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Cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is in the nucleus

A

Nucleolus, chromosome, chromatin, nuclear membrane, nuclear pore, nucleoplasm

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2
Q

What does the nuclear pore do

A

Let’s materials in and out of the nucleus

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3
Q

What does the nucleolus do

A

Manufactures ribosomal RNA and ribosomes

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4
Q

What are the functions of the nucleus

A

To proteinsynthesis (mRNA production)
Retain genetic information (DNA, chromosomes)
Manufacturer ribosomes, ribosomal RNA

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5
Q

What is in the mitochondrion

A

Double membrane, matrix, cristae, ribosomes, DNA

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6
Q

Why is the cristae in the mitochondrion adapted

A

It is highly folded to provide a large surface area for enzyme attachment for aerobic respiration

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7
Q

What is the rough and smooth E.R made of

A

Flat sacs - cisternae

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8
Q

What does the rough E.R do

A

It is the site of proteinsynthesis and is the pathway for proteins in the cell

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9
Q

What does the smooth E.R do

A

Involved in the synthesis, transport and storage of lipids and carbohydrates

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10
Q

What are the functions of the Golgi apparatus

A 
Add carbohydrates to proteins to form glycoproteins 
Make secretory enzymes
Secrete carbohydrates 
Transport, modify and store lipids
Form lysosomes
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11
Q

What is a lysosome and when are they formed

A

A vesicles containing digestive enzymes

Formed when vesicles pinch off the golgi

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12
Q

What are the functions of the lysosome

A

Release digestive enzymes to outside cell
Digest worn out organelles in cell
Digest materials ingested by phagocytic cells
Release digestive enzymes, break cells after they die(autolysis)

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13
Q

What are the two types of ribosomes and where are they found

A

70s - prokaryotic cells

80s - eukaryotic cells

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14
Q

What is in a chloroplast

A

Chloroplast enevelope, thylakoids, grana, chlorophyll, intergranal lamella, stroma

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15
Q

What is the stroma

A

Fluid filled matrix where the second stage of photosynthesis occurs. Inside are a number of structures e.g starch grains
Contains all the enzymes needed to make sugars in second stage of photosynthesis

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16
Q

What is the thylakoid

A

Membrane with large surface area for chlorophyll attachment- first stage of photosynthesis

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17
Q

Why can chloroplasts photosynthesis quickly

A

They have DNA and ribosomes so can quickly and easily synthesise protein for photosynthesis

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18
Q

What is the cell wall made of

A

Microfibrils of the polysaccharide cellulose embedded in the matrix they are strong and add to overall cell strength

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19
Q

What are the features of the chloroplast

A

Made of many polysaccharides

Thin layer middle lamella which is a boundary between adjacent cell walls, cements them together

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20
Q

What are the functions of the chloroplast

A

Provides strength to stop cell bursting due to osmosis
Mechanical strength to plants as whole
Let’s water pass so adds to water movement throughout plant

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21
Q

What are algae cell walls made of

A

Cellulose, glycoproteins of both

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22
Q

What are fungi cell walls made out of

A

Mix of chitin, glycan and glycoproteins

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23
Q

What surrounds a vacuole

A

The vacuole a fluid filled sac surrounded by a single membrane called the tonoplast

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24
Q

What does the solution in the vacuole contain

A

Mineral salts, sugars, amino acids, wastes and sometimes pigments

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25
Q

What is the function of a vacuole

A

Support herbaceous plants, making calls turgid
Sugar and amino acids act as a temporary food store
Pigment may colour petals attracting pollinating insects

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26
Q

What does the specimen need to be like when using a light microscope

A

Doesn’t need to be extremely thin

Can be living

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27
Q

What does the light microscope produce

A

The specimen can be in colour

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28
Q

What does the specimen need to be like for a transmission electron microscope

A

Must all be in a vacuum
A complex staining process must occur
Must be very thin

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29
Q

How does a transmission electron microscope work

A

Electrons are passed through the specimen using a very short wavelength producing a very high resolution 2D image on the screen

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30
Q

What is sometimes a problem with using electron transmission microscopes

A

When cutting the specimen it may contain artefacts - things on the image that aren’t part of the specimen

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31
Q

How does a scanning electron microscope work

A

Using a very short wavelength electrons are used to make a very high resolution 3D image

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32
Q

How must the specimen be when using a scanning electron microscope

A

Specimen doesn’t need to be extremely thin

Must be in a vacuum

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33
Q

What is the definition of resolution

A

Minimum distance apart two objects can be for them to appear as separate items

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34
Q

What do the letters in the AIM triangle represent

A

I - image (measurement)
A - actual size (real image)
M - magnification

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35
Q

What are the conversions (m, mm, micrometers, nanometers)

A

1m = 1000mm
1mm = 1000 micrometers
1 micrometer = 1000 nanometers

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36
Q

In cell fractionation what conditions is the tissue kept under

A

Ice cold water - stop autolysis
pH buffer - stop enzyme denaturing
Isotonic - keep constant (sugar, glucose..) concentration

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37
Q

What are the stages in cell fractionation

A

Tissue cut up and kept in certain conditions
Tissue further broken in homogeniser once homogenate filtered (remove debri)
Homogenised tissue spun in ultracentrifuge at low speed for 10 minutes
Then supernatant and sediment are split

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38
Q

What would be in sediment 1 and in supernatant 1 in an ultracentrifuge

A

Sediment 1 - nuclei (as most dense)

Supernatant 1 - mitochondria, lysosomes..

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39
Q

What type of ribosomes are in a prokaryotic cell

A

70s

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40
Q

What is in a prokaryotic cell

A

70s ribosomes, cytoplasm, plasmid, cell surface membrane, cell wall, capsule, flagellum, circular loop of DNA

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41
Q

What does the plasmid in a prokaryotic cell do

A

It has genes that aid bacteria survival in adverse conditions

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42
Q

What does the cell surface membrane in a prokaryotic cell do

A

It is differentially permeable later it controls the chemicals that go in and out

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43
Q

What is the function of the cell wall in a prokaryotic cell

A

It is a physical barrier that protects against damage and osmotic lysis

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44
Q

What does the capsule in a prokaryotic cell do

A

Protects bacterium from other cells and helps bacteria groups stick together for further protection

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45
Q

What is the job of the flagellum in a prokaryotic cell

A

It moves the cell

May be more than one for locomotion (only certain species)

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46
Q

What does the circular loop of DNA in a prokaryotic cell do

A

It has genetic information to replicate bacterial cells

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47
Q

What does a virus structure contain

A

Lipid envelope, genetic material RNA, matrix, capsid, reverse transcriptase

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48
Q

What does the capsid in the virus cell do

A

Is a protein layer in the envelope that encloses two single RNA strands and some enzymes

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49
Q

What does the reverse transcriptase in a virus cell do

A

It is an enzyme that catalyses DNA production from RNA

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50
Q

What is mitosis

A

Cell division in eukaryotes that makes two genetically identical daughter cells from one parent cell

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51
Q

What is mitosis used for

A

For growth and tissue repair

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52
Q

What occurs at interphase

A

This is the preparation phase
Chromosomes are not visible
Organelles are replicating
DNA replication

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53
Q

What occurs at prophase

A

DNA condenses to form chromosomes
Each chromosome has 2 arms (chromatids) held by the centromere
Nuclear membrane disappears spindle fibres form (from centrioles)

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54
Q

What occurs at metaphase

A

Chromosomes line along the equator

Spindle fibres attach to the centromere of each chromosome

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55
Q

What occurs at anaphase

A

Chromosomes separate and identical chromatids are pulled to opposite poles of the cell
Spindle fibres shorten pull chromatids apart

56
Q

What occurs at teleophase

A

Chromatids now called chromosomes
Nuclear membrane form around 2 groups
Cytoplasm / cell membrane constrict

57
Q

What occurs at cytokinesis

A

The cell divides and two cells form

DNA becomes indistinct

58
Q

What is the function of a phospholipid in a cell surface membrane

A

Stops water soluble substances going in/out of the cell
Let’s lipid soluble substances in/out
Makes flexible self-sealing membrane

59
Q

What is the function of a channel protein in the cell surface membrane

A

They form water-filled tubes that let water soluble substances / non lipid soluble substances diffuse across the membrane

60
Q

What is the function of a glycoprotein in the cell surface membrane

A

Acts as a recognition site, cells attach to each other to form tissues and this site helps cells recognise

61
Q

What is the function of a receptor protein in the cell surface membrane

A

Used in intercellular communication

62
Q

What is the function of a carrier protein in the cell surface membrane

A

Binds to ions/molecules e.g glucose then changes its shape to move it across the membrane

63
Q

What is the function of a glycolipid in the cell surface membrane

A

Acts as a recognition site, helps maintain the membranes stability and helps cells attach to each other to form tissues

64
Q

What is the function of cholesterol in the cell surface membrane

A

To reduce lateral movement of molecules including phospholipids
To make the membrane less fluid in high temperatures
Stop water leaking/dissolved ions from cell

65
Q

What is a phospholipid bilayer

A

Two phospholipids hydrophobic tails facing each others and hydrophobic heads away from each other

66
Q

What can uncontrollable cell division lead to

A

Formation of tumours and cancers

67
Q

How may cancer be treated

A

By controlling the rate of cell division

68
Q

What is a pathogen

A

A disease-causing microorganism

69
Q

How do pathogens cause harm

A

Produce toxins

Cause damage to host cells/tissues

70
Q

What is non specific immunity

A

Doesn’t distinguish between pathogens but fast acting
Phagocytosis
Pathogen barrier

71
Q

What is specific immunity

A

Distinguishes between different pathogens
Less rapid response but long term immunity
Involves white blood cell - lymphocyte (T and B)

72
Q

Why doesn’t our immune system attack own cells

A

Lymphocytes must be able to distinguish body’s own cells and chemicals (self) from foreign (non-self) if couldn’t do this would destroy own tissues
Each cell has specific molecules on surface identify it, variety of types, proteins that are most important as have enormous variety and high specific tertiary structure, distinguishes cells

73
Q

What do the proteins allow the immune system to identify

A

Pathogens
Non-self materials e.g. cells from other organism of same species
Abnormal body cells e.g. cancer
Toxins including those produced by pathogens e.g. cholera pathogen

74
Q

How does the correct lymphocyte replicate

A

Out of the 10million different lymphocytes a protein on lymphocyte surface will be complementary to the protein on pathogen surface, this lymphocyte recognises the pathogen and replicates

75
Q

Why is there a time lag between exposure to the pathogen and body’s defences bringing it under control

A

As so many types of lymphocyte, not many of each type. Complementary lymphocyte must replicate and build numbers to level where can be effective in destroying it

76
Q

Why must organ transplants have a close tissue match

A

The immune system recognises the donor tissue as non-self attempts to destroy transplant, minimise effect organs with close tissue matches used and immunosuppressant drugs of en used

77
Q

How does immune system ensure that none of the 10 million lymphocytes match own cell when a foetus

A

In foetus lymphocytes constantly colliding in other cells
Infection in foetus rare as protected from outside by placenta
Lymphocytes collide with body’s own material (self)
Die or be suppressed
Some lymphocytes have receptors that fits body’s own cells
Remaining lymphocytes might fit foreign material (non-self)

78
Q

How does immune system ensure that none of the 10 million lymphocytes match own cell when an adult

A

In adults, lymphocytes produced in bone marrow only initially encounter self-antigens
Any lymphocytes that show immune response to self-antigens undergo programmed death - apoptosis before mature lymphocytes
No anti-lymphocytes clones will appear in blood only leaving those that might respond to non-self antigens

79
Q

What are the two main types of white blood cells

A

Phagocytes - engulf and destroy pathogen by process phagocytosis before can cause harm.
Lymphocytes - involved in specific immune response

80
Q

How does phagocytosis occur

A

Phagocyte attracted to pathogen by a chemoattractant of pathogen, moves towards pathogen along concentration gradient
Receptors on phagocyte surface membrane attach to surface of pathogen
Lysosomes in phagosome migrate to pathogen formed by engulfing bacterium
Lysosomes release lysozymes into phagosome, hydrolyse bacterium - now soluble molecules absorbed into phagocyte cytoplasm

80
Q

What is an antigen

A

Usually a protein that is on the cell surface membrane of a pathogen that induces an immune response in the cell e.g. antibody production

80
Q

What do B-lymphocytes do and where are they made

A

Mature in bone marrow

Associated with immunity involving antibodies present in body fluids (“humour”) - humour also immunity

81
Q

What do T-lymphocytes do and where are they made

A

Mature in the thymus gland

Associated with cell-mediated immunity - involving body cells

82
Q

What do T-lymphocytes respond to

A

Organisms own body cells invaded by non-self material e.g. virus

83
Q

How do T-cells know when cells are genetically non-self

A

Respond to cells from individuals of same species as they’re genetically different so different antigens on cell surface membrane

84
Q

How do T-cells recognise forgein cells

A

Phagocytes which engulfed, digested/hydrolysed pathogen and body cells infected by a virus, present some of pathogens antigen on cell membrane
Transplanted cells different antigens on membranes
Cancer cells different from normal body cells, display antigens on membrane

85
Q

What are the four stages in cell-mediated immunity and which lymphocyte is involved (in order they occur)

A

Antigen presentation
T-helper cell activation
T-helper cells divide by mitosis
Cytotoxic T-Cells, memory cells, activates B-lymphocytes, stimulates phagocytosis

86
Q

What occurs at the antigen presentation stage

A

Pathogen broken down, protein from pathogen presented in surface of affected cell
Body cell ‘shows’ antigen to all T-cells

87
Q

What occurs at T-helper cell activation

A

Millions of different T-helper cells (still T-lymphocyte) in blood all with different shaped receptors
One with receptor which fits antigen binds and T-helper cell activated

88
Q

What happens once the T-her cells are activated

A

Divide by mitosis form T-helper cell clones
These:
Stimulate cytotoxic Tc cells
Develop into memory cells enable rapid response to future infection by same pathogen
Activates B lymphocytes divide, secrete antibody
Stimulates phagocytosis

89
Q

How do cytotoxic T-cells work

A

Kill body cells infected by pathogens
Produce protein - perforin that makes holes in infected cell membrane, freely permeable to all substances, dies
Most effective as viruses replicate inside cells

90
Q

Why are there so many different B-cells

A

Around 10million different B-cells produce a different type of antibody respond to specific antigen
Antigen enter blood one B-cell that has antibody on surface that’s complementary to the antigen
Antibody attaches to antigen (antigen-antibody complex)
Antigen enters B-cell by endocytosis is presented on surface
Th cell bind to processed antigens stimulate B-cell replicate by mitosis, clones produce same specific antibody - clonal selection

91
Q

What are the two B-lymphocytes

A

Plasma cells

Memory cells

92
Q

What is a plasma cell how long does it last and what does it do

A

Secrete antibodies directly
Only survive few days
Make 2000 antibodies every second
Antibodies destroy pathogen and toxins it produces
Responsible for immediate defence against infections
Primary immune response

93
Q

How long to memory cells live and what do they do

A

Longer than plasma cells sometimes decades
Don’t produce antibodies directly but circulate in blood and tissue fluid
If encounter same antigen at later date divide rapidly develop into plasma cells produce antibodies kill pathogen
Provide long term immunity against original antigen - secondary immune response
Produced far larger antibody amount more rapidly, pathogens destroyed before symptoms develop

94
Q

What occurs at humoral immunity

A

Surface antigens of invading pathogen taken up by B-cell (endocytosis)
B-cell processes antigens, presents in its surface
Helper T-cells (activated in process) attach to processed antigens in B-cell, activating them
B-cell now activated, divide by mitosis give clone of plasma cells
Clone produce, secrete specific antibodies fit antigen on pathogen surface
Antibody attaches to antigen on pathogen, destroys it
Some B-cells develop into memory cells, can respond to future infection by same pathogen by dividing rapidly into plasma cells

95
Q

What is the primary immune response

A

Initial exposure to antigen, immune response

Not many antibodies made

96
Q

What is the secondary immune response

A

Second exposure to same antigen, more antibodies produced rapidly kill pathogen before symptoms

97
Q

Why does each pathogen lead to numerous different antibodies

A

Typical pathogen has many different proteins on surface all act as different antigens
Some pathogens produce toxins
Each protein/toxin acts as antigen so many different B-cells make clones, produce own antibodies

98
Q

What is another name for an antibody

A

Immunoglobulin

99
Q

Describe the structure of an antibody

A

All have similar structure composed of 4 polypeptide chains (2 heavy and 2 light) joined by strong disulphide bonds to form a Y-shape
Stem of Y is the constant region, all have same amino acid sequence
Ends of Y arms are variable regions as all have different amino acid sequence and so different structures. These 2 sites are called antigen-binding sites
Variable regions where antigens bind to form antigen-antibody complexes

100
Q

How do bacterial cells destroy antigens

A

Cause agglutination of bacterial cells so clumps of bacteria are formed, easier for phagocytes to locate them
Serve as markers that stimulate phagocytes to engulf the bacterial cells to which they’re attached

101
Q

What chemical bind joins the amino acids in an antibody

A

Peptide bond

102
Q

How is passive immunity achieved

A

Introducing antibodies into individuals from outside source

No direct contact needed with antigen or pathogen

103
Q

Why isn’t passive immunity long lasting

A

Antibodies not being produced by individuals the antibodies aren’t replaced when broken down, no memory cells are formed

104
Q

What are some examples of passive immunity

A

Anti-venom given to victims of snake bites

Immunity acquired by foetus when antibodies pass across placenta from mother

105
Q

How is active immunity achieved

A

Stimulating the production of antibodies by the individuals own immune system
Direct contact with the pathogen is necessary
Immunity takes time to develop usually long lasting

106
Q

What is natural active immunity

A

Results from individual becoming infected with disease under normal circumstances
Body produces own antibodies and memory cells

107
Q

What is artificial active immunity

A

Forms basis of vaccination (immunisation)

Inducing immune response in individual (antibodies, memory cells produced) no disease symptoms

108
Q

What is a vaccination

A

Introducing appropriate disease antigen into body, injection or mouth
Contain dead or attenuated version of pathogen or usually one or more antigens from pathogen
Stimulates immune response, memory cells produced

109
Q

How does a vaccination work

A

Antigens in vaccination stimulate immune response to particular disease, producing antibodies and importantly memory cells
Memory cells remain in blood if individual comes into contact with same antigen/pathogen again there is rapid production of large amount of antibodies (secondary response) so that the pathogen is killed before any symptoms develop
When carried out on large scale provides protection against disease for whole populations

110
Q

What factors affect the success of a vaccination programme

A

Must be possible to vaccinate vast majority of vulnerable population to produce herd immunity
Administering vaccine properly at appropriate time, must train staff with right skills at different centres throughout population
Must be able to produce, store, transport vaccine usually involves technology advanced equipment, hygienic conditions, refrigerated
Suitable vaccine economically available in sufficient quantities to immunise most of vulnerable population
Few if any side effects

111
Q

What is herd immunity

A

When a large proportion of the population has been vaccinated make it difficult for the disease to spread within population
Concept based in idea disease passed from person to person in close contact
Vast majority of people vaccinated, unlikely susceptible person contact with infected one.

112
Q

Why is herd immunity important

A

Not possible to vaccinate everyone
Babies/young cant be as immune systems not fully functional
Dangerous if ill or have compromised immune systems
Vaccination percentage varies to achieve herd immunity for different diseases
Vaccination best carried out at one time, certain period very few infected, disease transmission interrupted

113
Q

Why might vaccination not eliminate disease

A

May fail to induce immunity in some
Many varieties of pathogen may exist, impossible develop vaccine that’s effective against all
Pathogen may mutate frequently, antigens change and vaccines ineffective, immune system no longer recognises them no antibodies made
Individuals may have objections to vaccines e.g. religious, ethics, medical
Certain pathogens ‘hide’ from immune system concealing in cells or living in places out of reach e.g. cholera in intestines

114
Q

What are some ethical questions raised due to vaccines

A

Production of vaccines often involves animals
Side-effects may cause long-term harm, how is side-effect risk balanced with risk of developing disease causing more harm
Who are they tested on
Is it ok to trial new vaccine with unknown health risks only in country where targeted disease is common on basis population has most to gain
How can any individual health risks from vaccination be balanced against advantages of controlling disease

115
Q

What is a monoclonal antibody

A

Antibodies produced from a single clone of B-plasma cell so they will only recognise one particular antigen

116
Q

Why can monoclonal antibodies be used in research and medicine

A

They’re specific to certain antigen so can be used to target specific substances/cells

117
Q

How are monoclonal antibodies used in cancer treatment

A

Produce specific monoclonal antibodies that are complementary to the antigens on the cancer cell
Given to patient, attach themselves to receptors on cell
Attach into surface blocking chemical signals that stimulate uncontrolled growth

118
Q

What are the advantages of using monoclonal antibodies to treat cancer

A

Antibodies aren’t toxic and are highly specific

Lead to fewer side effects than other therapy forms

119
Q

What is indirect monoclonal antibody therapy

A

Involves attaching radioactive/cytotoxic drug to monoclonal antibody
When antibody attaches to cancer cell, kills them

120
Q

What is the advantage of using indirect monoclonal antibody therapy over conventional

A

Referred to as ‘magic bullets’ can be used in smaller doses as they’re targeted on specific sites
Cheaper, reduces drug side effects

121
Q

How does a pregnancy test work

A

Urine sample applied to bottom of stick
Any hCG present binds to first anti-hCG antibody (complementary)
In test region is immobilised anti-hCG antibodies, bind alternative sites on hCG , trapping at the site, enzyme attached to first antibody changes colour of coating in stick, evidence of positive test
Control region has unbound antibodies, progress up stick here where bound by third type of antibody. Again attached enzyme causes colour change, proof only antibodies behaving properly

122
Q

Arguments for the use of monoclonal antibodies

A

Successfully treated diseases such as cancer, diabetes - saved lives
Used to indicate pregnancy
Diagnosis of influenza, hepatitis, chlamydia

123
Q

Arguments against the use of monoclonal antibodies

A

Mice induced with antibodies, to make antibodies needed in pregnancy test, but they may get cancer
Use of treatment caused deaths associated with MS

124
Q

What does the ELIZA test do and what is it used for

A

Uses antibodies to detect protein presence in sample, and quantity. Very sensitive, only detect very small amounts of a molecule in sample being tested. Used to detect HIV, TB, hepatitis and do particular drugs and allergens

125
Q

What would occur when trying to see if particular protein, in this case an antigen is present in a sample

A
  1. Apply sample to surface where all antigens in sample will attach
  2. Wash surface several times to remove any unattached antigens
  3. Add antibody (sample being tested) that’s specific to antigen we’re trying to detect, they bind
  4. Wash surface to remove excess
  5. Add secondary antibody, bind with first one. Secondary has enzyme attached
  6. Re-wash remove enzyme, add colourless substrate. Enzyme reacts change the colour. Amount of antigen present relative to intensity of colour
126
Q

What is HIV

A

Human immunodeficiency virus

127
Q

What is AIDS

A

Acquired immune deficiency syndrome

128
Q

What does HIV cause

A

AIDS

129
Q

What is the structure of HIV

A

Same as a virus cell

130
Q

How does HIV cause the symptoms of AIDS

A
  1. HIV virus specifically attracts T-helper cells, which are killed
  2. Uninflected person normally has 800-1200 helper T-cells in each mm^3 of blood. If have AIDS can be as low as 200mm^-3
  3. Not enough T-helper cells immune system can’t stimulate B cells to make antibodies
  4. Body can’t make immune response, becomes susceptible to infection
131
Q

Why do many AIDS suffers develop infections

A

Body can’t produce and immune response so susceptible to other infections

132
Q

Does HIV cause death

A

Not directly, but infecting immune system prevents functioning causing infections

133
Q

What occurs in the replication of HIV

A
  1. HIV enters the blood stream, circulates round body
  2. Protein on HIV readily binds to protein CD4, while protein occurs on cells, HIV most frequently attacks T-helper cells
  3. Protein capsid fuses with cell surface membrane, RNA and enzymes from HIV enter helper-T cell
  4. HIV reverse transcriptase converts virus RNA to DNA
  5. Newly made DNA moved into helper-T cell nucleus where incorporated into DNA cells
  6. HIV DNA in nucleus makes mRNA using cells enzymes, mRNA contains new viral protein/RNA to go into new HIV instructions
  7. mRNA passes out nuclear pores into cytoplasm, uses cells proteinsythesis mechanism crate HIV particles
  8. HIV breaks away from helper-T cell with piece of cell surface membrane surrounding which makes lipid envelope

Biology (4 decks)

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