compounds that interact in similar ways

48

What are the monomers that carbohydrates are made from?

Monosaccharides

49

How do disaccharides form?

When two monosaccharides join together

50

What is the test for sugars called?

Benedict's test for sugars

51

What do reducing sugars include?

All monosaccharides and some disaccharides

52

How do you test for sugar?

You add Benedict's reagent (blue) to a sample and heat with boiling water.

53

What will happen if the Benedict's test for sugars is positive?

It will form a coloured precipitate.

54

The higher the concentration of sugar...

The further the colour change goes

55

If Benedict's sample stays blue, what does it mean?

No reducing sugar present

56

If reducing sugar is present, what colour will the sample form?

Green
Yellow
Orange
Brick red precipitate

57

What is made from alpha glucose?

Amylose and amylopectin

58

What is amylose

Long chain of alpha glucose, it has a coiled structure like a cylinder, which makes it compact so it's good for storage

59

What is amylopectin

Long chain of alpha glucose, the side branches allow the enzymes that break down the molecule, so the glucose is released quickly

60

Is starch soluble in water? Why is this good?

No, so it doesn't swell - good for storage

61

What is cellulose made from

Long chains of beta glucose, the chains are linked by hydrogen bonds to form strong fibres which help support the cell

62

Explain the iodine test for starch

Add iodine dissolved in potassium iodide solution, if starch is present the sample changes from browny-orange to a dark blue-black colour

63

Why are lipids insoluble in water?

The triglycerides have fatty acid molecules that have 'tails' made from hydrocarbons, these tails are hydrophobic so they repel water molecules.

64

Which type of fatty acids have double bonds?

Unsaturated fatty acids

65

How are triglycerides formed?

Condensation reactions