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Biology Paper 1 Summary > Topic 2 > Flashcards

Topic 2 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

name the organelles of eukaryotic cells

A

cell surface membrane
cell wall
lysosomes
nucleus
Golgi apparatus
rough endoplasmic reticulum
smooth endoplasmic reticulum
mitochondria
chloroplasts
ribosomes
vacuole

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2
Q

structure of nucleus

A

nuclear envelope > double membrane
nuclear pores
nucleoplasm > granular, jelly like material
chromosomes > protein-bound linear DNA
nucleolus > smaller sphere

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3
Q

what is the function of nucleus

A
  • site of DNA replication and transcription (making mRNA)
  • contains genetic code for each cell
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4
Q

structure of smooth endoplasmic reticulum

A

folded membranes called cisternae

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5
Q

function of smooth endoplasmic reticulum

A

synthesis and stores lipids and carbs

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6
Q

what are the membranes of the endoplasmic reticulums called

A

cisternae

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7
Q

structure of rough endoplasmic reticulum

A

folded membranes called cisternae with ribosomes on the cisternae

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8
Q

function of rough endoplasmic reticulum

A

protein synthesis

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9
Q

structure of Golgi apparatus and vesicles

A
  • folded membranes called cisternae
  • vesicles bud off from cisternae
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10
Q

function of Golgi apparatus and vesicles

A
  • add carbs to proteins to form glycoproteins
  • form lysosomes
  • secret carbs
  • produce secretory enzymes
  • transport, modify and store lipids
  • molecules are ‘labelled’ with their destination
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11
Q

structure of lysosomes

A

bag of digestive enzymes (up to 50 different enzymes)

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11
Q

function of lysosomes

A
  • hydrolyse phagocytic cells
  • autolysis (breaking diwn cells)
  • exocytosis (release enzymes to outside of cell to destroy material)
  • digest worn out organelles
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12
Q

structure of mitochondria

A

double membrane
inner membrane > cristae
mitochondrial matrix > fluid centre
loop of mitochondria DNA

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13
Q

function of mitochondria

A

site of aerobic respiration
site of ATP production
DNA > to enable coding for enzymes needed during respiration

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14
Q

structure of ribosomes

A

made of protein and rRNA

eukaryotes > 80s
prokaryotes, mitochondria and chloroplasts > 70s

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15
Q

function of ribosomes

A

protein synthesis

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16
Q

structure of vacuole

A

filled with fluid surrounded by single tonoplast membrane

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17
Q

function of vacuole

A

makes cell turgid
temporary store of sugars and amino acids
pigments colour petals > attracting pollinators

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18
Q

structure of chloroplasts

A

double membrane
thylakoids > folded membranes embedded with pigment
fluid filled stroma contains enzymes for photosynthesis

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19
Q

function of chloroplasts

A

site of photosynthesis
thylakoids > light dependant reactions

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20
Q

structure of cell wall in plants

A

made of microfibrils of cellulose

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21
Q

structure of cell wall in fungi

A

made of chitin

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22
Q

function of cell wall

A

provides structural strength to the cell

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23
Q

structure of plasma membrane

A

found in all cells
phospholipid bilayer > molecules embedded within and attached on the outside
(proteins, carbs and cholestrol)

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24
Q

function of plasma membrane

A

controls entrance and exit of molecules

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25
Q

outline key differences between eukaryotes and prokaryotes

A
  • prokaryotes are smaller
  • prokaryotes have no membrane bound organelles
  • prokaryotes have no nucleus
  • prokaryotes have smaller ribosomes
  • prokaryotes cell wall made of murein
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26
Q

structure of viruses

A

genetic material, capsid and attachment proteins

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27
Q

function of viruses

A

replicate inside of host cells making it difficult to destroy them harming host cells

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28
Q

why are viruses considered non-living

A
  • they cant replicate independantly > require a host cell because they dont have their own organelles
  • do not produce their own energy > no mitochondria
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29
Q

why are viruses considered acellular

A

they lack membrane bound organelles and a cytoplasm

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30
Q

what are the three methods of studying cells

A

microscopy
cell fractionation
ultracentrifugation

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31
Q

what are three types of microscopes

A

optical light ms
transmission electron ms
scanning electron ms

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32
Q

define magnification

A

refers to how many times larger the image is compared to the object

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33
Q

define resolution

A

the minimum distance between two objects making them seen as seperate

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34
Q

how do optical light microscopes work

A

a beam of light is condensed to create the image

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35
Q

why does optical light microscopes have a poorer resolution

A

light wavelength is longer

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36
Q

how do electron microscopes work

A

beam of electrons is condensed to create the image
- electromagnets used to condense the beam

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37
Q

compare magnification of optical and electron microscopes

A

optical has a lower magnification than electron

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38
Q

compare resolution of optical and electron microscopes

A

optical has lower resolution than electron because light has a longer wavelength than electrons

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39
Q

compare colour of images between optical and electron microscopes

A

optical produces colour images whereas electron produces black and white images

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40
Q

compare the conditions of the specimen used between optical and electron microscopes

A

optical microscopes allow for living specimen to be used but with electron sample must be in a vacuum and non-living

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41
Q

summarise advantages and disadvantages of optical light microscopes

A

+ colour images
+ live specimen sample
- poorer resolution
- poorer magnification

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42
Q

summarise advantages and disadvantages of electron microscopes

A

+ higher resolution
+ higher magnification
- specimen must be dead
- black and white images

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43
Q

what is the impact of using optical light microscopes and therefore having a poorer resolution

A

smaller organelles arent visible

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44
Q

explain how transmission electron microscopes work

A
  • thin specimen prepped in vacuum is stained
  • electron gun produces beam of electrons which pass through specimen
  • some parts of specimen absorb electrons
  • darker areas on image show electron absorption
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45
Q

explain how scanning electron microscopes work

A

electrons beamed onto the surface of specimen and then are scattered in diff ways depending on the contours > producing 3D images

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46
Q

what is cell fractionation

A

isolating of organelles so that they can be studied

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47
Q

what are the two steps of cell fractionation

A
  1. homogenisation
  2. ultracentrifugation
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48
Q

describe homogenisation

A

cell is broken down and blended in a cold isotonic buffer solution

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49
Q

why is the solution filtered after homogenising

A

to remove large debris

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50
Q

describe ultracentrifugation

A

the filtered solution is placed in a centrifuge and spun at different speeds
- organelles form pellets at the bottom of test tube depending on its density

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51
Q

why is the cell blended in a cold solution

A

to prevent enzyme activity and prevent damage to the organelles

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52
Q

why is the cell blended in an isotonic solution

A

to prevent osmosis > could burst/shrivel the organelles

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53
Q

why is the soltuion that the cell is blended in buffered

A

to prevent damage to organelles > could be too acidic / alkaline

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54
Q

what is differential centrifugation

A

centrifuge spins and centrifugal forces causes pellets of the most dense organelles to form at the bottom
- speed of centrifuge increases each time
- supernatant is removed and spun again

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55
Q

what is the order of differential centrifugation of the organelles

A

nuclei
chloroplast s(plants only)
mitochondria
lysosomes
endoplasmic reticulums
ribosomes

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56
Q

compare cell division between eukaryotes and prokaryotes

A

eukaryotes > mitosis or meiosis

prokaryotes > binary fission

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57
Q

why do viruses not undergo cell division

A

they are non-living

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58
Q

how do viruses replicate

A

by injecting their nucleic acid into a host cell and invading them

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59
Q

what are the three key stages of the cell cycle

A

Interphase (G1, S, G2)
Nuclear division > mitosis / meiosis
Cytokinesis

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60
Q

what is the longest stage of the cell cycle

A

Interphase

61
Q

what happens in interphase

A

organelles double, cell grows and DNA replicates

62
Q

what are the two types of nuclear division

A

mitosis and meiosis

63
Q

what does mitosis create

A

two identical diploid cells

64
Q

what does meiosis create

A

four genetically different haploid cells

65
Q

what is cytokinesis

A

division of the cytoplasm to create new cells

66
Q

what is G1

A

growth stage

67
Q

what is S phase

A

DNA synthesis

68
Q

what is G2

A

growth and preparation for nuclear division

69
Q

what are the 4 stages of mitosis

A

prophase
metaphase
anaphase
telophase

70
Q

how many rounds of division are there for mitosis

A

one

71
Q

describe prophase

A
  • chromosomes condense and become visible
  • nucleolus disappears
    (animal cells)
  • centrioles separate to opposite poles of the cell
72
Q

what do centrioles do

A

create spindle fibres which attach to the chromatids to pull them to opposing poles of the cell

73
Q

describe metaphase

A
  • chromosomes align at equator
  • spindle fibres released from poles and attach at the centromere to the chromatid
74
Q

where do the spindle fibres attach on the chromosomes

A

at the centromere

75
Q

describe anaphase

A
  • spindle fibres retract and pull centromere and chromatids to opposing poles
  • causing centromere to divide into two and pull the individual chromatids away
76
Q

where is the energy needed for anaphase produced from

A

mitochondria

77
Q

describe telophase

A
  • chromosomes at each pole become long and thin again
  • spindle fibres disintegrate and nucleus reforms
  • cytokinesis occurs > two genetically identical cells are formed
78
Q

how do you calculate mitotic index

A

(number of cells in mitosis / total number of cells) x 100

79
Q

what cell division occurs in prokaryotic cells

A

binary fission

80
Q

what model describes the structure of all membranes

A

fluid mosaic model > mixture and movement of phospholipids, glycoproteins, proteins and glycolipids

81
Q

why do the phospholipids align as a bilayer

A

hydrophilic heads and hydrophobic tails

82
Q

why are the phospholipid heads hydrophilic

A

the negative charge on the phosphate group is attracted to water

83
Q

why are phospholipid tails hydrophobic

A

because they repel water

84
Q

what is the impact of the prescense of cholesterol

A

restricts lateral movement of other molecules > prevents fluidity of the membrane at high temperatures

85
Q

why is the reduced fluidity of the membrane due to the presence of cholesterol an advantage

A

prevents water and dissolved ions from leaking out of the cell

86
Q

what is osmosis

A

movement of water from an area of higher water potential to an area of lower water potential across a partially permeable membrane

87
Q

what is water potential

A

the pressure created by water molecules and is measured in kPa

88
Q

what is the water potential of pure water

A

0

89
Q

what happens to the water potential of water when solutes are dissolved in it

A

becomes negative

90
Q

what is an isotonic solution

A

water potential is the same in the solution and the cell within the solution

91
Q

what does hypotonic mean

A

water potential of solution is more postive (closer to 0) than the cell

92
Q

what does hypertonic mean

A

when water potential of a solution is more negative than the cell

93
Q

whats active transport

A

movement of substance from a low conc area to high conc area using metabolic energy via carrier proteins

94
Q

explain active transport

A
  1. molecule binds to complementary receptor cells onto the carrier protein
  2. ATP binds to carrier protein from inside of the cell an =d its hydrolysed into ADP+Pi
  3. this causes carrier protein to change shape and release molecule to the other side
  4. phosphate ion is released and protein returns to og shape
95
Q

what type of transport is co transport

A

active

96
Q

outline the steps of co-transport of glucose and sodium ions in the ileum

A
  1. sodium ions are actively transported out of the epithelial cell into the blood
  2. this reduces the sodium ion concentration in the epithelial cell
  3. sodium ions can then diffuse down their conc gradient from the ileum into the epithelial cell via a co transporter protein
  4. glucose / amino acids co transport against their conc gradient from the ileum into the epithelial cell with the sodium ion
  5. the glucose/amino acid can then move from the epithelial cell into the blood capillary via facilitated diffusion
97
Q

how can cells be adapted for rapid transport

A
  1. increased surface area > e.g. microvilli
  2. increased number of protein channels and carriers in their membranes
98
Q

what are lymphocytes

A

the cells that can identify whether a cell is a self cell or a non-self cell and then destroy it if its a non-self cell

99
Q

examples of non-self cells

A

pathogens
cells from other organisms
toxins
abnormal body cells

100
Q

whats an antigen

A

molecules (usually proteins) that trigger an immune response

101
Q

what is antigen variability

A
  1. DNA of pathogens can mutate frequently meaning a mutation in the gene which codes for the antigen will result in a different shaped antigen
102
Q

what is the impact of antigen variability to the human body

A

any previous immunity against the pathogen is no longer effective since the shape of the antigen has changed so any of the memory cells in the body will not be able to bind to the new shape

103
Q

why does a new influenza virus vaccine have to be created every year

A

because the virus mutates and changes its antigens very quickly

104
Q

what is the bodys first line of defence

A

chemical and physical barriers
e.g. skin, stomach acid, nails, mucus

105
Q

what is the bodys second line of defence

A

white blood cells

106
Q

what are the two types of white blood cells involved in immune response

A

phagocytes and lymphocytes

107
Q

which type of WBC is responsible for a non-specific immune response

A

phagocyte

108
Q

what type of immune response is a lymphocyte used for

A

specific

109
Q

what is phagocytosis

A

the destruction of any non-self cell carried out by phagocytes

110
Q

where are phagocytes found

A

blood and tissue

111
Q

outline steps of phagocytosis

A
  1. chemicals / debris released by pathogen attracts the phagocyte to itself
  2. receptors on the phagocyte bind to the antigens on the pathogen
  3. phagocyte starts to change shape and engulfs the pathogen in a phagosome vesicle
  4. lysosome within phagocyte fuses with the phagosome and release its contents (enzymes)
  5. the lysozymes released hydrolyse the pathogen
  6. this destroys the pathogen and any soluble products are absorbed and used by phagocyte
112
Q

where are lymphocytes made

A

bone marrow

113
Q

where do t cells mature

A

thymus

114
Q

what is the cell-mediated response

A

the response involving t cells and body cells

115
Q

what are antigen presenting cells

A

cells which present non-self antigens on their surface

116
Q

examples of APC

A
  1. infected body cells
  2. macrophage which has engulfed and destroyed a pathogen
  3. transplanted organ cells
  4. cancer cell
117
Q

outline steps of cell mediated response

A
  1. helper t cell receptors bind to APC
  2. this activates the helper t cells to divide by mitosis and clone themselves
  3. cloned helper t cells differentiate into different cells
118
Q

what do t helper cells differentiate into

A
  • some remain as t helper cells to activate B lymphocytes
  • stimulators of macrophages for phagocytosis
  • memory cells for that antigen
  • cytotoxic t cells > destroy abnormal / infected cells
119
Q

what do cytotoxic t cells do

A

destroy abnormal or infected cells

120
Q

how do cytotoxic t cells destroy abnormal cells

A

release a protein called perforin which embeds in the c.s.m and creates a pore allowing for substances to enter and leave the cell > causing cell death

121
Q

what does the humoral response use

A

B cells and antibodies

122
Q

outline the steps of the humoral response

A
  1. B cells have Ab on their c.s.m
  2. These Ab will bind to Ag when they collide with them
  3. B cell will engulf the Ag (endocytosis) and then present the Ag on its self
  4. t helper cells have receptors which are going to attach to the B cell and activate it to go under clonal expansion and differentiation
  5. B cells undergo mitosis and differentiate into memory B cells or plasma cells
  6. the plasma cells can then secrete Ab which can then bind to their specific Ag
123
Q

can B cells produce antibodies

A

no, but they can differentiate into plasma cells which can

124
Q

what type of immunity is the humoral response

A

active

125
Q

compare memory B cells and plasma cells

A
  1. mBcells cant produce Ab but plasma cells can
  2. plasma cells are short lived whereas mBcells can live in the body for decades
126
Q

what is the structure of an antibody

A

quaternary proteins

127
Q

how many chains make an antibody

A

4
2 long
2 short

128
Q

what is agglutination

A

clumping of Ab-Ag complexes

129
Q

what is the advantage of agglutination

A

makes it easier for phagocytes to locate and destroy the pathogens

130
Q

what is passive immunity

A

when the Ab are introduced to the body and not naturally made and so plasma cells and memory cells arent made > therefore theres no long term immunity

131
Q

examples of passive immunity

A

Ab passed through the placenta to the fetus or through breast milk to a baby

132
Q

what is active immunity

A

immunity created by your own natural body systems from exposure to the pathogen or its antigen

133
Q

outline the differences between natural and artificial active immunity

A

natural > following infection
artificial > following introduction of a weakened version of pathogen or antigens via a vaccine

134
Q

how do vaccines work

A
  • small amounts of weakened or dead pathogen or antigens are introduced into the mouth or by injection
  • exposure to the antigens activates the B cells to go through clonal expansion and differentiation
  • B cells undergo mitosis and differentiate > plasma cells and mBcells
  • plasma cells produce Ab
135
Q

how does herd immunity work

A

if enough of the population are protected against the pathogen, it cant easily spread

136
Q

what is the structure of HIV

A
  • core > genetic RNA material + reverse transcriptase
  • capid
  • envelope
  • protein attachments > enables attachment to the hosts helper t cells
137
Q

how does HIV replicate in helper t cells

A
  • HIV attached to CD4 protein on helper t cells
  • HIV protein capsule fuses with helper t cell membrane so RNA and enzyme can enter
  • HIV enzyme RT copies viral RNA into a DNA copy and then moves to the t helper cell nucleus
  • mRNA is transcribed and helper t cell starts to create viral proteins to make new viral particles
138
Q

difference between HIV and AIDS

A

HIV is when the person is infected with the virus
AIDS is when the replicating virus is interfering with the functioning of the immune system

139
Q

how does AIDS interfere with the functioning of the immune system

A

helper t cells are destroyed so host is unable to produce an effective immune response to other pathogens > leading to infections and cancer

140
Q

whats a monoclonal Ab

A

type of Ab which can be isolated and cloned

141
Q

uses for mcAb

A

medical treatment
medical diagnosis
pregnancy tests

142
Q

explain how direct mcAb therapy can treat some cancer

A
  • mcAb is given to patient
  • mcAb complementary to the antigens on cancer cells bind to cancer cells
  • this prevents other chemicals binding to the cancer cell and prevents uncontrolled cell division
  • stops the growth of the cancer cell and doesnt harm other cells
143
Q

explain how indirect mcAb therapy can treat cancer

A
  • mcAb is complementary to cancer cells antigens and the mcAb has a drug attached
  • this drug will kill the cancer cells upon binding
    > “bullet drugs”
144
Q

what type of test do medical diagnosis use

A

ELISA test

145
Q

what is ELISA

A

enzyme linked immunosorbent assay

146
Q

how does ELISA test strip kit work

A
  • a mobile Ab which is complementary to the
    Ag being tested for and has pigment attached to it will drive up the test strip
  • if the Ag being tested for is present, the mobile Ab with the Ag binded to it, will bind to an immobilised Ab which is also complementary to the Ag being tested for > a coloured line will show up due to the pigment
  • the Ab will continue travelling up the test strip and bind to another immobilised Ab which is complementary to the first Ab > a colour line will show
147
Q

why is there a third Ab used in an ELISA test which is complementary to the first Ab

A

so we know the Ab is present and is moving up along the test strip

148
Q

how does the ELISA test in a beaker work

A
  • add patient test sample to beaker
  • wash to remove unbound test sample
  • add Ab which is complementary to Ag being tested for
  • wash to remove unbound Ab
  • add second Ab which is complementary to first Ab and has an enzyme attached
  • wash again
  • add colourless substrate for enzyme to beaker
    > if Ag is present, coloured products formed due to enzyme-substrate complex
    > intensity of colour indicates prescence of Ag
149
Q

what are the ethical issues surround mcAb

A
  • requires mice
    > is it justified to use animals for the better treatment of humans

Biology Paper 1 Summary (4 decks)

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