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biology_2_biochemistry_20150520080600 Flashcards

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1
Q

Draw and label a diagram of a water molecule

A

Water is made out of the covalent bondings of two positive hydrogen atoms and one negative oxygen atom.

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2
Q

What is a hydrogen bond?

A

It is the bond between different water molecules. This is due to the fact that the water molecule has polar charged regions that attract itself to other water molecules’ polar regions.

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3
Q

What is a thermal property of water?

A

Thermal properties of water include heat capacity, boiling and freezing point.

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4
Q

Does water have a low or high heat capacity?

A

Water has a high heat capacity meaning that it takes much more energy to increase change its temperature than, say methane.

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5
Q

Why does water have a high heat capacity?

A

Water has a high heat capacity due to its strong hydrogen bonds that make it difficult for them to break without sufficient energy. This means that water remains relatively stable. This property is often used for animals as they can cool themselves or warm themselves in the water.

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6
Q

Water takes boils at a higher temperature than methane. Why is this?

A

Due to water’s high latent heat capacity, it takes water molecules much more energy to convert from liquid to gas. This means that because of the strong hydrogen bonds, they require a lot of energy to break apart in order for water to evaporate.

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7
Q

Why is sweating ineffective in a very humid climate?

A

Sweat is released in order cool the body down, as the sweat evaporate, leaving the surface of the skin cooler as all the high energy (hot) molecules are released into the atmosphere. In a humid climate, the air already contains lots of water which means that there is not enough space for the sweat to evaporate, leaving the body hot and drenched.

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8
Q

Why is the high boiling point of water vital to life?

A

The high boiling point enables organisms to survive in hotter climates. If water did not have such high specific heat capacity, organisms would boil along the water and be unable to survive.

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9
Q

How does water in its solid state become beneficial to organisms?

A

When water freezes, it becomes less dense. This means that the ice blocks will float atop of the water. Ice covered surface on lakes and seas acts as an insulator for the water underneath to maintain habitats for organisms.

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10
Q

How do plants benefit from water properties?

A

One of the properties water has is its cohesion. Due to the hydrogen bonds, water is able to be transported from the roots to leaves through long columns.

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11
Q

What property is present when sugar is mixed with water?

A

When sugar is mixed into water, it dissolves presenting water’s solvent properties because of its polarity.

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12
Q

How is oxygen transported in blood?

A

Oxygen has low solubility in water and therefore needs to be transported through haemoglobins.

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13
Q

Which molecules have high solubility in water and can be transported through blood plasma?

A

Glucose, amino acids and sodium chloride are soluble.

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14
Q

If molecules have low solubility in water, how can they be transported in blood?

A

Molecules like fats and cholesterol have low solubility, and need to be transported inside lipoproteins in blood.

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15
Q

Which elements make up carbohydrates?

A

CHO - Carbon, Hydrogen, Oxygen

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16
Q

Which elements make up Proteins?

A

CHON - Amino acid: Carbon, Hydrogen, Oxygen and Nitrogen

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17
Q

What elements make up Lipids?

A

CHO - Carbon, Hydrogen, Oxygen

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18
Q

What elements make up DNA?

A

CHOP - Carbon, Hydrogen, Oxygen, Phosphate

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19
Q

What is the definition of inorganic chemicals?

A

Mineral compounds such as salts, i.e. sodium chloride, potassium sulphate, ammonium nitrate, etc.

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20
Q

What is the definition of organic chemicals?

A

Carbon based molecules found in living organisms.

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21
Q

What are some exceptions of organic chemicals?

A

These carbon based molecules are found in living organisms but are considered inorganic:Carbon MonoxideCarbon DioxideCarbonatesHydrogen Carbonates

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22
Q

Is it possible to produce organic chemicals without use of living organisms?

A

Friedrich Wöhler has proven that you can artificially make urea in laboratory. As Urea is an organic matter, you can produce organic matter with inorganic matter without vital force.

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23
Q

Draw a diagram of ribose.

A

Ribose is a pentose sugar. It is a monosaccharide.

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24
Q

Draw a diagram of alpha glucose.

A

Glucose is a hexose sugar. It is a monosaccharide.

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25
Q

Draw a diagram of beta glucose.

A

Glucose is a hexose sugar. It is a monosaccharide.

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26
Q

How is sucrose created?

A

Sucrose is disaccharide of glucose and fructose.

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27
Q

What is the difference between pentose and hexose?

A

Pentose is a sugar made of 5 carbon atoms while a hexose sugar has 6 carbon atoms

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28
Q

What is an example of a disaccharide?

A

Sucrose, Maltose, Lactose

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29
Q

What is a polysaccharide?

A

A Polysaccharide is a carbohydrate of a chain of many sugars which are for example starch or cellulose.

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30
Q

What is a glycosidic bond?

A

Glycosidic bond is formed between sugar molecules.

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31
Q

Draw and label a molecular diagram of a generalized amino acid.

A

Each amino acid contains: R group, carboxylic acid group, amino group, hydrogen atom and carbon atom in the middle.

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32
Q

How do amino acids join together?

A

Two amino acids bond to form a dipeptide. Amino acids join together through peptide bonds. This is a condensation reaction meaning it forms water as a by product.

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33
Q

What is a carbohydrate?

A

carbohydrates are organic compounds that contain one or more simple sugars.

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34
Q

What is a protein?

A

Large organic compounds made of a polypeptide of amino acids arranged in a linear shape.

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35
Q

Draw a molecular diagram of a saturated fatty acid.

A

Saturated lipids are linear, meaning they have no double carbon-carbon bonds.

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36
Q

What are examples of lipids?

A

Triglycerides, phospholipids and steroids.

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37
Q

Is this a carbohydrate, lipid or protein?

A

This is triglyceride which is a lipid.

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38
Q

Is this a carbohydrate, lipid or protein?

A

This is a phospholipid which is a lipid.

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39
Q

Is this a carbohydrate, lipid or protein?

A

This is a steroid which is a lipid.

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40
Q

What are some functions of lipids?

A

Lipids are used for electrical insulation, energy storage, plasma membrane (phospholipid and cholesterol) and thermal insulation.

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41
Q

Why are lipids surrounding our nerve cells?

A

Lipids a good electrical insulators as they do not conduct electricity.

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42
Q

What is metabolism?

A

Metabolism are the chemical reactions within the cell in its cytoplasm. It is the enzyme-catalyzed reactions in living organism.

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43
Q

What is anabolism?

A

Anabolism is the synthesis of small, simple molecules forming a complex compound. This includes the formation of macromolecules from monomers by condensation reaction.

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44
Q

What is catabolism?

A

Catabolism is the breakdown of complex compounds to small simple molecules. This includes the hydrolysis of macromolecules into monomers.

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45
Q

Draw a diagram of two sugars forming maltose.

A

Maltose is disaccharide created through the condensation of two alpha glucose which are bonded through a glycosidic bond.

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46
Q

How is sucrose formed?

A

Sucrose is a disaccharide formed through two monosaccharides, glucose and fructose.

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47
Q

How is lactose formed?

A

Lactose is a disaccharide formed through two monosaccharides, galactose and glucose.

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48
Q

How is maltose formed?

A

Maltose is formed through two alpha glucose.

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49
Q

What are some structures of starch?

A

Starch is polysaccharide of alpha glucose which comes in the form of amylose and amylopectin together.

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50
Q

What does amylose look like?

A

Amylose is a chain of alpha glucose bonds which is spiralled.

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51
Q

What does amylopectin look like?

A

Amylopectin is similarly to amylose made of alpha glucose but it branched.

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52
Q

How is cellulose formed?

A

Cellulose is polysaccharide made of a chain of beta glucose. It serves as a material to form plant cell walls.

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53
Q

What does glycogen look like and what is it used for?

A

Glycogen is very similar to amylopectin and is therefore made of alpha glucose. It is more branched. It serves as an energy source in human liver and muscles.

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54
Q

What is the difference between a saturated and unsaturated fatty acid?

A

Unsaturated fatty acids have double carbon-carbon bonds. This makes them bend.

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55
Q

What is the difference between monounsaturated and polyunsaturated fatty acids?

A

Monounsaturated fatty acids only have one double carbon-carbon bond. Polyunsaturated fatty acids have 2 or more double carbon-carbon bonds.

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56
Q

What kind of carbohydrates are cis and trans associated with?

A

Cis and trans are structures of unsaturated fatty acids.

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57
Q

Draw a molecular diagram of a cis unsaturated fatty acid

A

Cis resembles a C meaning that it curves back.

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58
Q

Draw a molecular diagram of a trans unsaturated fatty acid.

A

Trans is a nonpolar molecule, this makes the fatty acid a kink but stay relatively linear

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59
Q

How is triglyceride formed?

A

Triglyceride is formed through 3 fatty acids and a glycerol. The fatty acids attach themselves through condensation reaction which gives water as a byproduct

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60
Q

Explain how to find out your BMI

A
  1. Measure your mass with a scale in kg2.Measure your height with a tape in meters 3. Divide your mass by your height squared=> BMI = weight/ (height)^2
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61
Q

Distinguish the differences of using lipids and carbohydrates as an energy source.

A

Lipidsare more suitable for long term energy storage.Carbohydratesare more suitable for short term energy storage.
Lipidsrelease double the amount of energy with the same amount of gramsascarbohydrates.Carbohydratesrelease much less energy copared to lipids.
Lipidsare stored in specialized cells such as triglycerides in adipose.Carbohydratesare stored in muscle tissues and the liver. This makes lipids more readily stored than carbohydrates.
Lipidstake longer to break down.Glycogenis easier and faster to break down into glucose.

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62
Q

How can trans fats and saturated fatty acids affect our health?

A

There is a high correlation that a high intake of trans fats and saturated fatty acids. This is due to the fact that trans fats and saturated fatty acids can stack on each other and clot up blood vessels.

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63
Q

What are biological proteins composed of?

A

Biological proteins are made up of 20 different types of amino acids.

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64
Q

Where do our cells get the amino acids?

A

Amino acids can be found through our diet and nutrients. Some amino acids can also be synthesized by human cells.

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65
Q

How are amino acids considered polar or nonpolar?

A

Whether amino acids are polar or nonpolar depends on their variable group (R group).Polar makes them hydrophilic.Non Polar makes them hydrophobic.

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66
Q

How does the polarity of an amino acid affect enzyme solubility?

A

The outer layer of an enzyme contains polar (hydrophilic) amino acids. This helps to make the enzyme soluble.

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67
Q

How does the polarity of an amino acid affect membrane proteins?

A

The inner pore of a membrane channel will contain polar amino acids, while the amino acids in contact with the lipid bilayer will be nonpolar. This keeps the protein from floating away.

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68
Q

How does the polarity of an amino acid affect proteins stability?

A

The inner layer of proteins will contain many non polar amino acids that help to stabilize the shape of a soluble protein.

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69
Q

Where do most organisms assemble their proteins from?

A

Most organisms have proteins that consist of the same 20 amino acids.There are a few exceptions that are likely to come from distant evolutionary relatives.

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70
Q

How do amino acids link together?

A

Amino acids link through condensation reaction, forming a peptide bond to make a dipeptide or polypeptide.

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71
Q

How are amino acids joined together in cells?

A

In cells, amino acids are joined by free ribosomes or by ribosomes attached to the RER.

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72
Q

What is the significance of the sequence of amino acids in polypeptides in living organisms?

A

The sequence of amino acids in polypeptides are codes for the genes.

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73
Q

What is the primary structure of protein structure?

A

Primary structure is a sequence of amino acids. The moleculeis called a polypeptide.

74
Q

What is the secondary structure of protein structure?

A

Secondary structure is the folding of the polypeptide to a combination of spiralled alpha helices and pleated beta sheets. They are held together by hydrogen bonds.

75
Q

What is the tertiary structure of protein structure?

A

Tertiary structure is the chain folding into a specific 3D structure. The structure is held together by a number of different kinds of bonds.

76
Q

What is the quaternary structure of protein structure?

A

A quaternary structure does not always occur.This occurs when two or more proteins in tertiary structure are bonded together to make 1 molecule.

77
Q

What does the quaternary structure involve to form a conjugated protein?

A

To form a conjugated protein, the quaternary structure involves the binding of a prosthetic group.

78
Q

What is the difference between fibrous proteins and globular proteins?

A

Fibrous proteins such as keratin which is found in hair is linear. While globular proteins such as pepsin are round.Fibrous proteins such are Keratin are insoluble. Other, globular proteins such as pepsin are soluble in water

79
Q

What is proteome?

A

Proteome is the sum of all the proteins in one biological individual. This differs and is unique for every individual as we do not make the same amount of proteins.

80
Q

What is the role of rubisco?

A

Rubisco is the enzyme that catalyzes carbon fixation in green plants. This is a key event in photosynthesis.

81
Q

What is the role of insulin?

A

Insulin is hormone involved in the regulation of blood glucose concentration. It is composed of 2 peptides chains and totalling 51 amino acids.

82
Q

What is the role of immunoglobulins?

A

Immunoglobulins act as antibodies which are large Y-shaped proteins that are used by the immune system to identify and neutralize foreign objects such as bacteria and viruses.

83
Q

Are immunoglobulins fibrous or globular?

A

Immunoglobulins are globular.

84
Q

What is the role of collagen?

A

Collagen is composed of three interwoven polypeptide chains, and is found in fibrous tissues such as tendons, ligaments, skin, bones and blood vessels. It serves to help our structure and support body tissues.

85
Q

Is collagen fibrous or globular?

A

Collagen is fibrous.

86
Q

What is an enzyme?

A

An enzyme is a biological catalyst which speeds up te rate of reactions.

87
Q

What is an active side?

A

All enzymes have an active side whose shape is complementary to the substrate molecule(s).Enzymes are specific meaning that they can only speed the reaction of a specific substrate.

88
Q

How do enzymes work?

A
  1. Enzymes are shaped complementary to a substrate.2.Substrate moves into the enzyme and locks in. 3.An enzyme substrate complex is formed.4.A chemical reaction happens. The substrate is turned into products. Enzyme may act as catabolic or anabolic. 5. Products move out of enzyme 6. Enzyme is ready to accept another substrate molecule
89
Q

Explain enzyme-substrate specificity.

A

Enzymes’ active side and substrates have complementary shapes, so that the substrate fits into the enzyme like a key. This is called a lock and key model of enzyme action.A different kind of substrate cannot fit as the shape needs to fit perfectly. This makes enzymes specific. They are specific in order to make different products that the protein is assigned to.

90
Q

If an enzyme is a protein, is it fibrous and globular?

A

Enzymes are globular proteins.

91
Q

What happens to an enzyme when in extreme pHs or high temperatures?

A

The enzyme will be denatured. Denaturing refers to a permanent structural change in a protein that results in a loss of its properties Denaturing causes a change of shape of the active side of the enzyme which means it will not function anymore.

92
Q

Draw a graph to show the expected effects of temperature on enzymes.

A

As temperature increases, relative activity increases until the enzymes is denatured where it will rapidly fall.

93
Q

Draw a graph to show the expected effects of pH on enzymes.

A

As pH increases towards its optimum pH, relative activity increases. As pH increases away from its optimum pH, activity decreases.

94
Q

Draw a graph to show the expected effects of substrate concentration on enzymes.

A

As concentration increases, activity increases to its point of saturation. Beyond the point of saturation, the increase in concentration remains constant.

95
Q

Explain the effects of temperature on enzymes

A

As temperature increases, increases due to collision theory. As higher temperatures cause more movement, collisions occur more frequently. As temperature increases beyond the optimum temperature, the enzyme will denature causing activity to slow down rapidly.

96
Q

Explain the effects of pH on enzymes

A

As the pH increases, enzymes are closer to their optimum pH where they work most efficiently. As pH increases beyond the optimum pH, the enzyme slowly starts to denature, slowing the activity.

97
Q

Explain the effects of substrate concentration on enzymes.

A

When substrate concentration increases, collision frequency increases as there are more substrates enzymes can react with. After reaching point of saturation, activity can no longer be increase regardless of increase in substrates, as all enzymes are bound and reacting at maximum rate

98
Q

What are immobilized enzymes?

A

Immobilized enzymes are enzymes which are restricted from movement and are in a fixed space.

99
Q

How are immobilized enzymes used in industry of production?

A

Immobilized enzymes are used in many industries. 1. Production of lactose free milk by having the enzyme lactase.2. Production of sodas where glucose isomerase is used to break glucose to fructose to make the drinks sweeter3. Production of fruit juice to break down pectin which makes it cloudy with the enzyme pectinase. 4. Biological washing powder contains protease, amylases and lipases. This makes it effective at breaking down food stains in low temperature that saves household costs.

100
Q

How is lactase used in the production of lactose free milk?

A

Lactase breaks down lactose into glucose and galactose This creates lactose free milk which can be enjoyed by consumers around the world, regardless of whether they are lactose intolerant or not.

101
Q

Outline advantages of lactose-free milk production

A
  1. Allows people who are lactose intolerant to consume milk products. 2. It makes the milk taste sweeter, because glucose and galactose taster sweeter than lactose. This is good for smoothies and milk shakes. 3. Glucose and galactose are more soluble, making milk smoother and ice cream less crystallized. 4. It reduces production time for yogurt and cheese, as glucose and galactose are quicker to ferment than lactose.
102
Q

What is the name of the structure of DNA?

A

DNA consists of many nucleotides. This is called a polynucleotide.

103
Q

How are DNA polynucleotide monomers linked?

A

DNA polynucleotide monomers are linked together by covalent bonds into single strand DNA polymers.

104
Q

Draw a labelled diagram of single DNA Nucleotide.

A

Composed of deoxyribose sugar, nitrogenous bases and phosphorus group.

105
Q

What are the 4 different nitrogenous bases for DNA?

A

A - Adenine G - GuanineT - Thymine C - Cytosine (Always go to chemistry)

106
Q

What nitrogenous base is complementary to Adenine?

A

Adenine is complementary to Thymine. Double Hydrogen Bond.

107
Q

What nitrogenous base is complementary to Cytosine?

A

Cytosine is complementary to Guanine. Triple Hydrogen Bond.

108
Q

What are the base pairing rules?

A

Adenine double bond ThymineCytosine triple bond Guanine

109
Q

Which nitrogenous bases are Purines?

A

Adenine and Guanine are purines.

110
Q

Which nitrogenous bases are pyrimidine?

A

Thymine and Cytosine are pyrimidine.

111
Q

Draw a structure of DNA with 6 DNA nucleotides.

A

DNA strands are antiparallel to form a double helix. Include: - Sugar phosphate backbone - complementary base pairs - Hydrogen bases between bases of two strands (dotted line)

112
Q

What is the general structure of a DNA polynucleotide?

A

a DNA polynucleotide is a double stranded helix. The DNA strands are antiparallel linked by hydrogen bonds between the complementary nitrogenous base pairs.

113
Q

Describe the structure of RNA.

A

RNA is a polynucleotide. RNA nucleotide monomers are linked together by covalent bonds into single stranded DNA polymers.

114
Q

What are RNA nucleotides composed of?

A

RNA nucleotides are composed of ribose, one sugar phosphate group and a nitrogenous base.

115
Q

What are the RNA complementary base pairing rules?

A

Adenine and Uracil Cytosine and Guanine

116
Q

Draw a labelled RNA polynucleotide

A

Include sugar phosphate backbone.

117
Q

Compare the structures of DNA and RNA

A

Similarities:
* Both have sugar phosphate groups
* Both have nitrogenous bases
* Both have pentose sugars
* Both are poly nucleotides
* Both have covalent bonds
* Both have sugar phosphate backbones
* Both have Adenine and Guanine as purines
* Both store genetic information
Differences:
* DNA has deoxyribose. RNA has ribose
* DNA is a double helix and is therfore double stranded. RNA is single stranded DNA must have hydrogen bonds between the nitrogen bases. RNA is mainly covalently bonded and onlyoccasionallyhas hydrogen bonds.
* DNA has Thymine and Cytosine as pyrimidines. RNA has Uracil and Cytosine as pyrimidines.
* DNA has an anti-parallel structure. RNA with only one strand has only one direction. 5’ to 3’

118
Q

How does the discovery of the DNA structure give insight into the mechanism of DNA replication?

A

As we know that DNA has a double stranded structure, and is defined by their sequence in order to store genetic information, we can deduct that a replication of a strand can be created through the information of the complementary strand.

119
Q

Outline the protocol of the Hershey and Chase experiment.

A
  1. Phages were attached to a bacterial cell. 2. The DNA is transferred through injection into the bacterial cell.3. Phage had normal DNA but was covered in radioactive protein coat4. Phages were attached to bacterial cell, and DNA was transferred and reproduced. Next generation was not radioactive. 5. Phage had radioactive DNA covered in normal protein coat.6. Next generation was radioactive.
120
Q

What is a phage?

A

A phage is a type of virus that infects bacteria. Phages are made from DNA covered with a coat of protein.

121
Q

From the Hershey and Chase experiment, what can we deduce?

A

From the experiment we can deduce that protein does not pass on genetic information or even contain such.From the experiment we can also deduce that DNA is inherited by the next generation. Therefore, DNA stores genetic material that is information needed for the next generation

122
Q

What can we deduce from the X-ray crystallography?

A

From the crystallography we can find that strands over lap like intersections and therefore DNA should be a double stranded helix.

123
Q

What does the DNA Helicase do?

A

In DNA replication, DNA Helicase unzips the double stranded DNA helix by breaking apart the hydrogen bonds.

124
Q

What does DNA gyrase do?

A

DNA gyrase releases tension from the DNA double helix. It does this by breaking both strands and unwinding the strand by 2 coils and then fusing the DNA strands back together.

125
Q

What does DNA polymerase I do?

A

DNA polymerase I replaces the RNA strand with a DNA strand.

126
Q

What does DNA polymerase III do?

A

DNA polymerase builds complementary DNA strands (sugar phosphate backbone)

127
Q

What do single stranded binding proteins do?

A

Single stranded binding proteins prevent the single DNA strands from sticking back together.

128
Q

What does DNA primase do?

A

DNA primase inserts a piece of RNA to the single strand

129
Q

What are Okazaki fragments?

A

Are the sections of DNA on the lagging strand that need to be connected

130
Q

What does dNTP do?

A

DNA polymerase II uses dNTP (Deoxynucleotide triphosphate) to build a new complementary strand of DNA (connecting the Okazaki fragments). Two phosphate groups are removed

131
Q

What does DNA ligase do?

A

DNA ligase is responsible for joining the Okazaki fragments to create a continuous strand.

132
Q

Name at least 5 functions in DNA replication.

A

○ Helicase ○ DNA gyrase ○ single strand binding proteins ○ DNA primase ○ DNA polymerases I ○ DNA polymerases III ○ Okazaki fragments ○ deoxynucleoside triphosphates (dNTPs) - also known as ‘free nucleotides’

133
Q

In which direction does DNA replication occur?

A

DNA replication occurs in a 5’ to 3’ direction because DNA polymerase 3 only adds nucleotides to the 3’ end of the primer.

134
Q

Outline the process of DNA replication (on the leading strand)

A
  1. DNA helicase unzips the double stranded DNA helix by breaking the hydrogen bonds 2. The single stranded binding proteins attach themselves to each strand to prevent them from sticking back together. 3. DNA Primase adds a new RNA strand to the single strand.4. DNA polymerase III builds a new complementary DNA strand. The existing strand is used as a template using the complementary base pairing rules5. DNA polymerase I replaces the RNA primer with a short DNA strand. On the leading strand DNA polymerase III can build a complementary DNA strand continuously.
135
Q

Outline the process of DNA replication (on the lagging strand)

A
  1. On lagging strand the new complementary DNA strand must be built in sections called Okazaki fragments due to the fact that the DNA polymerase III only goes in one direction, 5’ to 3’2. DNA ligase is required to join together the Okazaki fragments. On the lagging strand DNA polymerase III has to work discontinuously because it only works in one direction from 5’ to 3’
136
Q

When does DNA replication occur in eukaryotic chromosomes?

A

DNA replication initiates at many points in eukaryotic chromosomes. This is because eukaryotic genomes are usually larger than prokaryotic genomes. So DNA is replicated at many points simultaneously in order to limit the time required for DNA replication to occur.

137
Q

What are the sites called where DNA unwinding and initiation of replication occurs?

A

These sites are called origins of replication and form replication bubbles.As replication bubbles expand they eventually fuse together. Two generate two separate semi conservative double strands of DNA

138
Q

Is DNA replication conservative, semi-conservative or dispersive?

A

DNA replication is semiconservative. One strand will form from the original DNA strands. One strand will be newly synthesized.

139
Q

Outline the protocol of Meselson and Stahl’s DNA replication experiments

A

Meselson and Stahl grew an E.Coli bacteria in a medium containing N15 Nitrogen atoms. After several generations all of the bacteria contained heavy DNA with two strands made from N15.Then the E.Coli bacteria was transferred into a medium containing N14 nitrogen Scientists allowed bacteria to complete 1 cell division by binary fission. They then took samples of the cells and tested the DNA in a centrifuge to measure its weight. The bacteria then was allowed to complete several more replications by binary fission. Each time DNA was taken and measured in a centrifuge.

140
Q

What can we conclude from Meselson and Stahl’s experiment?

A

From Melson and Stahl’s we can deduct that DNA replication is semi conservative as there is as DNA is always semi-transferred and semi conserved into the new generation.

141
Q

What is the significance of the complementary base pairing rules to determine

A

DNA polymerase uses the complementary base pairing rules to determine the sequence of nucleotides as it builds a new strand of DNA. This ensures that the two daughter cells produced by mitosis are genetically identical

142
Q

What is Taq polymerase?

A

Taq polymerase is a thermo-stable DNA polymerase enzyme. This is enzyme is found from the heat loving bacteria, thus does not denature at extreme temperatures.

143
Q

What does Taq polymerase do?

A

Taq polymerase performs the same role as DNA polymerase by producing several copies of of DNA during polymerase chain reaction. In order to artificially replicate human DNA.

144
Q

What is the relationship between one gene and one polypeptide?

A

One gene holds information to make one polypeptide. (A gene is a section of the DNA)

145
Q

Outline the process of transcription.

A

Process takes place inside the nucleus1. RNA polymerase will attach it self to the promoter site of the DNA.2. RNA polymerase unwinds the DNA by breaking hydrogen bonds. This creates a transcription bubble.3. RNA polymerase will build a new strand using complementary base pairing rules to pair RNA nucleotides along the anti sense strand. 4. RNA polymerase reaches terminator where transcription is completed. 5. RNA polymerase breaks away from DNA6. DNA double helix rewinds and mRNA is released

146
Q

What are the three types of RNA?

A

mRNA (messenger = transcription)tRNA (transfer = translation)rRNA (ribosome = translation)

147
Q

Outline the process of translation. (SL)

A
  1. Small ribosome sub-unit attaches itself to mRNA strand. 2. mRNA is made of codons which is a sequence of 3 consecutive RNA bases. tRNA has anti codons which is also made of 3 consecutive RNA bases. A tRNA molecule always corresponds to a specific amino acid. 3. Ribosomes will read the codons on the mRNA and using complementary base pairing rules, pair appropriate tRNA molecules. 4. The ribosome works its way along the mRNA in direction of 5’ to 3’. Until it finished building the polypeptide chain.
148
Q

Where does translation occur?

A

In a cell’s cytoplasm

149
Q

When does translation occur in the cell cycle?

A

G1 and G2 Phase

150
Q

Why does translation happen?

A

Translation happens in order to make polypeptides for protein synthesis.

151
Q

What is the role of a ribosome?

A

The role of a ribosome is to read the base sequence of the mRNA and use this information to build a polypeptide.

152
Q

What is the role of mRNA?

A

The role of mRNA is to hold genetic information from the nucleus to the ribosome.

153
Q

What is the role of tRNA?

A

The role of tRNA is to bring specific amino acids to the ribosomes for protein synthesis.

154
Q

How does amino acid sequence of polypeptide is determined by base sequence of mRNA?

A

As the sequence of mRNA is composed of codons it directly corresponds to an anti codon with its specific amino acid that is always the same for the specific code. Thus, the amino acid sequence is determined by the genetic code.

155
Q

Does the amino acid correspond to mRNA or tRNA?

A

Amino acids are determined by the mRNA and not the tRNA.

156
Q

What is GMO?

A

GMO means genetically modified organisms.

157
Q

What is an example of the universality of the genetic code allowed gene transfer between species?

A

The production of human insulin in bacteria is a demonstration as to how bacteria can be genetically modified through transfer of gene. This is done by replacing a gene for human insulin into a bacterial plasmid, which in the bacterial organism will produce human insulin to treat diabetics.

158
Q

What happens after the process of transcription in eukaryotic cells?

A

In eukaryotic cells, the mRNA has to be modified after transcription.

159
Q

How can eukaryotic RNA form into a mature mRNA?

A

Eukarytoic RNA has to remove introns.

160
Q

Why is splicing important?

A

mRNA splicing has to function to remove unnecessary non-coding regions before translation. Introns allow cells to make a variety of slightly different polypeptides from the same gene. Sometimes an intron can be included in the mRNA. This will produce a slightly different polypeptide. Thus a slightly modified protein.

161
Q

What is an example of a non coding region with a function?

A

A promoter site is an example of a non-coding DNA with a function.

162
Q

When does specialization occur?

A

Cell specialization occurs through a process of differentiation where genes are swicthed off.

163
Q

What is a major role in affecting cell specialization?

A

The environment plays a major role in affecting whether genes are switched off or on. It has an effect of the gene expression.

164
Q

What is phenotypic plasticity?

A

It is the ability of an organism to develop in different ways according to its environment.

165
Q

What is a nucleosome?

A

One nucleosome is made of 8 histone proteins, with DNA wrapped around the outside. Only eukaryotic cells have nucleosomes.

166
Q

What is the function of a nucleosome?

A

Nucleosomes protect DNA from damageThey allow long lengths of DNA to be supercoiled for mobility of mitosis.Nucleosomes help to regulate DNA transcription.

167
Q

How do nucleosomes act to regulate DNA transcription?

A

While a DNA strand is wrapped around a histone protein, in a nucleosome, the enzyme RNA polymerase cannot unwrap the DNA double helix for transcription to occur. Some parts of a cell’s DNA is permanently wrapped into nucleosomes that permanently switch off the gene.

168
Q

Do prokaryotic cells have nucleosomes?

A

No. Prokaryotic cells have naked DNA meaning that they do not have histone proteins to form nucleosomes.

169
Q

How can gene expression be regulated?

A

Through proteins, gene expression can be regulated and therefore temporarily regulated. This happens when proteins bind to specific base sequences in the DNA, such a promoting protein or a blocking protein on the operator site.

170
Q

Outline the structure of a ribosome.

A

Ribosomes are made of rRNA and proteins.It is composed of 2 sub-units: a large sub-unit and a small sub-unit. It consists of 3 binding sites for tRNA.It has one binding site for mRNA.

171
Q

What is the structure of a tRNA?

A

A tRNA molecule is a polynucleotide chain. It is folded back to form a region of double helix, according to RNA complementary base pairing rule.It contains 3 loops.It contains an anti-codon with 3 RNA bases.It has a binding site for an amino acid.

172
Q

How are tRNA molecules charged?

A

tRNA molecule has to be linked to a specific amino acid through a tRNA - activating enzyme. 1. Specific amino acid binds to active side of a tRNA-activating enzyme.2. ATP binds to active site of the enzyme to provide energy stored in the 3 phosphate groups.3. 2 of the phosphate groups break away which releases energy captured by the amino acid.4. A specific tRNA molecule binds to the active site of tRNA activating enzyme which active site has to be complementary to the anti codon of tRNA. 5. High energy bond between the amino acid and tRNA molecule is formed which activates the tRNA molecule. The energy carried by the tRNA molecule will be used for to form a peptide bond. 6. The tRNA molecules leaves the enzyme to find a ribosome

173
Q

What is the tRNA activating enzyme an example of?

A

tRNA activating enzyme is an example of enzyme-substrate specificity

174
Q

What is the first process of translation?

A

Initiation 1. The small ribosome sub-unit binds to the mRNA 2. The complementary anti-codon of the tRNA molecule binds to with the start codon at the P-Site3. The large sub-unit of the ribosome binds to the mRNA.

175
Q

What is the second process of translation?

A

Elongation 1. A second tRNA molecule moves into the A-site2. A peptide bond forms between the two amino acids held in A Site and P site.

176
Q

What is the third process of translation?

A

Translocation1. The ribosome moves 3 nucleotides along the mRNA strand.2. the first tRNA molecule moves into E-site and exits the ribosome 3. A-Site is available for a new tRNA molecule.

177
Q

What is the fourth process of translation?

A

Termination1. Eventually the ribosome will reach the stop codon 2. The ribosome breaks apart into two sub-units Polypeptide is complete.

178
Q

In which direction does translation occur?

A

5’ to 3’ direction

179
Q

What is the difference of the function of free ribosome and ribosome on the RER?

A

Free ribosome: make protein primarily for inside the cell.Ribosome on RER: make protein for export out of the cell or for lysosome (i.e. hormones such as insulin)

180
Q

Is translation in eurkayrotic cells as quick as in prokaryotic cells?

A

No. Translation in prokaryotes can occur immediately after transcription due to the absence of the nuclear membrane.

181
Q

What is a polysome?

A

A polysome is formed when several free ribosome attach themselves to the same strand of mRNA. The advantage of this is that it produces the same amount of polypeptides in a shorter amount of time.

182
Q

What kind of bonds maintain the tertiary and quaternary structure of protein?

A

Hydrogen BondsDisulfide bridgesIonic BondsHydrophobic Interactions (Inter molecular Forces)

Biology 2. Biochem (1 decks)

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