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Cells Flashcards

1
Q

What are antigens

A

Proteins on the surface of cells that cause an immune response
Allows immune systems to recognise : pathogens , cells from organisms of the same species, abnormal body cells, toxins

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2
Q

Self antigens

A

On our own cells

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3
Q

Non- self

A

Foreign

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4
Q

What is a pathogen?

A

Organisms that cause disease, destroy host cells.

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5
Q

Cellular immune response

A

Phagocytosis and t-cells

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6
Q

Humoral response

A

B-cells and plasma cells

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7
Q

What is bacteria

A

Living cells that can multiply rapidly, attack tissues in host and release toxins

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8
Q

What are viruses

A

Burst out of host cell into bloodstream, difficult to treat without affecting the host

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9
Q

Phagocytosis:

A

First line of defence
Identifies the foreign antigen and engulfs it into the phagocytic vacuole.
Lysosomes fuse with the phagocytic vacuole which break the bacteria down.

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10
Q

Components of cell: red blood cell

A

Contains haemoglobin which carries oxygen around the body

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11
Q

Plasma

A

Contains salts, sugars and proteins. Distributes materials and hormones throughout the body. Also carries waste products

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12
Q

Platelets

A

Bits of dead cell to help clot the blood

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13
Q

White blood cell

A

Destroy invading microbes

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14
Q

Active immunity

A

When you make your own antibodies
Natural - produce antibodies + memory B cells
Artificial - vaccination
Slow, long term , make memory cells, exposed to antigen

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15
Q

Passive immunity

A

When you are given antibodies by another organism
Natural - mother to child
Artificial - given someone else’s antibodies (blood transfusion )
Fast, short term, dont make memory cells, no exposure to antigen

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16
Q

T-cells

A 
Made in the bone marrow 
Mature in the thymus 
Carry out cell mediated response 
Recognise and destroy abnormal cells 
Produce a protein that makes holes in the cells surface membrane 
TH cells active B cells 
TC kill pathogens
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17
Q

B-cells

A

Made in and mature in the bone marrow
Responsible for antibody production
B cell with the complimentary antibody forms antigen-antibody complex
Selected b cels divides and clones itself

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18
Q

Plasma cells

A

Clones of the selected B cell
Make monoclonal antibodies
Stick pathogens together = agglutination
When infections is over , plasma cells are saved as memory b cells

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19
Q

Lymphocytes

A

Have an englarged nucleus because they are producing lots of ribosomes|+mRNA. Produced in the bone marrow

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20
Q

Antibody

A

A molecule made by b lymphocytes in response to stimulation by the appropriate antigen
Also known as immunoglobins
Specific to a particular antigen
Usually a protein or glycoprotein

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21
Q

Structure of an antibody :

A

4 polypeptide chains held together by disulfide brides
A genetic constant region allowing antibodies to attach to phagocytic cells
Variable regions which is specific to a particular antigen this depends on amino acid sequence
Hinge region which allows the antigen to flex in order to bind to more than one antigen

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22
Q

Primary immune response

A

Slow- phagocytosis
Pathogen multiplies - feel symptoms
After the infection you save memory cells

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23
Q

Secondary immune response

A

Same pathogen infects you
Faster+stronger
No symptoms

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24
Q

What is the Elisa test

A

Test to see if patients have a specific antibody or antigen

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25
Direct elisa test
Only one antibody used test for antigens 1) immobilised antipodes attached to a wall 2) sample added (e.g blood plasma ) 3) if blood plasma companies antigen an antigen- antibody complex formed 4) rise to remove unbound antigens 5) antibody+ enzyme added 6) rinse 7) add substrate = if there’s a colour change it is a positive test
26
Indirect Elisa test
Uses two antibodies( a primary antibody and a secondary enzyme ) 1) antigen is fixed to the well 2) sample is added - if complimentary an antigen-antibody complex formed 3) rinsed to remove unbound antibodies 4) different antibody added + enzyme 5) will only bind if 1st antibody is present 6) rinses to remove antibodies are unbound 7) substrate added = colour change
27
Vaccine
Contains antigens from a dead/weakened pathogen Stimulates immune system to produce antibodies/plasma cells/ memory cells without causing illness If infected post vaccine you undergo secondary response
28
Why don’t you feel ill from a vaccine
Because they contain an unactivated form of the pathogen killed by heat treatment
29
Herd immunity
The higher % that are vaccinated, the fewer people there are to pass on the disease
30
Antigenic variability
Antigens on the surface of pathogens change due to mutation Antigen is no longer complimentary to the antibody Infected again - primary response Some pathogens may have strains - vaccines only work on some strains
31
The MMR controversy
1998- scientific paper speculated that the MMR vaccine causes autism The vaccine could damage the bowel allowing the toxins cause autism in the brain The authors did not prove that this was the case but still recommended that doctores stopped administering the MMR vaccine until more research was done
32
Virus reproduction
1) virus attachment proteins binds to receptor of the host (th cells) 2) reverse transcriptase makes double stranded DNA from RNA 3) DNA enters nucleus via nuclear pore 4) TH cells makes copies of virus, genetic material and protein 5) reforms capsid 6) leaves host cell taking on envelope from hosts membrane
33
What are monoclonal antibodies
Identical antibodies made from same B cell/ plasma cell
34
Uses : targeting medication
Used to deliver drugs Bind to only target cell Attach drugs to antibodies
35
Uses : medical diagnosis
1) monoclonal antibodies added to a plate 2) sample added - if antigen present it forms an antigen-antibody complex 3) rinsed to remove unbound antigens 4) same monoclonal antibody is added with an enzyme/ colour attached 5) rinsed again 6) observe for a marker - colour change
36
Formation of monoclonal antibodies
1) antigen is injected into a mouse 2) the mouse naturally produces lymphocytes 3) spleen cell produce lymphocytes are removed 4) spleen cells are fused with cancerous white blood cell to form hybridoma cell 5) the hybridoma cells divide and produce millions of monoclonal antibodies specific to the original antigen.
37
HIV
Human immunodeficiency virus Infects t-helper cells so the immune system becomes weak and develops AIDS Doesn’t kill you directly
38
AIDS
Acquired immune deficiency syndrome
39
Eukaryotic cell organelles :nucleus
Nucleus= where chromosomes are found, controls activities s
40
Eukaryotic- RER
RER= usually attached to nucleus, covered in ribosomes, modifies and folds proteins
41
Eukaryotic - SER
SER= not attached to the nucleus, modifies and folds proteins
42
Eukaryotic - golgi apparutus
Golgi apparatus = modify and package proteins and lipids and put them in vesicles for transport. Make lysosomes
43
Eukaryotic=lysosomes
Lysosomes = contain digestive enzymes, used to hydrolyse pathogens
44
Eukaryotic - mitochondria
Mitochondria = make ATP, site of aerobic respiration.
45
Eukaryotic - chloroplast
Grana is a stack of thykaloid, double membrane | Site of photosynthesis
46
Eukaryotic - cell wall
Strong that protects the cell from changing shape
47
Eukaryotic - vacuole
Contains sugar and salt ( cellulose ), keeps cell fugid
48
Eukaryotic - ribosomes
Makes proteins, attached to RER, made of proteins and RNA
49
Prokaryotic - plasmid
Small loop of dna Can be passed between bacteria Carry useful genes
50
Prokaryotes - cell wall
Made of a glycoproteins | Strength = shape
51
Prokaryotes - flagella
Rotates to move the cell
52
Prokaryotes - small ribosomes
Makes proteins
53
Prokaryotes- loop of dna
No nucleus , dna is free in the cytoplasm
54
Prokaryotes- capsule
Slime layer, adds protection
55
Prokaryotes - cell membrane
Controls what goes in and out
56
Cell fractionation
1) break cells open - Keep ice cold to prevent enzyme activity Keep isotonic to prevent osmosis Use buffer to keep pH same 2) filter solution - removes cell debris and whole cells 3) ultra centrifugatiom- Spin the test tube , heaviest organelles compressed into a pellet at the bottom Remaining liquid is poured off Spin again Repeat ...
57
Order of organelles in cell fractionation
Ribosomes at the top | Nuclei at the bottom then chloroplast then mitochondria
58
Light microscope
``` Easy to use Cheap Colour image Much lower magnigfication Can’t see small organelles - ribosomes ```
59
Scanning electron microscope
Much better magnification + resolution than light 3D image Don’t need a thin section Can’t see internal structures s
60
Transmission electron microscope
``` Best magnification + resolution -shorter wavelength of light Internal structure Can’t see living cells Specimen needs to be in a vacuum Use thin slice No colour ```
61
Why do specimens have kept in a vacuum for an electron microscope
Electrons are absorbed by molecules in air , this would prevent the electrons reaching the specimen §
62
Microscope calculation
Imagine size= actual x magnification
63
What happens in Interphase
DNA replicates | Chromosomes are loosely coiled = chromatin
64
What happens in prophase
Chromosomes condense Nuclear membrane centrioles move to the poles Two chromatids joined at the centrometre
65
What happens in metaphase
Double chromosome line up at the equator , spindle fibres forms Translocation of chromosomes
66
What happens in anaphase
Centrometres spit | Chromatids are pulled to opposite poles
67
What happens in telophase
Nuclear membrane reforms | Cytokinesis - cytoplasm divides
68
Mitosis and cancer
= uncontrolled cell division Mutation in the oncogene and proncogene that switch on and off the proces Malignant, cancerous tumors may spread from their origin . They develop their own blood supply which can transport malignant cells to other sites in the body
69
Structure of the cell surface membrane
=phospholipid belayer Hydrophilic heads face outward Hydrophobic tails face inwards Phospholipids can slide over each other = fluid mosaic model
70
Diffusing through the cell membrane
Small non polar molecules diffuse through | Large polar molecules cant diffuse through easily
71
Cholesterol and the cell surface membrane
Cholesterol binds to hydrophobic tails, makes the membrane more rigid , for strength and support
72
What is diffusion
Net movement of molecules from high to low concentration and is passive Carries on till equilibrium is reached
73
How does concentration gradient affect rate of diffusion
The steeper the concentration gradient the faster the rate of diffusion
74
How does surface area affect rate of diffusion
Bigger surface area, faster rate of diffusion
75
Ficks law
Rate of diffusion = surface area x concentration gradient / thickness of membrane
76
What is facilitated diffusion
The passive movement of molecules across the cell membrane via a specific transmembrane protein Has a slower rate Carrier proteins = intrinsic globular proteins Carrier proteins are specific for the molecules they transfer
77
Active transport
Against the concentration gradient Uses energy from atp Via a carrier protein Affected by temperature, enzyme availability and cellular glucose concentration
78
Co transport
Via carrier protein Moves 2 molecules at one One goes down its concentration gradient and one going against
79
Absorption of glucose
1) sodium ions are transported out of epithelial cells by a sodium-potassium pump into the blood. - this maintains a much higher concentration of sodium ions in the lumen of the intestine than inside the epithelial cells 2) sodium ions diffused into the epithelial cells down the concentration gradient through a co-transport protein. As they diffuse they carry either amino acid molecules or glucose molecules with them 3) the glucose/amino acid pass into the blood plasma by facilitated diffusion using another type of carrier.
80
What is osmosis
The passage of water from a region of higher water potential to a region of lower water potential through a selectively permeable membrane.
81
What is a solute
Any substance that is dissolved in a solvent
82
Water potential
High water potential - high % of water molecules, low % of solute , hypotonic. Pure water has a high water potential when its next to a solute Low water potential ‘ lower % of water molecules, high % solute , hypertonic The more solute that is added, the lower its water potential

Biology (17 decks)

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