Cells 2 Flashcards
(146 cards)
1
Q
Samsung notes(CELL FLASHCARDS)
A
YASSSS
2
Q
Define nucleus
A
Site of DNA replication and transcription
Contains the genetic code
3
Q
Name all 5 structures in a nucleus
A
Nuclear envelope
Nuclear pores
Nucleoplasm
Chromatin
Nucleolus
4
Q
What is nuclear envelope, Histone and the function of nucleolus
A
Nuclear envelope- outer and inner membrane
Chromatin- protein bound in linear DNA
Nucleolus- makes ribosomes
5
Q
Define mitochondria
A
Site of aerobic respiration
Contains DNA that codes for enzymes in respiration
6
Q
Name 5 parts of the mitochondrion
A
Inner membrane
Outer membrane
IMS(Inter membrane space)
Matrix
Cristae(folding of the inner membrane)
7
Q
What is RER AND SER
A
RER: Protein synthesis
SER: Synthesises and processed lipids and carbohydrates
8
Q
Define Cisternae
A
Fluid filled sacks surrounded by ribosomes
9
Q
Define Ribosomes
What are the 2 sizes and where are they found
A
Site of protein synthesis
70s 80s
70s - Prokaryotes, Mitochondria, Chloroplast
80s- Eukaryotes
10
Q
What are Ribosomes made from
A
Proteins and RNA
11
Q
What is the function of Golgi apparatus/body and what does it make and what does that do
A
Processes and packages new lipids and proteins
Makes lysosomes
Breaks down worn out cells(autolysis)
Breaks down worn out organelles
12
Q
What do lysosomes do
A
Lysosomes fuse with vesicles, releasing lysozomes(hydrolytic enzyme)
Break down worn out cells(autolysis)
Break down worn out organelles
13
Q
Does an animal or plant cell have centriole
A
Animal cell
14
Q
What is the structure and function of the cell membrane
A
STRUCTURE Made of a phospholipid bilayer
FUNCTION Controls movement of substances in and out of the cell
15
Q
What is embedded in the phospholipid bilayer
A
Proteins (Channel/Carrier which are both Intrinsic proteins)
Antigens (Proteins on the otisde of a cell)
16
Q
In a chloroplast, what is one stack of thylakoids called
A
Granum
17
Q
What is the function of a chloroplast and where does this process take place
A
Site of photosynthesis
It takes place in Grana and Stroma
18
Q
List 3 facts about the chloroplast
A
Double membrabe
Contains 70s Ribosomes
Contains circular DNA
19
Q
What is the stroma in a chloroplast
A
Liquid that contains enzymes used for photosynthesis
20
Q
What organelles have a double membrane
Which organelle has no membrane
A
Nucleus, mitochondria, chloroplast
Ribosome
21
Q
What are 2 facts about the cell wall
A
Strong to prevent shape changes due to osmotic pressure
Rigid structure
22
Q
What is the cell wall made from in plant cells Fungi and bacteria
A
PLANT - Cellulose
FUNGI - Chitin
BACTERIA - Murein/peptidoglycan
23
Q
Give 2 facts about the cell vacuole
What is the membrane of a vacuole called
A
Maintains pressure
Keeps cell rigid
Tonoplast
24
Q
What do golgi vesicles do
A
Vesicles fuse with plasma membrane releasing contents
25
A simple ---- glass lens can act as a magnifying glass but such lenses work more effectively if they are used in ---- in a compound light microscope
Convex
Pairs
26
In a light microscope, what is the distance between two objects that is needed for the two objects to be distinguishable
What property of light rays causes this
How can you overcome this issue
How does this work
0.2 um
Long wavelength
Using beams of electrons instead of beams of light
The shorter wavelengths means the beams of electrons in the electron microscope can distinguish between objects 0.1 nm apart
27
What is the formula for magnification
Magnification = Image size / Actual size
28
What is the resolution of a microscope
The minimum distance apart two objects can be in order for them to appear as seperate items
29
What does the resolving power of a microscope depend on
Wavelength or form of radiation used
30
What must you obtain before studying the structure and function of various organelles that make up cells
Large numbers of isolated organelles
31
Cell fractionation is the process where...
Cells are broken up and the different organelles they contain are separated out
32
Before cell fractionation, where must the tissue be placed and explain why
The tissue is placed in a cold, buffered solution of the same water potential as the tissue
COLD - To reduce enzyme activity that might break down organelles
SAME WATER POTENTIAL AS TISSUE - To prevent organelles from bursting or shrinki due to osmotic gain or loss of water
BUFFERED - The pH stays constant + doesn't fluctuate. Any change in pH could denature enzymes
33
What are the two stages to cell fractionation
Homogenation
Ultracentrifugation
34
Explain homogenation
-Cells are broken up by a homogeniser (blender)
-This releases organelles from the cell
-The resultant fluid, homogenate is then filtered to remove any complete cells and large pieces of debris
35
What are the differences between prokaryotic cells and eukaryotic cells
-P is smaller and less complex
-P has no nucleus and no membrane bound organeles(ER, mitochondria, chloroplast)
-P contains 70s Ribosomes which are smaller
-in P, the cell wall is made from murein/peptidoglycan
36
Name the structures in a bacteria cell
Plasmid
Nucleoid
Plasma membrane
Mesosome
Cell wall
Capsule
Flagella
37
In a bacterial cell, there is plasmid, nucleoid, plasma membrane mesosome, cell wall capsule, flagella
Explain all of these
PLASMID small loop of DNA that contains genes(genes can be for antibiotic resistance)
NUCLEOID Circular DNA, free floating (no nucleur membrane), no histone
PLASMA MEMBRANE Made mostly from lipids and proteins
MESOSOME Folded region of plasma membrane, increases surface area for enzymes
CELL WALL Made of murein/Peptidoglycan
CAPSULE Thick polysaccharide layer, sticks cells together, food reserve, protection against outside chemicals and phagocytosis
FLAGELLA Helical shaped tail for movement, embedded in a membrane, driven by a proton gradient
38
How does bacteria divide
By binary fission every 20 minutes
Also divide asexually - no division of genes
39
Describe the Gram stain
Gram positive bacteria have thick walls and purple stain
Gram negative bacteria have thin walls with an outer lipid layer and stain pink
40
Describe the process of ultracentrifugation
The fragments in the filtered homogenate are separated in a centrifuge. This spins tubes of homogenate at a very high speed to create a centrifugal force.
1-The tube of filtrate is placed in the centrifuge and spun at a slow speed
2- The heaviest organelles, the nuclei are forced to the bottom of the tube, forming a pellet
3- The supernatant is removed, leaving the sediment of nuclei
4- The supernatant is transferred to another tube and spun at a faster speed than before
5- The next heaviest organelles, the mitochondria, are forced to the bottom of the tube, forming a pellet
6- This process continues so as each increase in speed, the next heaviest organelle is sedimented and separated out
41
What is the order of pellets in cell fractionation
Nuclei Never
Chloroplast(If using plant) Choke
Mitochondria My
Lysosomes Lovely
Endoplasmic reticulum Energetic
Ribosomes Rabbit
42
What are the differences between DNA in the nucleus and Prokaryote
Linear, histones, no plasmid, longer, introns
Circular, no histones, plasmid, shorter, no introns
43
Viruses are accelular(not cells) they are...
Nucleic acid surrounded by proteins
44
Viruses are not prokaryotic/eukaryotic, they are...
A type of obligate intracellular parasite
45
What is smaller. Bacteria or Virus and give a size
Viruses are smaller than bacteria (<0.1 micrometres)
46
What is a bacteriophage
A virus that can invade bacteria
47
What are the 5 parts of HIV and explain each of them
ATTACHMENT PROTEINS Allows virus to attach to host cell
VIRAL ENVELOPE Outer membrane and contains attachment proteins, made out of a membrane taken by host's cell membrane
CAPSID Protein coat containing nucleic acid
RNA Genetic information
REVERSE TRANSCRIPTASE Enzyme for replication
48
Why are viruses not killed by antibiotics
They replicate inside cells so it is difficult to destroy the virus without harming the host cell it is in
Viruses have different mechanisms and chemical reactions and no cell walls
49
Define magnification and resolution
What does the resolution depend on for an optical and electron microscope
How much times larger the image is compared to the object
The minimum distance needed betweeb 2 objects for them to appear as two seperate objects
Resolution of an optical microscope depends on the wavelength of light
Resolution of an electron microscope depends on the wavelength of beams of electrons
50
Difference between optical microscope and electron microscope
-A beam of light is condensed to create an image / A beam of electrons is condensed to create an image (electromagnet used to condense the beam of electrons)
-Lower resolution due to light having a longer wavelength/ higher resolution due to electrons having a shorter wavelength
-Lower magnification / higher magnification
-Coloured images / Black and white images
-View living cells/ Sample must be in a vacuum so can't view living cells
-Optical microscope is a time consuming process to prepare slides
-Optical microscope can't view smaller organelles (Ribosomes and ER)
51
Explain the Optical microscope
What is the max resolution and magnification
Light passes through the specimen and is projected through glass lenses where the image is magnified
0.2 micrometers
×1500(useful until resolution stays clear)
52
In an optical microscope, explain why you stain it, why the specimen should be thin, use an absorbent paper, use a cover slip
Stain it - Use potassium iodide to make certain structures visible
Specimen should be thin - single layer of cells, light can pass through
Use an absorbent paper - To absorb excess iodine
Use a cover slip - To remove air bubbles/excess iodine on specimen
53
Explain how you prepare a temporary mount (temporary coverslip)
-Use a pippete to place a drop of water onto the slide (keeps Tissue flat)
-Use tweezers to place a thin layer of the specimen on the slide
-Lower the coverslip using a mounted needle (protects the specimen and prevents airbubbles)
54
What is the eyepiece graticule
What is a stage micrometer and how long are the subdivisions
Scale in the eyepiece
A slide with a scale etched on - 10 micrometers
55
What are the two types of electron microscopes
Why must these specimen be in a vacuum
TEM Transmission Electron Microscope
SEM Scanning Electron Microscope
Electrons are absorbed by the air so do not reach specimen and do not form an image
56
Describe Transmission Electron Microscope
-Thin specimens are stained fo allow electrons to pass through
-Some beams of electrons pass through the specimen, some is absorbed by the specimen, darker parts of the cells is where more electrons have been absorbed as it is harder for electrons to pass through
-2D image
-Max magnification is 250 000×
-Max resolution is 2nm
57
Describe Scanning Electron Microscope
-Specimen does not need to be thin as electrons are not passing through specimen
-Electrons are beamed onto the surface and are reflected and scattered in different ways depending on the depth. This produces a 3D image
-Specimen is coated with a thin layer of metal
-Max magnification is 100 000×
-Max resolution is 3 to 20 nm
58
What are the advantages and disadvantages of electron microscopes
ADVANTAGES:
- Higher resolution as electron beam's wavelength is shorter than light (smaller organelles can be seen)
-SEM produces 3D images
DISADVANTAGES
-Specimens must be in a vacuum so no living specimen can be seen (electrons are deflected when then hit gasmaking it difficult for the electron beam to focus)
-Images are in black and white
-Complex staining process as it may contain artefacts
- TEM specimen must be thin to allow electrons to penetrate
- TEM Produces flat, 2D images(can be overcame by taking a series of sections)
- SEM has lower resolution than TEM (still better than OM)
59
Define artefact
Give some examples
Why does this happen
Images seen under a microscope that are not part of the cell
Dust, air bubbles, fingerprints, folds
Occurs during the incorrect preparation of specimen
60
Explain the step done before homogenisation and ultracentrifugation
-Tissue is minced and placed in cold buffered, isotonic solution
61
What is differential centrifugation
Process involving centrifuging at different speeds
62
Why is the plasma membrane described as a fluid mosaic model
Due to the movement and mixture of the phospholipids, proteins, glycoproteins, glycolipids and carbohydrates it's made from
63
What are a few function of plasma membrane
Controls the movement of substance in and out of the cell
Isolates organelles and enzymes
Internal transport system
Provides surface for biochemical reactions
Allows cell to change shapes
64
In a phospholipid bilayer, where do the tails point
Tails point to the centre of the membrane
65
What is the function of cholesterol in the fluid mosaic model
At high temperatures, what us the fluidity like
Binds tails together which restricts the lateral movements of molecules on the membrane, less fluid and more rigid but not completely rigid
At high temperatures, there is low fluidity to prevent water and dissolved ions from leaking out the cell(prevents cell from dehydration and bursting)
66
How are the proteins in a plasma membrane embedded in it
Explained extrinsic and intrinsic(how much they span across the bilayer)
In a random arrangement
Extrinsic: does not extend completely across the membrane
Intrinsic: spans across one side of the bilayer to the other
67
Explain extrinsic proteins and intrinsic proteins
EXTRINSIC PROTEINS: Provide mechanical support, function is cell recognition such as receptors
INTRINSIC PROTEINS: Protein carriers or channel proteins transport molecules across the membrane
68
What is another name for extrinsic and intrinsic proteins
Extrinsic - Peripheral
Intrinsic - Integral
69
Define glycoproteins and glycolipids
GLYCOPROTEINS: Carbohydrate attached to protein
GLYCOLIPIDS: Carbohydrate attached to lipid
70
Explain protein channels and carrier proteins
Protein channels form tubed that fill with water to allow water soluble ions to diffuse
Highly selective channels, only open when the specific ion is present and binds to the protein
Carrier proteins bind to larger modelcules(e.g. amino acids, glucose) which causes the protein to change shape and transport then to the other side of the membrane and release it
71
What are glycoproteins and glycolipids involved in
Cell adhesion(attaching cells to eachother)
Cell recongition(allows cells to recognise one another)
Cell signalling(communication between cells)
72
Explain the partially permeable membrane
Lipid soluble molecules and very small molecules can diffuse through the plasma membrane
Water soluble substances and large molecules cannot pass through the membrane
73
Explain simple diffusion
Net movement of molecules from an area of high concentration to low concentration until equilibrium is reached
This process does not reuire ATP
Form of passive transport
74
Why do molecules in simple diffusion have kinetic energy
To allow them to constantly move in fluids
75
What are factors that affect diffusion
Concentration gradient: The greater the difference in gradient, the faster the rate of diffusion
Surface area: The larger the surface area, the faster the rate of diffusion
Length and thickness of diffusion pathway: He thinner or shorter the exchange surface the faster the rate of diffusion
76
Explain facilitated diffusion
Passive process, doesn't require ATP
Proteins are used to transport molecules such as ions and polar molecules that can't diffuse
They only occur at specific points on the plasma membrane
77
Define active transport
What two things does active transport require
What is one important fact about active transport
The movement of molecules from an area of low concentration to an area of high concentration using ATP and a carrier protein
It is highly selective
78
Explain the steps for active transport
-Molecules binds to receptors on specific carrier proteins
-ATP binds to the carrier protein on the inside of the cell
-ATP is hydrolysed into ADP and a Phosphate
-This causes the carrier protein to change shape and the molecule will be released on the other side of the membrane
-The Phosphate and ADP is released from the protein, causing the protein to return to its original configuration
-Phosphate and ADP combine to make ATP during respiration
79
What does passive transport rely on
Random movement of particles and diffusion
80
What are two types of transport
Passive and Active
81
What features prevent particles from passing through the membrane via simple diffusion
Polar, Charged, Large, Hydrophilic
82
Give 4 adaptations that maximise the rate of diffusion
Maintaining a steep concentration gradient
Shortest possible diffusion pathway
Higher surface area to volume ratio(more folds in membrane)
High number of transport proteins in a given area
83
Explain how water potential affects rate of diffusion
The greater the difference in water potential, the steeper the concentration gradient so the faster the rate of diffusion
84
Explain the process of co transport
A transport protein binds to the first moelcule and an ATP
The transport protein hydrolysis ATP into ADP and one Phosphate ion. This causes the transport protein to chnage shape so the molecule is released on the other side of the membrane. The shape change reveals a second binding site in the protein where the second particle binds. The Phosphate ion is released causing the protein to return to its original shape. The second particle is then released on the other side of the membrane
85
Not all carrier proteins that carry out co transport have ATP binding sites. Instead, some Co transport carrier proteins...
Transport one moelcule down the concentration gradient and use the resulting energy to move a second particle against its concentration gradient
86
Define osmosis
The movement of water moelcules from an area of higher water potential to lower water potential through a partially permeable membrane
87
What is water potential
What is the units
What is the symbol
The pressure created by water molecules
Kilopascals
88
What is the water potential of pure water
When solute is dissolved in water, does the water potential become positive or negative
0
Negative
89
What is the relationship between water potential and amount of solute dissolved
The more negative the water potential, the more solute dissolved in it
90
Define hypertonic, hypotonic and isotonic
Hypertonic: A solution with less water and more solute
Hypotonic: A solution with more solute and less water
Isotonic: A solution with the same amount of water and solute
91
What happnes to animal cells and plant cells when placed in pure water
Animal cells will eventually burst(haemolysed)
Plant cell, cytoplasm and vacoule push against the cell wall which stops the cell from getting any larger (turgid)
92
What happens to animal cells and plant cells when placed in sugar solution
Animal cells, cell content shrinks and membrane wrinkles(flaccid)
Plant cells, Cytoplasm and vacuole shrinks and membrane pulls away from the cell wall(plasmolysed)
93
When a plant cell is placed in a sugar solution, what is present in between the cell wall and cell membrane and why?
Sugar solutions is found as the cell wall isn't partially permeable
94
Explain the produces in sodium potassium pump
1)Sodium ions are actively transported out of the epithelial cells into the blood through a sodium potassium pump(potassium ions are actively transported in)
2) Now, there is a higher concentration of sodium ions in the lumen of the intestine than inside the epithelial cell
3) This causes sodium ions to diffuse into the epithelial cell through a co transport protein
4) As this happens, they carry a glucose/amino acid molecule into the epithelial cell against the concentration gradient
5) The glucose/amino acid molecule is brought into the blood by sodium ions through facilitated diffusion using carrier proteins
95
Uncertainty is ± ___________
Uncertainty is ± half the resolution
96
Starch grains (from sugars in photosynthesis) are found in...
Stroma/Seeds/Storage organs(e.g.potatoes)
97
What are the 3 stages in the cell cycle
Interphase
Mitosis
Cytokinesis
98
What is mitosis important for
Growth and Repair
99
Define mitosis
A type of division where a parent cell divides to form 2 genetically identical daughter cells which both have the same number of Chromosomes as the parent cell
100
What is the longest stage in cell cycle
Interphase
101
Explain the 3 steps in interphase
G1: All organelles double+Cell grows+proteins made+enzymes produced(used for DNA synthesis)
S: DNA synthesis
G2: Any error made during the synthesis of DNA is corrected here
102
What are the 4 stages in Mitosis
Prophase
Metaphase
Anaphase
Telaphase
103
Describe mitosis (all 4 stages) and cytokinesis
PROPHASE- Chromatin condense to form Chromosomes consisting of two Chromotids joined at the centromere
-In animal cells, the centrioles sepeare and move to opposite poles of the cell
-Centrioles create spindle fibres which are released from opposite poles
-Nuclear envelope breaks down and nucleolus dissapears
METAPHASE: -Chromosomes align along the equator of the cell
-The spindle fibres released from the poles attach to the centromere and chromatid
ANOPHASE: -The spindle fibres refract and pull the centromere and chromatid they are bound to towards opposite poles
-This causes the centromere to divide into two and tbe individual chromatids are pulled to opposite poles(This requires ATP provided by respiration in mitochondria)
TELOPHASE: -Chromosomes are now at opposite poles of the cell and become longer and thiner again
-Spindle fibres disintegrate and nucleus starts to reform
CYTOKINESIS
Cytoplasm splits to create two genetically identical daughter cells
104
What are the 3 functions of mitosis
-Increase the number of cells during growth
-Replace damaged cells and repair tissue
-Produce genetically identical cells during asexual reproduction
105
What are some examples of non specific defence mechanisms
Physical barriers like skin
Phagocytes
106
What are some examples of specific defence mechanisms
Humoral response (B lymphocytes)
Cell mediated response (T lymphocyte)
107
What are two types of phagocytes
Neutrophils
Macrophages/Monocytes
108
Explain the process of phagocytosis
When lsthogen invades body, cells under attack release histamine, these chemicals stimulate neutrophils towards cell (process if called chemotaxis), phagocytes have many cell surface recptors and attaches to surface of pathogen, use cell surface membrane to engulf pathogens into a phagosome - lysosomes fuse with phagosome to form hydrolysis enzymes which breaks down pathogens - soluble products are absorbed and used by phagocyte
109
What do macrophages/monocytes do
Cut pathogens to display antigens
This is called antigen presentation
110
Where are lymphocytes made
Bone marrow
111
Where do T cells mature
Thymus
112
What is an antigen presenting cell
Any cell that presents a non self antigen on their surface
113
Why are T cell responses described as a 'cell mediated' response
T cells only repsond to antigens which are presented on cells (Antigen presenting cells) and not antigens detached from cells and within body Fluids such as the blood
114
Explain the process of the cell mediated response
-When a pathogen gas been engulfed and destroyed by a phagocyte, the antigens are presented on the cell surface, this is now called an antigen presenting cell
-Helper T cells have receptors on their surface which can attach to the antigens on antigen presenting cells
-This activates helper T cells to divide by mitosis to replicate and make a large number of clones
-Cloned helper T cells differentiate into different cells
-Some remain as helper T cells and activate B lymphocytes
-Some stimulate macrophages to perform more phagocytosis
-Some become memory cells for that shaped antigen
-Some become cytotoxic T cells (killer T cells)
115
How do cytotoxic t cells (killer T cells) destroy abnormal or infected cells
They release a protein, perforin which makes holes in the cell surface membrane so it is permeable to any substance
This causes the cell death
116
Explain the humoral response
-B cells internalise and then present pathogens on its cell surface membrane
-Receptors on helper T cell bind to complementary antigens on B cells which activates the B cell to go through clonal expansion
-B cells undergo mitosis to make larger numbers of cells, these differentiate into plasma cells or memory B cells
-Plasma cells make antibodies
117
How long can memory B cells live
They can live for decades
118
How long can plasma cells live
For a few days
119
Explain how memory B cells are useful
- They internalise and present antigens on its cell surface membrane
- T helper cells have receptors which bind to complementary antigens on memory B cell stimulating it to divide by mitosis to form multiple clones
-The clones differentiate to form plasma cells that results in large numbers of antibodies being produced rapidly and memory cells
120
Primary Samsung notes
💂♂️
121
What protein are antibodies
Quaternary
122
How many polypeptide chains are in antibodies and what are they
4 polypeptide chains
2 light chains - shorter
2 heavy chains - longer
123
Example how antibodies carry out agglutination
Antibodies bind to multiple antigens causing pathogens to clump together, this makes it easier for phagocytes to locate and destroy the pathogens
124
What are antibiotics
Chemical substances that kill bacteria
125
How does a singular antibiotic resistance bacteria form and become many antibiotic resistant bacterias
Bacteria mutates to have alleles that are resistant to antibiotics, they have advantageous alleles and are more likely to survive and reproduce and pass on advantageous alleles to offspring. This process repeats over many generations which increases allele frequency of antibiotic resistance
126
What are 2 ways bacteria can be grown
Liquid nutrient broth
Agar gel plate in a petri dish
127
Bacteria Samsung notes
✨️
128
How do you achieve an aseptic environment in the lab
-Keep lid on petri dish (prevent unwanted bacteria from entering)
-Wear gloves (prevent contamination of bacteria on hands)
-Pass inoculating loop through bunsen burner (maintain outer culture of bacteria)
-Clean surface with disinfectant
129
What does the ELISA test stand for
Enzyme linked immunosorbent assay
130
Explain the direct ELISA test
First mobile antibody, complementary to the antigen being tested for has a coloured dye attached and moves forward
A second antibody complementary in shape to the antigen is immobilised in the test
A third antibody is immobilised and is complementary in shale to the first antibody
131
Explain the indirect ELISA test
Samsung ANTIGENNNN
132
In a indirect elisa yest, shat does the colour tell you and what does the intensity if the colour tell ypu
Colour indicates the presence of the antigen in the test sample
Intensity of colour indicates the quantity present
133
What are two types of immunities
Explain both and how they naturally and artificially occur
PASSIVE immunity
Antibodies are introduced in the body
Fast working
No long term immunity and no memory cells plasma cells made
Naturally passed to fetus though placenta or breast milk
Artificially though monoclonal antibodies
ACTIVE immunity
Antigens introduced to body
Naturally through infection
Articifically through vaccines
134
What is a vaccine
Weakened or dead pathogen
135
Explain how vaccines work
-Small amount of weakened or dead pathogen or antigens are introduced in the moth or by injection
-Exposure to the antigens activates B cells to go through clonal expansion and differentiation
-B cells undergo mitosis to make large number of cells these cells differentiate tk form plasma cells or memory B cells
-Plasma cells make antibodies
-B memory cells can divide rapidly into plasma cells when reinfected with the same pathogen to make large numbers of antibodies rapidly
136
What is herd immunity
If enough of the population are vaccinated the pathogen can't spread easily amongst the population
This provides protection for those who are not vaccinated
137
What is the genetic material and enzyme in HIV
Genetic material - RNA
Enzyme - Reverse transcriptase
138
What type of virus is HIV
Retrovirus
139
Why can't HIV replicate itself
No Ribosomes
No DNA
140
Describe the replication of HIV in a host cell
1. Hiv enters bloodstream
2. Hiv's glycoprotein binds to CD4 proteins on T helper cells
3. Capsid fuses with cell membrane so RNA and reverse transcriptase enter the Cytoplasm
4. Reverse transcriptase converts RNA into DNA
5. DNA is inserted into the DNA of host cell
6. Viral DNA is transcribed and translated in T cells to make viral proteins to make new viral particles
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142
What are the symptoms of HIV in the first few weeks
Flu like symptoms
Fever
High temperature
143
What is late stage HIV called
AIDS
144
When is HIV classed as AIDS and why is this more severe
When the virus interferes with the normal functioning of the immune system
T helper cell is destroyed by virus, host is unable to produce an adequate immune response to other pathogens and is vulnerable to infections and cancer
145
Explain the 3 HIV drugs
FUSION INHIBITORS - Blocks the fusion of HIV to host cell
REVERSE TRANSCRIPTASE INHIBITORS - Stops viral RNA from being sy thesised to DNA
PROTEASE INHIBITORS - Inhibit protease used in the synthesis of viral proteins
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