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Module 2 Cells Flashcards

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1
Q

whats the structure of the nucleus

A

Nuclear envelope, nuclear pores, nucleolus, and chromatin

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2
Q

whats the functions of the nucleus

A

Controls the cells activity through transcription on mRNA
Nuclear pores allow substances to move between the nucleus and cytoplasm
Nucleolus makes ribosomes which are made up of proteins and ribosomal RNA

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3
Q

whats the structure of the CSM

A

Phospholipid bilayer with embedded proteins

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4
Q

whats the functions of the CSM

A

Selectively permeable – enables control of the passage of substances in and out of the cell
The barrier between the internal and external environment of the cell

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5
Q

whats the structure of the mitochondria

A

Double membrane – inner membrane folded to form cristae.

Matrix containing small 70S ribosomes, small circular DNA, and enzymes involved in aerobic respiration

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6
Q

whats the function of the mitochondria

A

Site of aerobic respiration producing ATP for energy release

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7
Q

whats the structure of the golgi apparatus

A

3 or more fluid filled membrane bound sacs with vesicles at edge

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8
Q

whats the function of the golgi apparatus

A

Receives protein from rough endoplasmic reticulum
Modifies protein
Packages into vesicles
Makes lysosomes

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9
Q

whats the structure of the lysosomes

A

Type of Golgi vesicle

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10
Q

whats the function of the lysosomes

A

Release of lysozymes to pathogens or worn out cell components

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11
Q

whats the structure of the ribosomes

A

1 large and 1 small subunit

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12
Q

whats the function of the ribosomes

A

Site of protein synthesis

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13
Q

whats the structure of the RER

A

Ribosomes bound by a system of membranes

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14
Q

whats the function of the RER

A

Folds polypeptides to secondary and tertiary structure

Packages to vesicles, transport to the Golgi apparatus

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15
Q

whats the structure of the SER

A

System of membranes

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16
Q

whats the function of the SER

A

Synthesises and processes lipids

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17
Q

whats the structure of the chloroplasts (plants and algae)

A

Thylakoid membranes are stacked up in some parts to form grana, which are linked by lamellae. These sit in the stroma (fluid) and are surrounded by a double membrane. Also contains starch granules and circular DNA.

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18
Q

whats the function of the chloroplasts (plants and algae)

A

Absorbs light for photosynthesis to produce organic substances

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19
Q

whats the structure of the cell wall (plants, algae and fungi)

A

Made of cellulose in plants and algae, and of chitin in fungi

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20
Q

whats the function of the cell wall (plants, algae and fungi)

A

Rigid structure surrounding cells in plants, algae and fungi.
Prevents the cell changing shape and bursting (lysis)

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21
Q

whats the structure of cell vacuole (plants)

A

Contains cell sap which is a weak solution of sugars and salts.
Surrounding membrane is called the tonoplast.

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22
Q

whats the function of cell vacuole (plants)

A

Maintains pressure in the cell (stop wilting)

Stores/isolates unwanted chemicals in the cell

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23
Q

whats a specialised cell

A

The most basic structural subunit in all living organisms; specialised for a particular function

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24
Q

whats a tissue

A

Group of organised specialised cells; joined and working together to perform a particular function

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25
Q

whats an organ

A

Group of organised different tissues; joined and working together to perform a particular function

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26
Q

whats an organ system

A

Group of organised organs; working together to perform a particular function

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27
Q

How prokaryotic cells differ from eukaryotic cells (6 points)

A

Prokaryotic cell cytoplasm contains no membrane bound organelles WHEREAS eukaryotic cell contains membrane bound organelles

Prokaryotic cell has no nucleus WHEREAS eukaryotic cell has a nucleus containing DNA

Prokaryotic DNA is circular and isn’t associated with proteins WHEREAS eukaryotic DNA is linear and is associated with proteins

Prokaryotic cell wall contains murein and peptidoglycan WHEREAS eukaryotic cell wall is made of cellulose

Prokaryotic cells have smaller 70s ribosomes WHEREAS eukaryotic cells have larger ribosomes

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28
Q

what might prokaryotes have

A

One or more plasmid, a capsule, and one or more flagella

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29
Q

what does acellular mean

A

Not made of or able to be divided into cells

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30
Q

what does non-living mean

A

Unable to reproduce without a host cell

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31
Q

principles of an optical microscope

A

Use light to form a 2D image

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32
Q

advantages of optical microscopes

A

Can see living organisms

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33
Q

disadvantages of optical microscopes

A

2D image
Only used on thin specimens
Low resolution; can’t see internal structures of organelles or organelles smaller than 200nm
Low magnification

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34
Q

principles of a TEM

A

Use electrons to form a 3D image

Electromagnets focus beam of electrons onto specimen

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35
Q

advantages of TEM

A

High resolution so can see internal structures of organelles

High magnification

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36
Q

disadvantages of TEM

A

2D image
Only used on thin specimens
Vacuum; can’t see living organisms

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37
Q

principles of an SEM

A

Use electrons to form a 2D image
Beams of electrons scan the surface, knocking off electrons from the specimen, which is gathered in a cathode ray tube to form an image

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38
Q

advantages of SEM

A 
3D image
High resolution; can see
internal structures of organelles
High magnification
Used on thick specimens
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39
Q

disadvantages of SEM

A

Vacuum; can’t see living organisms

Lower resolution than TEM

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40
Q

why is resolution high

A

Electrons shorter wavelength

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41
Q

why is resolution low

A

Visible light longer wavelength

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42
Q

results of SEM

A

more dense = more absorbed = darker appearance

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43
Q

whats magnification

A

how much bigger the image of a sample is compared to the real size

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44
Q

how to measure the magnification

A

magnification = size of image/actual size

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45
Q

whats resolution

A

how well-distinguished an image is between 2 points; shows the amount of detail

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46
Q

how to measure the size of an object viewed with an optical microscope

A
  • Line up eyepiece graticule with stage micrometer
  • Use stage micrometer to calculate the size of divisions on eyepiece graticule at a particular magnification
  • Take the micrometer away and use the graticule to measure how many divisions make up the object
  • Calculate the size of the object by multiplying the number of divisions by the size of division
  • Recalibrate eyepiece graticule at different magnifications
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47
Q

how to prepare a ‘temporary mount’ of a specimen on a slide

A
  • Use tweezers to place a thin section of specimen e.g. tissue on a water drop on a microscope slide
  • Add a drop of a stain e.g. iodine in potassium iodide solution used to stain starch grains in plant cells
  • Add a cover slip by carefully tilting and lowering it, trying not to get any air bubbles
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48
Q

what are the principles of cell fractionation and ultracentrifugation

A
  1. Homogenise tissue using a blender to disrupt cell membrane and break open cell to release organelles
  2. Place in a cold, isotonic, buffered solution
  3. Filter homogenate to remove large, unwanted debris
  4. Ultracentrifugation occurs so centrifuge homogenate in a tube at a low speed and remove pellet of heaviest organelle and spin supernatant at a higher speed then repeat at higher and higher speeds until organelles separated out,
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49
Q

Why is the solution placed in a cold, isotonic, buffered solution

A
  • Cold reduces enzyme activity so organelles aren’t broken down
  • Isotonic so water doesn’t move in or out of organelles by osmosis so they don’t burst or shrivel
  • Buffered keeps pH constant so enzymes don’t denature
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50
Q

How are the organelles separated in ultracentrifugation

A

in order of mass/density

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51
Q

What’s the order in which organelles are separated

A

nuclei, chloroplasts, mitochondria, lysosomes, endoplasmic reticulum, ribosomes

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52
Q

what happens in interphase

A

s phase
g1
g2

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53
Q

what happens in s phase

A

DNA replicates semi-conservatively leading to two sister chromatids

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54
Q

what happens in g1 and g2

A

Number of organelles and volume of cytoplasm increases, protein synthesis, ATP content increased

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55
Q

what’s the structure of a virus

A

DNA and RNA, capsid and attachment proteins

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56
Q

whats mitosis

A

a parent cell divides to produce two genetically identical daughter cells, containing identical copies of DNA of the parent cell.

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57
Q

mnemonic for mitosis stages

A

‘PMAT’

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58
Q

what happens in prophase

A

Chromosomes condense, becoming shorter and thicker so appear as two sister chromatids joined by a centromere
Nuclear envelope breaks down and centrioles move to opposite poles forming spindle network

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59
Q

what happens in metaphase

A

Chromosomes align along equator

Spindle fibres attach to chromosomes by centromeres

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60
Q

what happens in anaphase

A

Spindle fibres contract, pulling sister chromatids to opposite poles of the cell
Centromere divides

61
Q

what happens in telophase

A

Chromosomes uncoil, becoming longer and thinner
Nuclear envelope reforms and forms two nuclei
Spindle fibres and centrioles break down

62
Q

what happens in cytokinesis

A

The division of the cytoplasm producing two new cell

63
Q

whats the importance of mitosis

A

Growth of multicellular organisms
Repairing damaged tissues
Asexual reproduction

64
Q

what does uncontrolled cell division lead to

A

formation of tumours and of cancers

65
Q

whats a malignant tumor

A

cancerous and spreads and affects other tissues

66
Q

whats a benign tumor

A

non-cancerous

67
Q

what are cancer treatments directed at

A

controlling the rate of cell division

68
Q

how do cancer treatments work

A

Disrupt the cell cycle
Mitosis slows
Tumour growth slows

69
Q

give 2 examples of how cancer treatments control the rate of cell division

A

Prevent DNA replication which prevents and slows down mitosis
Disrupts spindle activity so chromosomes can’t attach to spindle by their centromere and sister chromatids can’t be pulled to opposite poles of the cells which slows mitosis

70
Q

give an advantage and disadvantage of cancer treatments

A

Drugs more effective against cancer cells because dividing uncontrollably
Disrupt cell cycle of normal cells too, especially rapidly dividing ones

71
Q

explain the process of binary fission

A
  • Circular DNA and plasmids replicate
  • Cytoplasm expands as each DNA molecule moves to opposite poles of the cell
  • Cytoplasm divides
  • This produces 2 daughter cells, each with a single copy of DNA and a variable number of plasmids
72
Q

wy do viruses not undergo cell division

A

they’re non-living

73
Q

how do viruses replicate

A
  1. Attachment protein binds to complementary receptor protein on surface of host cell
  2. Inject nucleic acid (DNA/RNA) into host cell
  3. Infected host cell replicates the virus particles
74
Q

whats the fluid-mosaic model of membrane structure

A

Molecules within the membrane can move laterally and is a mixture of phospholipids, proteins, glycoproteins, and glycolipids

75
Q

what are the 5 parts of the cell membrane structure

A

phospholipid bilayer, embedded proteins, glycolipids, and glycoproteins, and cholesterol

76
Q

how is the phospholipid bilayer arranged

A

Phosphate heads are hydrophilic so attracted to water – orientate to the aqueous environment
Fatty acid tails are hydrophobic so repelled by water – orientate to the inside

77
Q

how does the phospholipid bilayer control how molecules can enter/leave a cell

A

Allows movement of non-polar small/lipid-soluble molecules down a conc gradient (simple diffusion)
Restricts the movement of larger/polar molecules

78
Q

how do the channel proteins and carrier proteins control how molecules can enter/leave a cell

A

Allows movement of water-soluble/polar molecules / ions, down a concentration gradient (facilitated diffusion)

79
Q

how do the carrier proteins control how molecules can enter/leave a cell

A

Allows the movement of molecules against a concentration gradient using ATP (active transport)

80
Q

how is the phospholipid bilayer adapted for other functions

A

Maintains a different environment on each side of the cell or compartmentalisation of cell

81
Q

how is the phospholipid bilayer is fluid adapted for other functions

A

Can bend to take up different shapes for phagocytosis / to form vesicles

82
Q

how is the surface proteins / extrinsic / glycoproteins / glycolipids adapted for other functions

A

Cell recognition / act as antigens / receptors

83
Q

how is cholesterol adapted for other functions

A

Regulates fluidity / increases stability

84
Q

what the role of cholesterol

A

Makes the membrane more rigid by restricting the lateral movement of molecules making up the membrane

85
Q

explain the movement across membranes by simple diffusion

A

Net movement of small, non-polar molecules across a

selectively permeable membrane, down a concentration gradient

86
Q

does simple diffusion require ATP

A

no - passive

87
Q

what are the factors affecting simple diffusion rate

A

surface area, concentration gradient, diffusion distance

88
Q

explain the movement across membranes by facilitated diffusion

A

Net movement of larger/polar molecules across a selectively permeable membrane, down a concentration gradient through a channel/carrier protein

89
Q

does facilitated diffusion require ATP

A

no - passive

90
Q

what are the factors affecting facilitated diffusion rate

A

surface area, concentration gradients, number of channel/carrier proteins

91
Q

what’s the role of carrier proteins

A

transport large molecules, the protein changes shape when molecule attaches

92
Q

what the role of channel proteins

A

transport charged/polar molecules through its pore

93
Q

what’s special about channels and carrier proteins

A

Different carrier and channel proteins facilitate the diffusion of different specific molecules

94
Q

explain the movement across membranes by active transport

A

Net movement of molecules/ions against a concentration gradient, using carrier proteins and using energy from the hydrolysis of ATP to change the shape of the tertiary structure andpush the substances though

95
Q

what are the factors affecting active transport rate

A

pH/temp (tertiary structure of carrier protein), speed of carrier protein, number of carrier proteins, rate of respiration (ATP production)

96
Q

explain the movement across membranes by co-transport, illustrated by the absorption of sodium ions and glucose by cells lining the mammalian ileum

A
  1. Sodium ions actively transported out of epithelial cells lining the ileum, into the blood, by the sodium-potassium pump. Creating a concentration gradient of sodium (higher conc. of sodium in lumen than epithelial cell)
  2. Sodium ions and glucose move by facilitated diffusion into the epithelial cell from the lumen, via a co-transporter protein
  3. Creating a concentration gradient of glucose – higher conc. of glucose in epithelial cell than blood
  4. Glucose moves out of cell into blood by facilitated diffusion through a protein channel
97
Q

explain the movement across membranes by osmosis

A

Net movement of water molecules across a selectively permeable membrane down a water potential gradient

98
Q

whats water potential

A

Water potential is the likelihood (potential) of water molecules to diffuse out of or into a solution

99
Q

what has the highest water potential

A

Pure water = 0

100
Q

how to make water potential more negative

A

adding solutes to a solution lowers the water potential

101
Q

what are the factors affecting osmosis rate

A

surface area, water potential gradient, diffusion distance

102
Q

how might cells be adapted for transport across their internal or external membranes

A
  • By an increase in surface area

- Increase in number of protein channels / carriers

103
Q

whats the antigen definition

A

Molecules which, when recognised as foreign by the immune system, can stimulate an immune response and lead to the production of antibodies

104
Q

where are antigens found

A

as proteins on the surface of cells

105
Q

why are antigens specific

A

proteins have a specific tertiary structure allowing different proteins to act as specific antigens

106
Q

what do antigens allow the immune system to identify

A

Pathogens
Cells from other organisms of the same species
Abnormal body cells
Toxins

107
Q

outline the process of phagocytosis

A
  1. Phagocyte recognises foreign antigens on the pathogen and binds to the antigen
  2. Phagocyte engulfs pathogen by surrounding it with its cell surface membrane
  3. Pathogen contained in phagosome in cytoplasm of phagocyte
  4. Lysosome fuses with phagosome and releases lysozymes into the phagosome
  5. These hydrolyse the pathogen
  6. Phagocyte becomes antigen presenting and stimulates specific immune response
108
Q

outline the cellular response process

A

T lymphocytes recognise antigen-presenting cells after phagocytosis and specific T helper cell with receptor complementary to specific antigen binds to it, becoming
activated and dividing rapidly by mitosis to form clones

109
Q

What clones are formed and what do they do

A

a) Stimulate B cells for the humoral response
b) Stimulate cytotoxic T cells to kill infected cells by producing perforin
c) Stimulate phagocytes to engulf pathogens by phagocytosis

110
Q

outline the humoral response process

A

Clonal selection occurs:

a) Specific B cell binds to antigen presenting cell and is stimulated by helper T cells which releases cytokines
b) Divides rapidly by mitosis to form clones (clonal expansion)

  1. Some become B plasma cells for the primary immune response – secrete large amounts of monoclonal antibody into blood
  2. Some become B memory cells for the secondary immune response
111
Q

what is the primary response – antigen enters the body for the first time (role of plasma cells)

A

Produces antibodies slower and at a lower concentration because:

  • Not many B cells available that can make the required antibody
  • T helpers need to activate B plasma cells to make the antibodies (takes time)
  • So infected individual will express symptoms
112
Q

what is the secondary response – same antigen enters body again (role of memory cells)

A

Produces antibodies faster and at a higher concentration because:

  • B and T memory cells present
  • B memory cells undergo mitosis quicker / quicker clonal selection
113
Q

what are antibodies

A

Quaternary structured protein
Secreted by B lymphocytes
Binds specifically to antigens forming an antigen-antibody complex

114
Q

Describe and explain how the primary structure of an antibody relates to its function

A

Primary structure of protein = sequence of amino acids in a polypeptide chain

  • Determines the folds in the secondary structure as R groups interact
  • Determines the specific shape of the tertiary structure and position of hydrogen, ionic and disulfide bonds
115
Q

Describe and explain how the quarternary structure of an antibody relates to its function

A

comprised of 4 polypeptide chains (tertiary structured) held together by hydrogen, ionic, and disulfide bonds

  • Enables the specific shaped variable region (binding site) to form which is a complementary shape to a specific antigen
  • Enables antigen-antibody complex to form
116
Q

How do antibodies work to destroy pathogens

A

agglutination

117
Q

whats agglutination

A

Binds to two pathogens at a time at variable region forming an antigen-antibody complex

  • Enables antibodies to clump the pathogens together
  • Phagocytes bind to the antibodies and phagocytose many pathogens at once
118
Q

whats the hinge region

A

antibody can bind to antigens different distances part

119
Q

What is a vaccination?

A

Injection of antigens
From attenuated pathogens
Stimulates the formation of memory cells

120
Q

how can a vaccine lead to symptoms

A

some of the pathogens might be alive, the pathogen could reproduce and release toxins, which can kill cells

121
Q

how does the use of vaccines to provide protection for individuals against disease

A

On secondary exposure to the same antigen, the secondary response produces antibodies faster and at a higher concentration
- Leading to the destruction of a pathogen before it can cause symptoms = immunity

122
Q

what herd immunity

A

Large proportion but not 100% of population vaccinated against a disease

123
Q

how does the vaccine make it more difficult for the pathogen to spread through the population

A

More people are immune so fewer people in the population carry the pathogen-infected
- Fewer susceptible so less likely that a non-vaccinated individual will come into contact with an infected person and pass on the disease

124
Q

how does active immunity occur

A

Initial exposure to antigen e.g. vaccine or primary

infection

125
Q

are memory cells involved in active immunity?

A

yes

126
Q

where do the antibodies come from in active immunity

A

produced and secreted by (B) plasma

cells

127
Q

give an advantage of active immunity

A

Long term immunity so antibody can be produced

in response to a specific antigen again

128
Q

give a disadvantage of active immunity

A

Slow so takes time to develop

129
Q

how does passive immunity occur

A

No exposure to antigen needed

130
Q

are memory cells involved in passive immunity?

A

no

131
Q

where do the antibodies come from in passive immunity

A

Antibody introduced into the body from another
organism e.g. breast milk / across the placenta from
mother

132
Q

give an advantage of passive immunity

A

Fast-acting

133
Q

give a disadvantage of passive immunity

A

Short term immunity (antibody broken down and not replaced)

134
Q

what are the ethical issues associated with the use of vaccines (4 points)

A
  • Tested on animals before use on humans, have CNS so feel pain
  • Tested on humans and volunteers may put themselves at risk of getting disease, think they protected, and then vaccine not work
  • Have side effects
  • Expensive
135
Q

whats can antigen variability cause (3 points)

A
  • New vaccines against a disease need to be developed more frequently
  • Vaccines against disease hard to develop or can’t be developed
  • Experience a disease more than once
136
Q

what’s the effect of antigen variability on disease

A
  • Change in antigen shape
  • Not recognized by B memory cell so no antibody made
  • Not immune
  • Re-undergo primary immune response which is slower and releases a lower concentration of antibodies
  • Disease symptoms felt
137
Q

Explain the effect of antigen variability on disease prevention (vaccines)

A
  • Change in antigen shape
  • Existing antibodies with specific shape unable to bind to changed antigens and form an antigen-antibody complex
  • Memory cells won’t recognise different antigens
138
Q

whats the features of a successful vaccination program

A

Produce suitable vaccine that is:

  • Effective – make memory cells
  • No major side effects - side effects decrease uptake
  • Low cost
  • Easily produced / transported / stored / administered
  • Provides herd immunity
139
Q

whats a monoclonal antibody

A

antibody produced from a single group of genetically identical B cells/plasma cells with an identical structure

140
Q

what are the useful features of a monoclonal antibody

A
  • Only bind to specific target antigens
  • Antibodies have a variable region with a specific tertiary structure
  • is complementary to a specific antigen which can bind to the antibody
141
Q

what can the use of antibodies in the ELISA test to determine if a patient has

A

a) Antibodies to a certain antigen

b) Antigen to a certain antibody

142
Q

whats the ELISA test used for

A

Used to diagnose diseases or allergies

143
Q

Why use controls when performing the ELISA test?

A
  • Controls enable a comparison with the test
    To show that:
  • only the enzyme and nothing else caused color change
  • washing is effective and all unbound antibody is washed away
144
Q

Explain why the secondary and detection antibody must be washed away

A

Enzyme attached to antibody reacts with substrate turns solution diff colour; positive result

  • Not washed out so enzymes react with the substrate
  • Gives a positive result even if no antigen present (false positive)
145
Q

what are the ethical issues associated with the use of monoclonal antibodies

A
  • animals involved in production of monoclonal antibodies have CNS so feel pain and unfair to give them a disease
  • major side effects possible so patients need to be informed of risk and benefits before treatment so they can make informed decisions
146
Q

The structure of HIV – human immunodeficiency virus

A

capsid, lipid envelope, attachment protein, reverse transcriptase, and RNA

147
Q

outline the replication of HIV in helper T cells

A
  1. HIV infects T helper cells (host cell)
    - HIV attachment protein (GP120) attaches to a receptor on the helper T-cell membrane
  2. Virus lipid envelope fuses with cell surface membrane and capsid released into the cell which uncoats, releasing RNA and reverse transcriptase into the cytoplasm
  3. Viral DNA is made from viral RNA
    - Reverse transcriptase produces a complementary viral DNA strand from a viral RNA template
    - Double-stranded DNA is made from this (DNA polymerase)
  4. Viral DNA integrated into host cell’s DNA (by enzyme integrase)
  5. This remains latent for a long time in the host cell until activated
  6. Host cell enzymes used to make viral proteins from viral DNA (within human DNA) → viral
    proteins assembled with viral RNA to make a new virus
  7. New virus bud from the cell (taking some of cell surface membrane as an envelope)
  8. Eventually kills helper T cells
  9. Most host cells are infected and process repeat
148
Q

How HIV causes the symptoms of AIDS

A
  • Infects and kills helper T cells as it multiplies rapidly
  • T helper cells then can’t stimulate cytotoxic T cells, B cells, and phagocytes so impaired immune response
  • Immune system deteriorates
  • More susceptible to infections
  • Diseases that wouldn’t cause serious problems in a healthy immune system are deadly
149
Q

Why antibiotics are ineffective against viruses

A
  • Antibiotics can’t enter human cells
  • Viruses don’t have their own metabolic reactions
  • If we did use the - act as a selection pressure + gene mutation = resistant strain of bacteria via natural selection - reducing the effectiveness of antibiotics and waste money

Biology (3 decks)

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