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A-level Biology > Lifestyle health and risk > Flashcards

Lifestyle health and risk Flashcards

1
Q

what is a polar molecule?

A

molecule that contains both positive and negative charge

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2
Q

what type of molecule is water?

A

polar molecule

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3
Q

which part of water is more negative?

A

oxygen

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4
Q

which part of water is more positive?

A

hydrogen

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5
Q

what holds multiple water molecules together?

A

weak hydrogen bonds

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6
Q

what is a solvent?

A

a liquid in which things dissolve in

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7
Q

why does water form droplets?

A

cohesion, hydrogen bonds keep water molecules attracted to eachother

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8
Q

why is water a good solvent?

A

the hydrogen attracts negative ions, and the oxygen attracts positive ions

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9
Q

what is cohesion?

A

water being attracted to water

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10
Q

what is adhesion?

A

water being attracted to surfaces

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11
Q

what type of molecules are hydrophillic?

A

polar

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12
Q

what type of molecules are hydrophobic?

A

non-polar

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13
Q

why is it so hard to raise waters temperature?

A

alot of energy is needed to break the hydrogen bonds between water molecule

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14
Q

why do animals stay in water?

A

to maintain a cool temp and stop enzymes denaturing

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15
Q

what does buffer mean?

A

resistant to change

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16
Q

what is water potential?

A

the ability of water to move

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17
Q

how does water always move, relative to water potential?

A

from high water potential to low water potential

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18
Q

why is water polar?

A

the electrons spends more time near the oxygen.

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19
Q

why is water less dense as a solid?

A

hydrogen bonds form when water is below 4 C and fix the polar molecules slightly further apart than in liquid state.

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20
Q

what chemical structure is ice?

A

giant, rigid but open structure with every oxygen atom at the centre of a tetrahedral arrangement of hydrogen atoms

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21
Q

why is water so important for life?

A

acts as a medium for chemical reactions and also helps transport dissolved compounds into and out of cells

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22
Q

what is capillary action?

A

the process by which water can rise up a narrow tube against gravity

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23
Q

why is the fact that ice floats so important for aquatic life?

A

ice forms an insulating layer above the water below.

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24
Q

name 2 examples of disaccharides?

A
  • maltose
  • sucrose
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25
Q

name 2 examples of monosaccharides?

A
  • glucose
  • fructose
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26
Q

name 2 examples of polysaccharides?

A
  • glycogen
  • starch
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27
Q

what is the generic formula for carbohydrates?

A

C:2H:0

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28
Q

what type of monosaccharide is glucose?

A

hexose monosaccharide

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29
Q

what is the difference between alpha and beta glucose?

A

in alpha, the hydroxyl group is below the ring plane

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30
Q

what happens when 2 alpha glucose are close enough to eachother?

A

their hydroxyl groups react, a bond is formed and H2O is lost

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31
Q

what type of reaction occurs between 2 alpha glucoses?

A

condensation reaction

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32
Q

what type of bond is formed between 2 alpha glucose?

A

1 - 4 glyosidic bond

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33
Q

what type of bond is a 1-4 glycosidic bond?

A

covalent bond

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34
Q

why is amylose less soluble than other sugars?

A

the angle of the bond means that this long chain of glucose twists which is further stabilised by hydrogen bonding within the molecule.

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35
Q

what 2 polysaccharides make starch?

A
  • amylose
  • amylopectin
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36
Q

how is amylose formed?

A

many alpha glucose molecules joined together by only 1-4 glycosidic bonds

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37
Q

how is amylopectins formation different than amyloses?

A

there are also some glycosidic bonds between carbon 1 and carbon 6 atoms

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38
Q

what does amylopectins 1-6 glycosidic bonds cause?

A

gives it a branch structure, with the 1-6 branching points being every 25 glucose subunits

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39
Q

what is starch used in?

A

plants

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40
Q

what is glycogen used in?

A

animals and fungi

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41
Q

why is glycogen more compact than starch?

A

forms more branches than amylopectin

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42
Q

why is branching needed for animals?

A
  • more compact
  • leaves many free ends where glucose molecules can be added or removed, speeding up the process
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43
Q

what are the 3 main properties of glycogen and amylopectin?

A
  • insoluble
  • branched
  • compact
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44
Q

what is the reverse of a condensation reaction?

A

hydrolysis reaction

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45
Q

why are beta glucose molecules not able to join together like alpha glucose molecules?

A

there hydroxyl groups on carbon 1 and 4 are to far apart to react

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46
Q

how do beta glucose molecules join together?

A

if an alternate glucose molecule is turned upside down

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47
Q

what is a polysaccharide formed from beta glucose molecules called and described as?

A

a straight chain molecule called cellulose

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48
Q

is cellulose branched?

A

no

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49
Q

what do hydrogen bonds between cellulose
molecules form?

A

microfibrilis

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50
Q

what do microfibrilis form?

A

macrofibrilis and then they form fibres

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51
Q

what are cellulose fibres used for?

A

cell walls

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52
Q

what are the characteristics of cellulose fibres?

A
  • strong
  • insolule
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53
Q

name 5 uses of lipids?

A
  • source of energy
  • energy storage
  • biological membranes
  • insulation
  • waterproof
  • protective cushioning for organs
  • steroid hormones
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54
Q

name 4 properties of lipids?

A
  • twice the energy of carbohydrates
  • made of only C,H,O
  • not polymers
  • insoluble in water
  • soluble in organic solvents like ethanol
  • energy dense
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55
Q

what are triglycerides made of?

A

1 molecule of glycerol and 3 fatty acids bonded together

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56
Q

how are triglycerides synthesised?

A

by the formation of an ester bond between each fatty acid and the glycerol

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57
Q

how is each ester bond in a triglyceride formed?

A

a condensation reaction

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58
Q

what is esterification?

A

the process in which triglycerides are synthesised

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59
Q

how are ester bonds broken down?

A

a hydrolysis reaction

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60
Q

what is the purpose of cholesterol?

A

stabilise the membrane

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61
Q

name the characteristics of cholesterol heads?

A

polar and hydrophillic

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62
Q

name the characteristics of cholesterol tails?

A

non-polar and hydrophobic

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63
Q

what are HDL’s and LDL’s examples of?

A

lipoprotiens

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64
Q

what do HDL’s do?

A

carries cholesterol to liver

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65
Q

what do LDL’s do?

A

carries cholesterol to cells

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66
Q

what makes cholesterol?

A

the liver

67
Q

what does cholesterol do to stabilize membranes?

A

binds the phospholipids together using its opposite head and tail

68
Q

what is cholesterol?

A

a steroid, as its made of carbon rings

69
Q

why does cholesterol form lipoprotiens?

A

so it can be transported in blood

70
Q

how does cholesterol regulate the fluidity of membranes?

A
  • keeps membranes fluid at low temperatures
  • stopping them becoming too fluid at high temperatures
71
Q

what does transmembrane mean?

A

spans the width of the phospholipid bilayer

72
Q

what type of substances can easily pass through a phospholipid bilayer?

A

small non-polar substances and water

73
Q

what are receptors made of?

A

glycoprotiens

74
Q

what type of substances can pass through protein channels?

A

ions/polar substances

75
Q

what makes a glycoprotein?

A

protein + carbohydrate group

76
Q

what are peripheral proteins?

A

receptors

77
Q

what do golgis do?

A

modify proteins

78
Q

what do vesicles do?

A

transfer proteins

79
Q

what do channel proteins do?

A

allow certain proteins through the phospholipid bilayer

80
Q

are channel proteins passive or active?

A

passive

81
Q

what do carrier proteins do?

A

transport ions or molecules by active transport, passive diffusion or facilitated diffusion

82
Q

what can carrier proteins do to substances that they transport?

A

change their conformity (shape)

83
Q

what molecules can pass through membranes?

A
  • water
  • small molecules
  • lipid-soluble molecules
84
Q

name 4 features of all cytosis?

A
  • moves large quantities
  • fusing and pinching of membranes
  • actives process
  • forming and moving vesicles
85
Q

what happens in endocytosis?

A

a solid substance is taken into the cell by the infolding of a membrane

86
Q

what happens in exocytosis?

A

a vesicle fuses with the membrane to release its contents

87
Q

what is pinocytosis?

A

endocytosis with liquids

88
Q

what does hypotonic mean?

A

more water than solute

89
Q

what does hypertonic mean?

A

more solute then water

90
Q

what does isotonic mean?

A

equal water and solute

91
Q

how many forms of RNA exist?

A

3

92
Q

name 3 differences in RNA from DNA?

A
  • single stranded
  • the base uracil is found instead of thymine
  • the sugar molecule is ribose instead of deoxyribose
93
Q

what are the 3 forms of RNA?

A
  • mRNA
  • tRNA
  • rRNA
94
Q

name 3 features of mRNA?

A
  • made in the nucleus
  • 3 adjacent bases = a codon
  • it carries the genetic code from the nucleus to the cytoplasm, where its used to make a protein during translation
95
Q

name 3 features of tRNA?

A
  • found in the cytoplasm
  • has an amino acid binding site at one end and an anticodon at the other
  • carries the amino acids for proteins to the ribosomes during translation
96
Q

name 2 features of rRNA?

A
  • forms the 2 subunits in a ribosome
  • helps to catalyse the formation of peptide bonds between amino acids
97
Q

what 2 phases converts DNA into proteins?

A
  • translation
  • transcription
98
Q

what does transcription mean?

A

to copy the DNA

99
Q

what does translation mean?

A

converting to another form

100
Q

what is the first phase of DNA replication?

A

transcription

101
Q

what happens in transcription? (6 steps)

A
  • double helix unzips by DNA helicase as the hydrogen bonds between base pairs break
  • so the 2 polynucleotide strands separate
  • the sense strand acts as a template, free RNA nucleotides form complementary base pairs to the exposed bases.
  • RNA polymerase forms sugar-phosphate bonds between nucleotides
  • The mRNA detaches from the sense strand
  • The two DNA strands join back together and The DNA molecules winds back up into a helix
102
Q

what is a transcription factor?

A

special proteins that recognise specific sequences of DNA in promoter regions

103
Q

where does translation occur?

A

ribosomes

104
Q

what is the main job of tRNA in translation?

A

to carry specific, individual, amino acids

105
Q

what is the main job of rRNA in translation?

A

stabilises protein synthesis & helps catalyse the reaction

106
Q

how does mRNA move out of the nucleus?

A

through a nuclear pore

107
Q

name the 7 stages of translation?

A
  • the mRNA attaches to a ribosome, and tRNA carries an amino acid to the ribosome
  • a tRNA with an anticodon complementary to the first codon on the mRNA attaches to the molecule
  • a second tRNA molecule attaches to the next codon in the same way
  • rRNA catalyses the formation of a peptide bond between the amino acids attached to the tRNA, the first tRNA moves away
  • an third tRNA binds to the next codon, its amino acid binds, then it moves away
  • this process continues, producing a polypeptide chain until a stop codon is reached
  • the chain moves away from the ribosome and translation is complete
108
Q

name the 3 parts of a general amino acid formula?

A
  • variable R group
  • amino group (NH2)
  • carboxyl group (COOH)
109
Q

what is a histone?

A

positively charged protiens

110
Q

how are chromosomes formed?

A
  • DNA wraps around histones to form nucleosomes
  • these clusters coil and supercoil to form chromosomess
111
Q

what is a centromere?

A

centre of a chromosome

112
Q

what are the 4 phases of mitosis?

A
  • prophase
  • metaphase
  • anaphase
  • telophase
113
Q

what occurs in prophase?

A
  • chromosomes become visible
  • nuclear membrane breaks down
  • centrioles move to opposite sides
  • spindles fibres develop from centrioles
114
Q

what occurs in metaphase?

A
  • spindle fibres attach to the centromeres
  • chromatids line up in the centre
115
Q

what occurs in anaphase?

A
  • spindle fibres pull chromatids apart
  • chromatids move to opposite sides
  • mitochondria surround the spindle fibres, providing energy
116
Q

what occurs in telophase?

A
  • nuclear membrane forms around chromosomes at opposite ends
  • chromosomes become indistinct
  • spindle fibres disapear
117
Q

what is a mutation?

A

random change in sequence of bases

118
Q

what are the 6 types of asexual reproduction?

A
  • binary fission
  • producing spores
  • regeneration
  • producing buds
  • propagation
  • parthenogenesis
119
Q

what is the definition of growth?

A

permanent increase in number of cells or size and mass

120
Q

what is the definition of assimilation?

A

incorporating new materials into cells

121
Q

what is independant assortment?

A

chromosomes from either parent are distributed randomly to different sides of the equator

122
Q

what is crossing over?

A

chromatids can tangle and break off then combine with new chromatids

123
Q

what is a homologous pair?

A

chromatids attached, joined by a centromere

124
Q

when does random fusion of gametes occur?

A

fertilization

125
Q

what is an autosome?

A

non-sex chromosome

126
Q

what is co-dominance?

A

2 alleles with equal influence

127
Q

what is an allele?

A

versions of a gene

128
Q

what is a locus?

A

position of a gene on a particular autosome

129
Q

how does gene locus affect variation?

A

2 or more genes with the same locus cross over

130
Q

what is ficks law?

A

(SA X concentration difference) / membrane thickness

131
Q

what is DNA?

A

the code for protiens

132
Q

what is a base?

A

compound that joins 2 strands of DNA

133
Q

what is a gene?

A

sub-section of a chromosome

134
Q

what is a genome?

A

all genetic material in an organism

135
Q

how are 2 DNA strands joined together?

A

one strand is flipped upside down so they are parallel and can join at bases

136
Q

how are nucleotides joined?

A

by phosphodiester bonds in a condensation reaction

137
Q

what bases are purines?

A

A + G

138
Q

what bases are pyrimidines?

A

T + C + U

139
Q

features of purines?

A
  • 3 bonds
  • bigger than pyrimidines
140
Q

features of pyrimidines?

A
  • 2 bonds
  • smaller than purines
141
Q

name 3 features of RNA?

A
  • ribose sugar
  • 1 strand
  • U over T
142
Q

what does DNA helicase do?

A

unzips DNA

143
Q

what does DNA polymerase do?

A

copies DNA

144
Q

what does DNA ligase do?

A

rejoins DNA strands

145
Q

what is a primary protien structure?

A

the order of amino acids (peptide bonds)

146
Q

what is a secondary protien structure?

A

alpha helices and beta pleated sheets (hydrogen bonds)

147
Q

what is a tertiary protien structure?

A

3D folding of amino acids and subunits, involves bonds ionic + hydrogen + disulphide bridges

148
Q

what is quaternary protien structure?

A

multiple tertiary shapes

149
Q

what is spermatogenesis?

A

process that forms sperm in mammals

150
Q

what is oogenesis?

A

process that forms eggs in mammals

151
Q

what is the zona palosida?

A

part on cell membrane on an egg cell that hardens

152
Q

name 2 processes that prevent polyspermy?

A
  • ion channels open then close
  • cortical reaction = hardens zona palosida
153
Q

what is semi conservative DNA replication?

A
  • DNA strand is unzipped
  • each strand acts as a template for a new strand
  • original strand and new strand join together
154
Q

why is semi conservative DNA replication called semi conservative?

A

half of the original DNA molecule is kept (conserved)

155
Q

name the 4 steps of messelson and stahl’s experiment?

A
  • bacteria were grown in a broth containing heavy nitrogen
  • a sample of DNA was taken and spun in a centrifuge
  • the bacteria containing only heavy nitrogen DNA were taken out and added to a light nitrogen broth
  • removed after 1 round of replication and centrifuge
156
Q

how many lines does semi-conservative DNA replication form after 1 generation?

A

1, a mix of both heavy and light nitrogen

157
Q

what is the function of mucus?

A

to trap bacteria

158
Q

what happens if mucus is too thick?

A

it cant be dislodged so bacteria builds up, causing infection

159
Q

what happens if mucus is too runny?

A

it cant trap bacteria

160
Q

what does cystic fibrosis cause?

A

gene mutation in the CFTR protein, causing to not open

161
Q

describe the 5 steps that occur in order to correct mucus that is too runny?

A

1) Na pump pumps out Na from epithelial cell into tissue fluid
2) causing a low Na conc. in the cell
3) so Na from mucus flows into cell
4) due to electrochemical gradient, Cl ions flow into tissue fluid from mucus
5) creating low water potential in the tissue fluid, so water flows in from the mucus

162
Q

describe the 6 steps that occur in order to correct mucus that is too thick?

A

1) Cl pump pumps in Cl ions from tissue fluid
2) when Cl conc. is high, CFFTR protein opens
3) Cl flows from cell into mucus
4) Na channel closes to keep Na from leaving mucus
5) Na from tissue fluid enters mucus, due to electrochemical gradient
6) lowering water potential in mucus, so water from tissue fluid enters mucus

163
Q
A

A-level Biology (6 decks)

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