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A2 Flashcards

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1
Q

Homeostasis

A

maintaining of a consistent internal environment even if the external environment changes

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2
Q

primordial soup

A

(hypothetical) water-based sea of simple monomers such as amino acids. This is thought to be the origin of living compounds

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3
Q

Vesicle

A

Any small bubble of fluid surrounded by a phospholipid bilayer

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4
Q

Compartmentalisation

A

Separation of functions into specific regions of the cells, allowing multiple distinct metabolic functions to occur at the same time

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5
Q

Coalescence

A

Phospholipids naturally arranging themselves to come together and form a ring-like structure

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6
Q

Three principles of cell theory

A
  1. All organisms are composed of one or more cells
  2. Cells are the smallest unit of life
  3. All cells come from pre-existing cells
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7
Q

Organic vs inorganic compound

A

Organic: generally complex carbon based compound, made in living organisms

Inorganic: don’t have to contain carbon (most don’t), found inside and outside living organisms

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8
Q

What did the Miller-Urey experiment demonstrate?

A

Inorganic gases can react to create organic compounds within conditions similar to early Earth.

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9
Q

How does the structure of fatty acids contribute to vesicle formation?

A

Phospholipids in an aqueous solution form a barrier to create a vesicle. This may have happened in primordial soup and creates cell membranes of early cells.

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10
Q

Requirements to be considered living

A

metabolism
growth
reproduction (independent)
response to stimuli
homeostasis
movement
nutrition

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11
Q

What is a cell?

A

Smallest unit of life

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12
Q

What is needed to create a living functional cell?

A

Catalysis: a catalyst that speeds up chemical reactions

Self-replication of molecules

Self-assembly of monomers into polymers (e.g. condensation reactions)

Compartmentalisation
- eukaryotes: organelles
- prokaryotes: ribosomes

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13
Q

Examples of how cells fulfill criteria for being living

A

Homeostasis -> regulates H2O balance

Metabolism (ability to carry out chemical reactions using ATP) -> cellular respiration happens in each cell

Reproduction/self-replication -> cell replication/mitosis

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14
Q

Examples of how viruses fail to meet the criteria for living

A

Homeostasis -/> no internal environment

Metabolism -/> does not use ATP

Reproduction/self-replication -/> needs a host

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15
Q

Conditions of the Miller Urey experiment

A

Inorganic gases: methane, ammonia, hydrogen

Vert hot ocean with water (due to high temperatures and lots of UV penetration)

Electrical activity (through an electrode)

= mimics conditions of Early Earth

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16
Q

Process of Miller Urey experiment

A

A lower chamber (the ocean) is heated, to mimic the hihg temperatures of Early Earth.

This produces water vapour that travels into the upper chamber. This upper chamber is filled with inorganic gases (methane, ammonia, hydrogen), which mixes with the H2O vapour. An electrode hits this upper chamber, to mimic lightning.

This goes through a condenser.

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17
Q

Proucts of the Miller Urey experiment.

A

Amino acids + carbon hydrogen chains, as well as water vapour. This combination is dubbed primordial soup. This contributed to evidence that biomolecules could spontaneously form under Early Earth’s conditions.

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18
Q

What does spontaneous vesicle formation provide evidence for?

A

Explains how all membranes arrived.

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19
Q

What is the process of spontaneous vesicle formation?

A

Amphipathic phospholipids spontaneously form a vesicle due to hydrophobic interactions

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20
Q

Ribozymes

A

Special type of RNA that can act as a catalyst. Has a role in protein synthesis

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21
Q

Protocell

A

General term for any unit contained by a membrane that is completing a cellular reaction

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22
Q

Radioactive isotope

A

Unstable form of an element that emits radiation

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23
Q

Half life

A

Length of time it takes for half of a radioactive isotope to change into another stable element

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24
Q

Index fossils

A

Distinctive, widespread and abundant fossils that is limited to a specific geological time

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25
Q

Hydrothermal vents

A

Places where hot water emanates from beneath the ocena floor. Formed when cracks of the crust of the seabed expose seawater to rocks below

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26
Q

Unique properties of RNA that suggest it could be an ideal first genetic material

A

Can spontaneously form from monomers as it is a simpler structure than DNA

Self-replicating properties

Can catalyse chemical reactions

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27
Q

Sequence of major stages in the evolution of life

A

Abiotic chemical compounds e.g. methane

Small organic compounds e.g. primordial soup

Polymers (aids by RNA catalysis)

Membranes (due to amphipathic nature)

Protocell

True cell with organelles

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28
Q

Last Universal Common Ancestor

A

Common ancestor to all currently living things. i.e. from before all prokaryotes and eukaryotes branched off

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29
Q

Relative dating of fossils

A

Whether the fossil is comparatively older or younger than nearby fossils absed on their placement in the rock

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30
Q

Absolute dating of fossils

A

Determining a specific age of a fossil in years, using carbon dating and knowledge of half lives

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31
Q

What is the RNA World Hypothesis?

A

Evolutionary theory that RNA was the initial genetic material, and evolved into DNA and proteins. This is contrasted by the Central dogma, which states DNA -> RNA -> proteins

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32
Q

Specific hypothesised details of RNA World Hypothesis

A

Within primordial soup, RNA easily self assembled. This is because of its simple structure. The RNA can then act as a catalyst for DNA replication (which requires many enzymes) and protein synthesis (ribozymes in RNA still do this).

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33
Q

Evidence for shared ancestry/Last Universal Common Ancestor

A

Universal genetic code

Same biomolecules

Same metabolic processes

Tracked ~300 shared genes

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34
Q

Why is it hypothesised that LUCA is in hydrothermal vents?

A

The ~300 shared genes were for anaerobic processes (occuring in the absence of O2). Therefore, LUCA may be found in a low oxygen environment. This low O2 environment, and other favourable conditions and many fossils, fits with Hydrothermal Vents

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35
Q

Most common substance for absolute dating of fossils

A

Carbon-14
5730 years half life

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36
Q

Cytology

A

Specific branch of biology focused on the study of the cell and all aspects related to cellular structure and function

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37
Q

Micrograph

A

Photo taken through a microscope

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38
Q

Micrometre compared to one centimetre

A

1 micrometre = 10^-4 cm = 10^-3 mm

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39
Q

Coarse v.s. fine focus on a microscope

A

Coarse makes larger adjustments to bring objects into focus

Fine makes small adjustments to add sharpness and clarity.

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40
Q

Contribution of cryogenic electron microscopy

A

Provides a resolution at 0.12 nanometres, allowing for the atoms within a protein to be visualised

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41
Q

Magnification

A

How many times larger the viewed image is than the actual image size

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42
Q

Resolution

A

How well you can differentiate two objects as separate (i.e. clarity and sharpness)

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43
Q

With a light microscope, what occurs when magnification increases?

A

Resolution decreases. Therefore, ideal magnification of a light microscope is 400-1000x, although some light microscopes can reach 2000x

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44
Q

What is the difference between electron and light microscopes in terms of resolution/magnification?

A

Electron microscopes can preserve resolution even at high magnifications. However, light microscopes decrease in resolution as magnification increases, usually working from 400-1000x

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45
Q

Formula for magnification

A

Magnification = image size/actual size

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46
Q

How to calculate magnification using a scale bar

A

Magnification = measured scale bar with ruler / given size on bar

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47
Q

What can light microscopes observe?

A

Living organisms. Both surface and internal (if thin).

Creates 2D images

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48
Q

What magnification do light microscopes work well with?

A

400-1000x. Some can go up to 2000x

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49
Q

What type of images do light microscopes create?

A

2D

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50
Q

Advantages of light microscopes

A

Can observe living organisms (see processes in action)

Can be in colour

Affordable (increases access)

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51
Q

Disadvantages of light microscopes

A

Poor resolution limits magnification

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52
Q

What is a scanning electron microscope (SEM)?

A

Electron microscope that uses a beam of electrons to scan outer surfaces of dead matter, creating detailed images of the exterior

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53
Q

What is a transmission electron microscope (TEM)?

A

Electron microscope that uses a beam of electrons through a very thin section of specimen that allows for internal structures to be viewed.

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54
Q

What can scanning electron microscopes observe?

A

Dead matter, detailed 3D images of surface.

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55
Q

Magnification of scanning electron microscopes

A

Up to 1,000,000x with great resolution

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56
Q

Advantages of scanning electron microscope

A

Higher magnification, 3D images

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57
Q

Disadvantages of scanning electron microscopes

A

Only black and white
Only non-living matter
Expensive

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58
Q

Type of images created by scanning electron microscopes

A

3D

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59
Q

What can transmission electron microscopes observe?

A

Dead matter, 2D images of internal structures

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60
Q

Magnification of transmission electron microscopes

A

Up to 1,000,000x with great resolution

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61
Q

Advantages of transmission electron microscopes

A

Higher magnification, has revealed organelle structure

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62
Q

Disadvantages of transmission electron microscopes

A

Must be very thin specimen (techniques required)

Non-living

Black and white only

Expensive

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63
Q

Advances to micrography

A

Freeze fracturing

Cryogenic electron microscopy

Use of fluorescent stain

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64
Q

Freeze fracturing

A

Technique that aids in viewing internal structures with an electron microscope.
Specimen is frozen and then broken at plane (i.e. fracture plane). Then, an etching of the plane is created and observed under an electron microscope

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65
Q

What scientific developments are a result of freeze fracturing?

A

Understanding the bilayer

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66
Q

Cryogenic electron microscopy

A

Protein structure is frozen on grid. The grid is placed under an electron microscope. Pattern of electron transmission reveals the structure of protein down to atoms. Software is used ot create a 3D image

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67
Q

What scientific developments are a result of cryogenic electron microscopy?

A

Detailed understanding of protein structure

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68
Q

Fluroescent stain

A

Fluroescent stain binds to a cellular component (only binds with specific ones). This is observed with a fluroescent light via microscopes with UV lights.

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69
Q

What scientific developments are a result of fluroescent stain?

A

Bright images of cellular structures

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70
Q

Immunofluoresence

A

Technique that uses antibodies with flurosence added. Antibodies are matched to bind to certain target molecules and give them a viral glow once bound

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71
Q

What scientific developments are a result of immunoflourescence?

A

Visualisation of specific proteins (i.e. whether present or not)

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72
Q

Prokaryotic cell

A

Simple and small cells that lack complex organelles

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73
Q

Eukaryotic cell

A

More complex cells that have membrane-bound organelles carrying out unique functions & all DNA is enclosed in a nucleus

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74
Q

Peptidoglycan

A

Carbohydrate and protein polymer that usually makes up the cell wall of prokaryotes

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75
Q

Features common to all cells

A

Cell membrane
DNA
Ribosomes
Cytoplasm

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76
Q

Gram positive bacteria

A

Has thick layer of peptidoglycan as cell wall

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77
Q

Gram negative bacteria

A

Has additional thin layer of membrane surrounding the thick layer of peptidoglycan

78
Q

Examples of eukaryotic organelles

A

Nucleus
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Golgi apparatus
Mitochondria

79
Q

Difference between ribosomes of prokaryotes and eukaryotes

A

In eukaryotes, ribosomes are 80s and are larger and denser than the 70s ribosomes of prokaryotes.

80
Q

Similarities between ribosomes of prokaryotes and eukaryotes

A

Both are made of two separate subunits that clamp together in translation

81
Q

Functions that a unicellular organism must carry out to be classified as living

A

Metabolism
growth
reproduction
reponse to stimuli
homeostasis
nutrition
excretion
movement

82
Q

Size difference between prokaryotes and eukaryotes

A

Eukaryotes are much larger

83
Q

Features of all prokaryotic cells

A

Cell membrane
cell wall
DNA/nucleoid region
ribosomes
cytoplasm

84
Q

Features of some prokaryotic cells

A

Plasmids
Flagellum
Capsule
Pili

85
Q

Cytoplasms

A

Interior of the cell, containing the fluid cytosol. Provides internal space for chemical reactions (metabolic processes). Other cellular structures can exist within them

86
Q

Ribosomes

A

Sites of translation where polypeptides are formed. No exterior membrane and made up of mRNA/protein

87
Q

Pili

A

Small hair structures on the outside of a cell wall. Can be used for adhesion/attachment to other prokaryotic cells or to
facilitate DNA exchange (as a part of sexual reproduction)

88
Q

Nucleoid region (prokaryotic cell)

A

One circular region where the DNA of a prokaryotic cell is found.

This DNA is free in the cytoplasm with no nucleus, providing instructions

89
Q

Cell wall

A

Rigid external layer that is specifically designed to provide structural support and rigidity

90
Q

Different cell wall materials across cell types

A

Bacteria (almost all have) = peptidoglycan
Plant = cellulose
Fungi (many have) = chitin

91
Q

Do all prokaryotes have a cell wall?

A

Almost all esp. bacteria

92
Q

Cell membrane

A

Phospholipid bilayer that allows transport in + out of the cell.
Therefore, it has a role in homeostasis, transport and cell communication

93
Q

What organelle has a role in homeostasis?

A

Most important is the cell membrane

94
Q

Capsule

A

Additional thick layer outside the cell wall, made up of polysaccharides.

Allows adhesion + protection

Some bacteria have

95
Q

Do all prokaryotic cells have a capsule?

A

No, just some bacteria

96
Q

Flagellum

A

Whip-like tail for movement/locomotion

97
Q

Plasmids

A

Single circular rings of DNA that are not connected to the main chromosome. Not essential but helpful. Often contain additional adaptive DNA e.g. antibiotic resistance

98
Q

Organelles specific to animal cells

A

Centrosomes and lysosomes

99
Q

Organelles specific to plant cells (not animal cells)

A

Chloroplasts
Cell wall
Large central vacuole
Amyloplast

100
Q

Organelles of animal cells

A

Golgi apparatus
Rough endoplasmic reticulum
Ribosomes
Plasma membrane
Nucleus
Smooth endoplasmic reticulum
Lysosomes
Centrosome
Cytoskeleton
Small vacuole
Cytoplasm
Mitochondria

101
Q

Rough endoplasmic reticulum

A

Interconnected network of tubules extending from the nucleus throughout the cell with ribosomes on the surface. Transports polypeptides in cell

102
Q

Two types of eukaryotic ribosome

A

Free or attached

103
Q

Nucleus

A

Organelle in which DNA resides. Has a porous double membrane (nuclear envelope) that mRNA exits from.

Contains linear DNA wrapped around histones.

Contains a spherical structure that produces and assembles ribosomal subunits -> nucleolus

104
Q

Smooth endoplasmic reticulum

A

Interconnected network of tubules that extend from the nucleus without ribosomes. Makes and transports lipids e.g. phospholipids, steroids

105
Q

Lysosome

A

Single membrane vesicle full of hydrolytic enzymes to break down biomolecules

106
Q

What type of cells are cytoskeletons found in?

A

All eukaryotic cells

107
Q

Cytoskeleton

A

Network of filaments and microtubules that maintain cell shape, anchor organelles, aid in cell and organelle movement, etc.

108
Q

Small vacuole

A

(Found in animal cells) Storage organelle formed by the Golgi Apparatus that stores H2O, food, wastes, etc.

109
Q

Mitochondria

A

Rod-shaped organelle that performs aerobic cellular respiration.
Has its own DNA and ribosomes, as well as highly folded innner membrane

110
Q

Centrosome (two centrioles)

A

Structure of animal cell that aids in cell division

111
Q

Golgi apparatus

A

Set of flattened saccs (cisternae) that collect/packages/modifies/distributes cellular products

112
Q

Organelles of plant cell

A

Chloroplast
Golgi apparatus
Rough ER
RIbosomes
Cell membrane
Mitochondria
Cell wall
Smooth ER
Nucleus
large central vacuole

113
Q

Purpose of cell wall in plants

A

Protection and structure of cell

114
Q

Purpose of large central vacuole

A

Storage organelle that stores water and other materials.

115
Q

What happens if the large central vacuole is full in plant cells?

A

Gives turgidity/shape to the cell

116
Q

Plant organelle that not all have

A

Amyloplast

117
Q

Amyloplast

A

Plant organelle (not all have) that stores starch granules inside cell

118
Q

Chloroplast

A

Organelle that has flattened membrane discs (thylakoids) to absorb sunlight for photosynthesis to make glucose.

Has inner and outermembrane, as well as own DNA and ribosomes

119
Q

Specialised cells

A

Cells that change structure to carry out a specific function within a multicellular organism

120
Q

Cell differentiation

A

Process by which a stem cell turns off unneeded genes and expresses only ones relevant to its function in order to become specialised

121
Q

Characteristics of animal cells that make them unique from other eukaryotes

A

No cell wall, centrioles that form the centrosome, store carbohydrates in specialised cells, small and numerous vacuoles, may have flagella

122
Q

Characteristics of plant cells that make them unique from other eukaryotes

A

Fixed cell wall shape, chloroplasts for photosynthesis, large central vacuole for storage, no flagella/cili, no centrioles

123
Q

Characteristics of funal cells that make them unique from other eukaryotes

A

Protective and flexible cell wall, no chloroplasts, store carfbohydrates, no centrioles, occasionally have cilia

124
Q

What allows for cells to differentiate in multicellular organisms?

A

Only some genes are expressed/used

125
Q

Do animal cells have plastids?

A

No

126
Q

Do animal cells have a cell wall?

A

No, which makes them flexible and round

127
Q

Do animal cells have vacuoles?

A

Yes. Small and many - can have different functions

128
Q

DO animal cells have centrioles?

A

Yes. They grow microtubules for mitosis

129
Q

Cilia

A

Small, hair-like structures present on the surface of some animal cells. Used for trapped dust, pathogens and food

130
Q

Do animal cells have cilia?

A

Lots do

131
Q

Do animal cells have flagella?

A

Some have a flagella

132
Q

Do plant cells have plastids?

A

Yes (chloroplasts and amyloplasts)

133
Q

Do plant cells have a cell wall?

A

Yes, made of cellulose, which creates a fixed and angular shape

134
Q

Do plant cells have vacuoles?

A

Yes, one large central vacuoles that stores all components

135
Q

Do plant cells have centrioles?

A

No. They do have a centrosome region that grows microtubules

136
Q

Do plant cells have cilia/flagella?

A

Rarely have either, as they make their own food source

137
Q

Do fungal cells have plastids

A

No

138
Q

Do fungal cells have a cell wall?

A

Yes made of chitin, which makes the fungal cells protective anf flexible

139
Q

Do fungal cells have vacuoles?

A

Depends on fungal species, but either like animal (small and many) or plant (one central)

140
Q

Do fungal cells have centrioles?

A

No, but they do have a centrosome region that grows microtubules

141
Q

Do fungal cells have cilia/pili?

A

Rarely have either

142
Q

Examples of atypical cells that break the ‘one nucleus per cell’ rule

A

Fungal hyphae
Phloem sieve tube element
Skeletal muscle cells
Red blood cells

143
Q

SIgn that a cell is specialised

A

Lack certain crucial organelles

144
Q

Fungal hyphae (atypical cell example)

A

Long one-cell-wide filaments with many nuclei, due to a loss of membrane between cells.

Produced by fungi, usually expand underground and play a role in cell absorption

145
Q

Phloem sieve tube elements (atypical cell example)

A

Cells that form thin tubes to transport sugars in plants.
Lost all organelles, so have companion cells with a nucleus and mitochondria. These companion cells meet the needs of the sieve cells as well as their own

146
Q

Skeletal muscle cells (atypical cell example)

A

Long tubular cells that can contract and relax with multiple nuclei. Have internal and external mitochondria / additional mitochondria

Fibres of long thin cells = best for contractions

147
Q

How are skeletal muscle cells adapted for contraction?

A

Fibres of long thin cells = best for contractions

148
Q

Red blood cells (atypical cell example)

A

No nucleus in order to reduce volume and thus, increase SA:V to allow more haemoglobin to be at the surface to carry more O2.
This is also seen with the biconcave shape

149
Q

Are red blood cells considered to be cells?

A

No, as they lack the criteria

150
Q

Endosymbiotic theory

A

Theory that an early eukaryotic ancestor engulfed a prokaryotic cell, which remained functional due to no enzymes to digest. The prokaryote functions inside the eukaryote, producing energy for the eukaryote to use. This makes this particular eukaryote the fittest of all cells. Overtime, due to natural selection, eukaryotes with this adaptation became the norm. The prokaryote became mitochondria first, and then later some cells gained a chlorplast through a similar process

151
Q

Evidence for endosymbiotic theory

A

Both mitochondria and chloroplasts have:

Own 70s (prokaryote size) ribosomes -> not from parent cell

Double membrane -> outer one from host (gained when entering cell)

Own DNA. Circular like that of prokaryotes

Same size as prokaryotes

Self-replicate separate to cell

i.e. behave like a prokaryote

152
Q

How do multicellular organisms develop specialised cells?

A

Gene expression (i.e. turning genes on)

153
Q

Virus

A

Non-living particle that infects cells and reproduces inside of them

154
Q

Capsid

A

Simple protein that contains the genetic material of a virus.

155
Q

Prophage

A

The combined nucleic acid of the viral DNA and host DNA

156
Q

Outbreak v.s. epidemic v.s. pandemic

A

Outbreak = spread of infection isolated to a small geographic area

Epidemic = moves more quickly than expected and to more areas

Pandemic: epidemic crosses countries

157
Q

In what forms can genetic material of viruses exist?

A

DNA
RNA
RNA transcribed to mRNA
RNA reversed transcribed to DNA

158
Q

Features common to all viruses

A

Protein spikes
Nucleic acid
Protein capsid

159
Q

Are viruses living?

A

No

160
Q

Role of protein spikes in viruses

A

These protein spikes are a form of ID recognised by the host, allowing the virus to invade the host cell

161
Q

What is a common feature of viruses (many not all)?

A

An envelope that surrounds the protein capsid. This envelope is a phospholipid bilayer and is the host cell’s membrane

162
Q

Types of nucleic acid within viruses

A

DNA: either double or single stranded

RNA: either double or singl estranded

163
Q

Host cell of bacteriophage lambda

A

E. Coli bacteria

164
Q

Nucleic acid of bacteriophage lambda

A

Double stranded DNA

165
Q

Structure of bacteriophage lambda

A

Has capsid and DNA, tail sheath, base plate with protein spikes and tail fibres

166
Q

Life cycle of bacteriophage lambda

A

Can follow either lytic or lysogenic life cycle

167
Q

Host cells of Coronavirus

A

Human respiratory cells

168
Q

Nucleic acid of coronavirus

A

Single stranded RNA

169
Q

Structure of coronavirus

A

Spherical shape, single stranded RNA as genetic material, envelope and capsid attached closely to RNA, spike proteins on the envelope.

170
Q

What is Coronavirus an example of?

A

Zoonosis (transferred between species)

171
Q

Host cell of Human Immunodeficiency Virus (HIV)

A

Human Helper T Cells (WBCs)

172
Q

Nucleic acid of Human Immunodeficiency Virus

A

Two identical RNA strands that convert into DNAS

173
Q

Structure of HIV

A

Two identical strands of RNA (that are copied into DNA) and the reverse transcripase enzyme within a capsid coat; outer envelope; glycoprotein spikes

174
Q

Extra information about Human Immunodeficiency Virus

A

Is a retrovirus. If untreated, causes AIDS (acquired immunodeficiency syndrome)

175
Q

Lytic cycle steps

A

Step one: attachment (virus attaches to host cell)
Step two: DNA penetration (virus inserts DNA into host cell)
Step three: DNA replication
Step four: transcription (DNA is transcribed to become mRNA)
Step five: translation of viral parts
Step six: assembly and lysis (viral parts assemble into viruses, placing pressure on the cell, which forces it to lyse and release virus)

176
Q

How quickly will symptoms occur if a virus works in the lytic cycle?

A

Quickly

177
Q

How is the lysogenic crycle different to the lytic cycle?

A

Involves integration of viral DNA into the host DNA without being used to make viral parts. Slowly spreads as the cell reproduces. If viral DNA is released from the prophage, the lytic cycle is initiated

178
Q

Steps of lysogenic life cycle

A

Step one: attachment (virus attaches to host cell)
Step two: DNA penetration (virus releases DNA into the host cell)
Step three: integration (viral DNA combines with the hsot DNA to become a prophage)
Step four: cell division (mitosis or binary fission)

Could leave the prophage and enter the lytic cycle

Step five: DNA replication
Step six: transcription
Step seven: translation of viral parts
Step eight: assembly and lysis

179
Q

Why might viruses be an example of convergent evolution?

A

Wide variety in viral structure so are likely to have evolved separately and lack a common ancestor. This is seen through the diversity in genetic material

All similarities are a result of convergent evolution (e.g. spikes for attachment)

180
Q

Theories about where viruses come from

A

Viruses first hypothesis
Regressive hypothesis
Progress hypothesis

181
Q

Virus first hypothesis

A

Viruses existed before cells. Cells evolved from them

182
Q

Why is the virus first hypothesis weak?

A

Viruses have genetic diversity + primordial soup was the origin of cells

183
Q

Regressive hypothesis

A

Viruses were once cells that lost structure and function, becoming reliant on a host

184
Q

Progressive hypothesis

A

Cellular components escaped, evolving into a virus by gaining function

185
Q

Antigenic shift

A

Two or more different viruses invade the same cell and recombine genetic material, leading to dramatic changes in a short amount of time.

186
Q

Example of antigenic shift

A

Influenza

187
Q

What is the result of antigenic shift?

A

Rapid new virus formation, with new spikes that are not recognised by memory cells

188
Q

Antigenic Drift

A

Once a virus invades a host, mutations occur to the viral DNA within a host cell. These smaller genetic changes accumulate overtime, leading to a new virus that is no longer recognised.

189
Q

Example of antigenic drift

A

HIV

190
Q

Why did the influenza virus evolve so rapidly?

A

Antigenic shift

191
Q

What contributes to the rapid evolution rate of HIV?

A

Antigenic drift

IB Biology (10 decks)

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