ATP, Inorganic Ions And Water

Question 1

What is energy required for in all organisms

Answer 1

In anabolic reactions – building larger molecules from smaller molecules

To move substances across the cell membrane (active transport) or to move substances within the cell
In animals, energy is required:

For muscle contraction – to coordinate movement at the whole-organism level
In the conduction of nerve impulses, as well as many other cellular processes

Question 2

What does ATP stand for and what does it do?

Answer 2

ATP or Adenosine Tri Phosphate, is an immediate source of energy for biological processes. Metabolic reactions in cells must have a constant, steady supply of ATP.

Question 3

What is ATP?

Answer 3

ATP is another type of nucleic acid and hence it is structurally very similar to the nucleotides that make up DNA and RNA
It is a phosphorylated nucleotide

ATP is described as a universal energy currency
Universal: It is used in all organisms
Currency: it can be used for different purposes (reactions) and is reused countless times

Question 4

What can the nucleotide adenosine combine with?

Answer 4

Adenosine (a nucleoside) can be combined with one, two or three phosphate groups
One phosphate group = adenosine monophosphate (AMP)
Two phosphate groups = adenosine diphosphate (ADP)
Three phosphate groups = adenosine triphosphate (ATP)

Question 5

What type of molecule is ATP

Answer 5

ATP is a small and soluble molecule that provides a short-term store of chemical energy that cells can use to do work

It is vital in linking energy-requiring and energy-yielding reactions

Question 6

Why does atp play a significant role in energy transfer

Answer 6

ATP contains three phosphate ions that play a significant role in energy transfer and this biological molecule is essential to metabolism, which is all the chemical reactions that take place in a cell.

Question 7

The energy released by ADP

Answer 7

breaking one of the bonds between the inorganic phosphate groups in a hydrolysis reaction, a small amount of energy is released to the surroundings, which can be used in chemical reactions.
This is why ATP is an immediate energy source- only one bond has to be hydrolysed to release energy.

ATP can also transfer energy to different compounds. The inorganic phosphate released during the hydrolysis of ATP can be bonded onto different compounds to make them more reactive. This is known as phosphorylation, and this happens to glucose at the start of respiration to make it more reactive.

Question 8

The products of the hydrolysis of atp

Answer 8

Hydrolysis of ATP to adenosine diphosphate (ADP) and an inorganic phosphate group (Pi) is catalysed by the enzyme ATP hydrolase sometimes called ‘ATPase’

Question 9

The hydrolysis of ATP can be coupled to energy-requiring reactions within cells such as:

Answer 9

The active transport of ions up a concentration gradient

Enzyme controlled reactions that require energy

Muscle contraction and muscle fibre movement

Question 10

What is the other product of the hydrolysis of ATP other than ADP?

Answer 10

The inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds, often making them more reactive

Question 11

How is atp synthesised

Answer 11

Atp is made during respiration from ADP, adenosine diphosphate, by the addition of an inorganic phosphate via a condensation reaction and using the enzyme ATP synthase.

Question 12

Types of ATP synthesis

Answer 12

Types of ATP synthesis
ATP is made during the reactions of respiration and photosynthesis
All of an animal’s ATP comes from respiration

ATP can be made in two different ways:
Substrate-linked phosphorylation (occurs in the glycolysis stage of respiration)

Chemiosmosis (occurs in the electron transport chain stage of respiration)

Question 13

Why is there a separation of charge in water?

Answer 13

This separation of charge due to the electrons in the covalent bonds being unevenly shared is called a dipole. When a molecule has one end that is negatively charged and one end that is positively charged it is also a polar molecule

Water is a polar molecule

Question 14

What properties of water molecules do hydrogen bonds contribute to

Answer 14

An excellent solvent – many substances can dissolve in water
A relatively high specific heat capacity
A relatively high latent heat of vaporisation
Water is less dense when a solid
Water has high surface tension and cohesion
It acts as a reagent

Question 15

Hydrogen bonds in water molecules

Answer 15

Hydrogen bonds form between water molecules
As a result of the polarity of water hydrogen bonds form between the positive and negatively charged regions of adjacent water molecules

Hydrogen bonds are weak, when there are few, so they are constantly breaking and reforming. However when there are large numbers present they form a strong structure

Question 16

Water as a solvent

Answer 16

charged molecules dissolve in water due to the fact water is dipolar.
The slight positive charge on hydrogen atoms will attract any negative ions solutes and the slight negative charge on the oxygen atoms of water will attract any positive ions in solutes.
These polar molecules are often described as hydrophilic, meaning they are attracted to water.
Non-polar molecules, such as lipids, cannot dissolve in water and are therefore described as hydrophobic- they are repelled by water.

Question 17

What is specific heat capacity

Answer 17

Specific heat capacity is a measure of the energy required to raise the temperature of 1 kg of a substance by 1oC

Question 18

Why does water have a high specific heat capacity

Answer 18

The high specific heat capacity is due to the many hydrogen bonds present in water. It takes a lot of thermal energy to break these bonds and a lot of energy to build them, thus the temperature of water does not fluctuate greatly

Water has a high specific heat capacity of 4200 J / Kg oC

Question 19

What is the advantage for living organisms that water has a high specific heat capacity?

Answer 19

is useful to organisms as it means the temperature of water remains relatively stable, even if the surrounding temperature fluctuates significantly.

Therefore, internal temperatures of plants and animals should remain relatively constant despite the outside temperature, due to the fact a large proportion of the organism is water.

is important so that enzyme do not denature or reduce in activity with temperature fluctuations.

Question 20

The role of water in the blood plasma

Answer 20

helping to maintain a fairly constant temperature

As blood passes through more active (‘warmer’) regions of the body, heat energy is absorbed but the temperature remains fairly constant

Water in tissue fluid also plays an important regulatory role in maintaining a constant body temperature

Question 21

Adavntage of waters high latent heat of vapourisation

Answer 21

is advantageous to organisms as it means that water provides a significant cooling effect. For example, when humans sweat they release water onto their skin.
Large amounts of heat energy from the skin is transferred to the water to evaporate it, and therefore removing a lot of heat and cooling the organism.

Question 22

What is cohesion

Answer 22

Hydrogen bonds between water molecules allows for strong cohesion between water molecules

Cohesion is the term used to describe water molecules ‘sticking’ together by hydrogen bonds.

Due to water molecules sticking together, when water moves up the xylem in plants due to transpiration it is as a continuous column of water. This is advantageous as it is easier to draw up a column rather than individual molecules.

Question 23

Cohesion and surface tension

Answer 23

Cohesion also provides surface tension to water.
This enables small invertebrates to move and live on the surface, providing them a habitat away from predators within water.
these hydrogen bonds occur between the top layer of water molecules to create a sort of film on the body of water (this is what allows insects such as pond skaters to float)

Question 24

What is adhesion

Answer 24

Water is also able to hydrogen bond to other molecules, such as cellulose, which is known as adhesion

This also enables water to move up the xylem due to transpiration

Question 25

What is an ion

Answer 25

An ion is an atom (or sometimes a group of atoms) that has an electrical charge An ion that has a +ve charge is known as a cation An ion that has a -ve charge is known as an anion

Question 26

What is an inorganic ion

Answer 26

An inorganic ion is an ion that does not contain carbon Inorganic ions play an important role in many essential cellular processes

Question 27

When do inorganic ions occur

Answer 27

Inorganic ions occur in solution in the cytoplasm and body fluids of organisms Some occur in high concentrations and others in very low concentrations The concentration of certain ions can fluctuate and can be used in cell signalling and neuronal transmission

Question 28

Hydrogen ions (H+)

Answer 28

Hydrogen ions are protons The concentration of H+ in a solution determines the pH There is an inverse relationship between the pH value and the hydrogen ion concentration The more H+ ions present, the lower the pH (the more acidic the solution) The fewer H+ ions present, the higher the pH (the more alkaline the solution)

Question 29

Why is the concentration of (H+) ions important for enzyme controlled reactions.

Answer 29

The maintenance of this normal pH is essential for many of the metabolic processes that take place within cells Changes in pH can affect enzyme structure For example, abnormal levels of hydrogen ions can interact with the side-chains of amino acids and change the secondary and tertiary structures of the proteins that make up enzymes This can cause denaturation of enzymes

Question 30

Why are iron ions essential for binding oxygen

Answer 30

Haemoglobin is the large protein in red blood cells that is responsible for transporting oxygen around the body Haemoglobin is made up of four polypeptide chains that each contain one Fe2+ This Fe2+ is a key component in haemoglobin as it binds to oxygen Myoglobin in muscles functions in a similar way (it is an oxygen-binding protein) but is only made up of one polypeptide chain (containing one Fe2+)

Question 31

The different versions of iron ions

Answer 31

There are actually two versions of iron ions (known as oxidation states) Iron (II) ions, also known as ferrous ions (Fe2+) Iron (III) ions, also known as ferric ions (Fe3+)

Question 32

How are iron ions essential for the transfer of electrons

Answer 32

Iron ions are an essential component of cytochromes (that are themselves a component of electron transport chains) Cytochrome c contains an iron ion that is essential to its function During the electron transport process, this iron ion switches between the Fe3+ and Fe2+ oxidation states, which allows for electrons to be accepted and donated

Question 33

What roles does the Na+ ion have?

Answer 33

Na+ is required for the transport of glucose and amino acids across cell-surface membranes (e.g. in the small intestine) Na+ is also required for the transmission of nerve impulses, muscle contraction and regulating fluid in the body

Question 34

Na+ role in co-transport

Answer 34

Glucose and amino acid molecules can only enter cells (through carrier proteins) alongside Na+ This process is known as co-transport First, Na+ is actively transported out of the epithelial cells that line the villi The Na+ concentration inside the epithelial cells is now lower than the Na+ concentration in the lumen of the small intestine Na+ now re-enters the cells (moving down the concentration gradient) through co-transport proteins on the surface membrane of the epithelial cells, allowing glucose and amino acids to enter at the same time

Question 35

Phosphate Ions PO43- as essential components of DNA, RNA and ATP

Answer 35

In DNA and RNA, the phosphate groups allow individual nucleotides to join up (to form polynucleotides) In ATP, the bonds between phosphate groups store energy These phosphate groups can be easily attached or detached When the bonds between phosphate groups are broken, they release a large amount of energy, which can be used for cellular processes

Question 36

Where else are phosphate ions found

Answer 36

Phosphates are also found in phospholipids, which are key components of the phospholipid bilayer of cell membranes

Question 37

Ca2+ being essential in the movement of organisms:

Answer 37

Ca2+ is essential in the movement of organisms: In synapses, calcium ions regulate the transmission of impulses from neurone to neurone

Question 38

Ca2+ also stimulating muscle contraction

Answer 38

When an impulse reaches a muscle fibre, Ca2+ is released from the sarcoplasmic reticulum This Ca2+ binds to troponin C, removing the tropomyosin from myosin-binding sites on actin This allows actin-myosin cross-bridges to form when the muscle fibre contracts

Question 39

What can Ca2+ ions help regulate

Answer 39

protein channels, which affects the permeability of cell membranes

Question 40

Why are Ca2+ ions these ions key regulators in many biological reactions

Answer 40

Many enzymes are activated by Ca2+

Question 41

Potassium ions K+

Answer 41

- important to generate nerve impulses, muscle contraction and regulating fluid balance in the body - activating essential enzymes needed for photosynthesis and plant cells.

Question 42

Hydrogen ions (H+)

Answer 42

Affects PH of substances (more conc = more acidid) Also important for photosynthesis reaction that oocur in thylkaloid membranes inside chloroplasts

Question 43

Ammonium (NH4+)

Answer 43

Absorbed from the soil by plants and is an important source of nitrogen (which is then used to make eg amino acids nucleic)

Question 44

Hydrogen carbonate (HCO3-)

Answer 44

Acts as a buffer which helps maintain the PH of blood

Question 45

Chloride (Cl-)

Answer 45

Involved in the chloride shift which helps maintain the ph of blood during gas exchange Acts as a cofactor for the enxyme amylase Involves in some nerve pulses

Question 46

Hydroxide (OH-)

Answer 46

Affects ph pf substances (more concentrated = more alkali)

Question 47

Explain 5 properties of water that is useful in living organism

Answer 47

A metabolite in condensation/hydrolysis/ photosynthesis/respiration; A solvent so (metabolic) reactions can occur A solvent so allowing transport of substances; High (specific) heat capacity so buffers changes in temperature; Large latent heat of vaporisation so provides a cooling effect (through evaporation); Cohesion (between water molecules) so supports columns of water (in plants); Cohesion (between water molecules) so produces surface tension supporting (small) organisms;

Question 48

State and explain property of water that can help buffer changes in temperature

Answer 48

High specific heat capacity Can gain loss a lot of heat / energy without changing the state

Question 49

What is atp compromised of

Answer 49

Adenine a nitrogenous base (meaning a base that contains nitrogen) • Ribose (a pentose sugar) • Three inorganic phosphate groups.

Question 50

Water as a metabolite

Answer 50

Water in involved in may reactions, such as photosynthesis, hydrolysis and condensation reactions. This is one reason why it is essential that approximately 90% of the plasma in blood is water and the cytoplasm in cells is largely composed of water.

Question 51

Properties of ATP - releasing energy in a small manageble way

Answer 51

means that cells do not over heat from wasted heat energy and cells are less likely to run out of resources. In comparison to glucose, this would release large amounts of energy that could result in wasted energy.

Question 52

ATP properties - small and solunle

Answer 52

transported around the cell. ATP can move around the cytoplasm with ease to provide energy for chemical reactions within the cell. This is a property ATP has in common with glucose

Question 53

Atp properties - only one bond is hydrolysed to release energy

Answer 53

is why energy release is immediate. Glucose would need several oonds to be bronch down to reicise ans energy.

Question 54

Atp properties - can transfer enetrgy

Answer 54

It can transfer energy to another molecule by transferring one of its phosphate groups. ATP can enable phosphorylation, making other compounds more reactive. Glucose cannot do this, as it does not contain phosphate groups.

Question 55

Atp properties - cant pass out the cell

Answer 55

can't pass out of the cell, the cell always has an immediate supply of energy. ATP cannot leave the cell, where as glucose can. This means that all cells have a constant supply of ATP or ADP +Pi, but a cell can run out of giucose

Question 56

What type of molecule is a water molecule

Answer 56

Water is a dipolar molecule (di meaning two and polar referring to charges). Water has an unevenly distributed charge due to the fact that the oxygen atom is slightly negative, and the hydrogen atoms are slightly positive.

Question 57

What are the five key properties of water

Answer 57

It is a metabolite (e.g. in condensation and hydrolysis reactions). An important solvent in reactions. Has a high heat capacity, it buffers temperature. Has a large latent heat of vaporisation, providing a cooling effect with loss of water through evaporation. Has strong cohesion between water molecules; this supports water columns and provides surface tension

Question 58

What does it mean when water has a large latent heat of vapourisation

Answer 58

This means that a lot of energy is required to convert water in its liquid state to a gaseous state. This is due to the hydrogen bonds, as energy is needed to break the hydrogen bonds between water molecules to turn it into a gas.