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IB Biology > B1 > Flashcards

B1 Flashcards

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1
Q

What is a macromolecule?

A

Macromolecules are larger molecules, made of many repeating subunits. To be classified as a macromolecule, it is generally made of a very large number of molecules and weighs over 10,000 atomic mass units.

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2
Q

What is a monomer?

A

A monomer is the repeating small units (molecules) that make up polymers and thus macromolecules. Different monomers= unique monomers

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3
Q

What is a condensation reaction and how is it done?

A

A condensation reaction involves the formation of a covalent bond between two monomers. This is done by removing a hydrogen from one monomer and a hydroxyl group from the other.

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4
Q

What is the result of a condensation reaction?

A

Dimer- two monomers bonded together. This will become a polymer when other condensation reactions occur
Water is a waste product

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5
Q

What is hydrolysis?

A

Hydrolysis is the opposite of condensation reactions- begins with polymers and water and ends with stable monomers.
Water is split to form H and OH to stabilise the monomers once separated.

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6
Q

What features of carbon makes it able to form many unique compounds?

A
  • Has 4 valence electrons- effective at forming covalent bonds with other atoms, including other carbons
  • Can form 4 covalent bonds- these can be single or double bonds, meaning it can form a variety of compounds
  • Can form long chains and rings- diverse structural compounds
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7
Q

What is the monomer of carbohydrates?

A

Monosaccharides

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8
Q

What is the monomer of lipids?

A

Fatty acids plus a glycerol or phosphate group

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9
Q

What is the monomer of proteins?

A

Amino acids

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10
Q

What is the monomer of nucleic acids?

A

Nucleotides

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11
Q

What are some examples of body processes that use condensation reactions?

A
  • Building body tissues
  • Protein synthesis- most crucial role of every cell
  • When energy is stored in larger carbohydrates
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12
Q

What are some examples of body processes that use hydrolysis reactions?

A
  • Digestion- consuming polymers and hydrolise using digestive enzymes to turn them into monomers for use in the body
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13
Q

Why is water produced in condensation reactions?

A
  • Previously stable monomers must become reactive
  • This is done by removing something from each monomer
  • To create a safe waste product, a hydrogen is removed from one monomer and a hydroxyl is removed from the other monomer
  • These combine to make water!
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14
Q

What role does water play in hydrolysis reactions?

A
  • After breaking the bond in a polymer, the monomers would be reactive and unstable
  • They would just reconnect if not made stable
  • To do this, water is split and the H and OH reattatch to either monomer
  • This makes the monomers chemically stable seperate
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15
Q

What is a monosaccharide?

A
  • Means ‘one sugar’- the monomer of all carbohydrates
  • Most have 5 or 6 carbons and form rings in aqueous solutions
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16
Q

What are some examples of monosaccharides?

A

Ribose, deoxyribose and glucose

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17
Q

What are polysaccharides/ complex carbohydrates?

A
  • Means ‘many sugars’
  • When many monosaccharides are chemically bonded together
  • They are a form of energy storage as they can be broken down into monosaccharides
  • They perform important roles in structures of cells
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18
Q

What is cellulose/ dietary fibre?

A
  • Cellulose is a polysaccharide that makes the cell wall of plants.
  • Made of a long chain of alternating beta glucose molecules
  • They make long straight fibres ideal for structures, and make bonds between chains
  • Most organisms cannot break down
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19
Q

What is a glycoprotein?

A
  • A carbohydrate chain bonded to a protein
  • They are found in cell membranes for cell recognition and communication
  • A ‘conjugated carbon protein’- a carbohydrate bonded to a protein
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20
Q

What is the difference between a pentose and a hexose sugar?

A
  • All sugars have a carbon backbone
  • Pentose sugars have a 5 carbon backbone e.g fructose, ribose- C(5)H(10)O(5)
  • Hexose sugars have a 6 carbon backbone e.g glucose- C(6)H(12)O(6)
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21
Q

What makes glucose a polar molecule?

A
  • Hydroxyl bonds (between the O and the H) are polar
  • As glucose has 5 OH groups, it is a polar molecule
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22
Q

How does the polarity of glucose determines the polarity?

A
  • Molecular stability- due to covalent bonds
  • High solubility in water- due to polarity
  • Easily transported- due to solubility (caused by polarity)
  • Yields high energy (ATP) when oxidised (broken apart)- due to strong covalent bonds
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23
Q

What is the difference between alpha and beta glucose?

A
  • They have the same elements
  • When in a ring structure (aqueous), the orientation of the hydroxyl and hydrogen on carbon 1 rotate
  • Most polymers use alpha glucose, but beta glucose is used in cellulose
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24
Q

What makes starch and glycogen ideal structurally for energy storage?

A
  • Long chains of glucose molecules
  • They form coils or chains which make them compact storage molecules
  • Fairly insoluble in water due to large size, makes them good for storage
  • Bonds between glucose molecules can break easily by hydrolysis into monosaccharides for cellular respiration
  • Note: plants= starch, animals= glycogen
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25
Q

What is the difference between amylose and amylopectin?

A
  • Amylose- glucose are connected to adjacent glucose, creating a linear chain which twists into a helix when long
  • Amylopectin- additional bonding on top of glucose between c1 and c6 creates a branched structure
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26
Q

What is the specific role of ABO glycoproteins?

A
  • ABO glycoproteins identify ones own blood type
  • Different types of ABO antigens that distinguish between Type A, B, O and AB blood
  • Based on that, our immune system builds antigens to OTHER blood types (not our own)
  • This is important as it determines which blood is compatible for transfusion
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27
Q

Draw the structure of glucose

A
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28
Q

Explain the structure and function of amylose

A

Structure: Straight chain of alpha glucose, made of only 1-4 linkages. Overall helix shape

Function: Long term storage in plants- makes up 20% of plant starch

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29
Q

Explain the structure and function of amylopectin

A

Structure: Branched chain of alpha glucose, has 1-4 linkages and some 1-6 linkages.

Function: Long term storage in plants- makes up 80% of plant starch

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30
Q

Explain the structure and function of glycogen

A

Structure: highly branched chain of alpha glucose, has 1-4 linkages and lots of 1-6 linkages.

Function: Short term storage for animals. In humans, it is stored in the liver

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31
Q

Explain the structure and function of cellulose.

A

Structure: Straight chain of alternating oriented beta glucose (right way up then upside down), has all 1-4 linkages.

Function: Structural polysaccharide- strong and insoluble fibres, used for plant cell walls. Don’t provide energy- most organisms cannot digest.

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32
Q

What are phospholipids?

A

Modified triglycerides that contain a glycerol, 2 fatty acids and a phosphate group. They are formed by condensation reactions (3 reactions with 3 waters as waste product to form 1 phospholipid). Make up the phospholipid bilayer.

33
Q

What is adipose tissue?

A

Adipose tissue is composed of dipocytes, specialised cells that store triglycerides as stored energy. Excess energy intake is stored as triglycerides in adipose tissue as long-term storage that can be broken down for energy.

34
Q

What are amphipathetic molecules?

A

They are molecules that have both hydrophilic (polar) and hydrophobic (non-polar) regions.

35
Q

What makes phospholipids amphipathetic molecules?

A

Phospholipids are amphipathetic because they have a hydrophilic head (glycerol and phosphate) and a hydrophobic (fatty acid) tail.

36
Q

What are endotherms?

A

Endotherms are organisms that maintain a steady internal temperature despite changes in the external temperature. Many use adipose tissue to trap metabolic heat and maintain body temperature in cold climates.

37
Q

How do non-polar covalent bonds impact the characteristics of lipids?

A

Lipids have long fatty acid chains primarily made of non-polar covalent bonds between hydrogens and carbons (strong covalent bonds). This give lipids the characteristic of not dissolving in water.

38
Q

What is a saturated fatty acid?

A

Type of fatty acid that only has single bonds, giving it a straight shape.

39
Q

What are the properties of saturated fatty acids?

A
  • Highly compressible, making them efficient storage in adipose tissue
  • High melting point due to stability
  • Solid at room temperature
40
Q

What is a monounsaturated fatty acid?

A

A type of fatty acid which has one double bond, which gives it a bend shape.

41
Q

What are the properties of monounsaturated fatty acids?

A
  • Less dense and more spread out than saturated fats
  • Ideal for cell membranes and waterproof layers e.g waxy cuticles
  • Lower melting point- generally liquid at room temperature
42
Q

What is a polyunsaturated fat?

A

A type of fatty acid with more than one double bond, which gives it a zig-zag shape.

43
Q

What are the characteristics of polyunsaturated fats?

A
  • Less dense and more spread out than saturated fats
  • Plants use a combination of mono- and poly- unsaturated fats
  • Can have specific, important roles
44
Q

What are some examples of saturated fatty acids?

A
  • Only in animals
  • Adipose tissue- fatty meats, butter
45
Q

What are some examples of monounsaturated fatty acids?

A
  • Plants
  • Coverings, waterproofing
  • E.g olive oil
46
Q

What are some examples of polyunsaturated fatty acids?

A
  • Fatty fish
  • Some plant oils
47
Q

What is the function of triglycerides?

A

Forms adipose tissue, stores triglycerides in cells

48
Q

Why are triglycerides good at long term storage in adipose tissue?

A
  • Stable but releases a lot of energy when broken (more than 2x energy per gram)
  • Hydrophobic, does not affect osmosis
  • Poor heat conductors, so provide good insulation e.g blubber
49
Q

What is the function of phospholipids?

A

Form the bilayer of cell and organelle membranes.

50
Q

Why are phospholipids good at forming membranes?

A

They are amphipathetic- polar and non-polar regions

51
Q

What is the function of steroids?

A

Makes up steroid hormones e.g sex hormones

52
Q

Why are steroids good at being hormones?

A

They are lipid based, so are hydrophobic. This means they can pass through the cell membrane to enter cells

53
Q

What is the structure of steroid hormones?

A

Have 4 fused carbon rings. 3 cyclohexane rings (6 carbons) and 1 cyclopentane ring (5 carbons)

54
Q

What is a peptide bond?

A

The covalent bond between 2 amino acids (the monomers of proteins). It forms between the carbon of the carboxyl end of the amino acid and the nitrogen of the amine group. Formed through a condensation reaction.

55
Q

What is a polypeptide?

A

A chain of amino acids formed through a condensation reaction. It will be folded and further bonds formed to turn it into a functional protein. Transation during protein synthesis forms polypeptides.

56
Q

What is denaturation?

A

When a protein is exposed to harsh environmental conditions, a protein can change shape due to weaker bonds breaking. As the function of the protein is linked to the shape, if the shape changes, it will decrease or lose its function.

57
Q

How is a dipeptide made from two amino acids?

A

Dipeptides are formed by a condensation reaction where a hydroxyl group is removed from the carboxyl end of the first amino acid and a hydrogen is removed from the amine end of the second amino acid. The carbon from the carboxyl group forms a peptide bond to the nitrogen of the amine group. The OH and the H combine to form water as a waste product.

58
Q

What is an essential amino acid?

A

An essential amino acid is one that we must eat in their exact form as we have no way of making them. We must obtain them from food because we cannot synthesise them (make them from parts)

59
Q

What are some examples of important proteins in the body?

A
  • Haemoglobin- transports oxygen on red blood cells
  • Digestive- enzymes break down food
  • Collagen and keratin- structural proteins
  • Histones- protein wraps around them
  • Hormones- e.g insulin
60
Q

How do higher temperatures or atypical pH levels impact proteins?

A

Globular proteins are fomed through folds rather than straight chains- folded through many types of bonds including H bonds. At high temperatures or in acidic or alkaline environments the weak bonds break and the protein denatures.

Note: proteins can renature/ rebond when conditiona return to normal so denaturation is often temporary.

61
Q

What is an R group?

A

An additional chain other than the amine and carboxyl group coming down from the central carbon, unique to each amino acid and gives the amino acid its unique properties.

62
Q

What are hydrophobic interactions?

A

The way that non-polar amino acids interact in the presence of water. Non-polar r-groups move inwards away from polar water molecules. When they pull inwards, the r-groups move towards each other.

63
Q

What are disulfide bonds?

A

The amino acid cysteine’s r-group is a sulfur bonded to a hydrogen. If 2 cysteine molecules are near one another the H’s can be removed and the sulfurs can covalently bond to each other. This bond is called a disulfide bond and it is very strong. Disulfide bonds are the strongest bond involved in the tertiary bonding protein structure

64
Q

What is the primary structure of proteins?

A

The specific sequence of amino acids that are covalently bonded together to create a straight, linear chain of amino acids. Protein structure is determined by the DNA code in the gene that codes for the protein. Primary structure can be altered by mutations but is not affected by denaturation.

65
Q

What is the secondary structure of proteins?

A

Folding begins to occur. The amine group of the amino acid has a slight positive charge and the carboxyl group has a slight negative charge. This causes bonds to form between the amino acids in the chain. It is consistent and forms a pattern throughout- alpha helix or beta pleated sheet. It is not directly impacted by mutations but can be lost in denaturation

66
Q

What is the tertiary structure of proteins?

A

Globular proteins have dfferent bonds between r-groups to create a non-uniform and unique set of folds giving it a unique shape. Bonds include ionic bonds between charged r-groups, hydrophobic interactions between non-polar r-groups, hydrogen bonds between polar r-groups, and disulfide bridges between cysteines. Mutations can impact by changing the r-group, and the tertiary structure can denature in extreme environments.

67
Q

What is the quanternary structure of proteins?

A

Sometimes multiple polypeptide chains join together to make one protein. This is the quaternary structure. They use the same types of bonds as tertiary structure but are between r-groups of different polypeptides. Can be conjugated or non-conjugated

68
Q

What is a conjugated protein?

A

A protein that contains at least one non-protein component, e.g heme group on haemoglobin, which is made of iron.

69
Q

What is a non-conjugated protein?

A

A protein that only contains polypeptide subunits

70
Q

What is an alpha helix structure?

A

In an alpha helix, the polypeptide is wound into a helix shape and the bonds form between the turns of the helix.

71
Q

What is a beta pleated sheet structure?

A

The beta pleated sheets are made of sections of polypeptide running in opposite directions and the hydrogen bonds form between the lines giving a pleated shape due to the bond angles.

72
Q

How does the polarity of an amino acid impact their structure within the protein?

A

Each amino acids reactive properties are from the r-group properties. There are 9 non-polar or hydrophobic r-groups, 6 polar r-groups and 5 charged r-groups. The polarity of the r-group determines the quaternary structure of the protein. Often amino acids with non-polar r-groups are in the centre of the cell with polar amino acids on the outside.

73
Q

What is a globular protein?

A

Globular proteins are highly folded proteins that end up with a spherical shape. They often have hydrophobic amino acids in the centre and polar amino acids on the outside making it hydrophilic. Globular proteins are diverse in shape, therefore also in function. They can act as enzymes, hormones, antibodies and in the cell membrane for transport and communication.

74
Q

What is a fibrous protein?

A

Fibrous proteins have long polypeptides that lack tertiary bonds and folding, typically don’t have a consistent secondary structure. Instead, they have a structure where multiple polypeptides are linked with fibres and filaments, and held together with hydrogen bonds. They are generally structural in function.

75
Q

How has cryogenic electron microscopy aided our understanding of protein structure?

A

Proteins cannot be observed by light microscopes and are unclear on electron microscopes. Cryo-electron microscopy involves flash freezing proteins in liquid ethane and taking images using a beam of electrons. Software is then used to develop the image into atoms of proteins that can be visualised, helping us understand protein structure.

76
Q

Describe the structure and function of collagen

A

Collagen are fibrous proteins with a quaternary structure of 3 polypeptides held together. Made of repeating sequence of glycine- hydroxyproline- x (x varies based on where it is in the body). It creates a strong and elastic fibre useful for building tendons, ligaments and cartilage etc.

77
Q

Describe the structure and function of insulin

A

Insulin is made of two polypeptide chains- one of 30 amino acids and one of 21. 2 chains held together by r-bond interactions, including disulfide bridges. The specific shape is crucial to bind to insulin receptors for its function as a hormone involved in glucose uptake

78
Q

Describe the structure and function of haemoglobin

A

Haemoglobin is the protein found on the surface of red blood cells. Oxygen binds to the heme group and is carried arount the body. Contains 2 different types of polypeptides- alpha and beta chain. 2 alpha globin and 2 beta globin in each haemoglobin. Sections of alpha helices are seen in the chain. Each chain has a complex tertiary structure and then are held together by bonds to form a quaternary structure. Also contains 4 heme groups that facilitate oxygen binding.

IB Biology (9 decks)

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