ILOs Flashcards

Question

explain briefly the key steps in amino acid catabolism

Answer 1

after removal of the ⍺-amino group the remaining carbon skeletons are converted into major metabolic intermediates and can then be converted to glucose or oxidised in the TCA cycle 1. deamination 2. conversion to metabolic intermediates 3. urea cycle

Answer 2

fat is used as an energy source, for essential fatty acids, and for fat soluble vitamins.

Answer 3

1. lipolysis - breakdown of lipids. initial cleavage by hormone sensitive lipases which release free fatty acids and glycerol 2. fatty acid oxidation - fatty acids are converted to coA derivatives (acyl CoA) 3. beta oxidation - acyl-carnitine to acyl coA and acetyl coA which will enter the TCA cycle lipogenesis - fatty acid synthesis. carbohydrates are converted to fatty acids and triglycerides in the liver, triglycerides formed in the liver are transported to adipose tissue by VLDL for storage

Answer 4

post prandial: after food ongoing digestion most abundant energy sources blood glucose levels rise directly due to food source post absortive: after digestion is complete 3-5 hour after meal - typically overnight blood glucose maintained by liver glycogen fasted state: a prolonged period of fasting > 12 hours glycogen depleted utilisation of gluconeogenesis

Answer 5

1. The immune system defends the body against harmful invaders like bacteria, viruses, and other pathogens. It has two main components: innate immunity (the body's first line of defense) and adaptive immunity (which provides a more specific and lasting defense). 2. a. Intrinsic epithelial barriers to infection: These include physical and chemical barriers such as the skin, mucous membranes, and secretions (like saliva, tears, and stomach acid) that help prevent pathogens from entering the body. b. Primary lymphoid tissues: These are where immune cells are created and mature. They include the bone marrow (where blood cells are produced) and the thymus (where T-cells mature). c. The lymphatic system: A network of vessels and organs that transport lymph (a fluid containing white blood cells) and helps in the removal of waste and pathogens from the body. It includes lymph nodes, spleen, and tonsils. d. Secondary lymphoid tissues: These are where immune responses are initiated and include structures like lymph nodes, spleen, tonsils, and mucosal-associated lymphoid tissues (MALT). They filter lymph and trap pathogens. 3. a. Innate immune system: The first line of defense against infections. It includes physical barriers (e.g., skin), immune cells (e.g., macrophages, neutrophils), and molecules (e.g., cytokines) that act immediately after infection. b. Adaptive immune system: Provides a more specific and long-lasting defense. It involves T-cells (which help control immune responses) and B-cells (which produce antibodies to neutralize pathogens). 4. a. Antigens and antibodies: Antigens are molecules found on pathogens (or abnormal cells) that trigger an immune response. Antibodies are proteins produced by B-cells that recognize and bind to specific antigens to neutralize or mark them for destruction. b. Complement system proteins: A group of proteins that work with antibodies to help destroy pathogens by promoting inflammation, enhancing phagocytosis, and directly attacking pathogens. c. Cytokines: Small proteins that are crucial in cell signaling during immune responses. They help regulate immune cell functions like activation, growth, and differentiation. 5. a.Recognition of the Pathogen: The immune system identifies pathogens (like bacteria, viruses, fungi, and parasites) using pattern recognition receptors (PRRs) that detect common molecular structures on pathogens, known as pathogen-associated molecular patterns (PAMPs). b.Innate Immune Response: i. First line of defense: This includes physical barriers (like skin and mucous membranes) and cellular components (like macrophages, neutrophils, and dendritic cells). ii. Inflammation: When a pathogen is detected, immune cells release cytokines to recruit other immune cells to the site of infection, causing redness, swelling, heat, and pain. iii. Phagocytosis: Cells like macrophages and neutrophils engulf and digest the pathogen. iv. Complement system: Activated by antibodies or pathogen surfaces to promote inflammation, phagocytosis, and direct destruction of the pathogen. c. Adaptive Immune Response: i. T-cell activation: Dendritic cells present antigens to T-cells in lymph nodes, activating them. Helper T-cells (TH cells) coordinate the immune response, while cytotoxic T-cells (CTLs) destroy infected cells. ii. B-cell activation: When B-cells encounter their specific antigen, they differentiate into plasma cells that produce antibodies. These antibodies bind to pathogens, neutralizing them and marking them for destruction by other immune cells. iii. Memory: After the pathogen is cleared, memory T-cells and memory B-cells are formed. These cells “remember” the pathogen and can mount a faster and stronger response if the pathogen is encountered again.

Answer 6

the immune system protects from pathogens and abnormal cells is a complex network of specialised cells, tissues and soluble factors that cooperate to kill and eliminate microorgansims and cancerous cells - by distinguishing self molecules from non-self molecules, or by identifying danger signals from acute inflammation immune overreaction - reaction to self (autoimmunity), reaction to innocuous substances (allergies), rejection of donor tissues (transplantation) immune underreaction - recurrent infections, cancer. the immune system protects against pathogens and abnormal cells. Malfunctioning immune responses can cause allergies, autoimmune diseases, and transplant rejection.

Answer 7

These are the body’s first line of defense (e.g., skin, mucous membranes, stomach acid) against pathogens.

Answer 8

Innate Immunity: Quick, general defense; non-specific; includes barriers, macrophages, mast cells, etc. Adaptive Immunity: Slower, specific response; includes T-cells and B-cells that recognize specific antigens and form memory.

Answer 9

Pathogen-associated molecular patterns (PAMPs) on pathogens are recognized by pattern recognition receptors (PRRs) like TLRs (Toll-like receptors)

Answer 10

Macrophages, mast cells, NK cells, neutrophils: a. Recognize pathogens via PRRs or antibodies. b. Kill pathogens through phagocytosis or cytotoxicity (e.g., NK cells killing infected cells).

Answer 11

Triggers systemic immune responses to fight pathogens. a. Acute phase response: Activation of proteins like CRP to mark pathogens. b. Complement system: Proteins that help destroy pathogens. c. Dendritic cell activation: Helps bridge innate and adaptive immunity.

Answer 12

Dendritic cells process and present antigens to T-cells, bridging innate and adaptive immunity.

Answer 13

Innate: Non-specific, fast, no memory. Adaptive: Specific, slower, forms memory, and has a diverse range of responses.

Answer 14

T-cells recognize MHC-presented antigens. B-cells recognize free-floating antigens (or those attached to pathogens).

Answer 15

Upon recognizing their specific antigen, lymphocytes (T/B-cells) proliferate and differentiate into effector cells.

Answer 16

MHC I presents intracellular antigens to CD8+ T-cells. MHC II presents extracellular antigens to CD4+ T-cells.

Answer 17

T-cells use their T-cell receptors (TCRs) to recognise antigens presented by MHC molecules on other cells.

Answer 18

T-cells become activated and differentiate into effector cells, cytotoxic T-cells or helper T-cells

Answer 19

CD4+ T-cells become helper T-cells, aiding other immune cells. CD8+ T-cells become cytotoxic T-cells, killing infected or cancerous cells.

Answer 20

In lymphoid tissues, B-cells recognise antigens directly and, with the help of helper T-cells, become activated and proliferate.

Answer 21

These are the areas in lymphoid tissues where B-cells undergo mutation and selection, leading to high-affinity antibodies.

Answer 22

Class switching: B-cells can change the type of antibody they produce (e.g., from IgM to IgG, IgA, or IgE) without changing their specificity for the antigen. Affinity maturation: B-cells undergo mutations to increase the affinity of their antibodies for the antigen, improving their effectiveness.

Answer 23

Plasma cells: Secrete large quantities of antibodies to fight current infections. Memory B cells: Remain in the body for years, ready to respond faster if the same antigen is encountered again.

Answer 24

B-cells have receptors (BCRs) that bind directly to antigens, typically from pathogens, leading to activation.

Answer 25

Helper T-cells (specifically TH2 cells) activate B-cells by providing co-stimulatory signals and cytokines, promoting their differentiation into plasma cells.

Answer 26

Structure: Antibodies are Y-shaped proteins with a variable region (that binds to antigens) and a constant region (that interacts with immune cells). Functions: Antibodies neutralize pathogens, opsonise them for phagocytosis, and activate the complement system.

Answer 27

B-cells undergo somatic hypermutation in germinal centers, where they generate a diverse range of antibodies and select the ones with the highest affinity for the antigen

Answer 28

Antigens bind to receptors on lymphocytes, initiating activation. Co-stimulatory molecules (like CD80/86 on antigen-presenting cells) are required for full lymphocyte activation, ensuring an appropriate immune response.

Answer 29

a. Cell cycle entry & clonal expansion: Lymphocytes proliferate to generate a large number of identical cells for a stronger immune response. b. Metabolic adaptation: Lymphocytes adjust their metabolism to support increased activity and energy needs. c. Differentiation into effector cells: Lymphocytes differentiate into specific effector cells to combat the pathogen (e.g., cytotoxic T-cells, plasma cells).

Answer 30

a) Cytotoxic T-cells (CTLs): Kill infected cells by inducing apoptosis. b) T helper 1 cells (TH1): Activate macrophages and promote inflammation, helping to fight intracellular pathogens. c) T helper 2 cells (TH2): Help B-cells produce antibodies and assist in the defense against parasites and allergens. d) T follicular helper cells (TFH): Provide help to B-cells in germinal centers, promoting antibody production. e) Plasma cells: Secrete large amounts of antibodies to neutralize pathogens.

Answer 31

a) maize (corn), rice, wheat, potatoes b) 45% of habitable land is used for agriculture

Answer 32

a) wild cereal is cultivated and domesticated into landraces where selective breeding occurs to form modern cereal. b) domestication of cereals selected for developmental traits that increase growth yield; loss of shattering, loss of grain dispersal aids, increase in grain size, loss of sensitivity to environmental cues for germination and flowering, synchronus tillering and ripening, compact growth habitat, enhanced cullinary chemistry. c) the rice gene qSH1 controls abscission zone formation at the base of rice flower. single nucleotide polymorphism (SNP) in 5' regulatory region of a single transcription factor was responsible for nonshattering rice two maize genes that both encode a transcription factor > teostine glume architecture promotes development of tough case around kernel, and teostine branched 1 suppresses branching to promote single stalk.

Answer 33

a) ?? b) green revolution and intense farming practices pushed yields higher c) green revolution varieties had defective gibberellin hormone biosynthesis or perceptrion

Answer 34

a) flooding b) flood tolerance/submergence tolerance c) sub1a transgene d) ethylene signalling pathway to inhibit gibberellin response e) involved selecting for DNA markers as it is faster than waiting for phenotypic expression

Answer 35

cell wall - provides structure to the pland cell and bonds with other cell walls to form the structure of the plant plasmodesmata - traverse the cell walls of plant cells, enabling transport and communication between plant cells, regulated by callose deposition in the cell wall. xylem - transports water and mineral salts from the roots up to other parts of the plant phloem - transports sucrose and amino acids between the leaves and other parts of the plant

Answer 36

symplastic transport - uses plasmodesmata that interconnect the cytoplasms of neighbouring cells apoplastic transport - involves passive diffusion of molecules in the extracellular space and the cell wall transcellular transport - combines apoplastic transport with a secretion, and, endocytosis-based or channel and carrier-based transport pathway to cross plasma membrane. the ROS wave glutamate

Answer 37

PRRs: PRRs are found on the cell surface and recognize PAMPs (Pathogen-Associated Molecular Patterns)—molecules that are conserved across many microbes but absent in the host. PRRs trigger PAMP-Triggered Immunity (PTI), which strengthens the plant’s defenses and prevents infection 1. PRRs recognize PAMPs → Activate receptor-like kinases (RLKs). 2. ROS (Reactive Oxygen Species) production → Helps kill microbes. 3. MAPK (Mitogen-Activated Protein Kinase) activation → Turns on defense genes. 4. Callose deposition → Strengthens the cell wall to block pathogen entry. 5. Defense-related gene expression → Produces antimicrobial compounds. NLRs: NLRs are intracellular receptors that recognize pathogen-secreted effector proteins. These effectors help pathogens suppress PRR-mediated immunity, but NLRs detect their presence and trigger a stronger immune response called Effector-Triggered Immunity (ETI). ETI often leads to programmed cell death (Hypersensitive Response, HR), which stops pathogen spread 1. NLRs recognize effector proteins inside the host cell. 2. Triggers a hypersensitive response (HR) → Infected cells undergo programmed cell death to stop pathogen spread. 3. Activates salicylic acid (SA)-dependent signaling, reinforcing systemic immunity.

Answer 38

the activation of enhanced plant defenses, which include cell wall strengthening, antimicrobial compound production, and programmed cell death to prevent pathogen spread. Plants feature a multilayer defence system. * Recognition of conserved pathogen molecules (MAMPs/PAMPs) by specific receptors (PRRs) triggers signalling cascades and defences. * Defence signalling involved production of ROS, ion fluxes, MAPK signalling cascades and leads to changes in gene expression. * Recognition of MAMPs evolved independently in plants and mammals. * Pathogens deliver molecules, called effectors, inside their host to interfere with plant defences. * Plants can recognize these effectors using another class of receptors called NLRs. * Similar immune receptors, with a unique conserved structure, evolved independently in mammals.

Answer 39

Both plants and animals have innate immunity with similar defense mechanisms such as PRRs, PAMP detection, ROS production, and cell death. Plants rely entirely on their innate immune system, while animals have both innate and adaptive immunity. Plants use structural barriers and chemical defenses, whereas animals use mobile immune cells and systemic responses.

Answer 40

physical barriers to infection skin - keratin, sebum (oil) langerhans cells can phagocytose microbes and form part of the skin-associated lymphoid tissue mucous membranes - trap and destroy pathogens. mucous layers slough off, removing pathogens. cilia remove microbes from the lungs. gut-associated lymphoid tissue - tonsils, adenoids and peyers' patch, specialised M cells. chemical barriers to infection: defensins - cationic peptides that destroy the cytoplasmic membrane of microbes.

Answer 41

1. the microorganism must be found in abundance in all organsims suffering from the disease but should not be found in healthy animals 2. the microorganism must be isolated from a diseased organism and grown in pure culture 3. the cultured microorganism should cause disease when introduced into a healthy organism 4. the microorganism must be re-isolated from the innoculated, diseased, experimental host and identified as being identical to the original microorganism.

Answer 42

ingestion - flagella propel pathogen to mucosa urease production - converts urea to carbon dioxide and ammonia to reduce acidity in the local area enzyme production - to soften the mucous lining allowing access to epithelial layer the lower level of acidity allows growth and division of bacterium, causing inflammation and damage to the stomach lining.

Answer 43

chlamydia syphilis pseudomembranous colitis clostridioides difficile

Answer 44

microorganisms that are unable to be cultured on artificial media when two or more organisms work insynergy to cause a disease symptoms or diseases that can be caused by several microbes ethical exceptions (i.e. cannot perform the experiments) highly contagious, virulent, or dangerous strains infection can be asymptomatic

Answer 45

molecular methods utilising SSU rRNA three distinct domains of life - archaea, bacteria, eukarya well conserved genes - 16S rRNA, 23S rRNA, ITS region, gyrB taxonomy > domain - kingdom - phylum - class - order - family - genus - species

Answer 46

the combined genetic material of the microorganisms in a particular environment the microorganisms in a particular environment.

Answer 47

amplicon sequencing of the 16S rRNA gene for bacteria or the ITS for fungi microbial potential < metabolic potential < microbial function cells < DNA < RNA < protein < metabolite alpha diversity - a measure of how diverse a sample is based on, how many species there are, and how abundant each species is within a sampled environment beta diversity - a measure of how different- or similar - two samples are to each other

Answer 48

viruses are not alive, they are obligate intracellular parasites that infect all forms of life

Answer 49

simple forms of virions - naked icosahedral capsid, enveloped icosahedral, naked helical nucleocapsid, enveloped helical nucleocapsid 1. type of nucleic acid - RNA or DNA 2. strandedness - single or double stranded 3. linear or circular 4. sense - positive or negative 5. number of segments 6. nucleotide sequence DNA molecules - linear single stranded, circular single stranded, linear duplex, duplex with closed ends, closed circular duplexes. RNA molecules - linear,single stranded infectious "positive" strand, linear,single stranded non-infectious "negative" strand, segmented positive strands, segmented negative strands, double stranded segment, diploid single strands

Answer 50

RNA molecules - linear,single stranded infectious "positive" strand, linear,single stranded non-infectious "negative" strand, segmented positive strands, segmented negative strands, double stranded segment, diploid single strands

Answer 51

mild pharyngitis fever is the primary infection, following this the virus transit up the peripheral nerve where it is latent following activation and subsequent recurrence a cold sore occurs.

Answer 52

primary infection is chickenpox following recurrence, shingles occurs

Answer 53

a vaccine is a biological preparation that improves immunity to a particular disease. a vaccine typically contains a small amount of an agent that resembles a microorganism. the agent stimulates the bodys immune system to recognise the agent as foreign, destroy it, and 'remember' it, so that the immune system can more easily recognise and destroy any of these microorganisms that it later encounters neuraminidase inhibitor - inhibits virion release and therefore halts viral replication oseltamivir - slows the spread of influenza virus between cells by stopping the virus from chemically cutting ties with its host cell zanamivir - binds to the active site of neuraminidase rendering the influenza virus unable to escape its host cell and infect others

Answer 54

respiratory or saliva spread airborne droplets direct contact surface contamination

Answer 55

The influenza virion consists of an envelope containing glycoproteins (hemagglutinin and neuraminidase), a matrix protein, a nucleocapsid with RNA segments and associated proteins, and a polymerase complex

Answer 56

The influenza virion is an enveloped virus, meaning it has a lipid bilayer membrane that surrounds the viral particle. This membrane is host-derived because the virus takes a portion of the host cell’s membrane during the process of budding out of the infected cell. The lipid bilayer serves as a protective barrier, helping the virus evade the host’s immune system and facilitating the fusion of the virus with host cell membranes during infection. Hemagglutinin (HA): This is a spike-like protein that is responsible for the virus's ability to bind to and enter host cells. HA recognizes and binds to sialic acid receptors on the surface of host cells, facilitating viral entry. Neuraminidase (NA): This is another spike-like protein involved in the release of new viral particles. NA cleaves sialic acid residues from glycoproteins on the host cell surface and from viral particles themselves, preventing clumping and allowing the virus to spread to other cells.

Answer 57

hemmagglutinin neuraminidase

Answer 58

influenza has a segmented, negative sense, RNA genome

Answer 59

antigenic drift - existing antigens are subtly altered. causes slight flu mutations year on year, from which humans have partial, but not complete immunity. antigenic shift - two or more strains combine.

Answer 60

Swine serve as "mixing vessels" for the genes of avian, porcine and human forms of the influenza virus. In the host pig, the avian and mammalian viruses can share (reassort) their genes and so create new strains of flu. Swine have probably played an important role in the history of human influenza epidemics.

Answer 61

zika ebola H1N1 influenza COVID 19

Answer 62

a) after a sneeze, large droplets of saliva and mucous shoot out of the mouth, but fall relatively quickly. a turbulent cloud carries smaller droplets and allows them to drift for up to 8 meters. b) incubation period - 2>14 days. infectious period - 1>2 days before symptoms appear and remain contagious for about 10 days c) emerged from a zoonotic spillover

Answer 63

oxford uni - astrazeneca = viral vector vaccine (genetically modified virus), 2 doses, stored at fridge temp pfizer - bioNtech = RNA vaccine (part of virus genetic code), 2 doses, stroed at -70ºC moderna - RNA vaccine, 2 doses, stored at -20ºC

Answer 64

PCR: detect viral RNA in a sample high sensitivity and reliable time-consuming and costly lateral flow test: detect antigens quick results and easy to use lower sensitivity and specificity RT-LAMP: detects viral RNA high sensitivity and rapid results limited availability

Answer 65

human angiotensin-converting enzyme 2 (ACE2) is the receptor for coronavirus Spike protein binds to ACE2 receptor on host cell. Virus enters the host cell via fusion or endocytosis. The viral RNA is released into the host cell, hijacking its machinery to produce more virus.

Answer 66

Coronaviruses form enveloped and spherical particles of 100-160nm in diameter. Contain a positive sense, single stranded RNA genome of 27-32 kb The 5’ terminal 2/3 of the genome encodes a polyprotein, pp1ab which is further cleaved into 16 non-structural proteins involved in genome replication and transcription The 3’ terminal 1/3 of the genome encodes structural proteins including envelope glycoprotein spike (S), envelope (E), membrane (M) and nucleocapsid (N) Spike protein binds to receptor on cell surface