You Got This 💜 Flashcards
Allergic Response
- Upon initial exposure to the allergen, complementary B cells are activated and plasma B cells will release IgE.
- IgE binds to mast cells to sensitise them.
- Upon re-exposure to the allergen, the allergen will bind and cross link to the IgE on sensitised mast cells. Triggers release of large amounts of histamine and causes symptoms of inflammation.
Inflammation
- Inflammation is initiated when damaged cells release cytokines to trigger nearby mast cells to release histamine.
- Histamine binds to blood vessels, resulting in vasodilation that increases blood flow (redness). Increased permeability makes the blood vessel and migrate to the blood vessels more leaky (swelling).
- Leukocytes can easily leave the blood vessels to the area of inflammation.
Cell-mediated Response
- Antigen presenting cells carrying a target antigen on their MHC II binds to a complementary naive T cell’s T cell receptor, triggering release of cytokines.
- The naive T cell is activated and undergoes clonal expansion and differentiation into helper T and Cytotoxic T cells.
- T helper cells will regulate the action of other immune cells whilst cytotoxic T cells will travel to the area of infection, bind to affected cells displaying the target antigen and will trigger the death of target cells via apoptosis or perforin or granzymes.
Attenuation (Trp High)
- Transcription + translation of the trp operon begin and occur simultaneously.
- When RNA polymerase reaches the attenuator in leader sequence it codes for 2 trp and causes terminator hairpin like structure in mRNA.
- This hairpin like structure causes pre-mature termination of transcription.
- RNA polymerase and mRNA detach from DNA and ribosome gets separated from mRNA.
- Non-functional protein is made.
Repression (Trp High)
- High amount of trp in cell
- Trp attaches to repressor protein to activate it.
- Activated repressor protein binds to operator region and prevents RNA polymerase from transcribing structural genes.
Antigen Presentation
- APCs present the antigen on MHCII marker to T helper cells.
- T helper cell receptor binds with antigen and become activated.
Humoral Response
ANTIGEN PRESENTATION (2 MARKS)
- APCs present the antigen on MHCII marker to T helper cells.
- T helper cell receptor binds with antigen and become activated.
HUMORAL (3 MARKS)
- T helper cells release cytokines to activate naive B cells which undergo clonal expansion and differentiation into plasma B cells and memory B cells.
- Plasma B cells release antibodies into the bloodstream to destroy the pathogen.
- Memory cells circulate in blood, to trigger strong + quick immune response upon reexposure to pathogen.
Bioethanol Production
- Biomass is made up of cellulose, broken down by heating, grinding and mashing.
- Broken down biomass is then exposed to enzymes which break down the cellulose and convert them into glucose and other sugars. This breaking down is aided by water (hydrolysis)
- Yeast is used to facilitate anaerobic fermentation of the sugars produced in step 2, ethanol and Co2 is produced.
- Ethanol is distilled via removal of water, making bioethanol. Bio ethanol is then purified and ready to be used as liquid fuel.
Light Dependent (Grana/Thylakoid Membrane)
Inputs:
- Light
- H20
- NADP+
- ADP +Pi
Outputs:
- NADPH
- O2
- ATP
Light Independent (Stroma)
Inputs:
- NADPH
- CO2
- ATP
Outputs:
- NADP+
- Glucose
- ADP +Pi
C4 Plants
Carbon Fixation(mesophyll)
- PEP carboxylase + CO2 = malate
Calvin Cycle (bundle sheath)
- Malate broken down into
pyruvate and CO2
- Pyruvate recycled back into PEP to
fix carbon again
- CO2 binds to Rubisco to produce
Glucose
E.g: Sorghum, sugarcane, maize
Aerobic Respiration
- Glycolysis (Cytosol):
Inputs:- Glucose
- NAD+
- ADP+Pi
Outputs:
- Pyruvate
- NADH
- 2 ATP
- Krebs Cycle (Matrix of mitochondria)
Inputs:- Pyruvate
- FAD+
- NAD+
- ADP+Pi
Outputs:
- CO2
- FADH2
- NADH
- 2 ATP
- Electron Transport Chain (Cristae of mitochondria)
Inputs:- O2
- FADH2
- NADH
- ADP+Pi
Outputs:
- H2O
- NAD+
- FAD+
- 26 or 28 ATP
Anaerobic Fermentation (Humans)
- Glycolysis (cytosol):
Inputs:
- Glucose
- NAD+
- ADP +PiOutputs:
- Pyruvate
- 2 ATP - Lactic Acid Fermentation (cytosol)
Inputs:
- Pyruvate
- NADHOutputs:
- Lactic Acid
- NAD+
Fossilisation (Example)
- Dinosaur dies in a river
- The body is covered with sediment. The soft tissues decompose and the hard body structures become fossilised by permineralisation.
- The sedimentary layers accumulate and the resultant pressure forms sedimentary rock.
- The earth’s movements raise the layers of the rocks to the surface.
- The rock erodes, exposing the fossilised body structures.
Natural Selection
- Variation: Individuals in a population vary genetically, which leads to phenotypic differences.
- Selection Pressure: An environmental selection pressure impacts the survivability of organisms within a population and their ability to reproduce.
- Selective Advantage: Individuals with phenotypes that are more advantageous against selection pressure confer a selective advantage, allowing them to survive and reproduce more successfully.
- Heritability: The advantageous trait must be heritable, allowing it to be passed on from the parents to the offspring.
PCR
- Denaturation: DNA is heated to approx 94°C to break the hydrogen bonds and separate the strands, forming single-stranded DNA.
- Annealing: The single-stranded DNA is cooled to approx 55°C to allow the primers to bind to complementary sequences on the single-stranded DNA.
- Elongation: The DNA is heated back to 72°C allowing Taq Polymerase to work optimally. It binds to the primer, which acts as a starting region, and begins synthesising a new complementary strand of DNA.
- Repeat: The cycle (steps 1-3) is repeated multiple times to create more copies of DNA.
Phagocytosis - 2nd Line of Defence
- Pathogen enter via plasma membrane
- Vesicle contains pathogen
- Lysosome fuses with vesicle and then releases lysozyme
- Lysozyme breaks pathogen into fragments
- Fragments presented on MHCII marker
Insulin Production
- Identify gene of interest coding for Human Insulin
- Same restriction enzyme cut plasmid and gene of interest (Insulin A subunit gene and Insulin B subunit gene)
- DNA ligase for inserting Insulin A subunit gene and Insulin B subunit gene into plasmids
- Antibiotic resistance gene (Amp R and tet R) added to each plasmid.
- Recombinant plasmids inserted into bacteria using heat shock or electroporation to make the bacterial cell membrane permeable to plasmid.
- Bacteria placed on 1 plate with Ampicillin and agar and another plate with tetracycline and agar.
- Surviving bacteria = transformed containing both gene of interest and antibiotic resistant gene.
Bacteria CRISPR
- After the injection of viral DNA, bacteria cuts the viral DNA segment with the help of CAS 1 and CAS 2 enzyme.
- Viral DNA (protospacer) is inserted into bacterial DNA as “spacer” between repeats (BECOMES CRISPR)
- Spacer is transcribed into gRNA, and gRNA combines with Cas9 to from CRISPR CAS-9 Complex
- Cas9 binds with PAM sequence and gRNA guides Cas9 to make the cut in viral DNA.
Artificial CRISPR
- Target gene was identified by scientists and the sgRNA was synthesised complementary to target gene.
- sgRNA combines with Cas9 protein to form the CRISPR-Cas9 complex.
- The CRISPR-Cas9 complex is injected into (organism), Cas 9 finds PAM sequence and sgRNA guides Cas9 to make the cut in the target gene on the (organism).
- DNA undergoes repairing/ Target gene knocked out or in
Transcription (Nucleus)
- RNA polymerase + transcription factor unzips the DNA.
- RNA polymerase binds to the promotor region of the template strand. RNA polymerase starts making complementary sequence of DNA template strand.
- RNA polymerase moves along from 3’ to 5’ direction of template strand and make pre-mRNA having 5’ to 3’ which is antiparallel of template strand of DNA.
- Termination occurs when termination sequence is reached. premRNA is made and detached from template strand.
Mammal Characteristics
- Fur or hair over their body surface
- Milk-producing mammary glands
- 3 bones in the middle ear
- Warm blooded
Primates Characteristics
- Opposable thumbs
- A long gestational period
- Binocular vision
- Large brains relative to their body
Hominoids Characteristics
- Larger and more complex brains
- Y5 molars
- Relatively long upper limbs
- Shoulder joints that permit the arms to be rotated
Hominin vs Hominoid
Hominin
- S shaped spine
- Barrel shaped ribcage
- Angled femur
- No prehensile feet
- Smaller brow ridge
Hominoid
- Larger brow ridge
- C shaped spine
- Funnel shaped ribcage
- Prehensile hands + feet with opposable thumbs
- Vertically long and narrow pelvis
Functions of Antibody
Neutralisation: Blocks the action of toxins, prevents pathogen from entering a host cell.
Agglutination: Clumping of pathogens together through the cross-linking of antibodies joining with the surface antigens on the pathogen (Enhances phagocytosis)
Inflammation: Triggers histamine release, increasing immune mobility
Functions of Complement Proteins
Opsonisation: Sticks to invading pathogens to tag foreign pathogens for elimination by phagocytes.
Chemotaxis: Attracts phagocytes to site of infection
Lysis: Creates holes in the membranes of invading micro-organism.s
Lymphatic System
Primary Lymphoid Organs
Function:
- Bone Marrow: Formation of T and B lymphocytes and site of maturation of B lymphocytes
- Thymus: site of maturation of T lymphocytes
Secondary Lymphoid Organs
Includes:
- Spleen: controls the level of white
and red blood cells and platelets.
- Lymph Nodes: filter substances
that travel through the lymphatic
fluid and they contain lymphocytes
(white blood cells) that help fight
infection and disease in the body.
Located along lymph vessels, site of
presentation of antigens to B cells
and T cells.
Function:
- Mature B and T cells are activated
once exposed to complementary
antigens so they become effector
cells: adaptive immune response.
Homologous Structure (Divergent Evolution)
Structures that have been derived from a common ancestor and thus show similarities in structure, even though they may have different functions.
E.g: upper limb of humans, cats, whales and bats
Vestigial Structure
Structures that are non-functional remnants of structure that were functional in ancestral species.
E.g Human tailbone
Analogous Structure (Convergent Evolution)
Features present in 2 or more species that fulfil the same function but do not originate from a common ancestor.
E.g: Wings of birds and insects
Endemic
Diseases which are consistently present in a population or region at relatively stable levels over time.
E.g Malaria
Epidemic
Diseases which occur when there is a sudden increase in the number of cases of a disease in a specific area or population, exceeding what is normally expected.
E.g Measles
Pandemic
A pandemic is when a new disease or new strain of an existing disease spreads worldwide.
E.g COVID-19
Genetic Drift
Changes to a populations allele frequencies due to sudden and random chance events.
Gene Flow
The movement of alleles between individuals from 2 different populations through either migration or interbreeding.
Allopatric Speciation (Finches)
- A geographical barrier separates a population, preventing gene flow.
- Different selection pressures act upon each population, favouring different phenotypes and allowing for genetic differences to accumulate.
- Eventually, sufficient mutation and genetic differences accumulate so that the 2 populations can no longer interbreed to produce viable and fertile offspring.
Sympatric Speciation (Howea Palms)
Occurs within populations sharing the same geographical location, where different selection pressures act on different phenotypes within a population, causing individuals with certain phenotypes to diverge from others and form a new species.
E.g: Different flowering times
Bottleneck Effect
The reduction in genetic diversity which occurs when a large proportion of a population is removed due to a chance event
Founder Effect
Occurs when a small unrepresentative sample of individuals separates from a larger population to colonise a new region and start a new population
Antigenic Drift
Small gradual changes in genes encoding for viral surface antigens, overtime leading to slight variations in virus.
Antigenic Shift
Sudden and significant changes in genes encoding for viral surface antigens, forming a new subtype of virus.
Universal
All living organisms use the same nucleotides in their DNA
Degenerate
Multiple codons can code for the same amino acid
Genome
The complete set of DNA in an organism
Proteome
The complete set of proteins expressed by an organism
Golgi Apparatus
Modifies proteins and packages into secretory vesicles for export (exocytosis)
Rough Endoplasmic Reticulum
Folds proteins and packages into transport vesicles to be transported to the Golgi
Protein Secretory Pathway
Nucleus - Ribosome - Rough ER - Transport vesicle - Golgi - Secretory vesicle (fuses with plasma membrane) - Extracellular space
Post- Transcriptional Modification
- Introns are removed
- Alternative Splicing of exons to create different amino acid sequences/proteins from same strand.
- Methylated G cap added to the 5’ end of mRNA.
- Poly-A tail added to the 3’ end of mRNA.
Translation (Ribosome)
- The mRNA strand goes to the ribosome and is read by it from 5’ to 3’ direction. The ribosome will read the mRNA in codons, initiating polypeptide synthesis when it encounters a start codon.
- As the ribosome reads codons in the mRNA, tRNA with complementary anticodons to the mRNA codon will bring the correct amino acids to the ribosome.
- The ribosome will join together amino acids into a polypeptide chain until a stop codon is read. Termination occurs and translation stops.
Structure of Amino Acid
H H O
\ | //
N— C —- C
/ | \
H R OH
Convergent Evolution
2 or more distinctly related species (without a recent common ancestor) can be seen to have independently evolved similar traits to adapts to similar environments and selection pressures.
Divergent Evolution
2 or more populations of a single species accumulate enough genetic differences to be classified a different species.
Interferon
- A type of cytokine released by an infected host cell that defends against further viral infections.
- Aids in inhibiting the ability of a virus to synthesise new viral proteins within a host cell.
- Attracts NK cells to assist in killing virus-infected host cells
Vaccination Response
- The first vaccination/ infection generates a primary immune response.
- The response creates a moderate level of antibodies and memory cells. The number of these antibodies and memory cells, however dwindles over time.
- As part of a vaccine program, a person may receive a second vaccination a few months after their first one.
- This second vaccination triggers the memory cells created by the first vaccine resulting in a secondary immune response. This response occurs extremely quickly and a large amount of antibodies + memory cells are created rapidly.
Anaerobic Fermentation (Yeast/Plants)
- Glycolysis (cytosol):
Inputs:
- Glucose
- NAD+
- ADP +PiOutputs:
- Pyruvate
- 2 ATP - Ethanol Fermentation (cytosol)
Inputs:
- Pyruvate
- NADHOutputs:
- Ethanol
- NAD+
CAM Plants
Carbon Fixation(mesophyll) - Night stomata open
- PEP carboxylase + CO2 = malate
Calvin Cycle (mesophyll) - Day stomata closed
- Malate broken down into
pyruvate and CO2
- Pyruvate recycled back into PEP to
fix carbon again
- CO2 binds to Rubisco to produce
Glucose
E.g: Cactus, Agave
C3 Plants
CO2 Binds to Rubisco
E.g: Soybean, rice
Cytokine
- A signalling molecule of the immune system.
- Released by immune cells and acts on other specific immune cells (lymphocytes) to activate further adaptive immune response.
E.g: Interferon
Natural Killer (NK) Cells
- Destroy virally infected or damaged host cells and cancerous cells through recognition of an absent of damaged MHC I marker.
- Released perforin to trigger cell death
- Release cytokines to attract other specific adaptive immune cells to site of infection.
Phagocytes
- Macrophages
- Dendritic Cells
- Neutrophils
Antigen-Presenting Cells
- Dendritic cells
- Macrophages
