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Biology OCR AS Jess > Topic 2 > Flashcards

Topic 2 Flashcards

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1
Q

Why can large ions and polar molecules not travel through the phospholipid bilayer? Reasoning?

A

They are soluble in water but insoluble in lipids. Water and fats repel.

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2
Q

In facilitated diffusion how can molecules and ions enter the cell?

A

Water filled pores in channel proteins.

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3
Q

Is a channel protein specific to one type of molecule or can all molecules use it?

A

It is specific.

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4
Q

When can a gated channel protein open or close?

A

When there is a hormone or change in potential difference.

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5
Q

What is a gated channel?

A

A protein in the membrane that opens or closes under the presence of a hormone or change in potential difference.

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6
Q

What is a carrier protein?

A

A protein that changes shape to push a molecule into/out of the cell once it binds to it.

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7
Q

What is passive transport?

A

No metabolic energy is required for the process.

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8
Q

What is osmosis?

A

The net movement of water molecules from a low solute concentration to a high solute concentration through a partially permeable membrane.

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9
Q

What is active transport?

A

The movement of substances against the concentration gradient.

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10
Q

What are the two things needed from active transport?

A

A carrier protein and energy from ATP.

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11
Q

When is ATP formed?

A

During respiration.

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12
Q

What is the reaction to make the energy needed for active transport? What happens?

A

ATP->ADP+P. When P is released water binds to it, this process releases lots of energy.

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13
Q

What happens to the phosphate in active transport?

A

Hydrolysis.

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14
Q

When is exocytosis and endocytosis used?

A

Mass transport or moving of large molecules.

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15
Q

What is exocytosis? Examples?

A

Mass movement of substances out of a cell. Proteins, polysaccharides, insulin.

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16
Q

What is endocytosis? Example?

A

Mass movement of substance into a cell. Cholesterol, white blood cells when engulfing.

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17
Q

What’s a vesicle? What happens to it during exocytosis?

A

Membrane bound sack. Fuses with the membrane of the cell during exocytosis.

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18
Q

What is the polarity of the two areas of an intrinsic protein?

A

Polar, hydrophilic outside. Non polar, hydrophobic centre.

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19
Q

What is a form of evidence for intrinsic proteins?

A

Freeze fracture.

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20
Q

How were membranes proved to be asymmetric.

A

A protein only blinded to one side of a membrane which proved that there was an uneven charge which only happens when a molecule is asymmetric. The molecule was polar.

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21
Q

What was another way the protein sandwich model was disproved?

A

The sandwich model was symmetric, when the Lenin protein only bonded to one side this proved that the membrane was intact asymmetric.

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22
Q

What was one way that the fluid mosaic model was proved?

A

A mouse and human cell was pushed and the membranes proteins intermixed; mixing can only happen with diffusion. Only something fluid can allow things to diffuse through it.

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23
Q

What type of fatty acid is more fluid?

A

Unsaturated

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24
Q

Why are one type of fatty acids more fluid than the other?

A

As the unsaturated fats have double bonds, these form kinks in the hydrocarbon. The fatty acids therefore take up more space so there is more room for movement.

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25
Q

What is diffusion?

A

The net movement of molecules or ions down the concentration gradient until equilibrium is reached.

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26
Q

What type of molecules use diffusion? How do they travel?

A

Small, uncharged molecules. They travel through the phospholipid bilayer.

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27
Q

What’s the only exception to diffusion? Why?

A

Carbon. It is polar but small enough to still be accepted.

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28
Q

What is facilitated diffusion?

A

The movement of polar molecules and large ions (bigger than CO2)

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29
Q

What role does a fibrous protein have?

A

Structural.

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30
Q

Example of fibrous proteins.

A

Keratin, collagen.

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31
Q

Where in the body are fibrous protein?

A

Skin and hair (keratin) tendons, bones, cartilage, blood vessels (collagen)

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32
Q

How many polypeptide chains does Collagen have?

A

3

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33
Q

Structure of a phospholipid?

A

Phosphate head and two fatty acid tails.

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34
Q

What is the phosphate heads attraction/ polarity towards water?

A

Hydrophilic, polar.

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35
Q

What are the fatty acid tails attraction/ polarity towards water?

A

Hydrophobic, non polar.

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36
Q

What is a micelle?

A

A sphere of phospholipids.

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37
Q

Why is a bilayer better then a micelle?

A

More space for the fatty acids.

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38
Q

Difference between glycoproteins and glycolipids?

A

A Glycoproteins Is a polysaccharide attached to a protein. A glycolipid is a polysaccharide attached the the phosphate of the membrane.

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39
Q

What is the name of the cell membrane model?

A

The fluid mosaic model

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40
Q

What was the original membrane structure thought to be?

A

Phospholipid bilayer with a layer of protein either side.

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41
Q

Why was the old model disproved?

A

The phosphate heads has no connection to water, no area could hold non polar hydrophilic amino acids.

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42
Q

Why was the original model thought to be true?

A

Two dark layers with a light centre when under an electron microscope. Dark=protein, light=lipid.

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43
Q

What was actually viewed under the microscope ?

A

Dark=dense phosphate heads, light=lipids

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44
Q

What are the two main types of proteins?

A

Intrinsic, extrinsic

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45
Q

Why would a quaternary structure be formed?

A

If the tertiary structure level results in a non functional protein.

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46
Q

What does a protein have to have to have a quaternary structure?

A

More than one polypeptide chain.

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47
Q

What is a quaternary structure?

A

Multiple tertiary structures.

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48
Q

What is a conjugated protein?

A

A polypeptide with another chemical group.

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49
Q

Examples of conjugated proteins?

A

Haemoglobin, myoglobin.

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50
Q

What is the shape of a globular protein?

A

Spherical.

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51
Q

Are globular proteins soluble or insoluble? Why?

A

Soluble; this is due to the hydrophilic protrusions

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52
Q

Why is the solubility of globular proteins important?

A

As it is needed for metabolic reactions and transport in the blood.

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53
Q

Example of something that is globular?

A

Enzymes.

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54
Q

Roles of globular proteins?

A

Transport proteins. Eg haemoglobin, myoglobin.

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55
Q

Why is a globular proteins shape crucial?

A

As it allows them to bind to other substances

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56
Q

Another function of globular proteins?

A

Antibodies.

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57
Q

Difference between haemoglobin and myoglobin?

A

Haem=blood, myo=muscle.

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58
Q

What shape is a fibrous protein?

A

Long chains

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59
Q

How to fibrous proteins have added strength?

A

Cross links.

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60
Q

Are fibrous soluble or insoluble?

A

Insoluble.

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61
Q

How long is a section of a pleated sheet?

A

15 amino acids

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62
Q

What is a tertiary structure?

A

The secondary structure folded once again into a 3D shape.

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63
Q

How is a tertiary structure maintained?

A

Chemical bonds and hydrophobic interactions between R groups.

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64
Q

What polarity is something asymmetrical?

A

Polar

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65
Q

What do polar molecules attract?

A

Other polar molecules.

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66
Q

Are polar hydrophobic or hydrophilic?

A

Hydrophilic.

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67
Q

Are non polar hydrophobic or hydrophilic?

A

Hydrophobic.

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68
Q

What polarity is something symmetrical?

A

Non polar.

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69
Q

How are hydrophobic non polar R groups arranged?

A

On the inside of a protein, excluding water from inside the protein.

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70
Q

Example of an amino acid containing sulphur?

A

Cysteine

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71
Q

What happens if two amino acids containing sulphur become close?

A

They from disulphide bonds.

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72
Q

What forms between ionised R groups?

A

Ionic bonds Between oppositely charged R groups.

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73
Q

What types of bonds are the strongest?

A

Disulphide and ionic.

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74
Q

Negative of disulphide and ionic bonds?

A

They are very sensitive to changes in pH

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75
Q

What are proteins made of?

A

Amino acids

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76
Q

How many amino acids do proteins usually contain?

A

50-2000.

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77
Q

How many amino acids occur commonly in proteins?

A

20.

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78
Q

What can make all the types of amino acids?

A

Plants.

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79
Q

What are essential amino acids?

A

Amino acids that you can only obtain through diet.

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80
Q

What is the structure of an amino acid?

A

Amine group, hydrogen, R group, carboxylic acid

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81
Q

What changes in the structure with different amino acids?

A

The R group.

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82
Q

What happens when you create a dipeptide?

A

A condensation reaction.

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83
Q

What is a peptide bond?

A

O=C-N-H

84
Q

What is the amine group?

A

H-N-H

85
Q

What is the carboxylic acid structure?

A

O=C-H

86
Q

What is double bonded in an amino acid?

A

The oxygen

87
Q

What is the primary structure of a protein?

A

It’s sequence of amino acids.

88
Q

What is the secondary structure of a protein? Examples?

A

The 3D shape first formed. Alpha helix or beta pleated sheet.

89
Q

How is the secondary structure formed?

A

Hydrogen bonds between the positive C=O and the negative N-H of a parallel amino acid.

90
Q

How long can an alpha helix be?

A

35 amino acids?

91
Q

In a pleated sheet how are the amino acids bonded?

A

Hydrogen bonds between parallel chains.

92
Q

How is the concentration gradient maintained in a cell?

A

The constant cycle of absorbed substances being used And waste substances such as CO2 forming.

93
Q

What is the equation for SA:V ratio?

A

SA/Vol

94
Q

Features of a gas exchange surface? What do they each do?

A

Alveoli- increase SA. Capillaries- maintains concentration gradient. Thin cell walls of alveoli and capillaries- short diffusion pathway.

95
Q

What is Ficks law?

A

Rate of diffusion=(SA x Concentration difference) / Thickness

96
Q

How does CF reduce gas exchange?

A

The bronchioles become blocked and the alveoli past this point become unused. This decreases the SA thus according to Ficks law the rate of diffusion will decrease.

97
Q

What other effects can CF cause other then inefficient diffusion?

A

Damaged lung elasticity as the mucus lets air in not out. This causes over-expansion.

98
Q

Why does CF music have reduced water levels? (2)

A

Raised salt content and faulty protein channels.

99
Q

What functions do proteins have?

A

Antibodies, enzymes, hormones.

100
Q

In columnar epithelium what covers the apical membrane? Why?

A

Microvilli. Increase SA.

101
Q

Where are ciliated epithelium Located?

A

Trachea, bronchi, bronchioles.

102
Q

Where is the cilia on ciliated epithelial cells?

A

Apical membrane.

103
Q

What is known as pseudo-stratified?

A

Epithelium with the apprentice with layers.

104
Q

How is illness in the lungs caused?

A

Microorganism a become trapped in the mucus.

105
Q

How is illness in the lungs usually prevented?

A

Cilia move music to the back of the mouth where it is swallowed and destroyed by stomach acid or it is coughed out.

106
Q

Why does CF cause lung infection?

A

The low water levels in the mucus cause it to be thick so the cilia can not move the mucus out. This causes it to build up and create anaerobic conditions as it has little oxygen; bacteria thrive in these conditions.

107
Q

How does the body try to prevent the bacteria growth in CF lungs?

A

Producing white blood cells to the site but when they die they release stick DNA which increases the problem.

108
Q

What does multiple lung infections cause?

A

The damage to the gas exchange system weakens the bodies ability to fight pathogens.

109
Q

What do the epithelial cells line?

A

The outer surface of mammals vessels and internal organs.

110
Q

What is a group of epithelial cells called?

A

Epithelium tissue.

111
Q

What is the structure of epithelium tissue?

A

Connective tissue, basement membrane, epithelial cells.

112
Q

What is the side of the epithelial cell that faces the basement membrane called?

A

Basal membrane.

113
Q

What is the side of the epithelial cell that faces the away from the basement membrane called?

A

The apical membrane.

114
Q

How many types of epithelium tissue are there? Name?

A
  1. Pavement, columnar, ciliated.
115
Q

What is the structure of epithelial cells in squamous epithelium?

A

Long, thin. Like pavement slabs.

116
Q

The walls of what are pavement epithelium?

A

Alveoli, capillaries.

117
Q

What do the goblet cells do?

A

Produce mucus.

118
Q

Where in the body bare their columnar epithelium?

A

The small intestine.

119
Q

Where is excess water in the membrane detected?

A

Epithelial cells.

120
Q

What is the process of removing water from mucus?

A

NA+ is pumped across the basal membrane through carrier proteins.
NA+ from the mucus diffuses to the epithelial cell through sodium ion channels using facilitated diffusion.
Cl- diffuses from the mucus to the tissue fluid through gaps in the epithelial cells due to the positive charge in the fluid.
There is not a high salt content in the tissue fluid. This causes osmosis to move water across the epithelial cell to the tissue fluid.

121
Q

What is the process of moving water into the mucus?

A

Cl- moved from the tissue fluid into the cell using facilitated diffusion.
Cl- diffused from the cell to the mucus through the CFTR protein which is now open. This closes the sodium channel.
The mucus is now negatively charged, this causes NA+ to diffuse from the tissue fluid to the mucus via gaps between the epithelial cells.
The music is now high in salt, this causes water to be drawn from the cell via osmosis.

122
Q

Why can’t people with CF regulate water in mucus?

A

The CFTR channel protein is non existent or doesn’t function.

123
Q

Process of water removal in CF

A

The NA channel is permanently open, causing sodium to build up in the tissue fluid. This causes Cl- to be moved here due to the electrical gradient. The high salt content cause water to be continuously removed from the mucus.
The CFTR channel is non functional so Cl- can not enter the mucus to ensure a concentration gradient to then endure osmosis.

124
Q

What does endocrine mean?

A

Ductless- directly to blood

125
Q

What does exocrine mean?

A

Substances secrete into ducts. They are easily blocked.

126
Q

Why do people with CF have bad digestion?

A

Pancreatic duct is blocked by mucus so enzymes can’t be released. Behind the blockage enzymes damage the tissue and insulin production is stopped.

127
Q

What type of proteins are enzymes?

A

Globular.

128
Q

How big is the active site?

A

A few amino acids wide.

129
Q

What is the lock and key theory?

A

A molecule has a complimentary shape to the active site. These bond temporarily with the amino acids in the active site to produce and enzyme substrate complex. This holds the substrate in place so it can react easily. The products are then released. Each enzyme only catalysis one reaction.

130
Q

What is the substrate?

A

The molecule to be broken or joined.

131
Q

What is the induced fit theory?

A

The active site is flexible, it changes shape slightly to fit the substrate. It still only catalysis one reaction.

132
Q

What do enzymes do? How?

A

Lower the activation energy by increasing the amount of collisions. Different areas of the active site are charged which pulls the substrate in two different directions, breaking it. The active site could also be acidic to favour the reaction.

133
Q

What are intercellular reactions?

A

Reactions occurring inside of cells

134
Q

What are extra cellular reactions. E.g.

A

Reactions out of cells e.g. Tissue fluid, blood or other aqueous solutions.

135
Q

What are catabolic reactions?

A

Breaking things down

136
Q

What are anabolic reactions?

A

Joining things

137
Q

What type of reaction is the hydrolysis of maltose by amylase?

A

Extra cellular, catabolic.

138
Q

Why do females have reduced fertility with CF?

A

There is a mucus plus in the cervix.

139
Q

Why do males with CF have reduced fertility?

A

Often missing a sperm duct or the remaining are blocked by mucus.

140
Q

What evidence is used for the structure of DNA?

A

X-ray diffraction.

141
Q

What does DNA produce?

A

Proteins.

142
Q

What is a gene?

A

A sequence of basis from a section of DNA that code for amino acids.

143
Q

What is the order of size for generic material?

A

Chromosome, DNA, gene.

144
Q

What’s a genome?

A

All of the genes in an individual.

145
Q

DNA is a long chain ______?

A

Polymer.

146
Q

What are DNA units called?

A

Nucleotides.

147
Q

What reaction links nucleotides?

A

Condensation.

148
Q

What are the three molecules of a nucleotide?

A

Deoxyribose sugar. Organic base. Phosphate group.

149
Q

What is a deoxyribose sugar also known as?

A

5 carbon sugar.

150
Q

What does an organic base contain?

A

Nitrogen.

151
Q

What does each shape code for on a DNA model?

A

Circle- phosphate
Pentagon- sugar
Hexagon-base

152
Q

How are the DNA molecules ordered

A

Sugar with phosphate above, base to the right.

153
Q

Where are separate nucleotides linked?

A

Condensation between sugar of one and the phosphate of the other.

154
Q

What is the bond between two nucleotides?

A

Phosphodiester

155
Q

What forms the backbone of DNA ?

A

Sugar, phosphate.

156
Q

What joins complimentary base pairs together?

A

Hydrogen

157
Q

What is anti parallel in terms of DNA?

A

The poly nucleotide strands that run in opposite directions.

158
Q

Are bases hydrophobic or hydrophilic?

A

Hydrophobic

159
Q

How many hydrogen bonds do CG, AT form?

A

AT-2 CG-3

160
Q

What bases have one ring structures?

A

T, C

161
Q

What bases have two rings?

A

A, G

162
Q

Why do bases paid with their complimentary base pairs?

A

To make each rung be three rings in length

163
Q

Where does transcription take place?

A

Nucleus.

164
Q

What is made in transcription? What is it made from?

A

A copy of a gene. RNA.

165
Q

What is the difference between DNA and RNA?

A

RNA is single stranded, ribose sugar, U replaces T.

166
Q

What is mRNA? What does it do?

A

Messenger RNA that carries code from the nucleus to the cytoplasm.

167
Q

What is the process of transcription?

A

RNA polymerase attaches to the DNA. This causes hydrogen bonds between bases to break and the molecule unwinds. The template strand is transcribed to form mRNA, this is the same as the coding strand. Each nucleotide is joined by phosphodiester bonds.

168
Q

What is a nuclear pore?

A

Space in nucleus envision where mRNA leaves

169
Q

What is the nuclear envelope?

A

Toe layers of membrane on the nucleus.

170
Q

What is the sense strand known as?

A

Coding strand.

171
Q

What is the antisense strand known as?

A

Template strand.

172
Q

What is translation?

A

Conversion of a sequence of bases into an amino acids.

173
Q

What is a triplet code?

A

3 bases on DNA that code for an amino acid.

174
Q

What is a codon?

A

Complimentary to triplet code. U replaces T on mRNA.

175
Q

What is an anticodon?

A

Complimentary to codon

176
Q

What does degenerate mean?

A

Multiple things coding for the same thing.

177
Q

What is tRNA?

A

Transfer RNA it carried one amino acid and joins it to the mRNA strand. It isn’t used up.

178
Q

What bond joins amino acids.

A

Peptide?

179
Q

What does a mutation in the base sequence cause?

A

Different triplet which results in a different codon, anticodon and amino acid.

180
Q

What would having a mutation in the base sequence cause to the protein?

A

Different primary structure which creates a different 3D structure and properties

181
Q

What is a frame shift?

A

One base is inserted or deleted meaning all amino acids after that point will be different.

182
Q

What are the types of DNA mutation?

A

Insertion, deletion, inversion, substitutions.

183
Q

What are ribosomes made from?

A

Ribosomal DNA and a protein.

184
Q

Where are the ribosomes found?

A

Free in cytoplasm or attached to endoplasmic reptillium

185
Q

What is the endoplasmic reptillium?

A

Flattened membrane bound sacks.

186
Q

What does a ribosome consist of?

A

2 units. One small one big.

187
Q

Which subunit of the ribosome does the mRNA attach to?

A

Smaller.

188
Q

How are amino acids transferred?

A

tRNA molecules.

189
Q

What is the shape of tRNA?

A

Three leaf clover.

190
Q

What are the bulges in tRNA?

A

Anticodons.

191
Q

What is at the top of tRNA?

A

An amino acid binding site.

192
Q

What is the start codon?

A

Aug.

193
Q

What bonds the codon and anticodon?

A

Hydrogen.

194
Q

What are the stop codons?

A

Uaa. Uag. Uga.

195
Q

What is the process of DNA replication?

A

DNA helicase breaks hydrogen bonds of bases. A primer is put over the start of the DNA strand. DNA polymerase enzyme moves along the strand and created a complimentary strand. Leading strand is 5’3’ and is continually synthesised. Lagging strand is in fragments due to DNA polymerase only working 5’3’.

196
Q

What type of replication does DNA use?

A

Semi conservative.

197
Q

How was semi conservative replication proved?

A

Heavy N15 DNA and light N 14 DNA. 50/50. After first centerfuse. After grown in more light N 14 second it was mid band and light band. So 50/50 and 75/25. Conservative would have one light one heavy. Fragment would have one mid band.

198
Q

What’s a homozygous genotype?

A

FF ff. two the same

199
Q

What is a heterozygous genotype?

A

Two different. Ff.

200
Q

What’s the phenotype?

A

Observable characteristics.

201
Q

When does an embryo become a foetus?

A

10 weeks.

202
Q

What is amniocentesis? Weeks?

A

Needle collect amniotic fluid to collect fetal cells that fell of placenta. 15-17

203
Q

What is chronic villus sampling? Weeks? Effect?

A

Placenta tissue via abdomen or cervix. 8-12. Higher rate of abortion.

204
Q

What’s is NIPD? Weeks?

A

Blood plasma from mother has some embryo DNA. 4-5

205
Q

What is PGD?

A

IVF and taking some of embryo cells during early replication. Doesn’t hurt the embryo.

Biology OCR AS Jess (4 decks)

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