Test 1

Question 1

Living organisms definition and explanation

Answer 1

Living organisms are open systems that survive by transforming energy and decreasing their local entropy to maintain homeostasis.

The transformation of energy is taking in food as fuel to react it with oxygen to create energy and CO2.

Open systems are always exchanging things.

Decreasing their local entropy to maintain homeostasis → creating order requires energy - we require information DNA. homeostasis means keeping the same.

Question 2

What is the correlation between structure and function?

Answer 2

often the structure corresponds to the job that it needs to do.

Question 3

The two types of science and definitions

Answer 3

Discovery - collecting data and trying to look for patterns.

Hypothesis - begins with an explanation that is tested.

Question 4

The scientific method

Answer 4

observation, question, hypothesis, prediction, experiment, results.

Has to have a control, only change one variable and consider ethics.

Question 5

Reductionism definition

Answer 5

breaking down the interaction into their simplest parts and then adding levels of complexity.

Remember that a cell will behave differently in a test tube than in its normal environment.

Question 6

Digoxin drug

Answer 6

used for treating heart disease. Someone with heart disease recovered quickly after drinking a herbal tea with foxglove. They were able to isolate the chemical structure that was active in treating heart disease.

Question 7

Taxol drug

Answer 7

used to treat ovarian cancer.

Discovery based science - testing many samples and tested whether the compounds killed the cancer cells.

Found that the extract from the bark of a pacific yew tree was cytotoxic and could kill the cancer cells.

Question 8

Influenza drug Tamiflu and Zanamivir

Answer 8

Influenza will attack the sialic acid in our cells.

Made a drug targeting the particular enzyme but will make it look like the natural substrate with slight changes.

Hypothesising that adding something on doing something else - may be an inhibitor.

Rational drug design - more specific approach rather than testing everything out there.

Question 9

Penicillin

Answer 9

Alexander Fleming was plating dishes and saw that there was a fungus growing with was inhibiting the growth f the bacteria on the plate - serendipity. Found a mouldy cantaloupe which made 200 times more penicillin than the fungi Fleming found.

Question 10

What is the evidence? How can we trust the science? 6 points.

Answer 10

Where did the research come from?

Are there conflicts of interest?

Is it reviewed and repeatable?

Are appropriate conclusions being drawn?

Correlation vs. causation

Is it good science?

Question 11

What elements occur mostly in humans?

Answer 11

Oxygen, carbon, hydrogen, nitrogen.

Question 12

Atoms (protons and electrons)

Answer 12

Elements have a different number of protons and electrons. For every proton there will be an electron. Slight differences in the protons will give elements different properties.

Question 13

Covalent bonds

Answer 13

Covalent bonds are the sharing of electrons - atoms are most stable with 2 electrons on the inner shell and 8 on the outside shell.

The atoms want more electrons to become stable.

Question 14

Non polar bonds

Answer 14

a bond where the electrons are shared equally between two atoms.

Question 15

Polar bonds

Answer 15

where electrons forming the bond are unequally distributed.

Question 16

Electronegativity

Answer 16

the tendency of an atom to attract a bonding pair of electrons.

Question 17

Unequal electron sharing results in….

Answer 17

polarity. If there is an electronegative atom they tend to steal the charge so the electrons hang around that atom which gains a negative charge and the other atom has a slightly positive charge. Results in polar bonds.

Question 18

How many bonds on hydrogen, oxygen, carbon and nitrogen?

Answer 18

1, 2, 3, 4

Question 19

Ionic bonds

Answer 19

the complete transfer of valence electrons between atoms. Generates two oppositely charged ions.

Question 20

Difference between covalent and ionic bonds

Answer 20

Covalent bonds share electrons, ionic bonds transfer electrons.

Question 21

Weak interaction in biology

Answer 21

two atoms like to be close to each other but if they get too close they start pushing apart and if they get too far apart they lose their force. With just the right amount of closeness they form a very stable arrangement. Weak interactions can accumulate.

Question 22

How do geckos stick to walls?

Answer 22

Van der waals forces

Question 23

Hydrogen bonds

Answer 23

form when we have lots of water molecules.

Where a hydrogen atom is covalently bound to an electronegative atom (nitrogen or oxygen).

Different atoms can accept a different number of hydrogen bonds.

Question 24

Surface tension of water molecules

Answer 24

surface tension is the force of hydrogen bond molecules holding the water molecules together so that insects can walk across the top of it.

Water droplets on leaves occur when the water diffuses out the tree and the water molecules gets dragged up by hydrogen bonds and as the water leaves the leaves all are attached by tiny chains of hydrogen bonds so that it pulls everything up.

Question 25

How does ice float?

Answer 25

unusually in water the solid floats on top due to the hydrogen bonds constantly breaking and reforming. The bonds interact with water and then they break and interact with another water and so on. When it turns solid - everything slows down - and we get a lattice pattern. The water molecules interact together to form a neat arrangement. They separate everything holding each other together but also pushing at the same time. Because they are further apart that makes it less dense so the ice floats on top.

Question 26

Ethanol vs. water

Answer 26

Ethanol only has one hydrogen that can interact with other atoms whereas water can accept and a donate a couple hydrogen bonds. Ethanol is a little bit bigger in size. Ethanol doesn't freeze in the freezer because it takes more effort to get the ethanol molecules to stick together as opposed to water. Water has a high melting point. Boiling is separating the molecules apart. Ethanol boils faster because water molecules tend to stick together. Water has a higher boiling point than ethanol.

Question 27

Why can water hold lots of energy?

Answer 27

due to all the hydrogen bonds in the water. You can get bad burns from steam or water because there is a lot of energy involved. To heat 1 kg of water it requires 4168kj. Steel has a relatively low heat capacity so will heat faster than the water in the pot - only requires a tenth of the energy to heat a kg of steel → 450kj, compared to heating water.

Question 28

Why does water have a high heat capacity?

Answer 28

due to hydrogen bonding: As we are absorbing a lot of heat, hydrogen bonds are breaking apart. As things are cooling down the hydrogen bonds start forming - this means that a lot of energy is stored.

Question 29

Evaporative cooling

Answer 29

the process whereby water molecules start transitioning from a gas to a liquid. There are different speeds of water molecules - some are more active and some are less active. As water starts evaporating the really high energy water molecules start leaving from the system (the temperature starts to drop) and the ones below have a lower average energy. We can release water by sweating.

Question 30

Why is water a good solvent?

Answer 30

because of its small size and polarity: putting salt in water breaks the hydrogen bonds easily. Solvents: the capability to dissolve other substances. This is important for our biological system because blood, oxygen, carbon dioxide, sugars, amino acids and ions are able to dissolve in water - we are 70% water.

Question 31

Why can water interact with lots of things?

Answer 31

Because it doesn't have a net charge.

Question 32

How can large molecules dissolve in water?

Answer 32

if they have ionic or polar regions.

Question 33

Diffusion

Answer 33

A high concentration of a molecule overtime will diffuse around in a low concentration but uniformly spread out.

Question 34

Osmosis

Answer 34

when we have a high concentration of things inside a cell that wont diffuse out then water will try come into the cell to dilute everything - we get a movement of water from one side to the other.

Question 35

Red blood cells and water potential.

Answer 35

Our blood is reasonably salty to stop cells from losing too much water. In a very salty solution - hypertonic solution - all the water diffuses out of the cells due to the high concentration inside the cell, outside the cell to the very salty concentration and the cell starts to shrivel up. In a water solution with no salts all the water rushes into the cell to dilute everything and the pressure builds up and the cells bursts - hypotonic solution.

Question 36

Polymers

Answer 36

Polymers are repeating units of molecules. They have a hydroxyl group at one end and a hydrogen group at the other. Polymers help manage water potential as joining the molecules together reduces osmotic potential.

Question 37

What happens when you add a monomer onto a polymer?

Answer 37

A monomer added onto the end of a polymer is a dehydration reaction because we are losing water. If we do the reverse this is a hydrolysis reaction → water comes and breaks the bond.

Question 38

Chemical functionality

Answer 38

A negatively charged region on one molecule and there can be a positively charged region on another molecule. We might have a hydrogen bond acceptor on one side and a hydrogen bond donor on the other.

Question 39

How can molecules recognise each other?

Answer 39

3D shape and chemical functionality.

Question 40

Lipids

Answer 40

Lipids are hydrocarbons. Fat is stored in the adipose cells.

Question 41

Fatty acids

Answer 41

Differ in the length of the chain. They have a carboxylic acid group at one end.

Question 42

Saturated fats

Answer 42

Palmatic acids and stearic acids are saturated fats. Saturated fats have all the hydrogens - unsaturated fats don't. only single bonds tend to be solid at room temperature

Question 43

Mono-saturated

Answer 43

One double bond

Question 44

Poly-unsaturated

Answer 44

Multiple double bonds.

Question 45

The difference between saturated and unsaturated fats.

Answer 45

saturated fats don't have double bonds, unsaturated fats do.

Question 46

Margarine is a...

Answer 46

Trans fat - hydrogenation

Question 47

Cis-fatty acids

Answer 47

Unsaturated fatty acids - hydrogen bonds are in a CIS transformation in which they both point to the same direction.

Question 48

Most fats are stored as...

Answer 48

Triacylglycerides. Which are three fatty acids stuck to a glycerol head unit in the adipose tissue.

Question 49

Lipids in membranes:

Answer 49

Only have two fatty acids attached and at the other end is a phosphate and a choline. Non polar and hydrophobic. Useful for providing an interface between two water regions. Phospholipids can interact with water but also have a greasy centre.

Question 50

Simple carbohydrates - structure

Answer 50

Length of carbon chains Distinction of aldose where chemical functionality is at the end and a ketose where the chemical functionality is somewhere in the middle. Structural isomers - same chemical arrangement but different 3D shape.

Question 51

Simple Carbohydrates - difference between glucose and galactose.

Answer 51

When the molecules are put into a ring structure the hydroxyl groups are pointing down in glucose and up in galactose.

Question 52

What makes a disaccharide?

Answer 52

Two monosaccharides stuck together by a dehydration reaction. By glycosidic linkages

Question 53

Fructose - sweetness

Answer 53

Fructose binds to our taste receptor proteins and the proteins can tell whether the hydroxyl group points up or down because it elicits the sweet taste in our mouth.

Question 54

How can we make a new artificial sweetener?

Answer 54

discovery by trying to lick different compounds and seeing if they are sweet. Discovery = screening. If we know the exact molecular arrangement of our taste bud receptor then we can design a compound that has a particular chemical functionality that can bind to the taste receptor.

Question 55

Saccharin - artificial sweetener

Answer 55

the guy had an accident in the lab, when he was eating a piece of bread he noticed a sweet taste on his fingers so he went back to the lab and licked some of the glassware that he was working with, he discovered that the compound he was working with was really sweet discovered by dumb luck

Question 56

Sodium Cyclamate

Answer 56

he put his cigarette down on the bench and then picked it up and noticed a sweet taste. discovered by accident.

Question 57

Aspartame

Answer 57

Noticed a sweet taste and the compound he was working on happened to be really sweet. Three amino acids joined together. Anti-ulcer drug. Turning pages and licking his finger and noticed a sweet taste.

Question 58

Sucralose

Answer 58

Isolating his compound and the boss asked him to test the properties but he thought he meant taste the properties.

Question 59

polysaccharides are... in plants and animals

Answer 59

energy stores. In plants long chains of glucose - starch for stability - plants don't need to run away. In animals - glycogen with free ends - branches - it isn't stable. We can break down the glycogen quickly in an emergency.

Question 60

Cellulose vs starch as a structural polysaccharide.

Answer 60

strach has an alpha linkage and cellulose has a beta linkage. humans can break down starch but not glucose because of the different linkages.

Question 61

difference between cellulose and starch

Answer 61

Hydrogen bonds - cellulose hydrogen bonds between the chains form microfibrils. starch has long filaments but limited interactions between the filaments since its one long line.

Question 62

Nitrogen attached to a hydrogen is... what bond? hydrophillic?

Answer 62

polar covalent bond = hydrophilic - like to interact with water.

Question 63

Acid group

Answer 63

some time we might lose the proton and the acidic group might have a negative charge. Lose a proton.

Question 64

Amino group

Answer 64

often acts as a base and will sometimes pick up an extra hydrogen and a corresponding positive charge. can start accepting a proton.

Question 65

Amino acid - peptide bond

Answer 65

add two amino acids together a dehydration reaction will occur and one hydrogen and water will be lost to make a particular link called a peptide bond. it has an amino end and an acid end

Question 66

Strcuture of Alpha helices

Answer 66

Chain forming a spiral called a helix. they spiral around each other so there is a hydrogen bond in the middle to lock the chain together. Hydrogen bond acceptors and donors find a partner everything is held together between the oxygen and hydrogen.

Question 67

parallel beta sheets

Answer 67

polarity with an acid end and an amino end going in the same direction so side chains are interacting.

Question 68

antiparallel beta sheets

Answer 68

the acid end and amino end are going in opposite directions so the side chains are not interacting.

Question 69

Sulfurs can form a...

Answer 69

disulphide bond - covalent bond - really strong.

Question 70

Protein unfolding

Answer 70

Boiling an egg - heat it up which will break the hydrogen bonds. adding salt and vinegar will break ionic interactions.

Question 71

Enzymes act as

Answer 71

catalysts.

Question 72

The roles of proteins

Answer 72

Strength and stability - collagen motors - create movement transporters and messengers - move things around the body. receptors - get things and out of the cell

Question 73

nucleic acids

Answer 73

Provide the info that means we can make a particular sequence of amino acid. Sequence of protein is determined by sequence of dna.

Question 74

DNA and RNA nucleotides

Answer 74

DNA and RNA have different nucleotides Sugar, phosphate and nitrogenous base. DNA in the bases has thymine where as in rna it has uracil. DNA has lost its hydrogen, RNA has not.

Question 75

DNA hydrogen bonds

Answer 75

form between the different bases.

Question 76

RNA structure

Answer 76

single stranded

Question 77

Lipids elements, polarity and does it like water?

Answer 77

C,H, Non polar and hydrophobic

Question 78

Carbohydrates elements, polarity and does it like water?

Answer 78

C,H,O hydrophilic

Question 79

Proteins Elements, do they like water?

Answer 79

C,H,O,N hydrophobic and hydrophilic depending on the side chain

Question 80

Nucleic acids Elements, do they like water?

Answer 80

C, H, O, N - phosphate added and a little bit of hydrophobic and hydrophilic.

Question 81

ATP

Answer 81

is a nucleotide. has a sugar, base and phosphate. three negatively charged regions tuck together. breaking the bond releases energy. we go from the 3 phosphates to the di-phosphates.

Question 82

How does ATP hydrolysis power motor proteins?

Answer 82

ATP binds to the motor protein, gets hydrolyzed, releases a phosphate and powers some form of the conformational change.

Question 83

How do we store our energy?

Answer 83

As fats and lipids.

Question 84

Why are fats a good storage for ATP?

Answer 84

Can hold twice as much energy as proteins or carbs. Carbohydrates are already oxidised whereas fats are a better store because they are already reduced. Fats are non-polar and can be stored close together.

Question 85

Where are carbs stored?

Answer 85

Carbs are stored as glycogen in the liver and muscles.

Question 86

Burning fats and exercise

Answer 86

At higher intensity workouts we will generally be burning carbs rather than lipids. Once we start exercising glycogen will start dropping. Sprint - using ATP reserves. Don't get the chance to burn anything else. Light exercises - short duration. Start off burning lipids, might start burning glycogen (carbs) as the pace increases.

Question 87

examples where structure is related to function

Answer 87

Lipids in membranes. Shape of a protein - enzymes.

Question 88

draw two water molecules with charge distribution shown and a hydrogen bond between them

Answer 88

refer to notes for answer.

Question 89

What are the properties of cellulose that are quite different to starch and glycogen?

Answer 89

Cant break down cellulose - more stable, less soluble.

Question 90

Where are the hydrogen bonds on beta sheets, and alpha helixes?

Answer 90

Beta sheets - between the strands, alpha helix - helping to hold the helix together.

Question 91

looking at a diagram of a saturated fat and unsaturated fat how can you tell them apart?

Answer 91

the unsaturated fat has a double bond.

Question 92

is a saturated or unsaturated fat more likely to be solid at room temp?

Answer 92

saturated.

Question 93

why are lipids suited to membranes?

Answer 93

Phospholipids have both a hydrophilic head and a hydrophobic core which is a barrier to polar things.

Question 94

structural difference between starch and glycogen

Answer 94

glycogen is highly branched and starch is not.

Question 95

membrane barriers

Answer 95

Phospholipids - hydrophobic core and hydrophilic head. the lipids keep things out of the cell. and there are proteins which transport things, enzymes to catalyse reactions, receptors to recognise things.

Question 96

Active transport inside a cell

Answer 96

moving against a gradient. Low concentration a high concentration - going against a concentration gradient requires energy - ATP.

Question 97

The central dogma reaction

Answer 97

How we move from DNA to RNA to a sequence of proteins. We need to be able to replicate DNA and copy it accurately each time our cells divide.

Question 98

The structure of DNA

Answer 98

Double helix, with the bases on the inside and the phosphates and sugars on the outside - hydrophobic bits in the middle and the hydrophilic bits on the outside. The strands aren't read in the same direction. Two strands one with the phosphate group and one with the hydroxyl group

Question 99

The strands of DNA

Answer 99

Can have two different types of bases - Purine base - double ring or the Pyridine - single ring. Proposing that there is a purine interacting with a pyridine - so one double interacting with a single. Hydrogen bonds hold the strands together.

Question 100

Hydrogen bonding in DNA

Answer 100

Hydrogen slightly positive (connected to a nitrogen) and oxygen slightly negative so we can get hydrogen bonds forming between these A-T. No hydrogen bonds can form between A & C (two hydrogen can't hydrogen bond together). Three hydrogen bonds form between G-C.

Question 101

How do we copy the DNA?

Answer 101

Pull the strands apart and use them as a template to make new strands. Use helicase and topoisomerase - helicase is an ATPase - breaking the hydrogen bonds require ATP. helicase and forms a donut strand protein around the dna - motor protein - converts atp into adp and turn the chemical energy into kinetic energy. Moves along the strands burning ATP to break the hydrogen bonds. Need one on each stranf going in opposite directions.

Question 102

Supercoiling in copying of DNA

Answer 102

To relieve the super coils we cut one of strands and then allow it to unwind and relieve the super coiling. The topoisomerase cuts and rejoins on strand to reduce super coiling.

Question 103

Where do we seperate the strands in DNA replication?

Answer 103

Start off the unwinding process at AT because its easier to pull apart two hydrogen bonds rather than if there were three between them - origins of replication - rich in ATs.

Question 104

How do we make a polymer? New strand of DNA

Answer 104

We make a new polymer out of monomeric subunits using DNA polymerase. Uses the DNA as a template to get a bond forming between the three primer hydroxyl group and the 5 prime phosphate group - the phosphodiester bond. requires pyrophosphate for energy one new strand (the leading strand) is made as a continuous piece. The other (the lagging strand) is made in small pieces.

Question 105

Joining the nucleotides on the new strand of DNA

Answer 105

Because DNA cannot join the first nucleotides we need another enzyme to add the bases onto the unwinded strand with primase which uses RNA. Now DNA polymerase can add on to the three prime end.

Question 106

How do we get rid of the RNA primer

Answer 106

When the DNA polymerase encounters RNA it breaks it down and removes the bonds.

Question 107

The gap in the new DNA strand

Answer 107

Is sealed by ligase which will join the strands.

Question 108

PCR reaction

Answer 108

Method to make copies of specific DNA sample. in the PCR reaction we want to separate the strands - won't use helicase we will use heat. Heat the sample of DNA which breaks the hydrogen bonds, so now we have single stranded DNA, the bases are exposed and we can start using them as a template. For our PCR reaction primers are applied.