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Biology‎ > Section 2- Cells > Flashcards

Section 2- Cells Flashcards

1
Q

What is a Eukaryote?

A

These are (mostly) multicellular organisms made up of eukaryotic cells like animals, plants, fungi, and protists.

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2
Q

What is a Prokaryote?

A

These are single-celled organisms made up of prokaryotic cells like bacteria.

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3
Q

What are eukaryotic cells?

A

These cells are more complex, contain membrane-bound organelles and have DNA in the form of chromosomes within a nucleus.

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4
Q

What is in an animal cell?

A
  1. Nucleus
  2. nucleolus
  3. smooth endoplasmic reticulum
  4. rough endoplasmic reticulum
  5. Golgi apparatus
  6. golgi vessels
  7. Ribosomes
  8. Lyosomes
  9. Mitochondria
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5
Q

State the relationship between a system and specialised cells.

A

Specialised cells make up tissues that perform a specific function. These tissues then form organs, and these organs that carry out a specific function are organ systems.

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6
Q

Describe the structure of the cell-surface membranes.

A

The structure is a ‘Fluid mosaic’ phospholipid bilayer with extrinsic and intrinsic proteins embedded.

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7
Q

Describe the Function of the cell-surface membrane.

A
  1. isolates cytoplasm from the extracellular environment
  2. selectively permeable to regulate the transport of substances
  3. involved in cell signalling/cell recognition.
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8
Q

Explain the role of cholesterol, glycoproteins and glycolipids in the cell surface membrane.

A

Cholesterol: steroid molecule connects phospholipids and reduces fluidity.
Glycoproteins: cell signalling, cell recognition and binding cells together,
Glycolipids: cell signalling and cell recognition.

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9
Q

Describe the structure of the nucleus.

A
  1. Surrounded by a nuclear envelope, a semi-permeable double membrane
  2. Nuclear pores allow substances to enter/ exit.
  3. Dense nucleolus made of RNA and proteins assembles ribosomes.
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10
Q

Describe the function of the nucleus.

A
  1. Contains DNA coiled around chromatin into chromosomes
  2. Controls cellular processes: Gene expression determines specialisation and site of mRNA transcription, mitosis, and semiconservative replication.
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11
Q

Describe the structure of a mitochondrion.

A
  1. Surrounded by a double membrane. The Folded inner membrane forms cristae which is the site of the electron transport chain.
  2. Fluid matrix: contains mitochondrial DNA, respiratory enzymes, lipids, and proteins.
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12
Q

Describe the structure of a chloroplast.

A
  1. Vesicular plastid with double membrane
  2. Thylakoids: flattened disks stacked to form grana; contain photosystems with chlorophyll.
    3: Intergrana Lamellae: tubes attach thylakoids in adjacent grana.
    Stroma: fluid-filled matrix.
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13
Q

State the function of mitochondria

A

Site of aerobic respiration to produce ATP

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14
Q

State the function of chloroplasts

A

Site of photosynthesis to convert solar energy to chemical energy.

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15
Q

Describe the structure of the Golgi apparatus.

A
  1. The planar stack of membrane-bound, flattened sac’s cis face aligns with the respiratory exchange ratio.
  2. Molecules are processed in cisternae vesicles bud off trans face via exocytosis.
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16
Q

Describe the function of the Golgi apparatus.

A
  1. modifies and packages proteins for export.
  2. synthesised glycoproteins
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17
Q

Describe the structure of a lysosome.

A
  1. Sac surrounded by a single membrane
  2. The embedded H+ pump maintains acidic conditions.
  3. Contains digestive hydrolase enzymes
  4. Glycoprotein coat protects cell interior.
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18
Q

Describe the Function of a lysosome

A
  1. Digest contents of phagosome
  2. exocytosis of digestive enzymes.
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19
Q

Describe the structure of a ribosome.

A
  1. Formed of protein and rRNA
  2. pree in cytoplasm or attached to Endoplasmic reticulum
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20
Q

Describe the function of a ribosome.

A
  1. site of protein synthesis via translation
  2. A large subunit joins amino acids
  3. small subunit contains mRNA binding site.
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21
Q

Describe the structure and function of the endoplasmic reticulum.

A
  1. Cisternae: a network of tubules and flattened sacs that extends from the cell membrane through the cytoplasm and connects to the nuclear envelope
  2. Rough ER: many ribosomes attached for protein synthesis and transport.
  3. Smooth ER: Lipid synthesis
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22
Q

Describe the structure of the cell wall.

A
  1. Bacteria: made of the polysaccharide murein
  2. Plants: Made of cellulose microfibrils. plasmodesmata allow molecules to pass between cells, middle lamella acts as a boundary between adjacent cell walls.
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23
Q

State the functions of the cell wall

A
  1. mechanical strength and support
  2. Physical barrier against pathogens
  3. Part of apoplast pathway (plants) to enable easy diffusion of water
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24
Q

Describe the structure and function of the cell vacuole in plants.

A
  1. Surrounded by a single membrane: the tonoplast
  2. contains cell sap: mineral ions, water, enzymes, and soluble pigments.
    - Controls turgor pressure
    - Absorbs and hydrolysis potentially harmful substances to detoxify cytoplasm
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25
Q

Explain some common cell adaptations.

A
  1. Folded membrane or microvilli increase surface e.g. for diffusion.
  2. Many mitochondria = large amounts of ATP for active transport.
  3. Walls one cell thick to reduce the distance of diffusion pathway.
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26
Q

State the role of plasmids in prokaryotes.

A
  1. Small ring of DNA that carries non-essential genes.
  2. Can be exchanged between bacterial cells via conjugation
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27
Q

State the role of flagella in prokaryotes.

A

Rotating cells (usually unicellular) organism

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28
Q

State the role of the capsule in prokaryotes

A

!. Prevents desiccation
2. Acts as a food reserve.
3. Provides mechanical protection against phagocytosis and external chemicals.
4. sticks cells together

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29
Q

similarities between eukaryotic and prokaryotic cells?

A

Both have:
1. cell membrane
2. Cytoplasm
3. Ribosomes (don’t count as an organelle as not membrane-bound)

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30
Q

Contrast Eukaryotic and Prokaryotic cells.

A

Prokaryotic :
unicellular. no membrane-bound organelles. no nucleus
circular DNA not associated with proteins
Small ribosomes (70s)/ 80s ribosomes eukaryotic
Binary fission - always asexual reproduction. / mitosis and meiosis bot a/ sexusl
murein cell walls cellulose /chitin cell walls
Capsule, sometimes plasmids and cytoskeleton.

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31
Q

Why are viruses referred to as ‘particles’ instead of cells

A

Acellular and non-living: contain no cytoplasm and cannot self reproduce also no metabolism.

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32
Q

Describe the structure of a viral particle

A
  1. Linear genetic material (DNA or RNA) and viral enzymes e.g. reverse transcriptase.
  2. surrounded by capsid (protein coat made of capsomeres
  3. no cytoplasm
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33
Q

Describe the structure of an enveloped virus.

A
  1. Simple virus surrounded by matrix protein
  2. Matrix protein surrounded by envelope
  3. Attachment proteins on surface
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34
Q

State the role of the capsid on viral particles

A
  1. protect nucleic acid from degradation by restricting endonucleases.
  2. surface sutes enable viral particle to bind to and enter host cells or inject their genetic material.
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35
Q

State the role of attachment protein on viral particles

A

Enable viral particles to bind to complementary sites on host cell: entry vial endosymbiosis

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36
Q

Describe how optical microscopes work.

A
  1. lenses focus rays of light and magnify the view of a thin slice of the specimen.
  2. different structures absorb different amounts and wavelengths of light
  3. reflected light is transmitted to the observer via the objective lens and eyepiece
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37
Q

Outline how a student could prepare a temporary amount of tissue for an optical microscope.

A
  1. obtain a thin section of tissue e.g. using ultratome or by maceration
  2. place plant tissue in a drop of water
  3. stain tissue on the slide to make structures visible
  4. add coverslip using a mounted needle at 45 degrees to avoid trapping air bubbles
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38
Q

Suggest the advantages and limitations of using an optical microscope

A

+ colour image
+can show living structures
+ affordable apparatus
- 2d image
- lower resolution that electron microscopes = unable to see ultrastructures

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39
Q

Describe how a transmission electron microscope works.

A
  1. pass a high beam of electrons through a thin slice of the specimen
  2. more dense structures appear darker since they absorb more electrons
  3. focus the image onto a fluorescent screen or photographic plate using magnetic lenses
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40
Q

Suggest the advantages and limitations of using a TEM

A

+ electrons have a shorter wavelength than light= high resolution so visible ultrastructures
+ high magnification x500000
- 2d image
-requires a vacuum
-extensive preparation may introduce artefacts
- no color image

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41
Q

Describe hoe a scanning electron microscope (SEM) works.

A
  1. focus a beam of electrons onto a specimen’s surface using electromagnetic lenses
  2. Reflected electrons hit a collecting device and are amplified to produce an image on a photographic plate
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42
Q

Suggest the advantages and limitations of using an SEM

A

+ 3d image
+ electrons have a shorter wavelength than light = high resolution
- requires a vacuum = cannot show living structures
- no colour image
-only shows the outer surface.

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43
Q

Define magnification and resolution

A

Magnification: the factor by which the image is larger than the actual specimen
Resolution: smallest separation distance at which 2 separate structures can be distinguished from each other

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44
Q

Explain how to use an eyepiece graticule and stage micrometre to measure the size of a structure.

A
  1. place on micrometer on stage to calibrate the eyepiece graticule
  2. line up scales on graticule micrometre. count how many graticule divisions are in 100um on the micrometre
  3. length of 1 eyepiece division = 100um / number of divisions
  4. use calibrated values to calculate the actual length of structures
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45
Q

State an equation to calculate the actual size of a structure from microscopy.

A

actual size = image size/magnification

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46
Q

Outline what happens during cell fractionation and ultracentrifugation.

A
  1. mince and homogenize tissue to break open cells and release organelles
  2. filter homogenate to remove debris
  3. perform differential centrifugation
    a) spin homogenate in a centrifuge
    b) the most dense organelles in the mixture form a pellet
    c) filter off the supernatant and spin again at a higher speed
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47
Q

State the order of sedimentation of organelles during differential centrifugation

A

most dense—> least dense
nucleus–> mitochondria-> lysosomes -> RER-> plasma membrane -> SER-> ribosomes

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48
Q

Explain why fractionated cells are kept in a cold buffered, isotonic solution.

A

Cold: slow action of hydrolase enzymes.
Buffered: maintain constant PH
isotonic: prevent osmotic lysis/ shrinking of organelles.

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49
Q

State what the cell cycle is and outline its stages.

A

Cycle of division with intermediate growth periods.
1. interphase
2. mitosis or meiosis
3. cytokinesis.

50
Q

Explain why the cell cycle does not happen in some cells.

A

After differentiation, some types of cells in multicellular organisms (e.g. neurons) no longer can divide.

51
Q

What is the difference between the cell cycle and mitosis?

A

The cell cycle includes a growth period between divisions; mitosis is only 10% of the cycle and refers only to nuclear division.

52
Q

state what the cell cycle is and outline its stages.

A
  • interphase
  • mitosis or meisos
  • cytokinesis
53
Q

Why dosent that cell cycle happen in some cells?

A
  • after differentiation some types of cell in multicelluar organisms (e.g. neurons) no longer have the ability to divide.
54
Q

Outline what happens during interphase.

A

G1: cell makes proteins for replication and cell size doubles
S: Dna replicates chromosomes consist of 2 sister chromatids joined at a centromere
G2: organelles divide.

55
Q

What is the purpose of mitosis?

A

Produces 2 genetically identical daughter cells for growth, repair and aesexual reproduction.

56
Q

Name the stages of mitosis

A
  • Prophase
  • Metaphase
  • Anaphase
  • telophase
57
Q

What happens during Prophase?

A
  • Chromosomes condense , becomming visible. they are x shaped with two sister chromatids joined at centomere
  • Centrioles moves to opposite poles of cell (animal) and mitotic spindle fibres form
  • Nuclear envelope and nucleolus break down so the chromosomes free in cytoplasm.
58
Q

What happens during metaphase?

A
  • sister chromatids line up at cell equator, attached to the mitotic spindle by their centromeres.
59
Q

What happens during Anaphase?

A
  • Using energy from atp hydrolysis,
  • spindle fibres contract and the centromeres divide
  • sister chromatides seperate into two distinct chromosomes and are pulled to opposite poles of the cell
  • spindle fibres break down
60
Q

What happens during telophase?

A
  • chromosomes decondense
  • new nuclear envelope form around each new set of chromosomes this makes two new nuclei.
61
Q

What is the procedure for a root tip sqaush experiment?

A
  • prepare a tempoary mount of root tissue
  • focus an optical microscope on the slide. count total number of cells in the field view and number of cells in a stage of mitosis
  • calculate mitotic index
62
Q

How do you prepare a tempoary root tip mount?

A
  • place root in hydrochloric acid to halt cell division and hydrolyse middle lamella
  • stain root tip with a dye that binds to chromosomes
  • macerate tissue in water using mounted needle
  • use mounted needle at 45 degree angle to press down coverslip and obtain a single layer of cells. avvoid trapping air bubbles.
63
Q

Name 2 dyes that bind to chromosomes.

A
  • toluidine blue (blue)
  • acetic orcein (purple-red)
64
Q

Why is only the root tip used whn calculating a mitotic index?

A
  • meristematic cells at root tip are activley undergoing mitosis
  • cells futher from root tip are elongating rather than dividing
65
Q

Describe the process of binary fission.

A
  • DNA loop replicates . both copies stay attache to the cell membrane. plasmids then replicate in the cytoplasm
  • Cell elongates , seperating the 2 DNA loops
  • cell membane contracts and septum forms
  • cell splits into 2 identical progency cells , each with 1 copy of the DNA loop but a variable number of plasmids.
66
Q

How do viruses replicate?

A
  1. Attachement proteins attach to receptors on host cell membrane.
    - enveloped viruses fuse with cell membrane or move in via endocytosis and release DNA / RNA into cytoplasm or inject it
    - host cell uses viral genetic information to synthesise ne viral proteins /nucleic acid
    - components of new viral particle assemble.
67
Q

What is simple diffusion?

A

the net movement of particles from an area of high to low concentration passivley until equilibrium is reached

68
Q

What are the features of simple diffusion?

A
  • small non-polar molecules involved
  • passive process
  • no carrier protiens involved.
69
Q

What factors affect the rate of diffusion?

A
  • Surface area
  • Temperature
  • Diffusion distance
  • Concentration gradient
70
Q

What is Fick’s law?

A
  • an equation used to determine the rate of diffusion across a cell membrane
  • rate of diffusion = surface area x concentartion gradient / diffusion distance (thickness of memebrane)
71
Q

What is facillitated difussion?

A

facilitated diffusion is the passive net movement of large molecules or ions from an area of high concentration to an area of low concentration via transport proteins until evenly distributed.

72
Q

What are the main features of facilliated diffusion?

A
  • passive pprocess.
  • large and polar moelcules or ions
  • uses transport proteins.
73
Q

What is osmosis?

A

the movement of water from an area of high water potential to an area of lower water potential across a partially permeable membrane.

74
Q

What is water potential?

A
  • the pressure created by water molecules
  • measured in kPa
  • pure water has a WP of 0 so when solutes are dissolved in water the water potential will become negative.
75
Q

What is an isotonic solution?

A

a solution where the water potential is the same in the cell and in the solution

76
Q

What is a Hypotonic solution?

A

a solution where the water potential is more positive that the cell so water moves in

77
Q

What is a Hypertonic solution?

A

a solution where the water potential is more negative than inside the cell so water moves out

78
Q

What is active transport?

A

The active movement of molecules in or out of a cell from an area of low concentration to an area of high concentration via carrier proteins and ATP

79
Q

How does active transport happen?

A
  1. molecule binds to the carrier protein that has a complimentary receptor shape
  2. ATP binds to the carrier protein from the inside of the cell and is hydrolysed into ADP +Pi
  3. this caused the carrier protein to change shape and release the molecule to the other side.
  4. the phosphate ion is then released and the protein returns to its original shape
80
Q

What happens in the co-transport of glucose and sodium ions in the ileum?

A
  1. sodium ions are actively transported out of the epithelia cell into the blood via the sodium /potassium pump
  2. this reduces the sodium ion concentration in the epithelial cell
  3. sodium ions can the diffuse from the lumen down the concentration gradient into the epithelial cell
  4. sodium diffuses through a cotransport protein so glucose attach to the cotransport protein and are brough into the epithelial cell against their concentration gradient.
  5. glucose then moves by facilitated diffusion from the epithelial cell into the blood.
81
Q

What affects the rate of diffusion?

A
  • an increased surface area of cells (micro villi)
  • an increase in the number of protein channels and carrier proteins
  • a short diffusion distance
  • temperature.
82
Q

What are glycoproteins?

A
  • extrinsic proteins that are associated with carbohydrates form glycoproteins
  • their function is cell recognition in the form of antigens
  • they help cells attach to one another and form tissues for mechanical strength
  • they form receptors sites for hormones or neuro transmitters.
83
Q

What are glycolipids?

A
  • carbohydrates covalently bonded with lipids.
  • they are used in cell recognition in the form of antigens
    -they help cells attach to one another and form tissues for mechanical strength.
84
Q

what is a pathogen?

A

a microorganism that causes communicable disease

85
Q

What are the main disease causing pathogens in humans?

A

Bacteria and viruses.

86
Q

What is an antigen?

A

a protein (glycoprotein) on the surface of the cell membrane that initiates an immune response

87
Q

what are examples of pathogens

A

bacteria , fungi, viruse,probotira

88
Q

What triggers an immune response?

A
  • foreign pathogens - cells from other organisms - abnormal cancer cells - cells infected by a virus - infected antigens - own cells if you have an auto immune disease.
89
Q

What type of white blood cells are involved in the immune response?

A
  • phagocytes (non specific
  • t-lymphocytes (specific)
  • b- lymphocytes (specific)
90
Q

What is an example of a non specific response?

A
  • phagocytosis
  • phagocyte binds to foreign antigen of pathogen and phagocytosis occurs creating a phagosome.
  • lysosome containing lysozyme enzymes fuses with phagosome and hydrolyses pathogen.
    -break down products are absorbed by the phagocyte and antigens can be presented on the cell membrane. ( phagocytes attracted to chemicals released by pathogens) moves toward in down a concentration gradient.
91
Q

what the two types of specific responses?

A
  • cellular response and humoral response. - carried out by t- lymphocytes made in the thymus gland.
  • only work on cells , phagocytes presenting foreign antigens, foreign cells, virus infected cells , virus infected cells and cancer cells
92
Q

What are the two types of t- lymphocytes? (t -cells)

A
  • helper (Th) lymphocytes
  • cytotoxic (Tc) lymphocytes
93
Q

What is the cellular response?

A
  • phagocyte presents foreign antigen on its cell surface membrane, phagocytes are antigen presenting cells
  • helper T cell with the correct receptor binds to the antigen
  • the activated t cells then divide and clone by mitosis.
  • these t cells then stimulate phagocytosis by phagocytes they also activate cytotoxic t cells to kill infected cells. they also stimulate b cells to divide (by releasing cell signalling molecules.
  • these cells also become memory cells
94
Q

What is the humoral response?

A
  • a specific b - lymphocyte (made in the bone marrow) with a complimentary receptor to the pathogen engulfs the pathogen via endocytosis.
  • the lymphocyte then presents the foreign antigen on its cell membrane.
  • a helper t- lymphocyte cell will bind to presented antigen and trigger mitosis of b cells
  • some of the be cells become plasma cells and trigger antibody production ( primary response
  • some b cells then become memory cells and rapidly divide upon reinfection.
95
Q

What is agglutination?

A
  • clumping of pathogens together so that its easier for phagocytes to find
  • marks for destruction by phagocytes.
96
Q

What is antigenic variability?

A

the idea that the antigens of pathogens that have many strains are constantly changing

97
Q

how is immunity achieved?

A
  • through exposure to the pathogen
  • through vaccination
98
Q

what is immunity?

A

the ability to resist infection

99
Q

what is passive immunity?

A
  • where antibodies are introduced by an outside source.
  • this immunity is short-lived as the body breaks these antibodies down
100
Q

what is active immunity?

A
  • where antibody simulation occurs in an organism naturally
101
Q

what makes a successful vaccination programme?

A
  • no to few side effects
  • sufficient quantities of the vaccine
  • efficient way of producing and transporting the vaccine to large populations
    -it must be possible to vaccinate all or most of the population
    -
102
Q

why do vaccination programs not always work?

A
  • some individuals have a defective immune system
  • if the disease is caught too soon after vaccination then the immune system may not have already built up resistance to the disease and then it will get passed on
  • if the pathogen mutates
  • some pathogens hide in parts of the body inaccessible to the immune system, like the intestines
  • some vaccinations may only be against the strain of one disease that has many strains
103
Q

What are the ethical issues of vaccines?

A
  • all vaccines are tested on animals before use as testing on humans is tricky
  • some people do not want to take risks or side effects of vaccines.
104
Q

What is the structure of an antibody?

A
  • 4 polypeptide chains (quaternary structure bonded by disulphide bridges)
  • variable region on the tips of the y each antibody has 2 variable regions
  • constant region is the same for all antibodies and binds to phagocytes
  • heavy region and a light region
  • variable region spec to a spec antigen
  • two variable regions allow agglutination
105
Q

General information about antibodies?

A
  • y shaped protein with a quaternary structure
  • 4 polypeptide chains
  • made and secreted by plasma cells
  • constant region is the same for all antibodies
  • variable region is specific to a singular antigen
  • forming an antigen antibody complex
  • hing protein alows for flexibility in the shape of the y
106
Q

What is the function of antibodies?

A
  • agglutination clumps pathogens together so many can be destroyed by a single phagocyte
  • neutralisation , neutralise pathogen or toxins by binding or blocking the pathogens attachment proteins so that it is unable to enter host cells.
107
Q

what is the primary response?

A
  • first immune response to a pathogen / antigen
  • longer lag time of antibody production as there are no memory cell
  • lag time due to clonal selection
  • pathogens multiply and damage the host cells so the host feels symptoms
  • at the end of infection t- cells and b- cells become memory cells
108
Q

what is the secondary immune response

A
  • secondary infection by the same pathogen / antigen
  • shorter lag time
  • more antibody produced
  • rate of antibody production is faster due to memory cells
  • do not feel symptoms
109
Q

what are monoclonal antibodies?

A

identical antibodies made from the same b cell / plasma cell

110
Q

how are monoclonal antibodies used?

A
  • targeting medication
  • diagnosing disease
111
Q

How are mc antibodies used in targeting medication?

A
  • mc antibodies can be used to deliver drugs
  • all cells have spec. antigens on their surface
  • mc antibodies can be made to bind to any target cell
  • attach drugs to antibodies so that they will bind to target cells e.g. tumour / cancer cells
  • drug and the antibody will only bind to target cells
112
Q

how are mc antibodies used in medical diagnosis?

A
  1. mc antibodies are added to a plate
  2. sample is added if the antigen is present it forms antigen- antibody complex
  3. plate is rinsed to remove unbound antigens
  4. same mc antibody is added with an enzyme or colour attached
  5. rinse the plate again to remove any unbound antibodies
  6. observe to look for marker e.g color change
    ( if enzyme is used add a substrate so that thr reactions results in a color change.
113
Q

what is a vaccine

A

a substance containing a dead / weakened / attenuated pathogen
antigenic material that stimulates an immune response.

114
Q

how do vaccinations lead to immunity?

A
  • vaccine contains the antigen
  • antigen is displayed on the surface of antigen presenting cells
  • specific t helper cells w a complimentary receptor binds to the presented antigen
  • this activates b cells with the complimentary antibody
  • the activated b cells divide by mitosis and differentiate into many plasma cells which make and secrete many antibodies
  • some t cells and b cells develop into memory cells
115
Q

What is the Elisa test?

A
  • a test to see if a patient has a specific antibody or antigen
116
Q

What is the direct ELISA test?

A
  • A test for antigens
    1. immobilised antibodies are attached to a well
    2. a sample is added e.g. blood plasma
    3. if the blood plasma contains the antigen then it will form an antigen-antibody complex with the immobilised antibody
    4. rinse to remove unbound antigens
    5. an antibody with an enzyme is added this antibody is the same as the immobilized antibody
    6. rinse to remove the unbound antibodies
    7. add substrate. if it is a positive test then there will be a colour change
117
Q

What is the indirect ELISA test?

A
  • A test for antibodies
    1. antigen is fixed to the well
      1. a sample is added if it’s complementary then it forms an antigen-antibody complex
      2. rinse to remove unbound antibodies
      3. a different antibody is added with an enzyme attached it will only bind if the first antibody is present
      4. rinsed to remove unbound antibodies + enzymes
      5. substrate is added if a positive colour change
118
Q

What is HIV? and how does it work?

A
  • Human immunodeficiency virus
  • infects TH cells
  • So that the immune system becomes weak and develops aids (Acquired Immune Deficiency Syndrome)
  • HIV doesn’t kill you directly -> immune system deteriorates until you can’t fight any other pathogens
119
Q

What is the structure of HIV?

A
  • RNA
  • capsid
  • Reverse transcriptase
  • Attachment proteins
  • Envelope stolen from host cell
120
Q

How do viruses replicate?

A
  1. Virus attachment protein binds to a complementary receptor on the host (T-H cell)
  2. reverse transcriptase makes double-stranded DNA from the RNA
  3. the DNA enters the nucleus via the nuclear pore
  4. TH cell makes more copies of the virus’s genetic material (RNA) and proteins (reverse transcriptase)
  5. virus reforms the capsid
  6. leaves host cell and takes the envelope from the host membrane

Biology‎ (11 decks)

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