Biomolecules

What is water made up of?

• Water is the substance in which all metabolic reactions take place in cells and in which all substances are transported around the body 

• Water is composed of atoms of hydrogen and oxygen

  • One atom of oxygen combines with two atoms of hydrogen by sharing electrons; this is covalent bonding

How do water molecules have a dipole nature?

• The sharing of the electrons is uneven between the oxygen and hydrogen atoms

  • The oxygen atom attracts the electrons more strongly than the hydrogen atoms, resulting in a weak negatively charged region on the oxygen atom (δ^-) and a weak positively charged region on the hydrogen atoms (δ⁺)

• This separation of charge due to the electrons in the covalent bonds being unevenly shared is called a dipole

How is water a polar molecule?

As a water molecule has one end that is positively charged and one end that is negatively charged

why do water molecules flow past each other in a liquid state?

• Hydrogen bonds form between the positive and negatively charged regions of water molecules as a result of the polar nature of water

  • Hydrogen bonds are weak when they are few in number, so they are constantly breaking and reforming; this means that water molecules flow past each other in a liquid state

What is cohesion and adhesion?

• Cohesion is the attraction of water molecules to each other ( hydrogen bonds between water molecules )

• Adhesion is the attraction of water molecules to molecules of a different substance( hydrogen bonds between water and other molecules )

How does water’s solvent properties make it good at transporting substances?

• As water is a polar molecule many ions, e.g. sodium and chloride ions, and covalently bonded polar substances, e.g. glucose, will dissolve in it

  • Water molecules surround charged particles; the positive parts of water are attracted to negatively charged particles and the negative parts of water are attracted to positively charged particles

  • The surrounded molecules break apart e.g. sodium chloride molecules break into sodium ions and chloride ions

  • The ions surrounded by water molecules have dissolved

• This allows chemical reactions to occur within cells as the dissolved solutes are more chemically reactive when they are free to move about

• Metabolites ( a molecule that takes part in a metabolic reaction ) can be transported efficiently in a dissolved state

What elements do carbohydrates contain?

Carbon (C), hydrogen (H), and oxygen (O).

Why is carbon important in organic compounds?

Carbon can form covalent bonds with many elements (including C, H, O, N, S), making compounds stable and able to form chains or rings.

What kinds of structures can carbon form in molecules?

Straight chains, branched chains, or rings.

What is a monomer and a polymer?

A monomer is a small single subunit; many monomers join via polymerisation to form a polymer.

What are the three main types of carbohydrates?

Monosaccharides, disaccharides, and polysaccharides

What are Monosaccharides?

the monomers of carbohydrate; they can join together to make carbohydrate polymers

Monosaccharides are simple carbohydrates

Monosaccharides are sugars

What are the four monosaccharides you need to know?

α ( alpha ) - Glucose , β (beta) - Glucose,

Fructose , Galactose

glucose is a hexose sugar

What is the structure and role of alpha glucose?

• The main substrate for respiration ( the main molecule that is used (broken down) in cellular respiration to release energy.)

• the form is which carbohydrate is transported in mammalian blood

• forms the polysaccharides starch and glycogen  

What is the structure and role of beta glucose?

Forms the polysaccharide cellulose 

What is the role of Fructose? 

• found in nectar and many fruits, it is sweeter than glucose, helps attracts animals for fruit dispersal , with glucose forms disaccharide sucrose

What is the role of galactose?

With glucose, form disaccharide lactose

What is the function of Monosaccharides?

The main function of monosaccharides is to store energy within their bonds

• When the bonds are broken during respiration, energy is released

• The structure of glucose is related to its function as the main energy store for animals and plants 

  • It is soluble so can be transported easily

  • It has many covalent bonds which store energy

• Monosaccharides can combine through condensation reactions to form larger carbohydrates

• Some monosaccharides are used to form long, structural fibers, which can be used as cellular support in some cell types

What are Disaccharides?

A type of carbohydrates formed when 2 monosaccharides join together via condensation reactions

What are Condensation and Hydrolysis reactions?

Condensation reaction: the joining together of molecules through the removal of water

Hydrolysis reaction: the splitting of molecules through the addition of water

What are the three disaccharides you need to know?

Maltose:

glucose + glucose —> maltose+ water

Lactose:
glucose + galactose —> lactose + water 

Sucrose:
glucose + fructose —> sucrose + water

—> joined by a glycosidic bond

Draw out the condensation reaction that forms maltose

Draw out the hydrolysis reaction that separates maltose

What is the function of disaccharides?

• to provide the body with a quick-release source of energy

  • Disaccharides are made up of two sugar molecules so they're easily broken down by enzymes in the digestive system into their respective monosaccharides and then absorbed into the bloodstream

• Due to the presence of a large number of hydroxyl groups, disaccharides are easily soluble in water

  • These hydroxyl groups form hydrogen bonds with the water molecules when dissolved in aqueous solutions

• Just like monosaccharides they are sweet in taste

  • Sucrose, also known as table sugar, is an example

What are polysaccharides?

are carbohydrate polymers, repeated chains of many monosaccharides joined by glycosidic bonds in a condensation reaction

what are the three polymers you need to know?

Starch, Glycogen , Cellulose

Name the two polymers starch is made up of 

Amylose and Amylopectin

Name the Monomers that make up starch, Cellulose and Glycogen  

Starch: Alpha glucose 

Cellulose: Beta glucose

Glycogen: Alpha glucose 

What are the bonds between monomers in amylose and amylopectin?

• 1-4 glycosidic bonds in amylose

• 1-4 and 1- 6 glycosidic bonds in amylopectin

What are the bonds between monomers in cellulose?

1-4 glycosidic bonds

What are the bonds between monomers in glycogen?

1-4 and 1-6 glycosidic bonds

what is the function of Starch 

Store of glucose as an energy reserve

What is the function of Cellulose?

Structural strength —> make up cell wall 

what is the function of glycogen?

Store of glucose

Where are these polysaccharides located?

Cellulose: In plants , cell wall

Starch: Stored as granules in plastids ( double-membrane-bound organelles found in plant and algal cells ) —> in plants

Glycogen: animals, mainly in muscle and lever cells

Explain the structure of Starch

• made of two polymers:

• Amylose: an unbranched, long chain that coils into a helix

• Amylopectin: a branched molecule

Explain the structure of cellulose 

-polymer forms long straight chain 

-chains are held in parallel  by many hydrogen bonds to form fibrils

-Microfibrils: strong threads made of long cellulose chains joined together by hydrogen bonds forming cross linkages 

Explain the structure of Glycogen

A highly branched molecule

• has more 1-6 bonds than starch 

Explain how the structure of starch leads to its function 

• helix can compact to fit a lot of glucose in a small space

• branched structures increases surface area for rapid hydrolysis back to glucose, which is released rapidly

• large and Insoluble →doesn't diffuse easily out of cells,  won’t affect water potential, so won't affect osmosis 

• Amylopectin is more soluble than amylose 

Explain. how the structure of cellulose leads to its function 

• Many hydrogen bonds provide collective strength

• insoluble → won’t affect water potential

Explain how the structure of  Glycogen leads to its function

• Branched structure  increases surface area for rapid hydrolysis back to glucose 

• insoluble → won’t affect water potential

What is the glycosidic bond?

When two hydroxyl (OH) groups on different monosaccharides interact to form a strong covalent bond called a glycosidic bond 

• one water molecule is always released 

• broken when water is added ( hydrolysis)