Intro to Y12 2025 Flashcards
Outline the steps (1-6) in bacterial transformation
Isolate gene for insulin chain A
Use reverse transcriptase to get c.DNA from isolated mRNA so that it contains no introns.
Cut gene and plasmid using the same endonuclease.
Stick insulin gene into plasmid using DNA ligase which joins the sugar phosphate backbone.
Transform bacteria using heat or electroporation and check for successful transformation by growing on an antibiotic plate with ampicillin and then an antibiotic plate with tetracycline
Bacteria with no plasmid will not grow on the ampicillin plate, successfully transformed bacteria with the non-recombinant plasmid will grow on both plates and the successfully transformed bacteria with the recombinant plasmid will only grow on the ampicillin plate.
How many polypeptides make up insulin?
2
What is the function of reverse transcriptase?
Convert c.DNA from isolated mRNA so that it contains no introns.
Why is reverse transcriptase used in the process?
So the introns are removed and a functional insulin is produced.
What is used to cut the plasmid when producing insulin?
Endonucleases
What is used to join the plasmid and insulin gene?
DNA ligase
What is the purpose of the AmpR and TetR genes in the plasmid?
To check for successful transformation of the bacteria
What is a recombinant plasmid?
A plasmid with the target gene (insulin gene)
What is the function of the promoter region?
Allows RNA polymerase to attach and transcribe the DNA
Which bacteria will only grow on ampicillin?
Bacteria that are successfully transformed with the recombinant plasmid
Which bacteria will grow on ampicillin and tetracycline?
Bacteria that are successfully transformed with the non-recombinant plasmid
Which bacteria will not grow on ampicillin or tetracycline?
Bacteria that have not been successfully transformed
Which antibiotics will bacteria that have been successfully transformed with the non-recombinant plasmid grow on?
Ampicillin and Tetracycline
Which antibiotics will bacteria that have been successfully transformed with the recombinant plasmid grow on?
Ampicillin only
Which antibiotics will bacteria that have not been successfully transformed with the recombinant plasmid grow on?
None (not ampicillin or tetracycline)
Qualitative data
Qualitative data is descriptions e.g. colour and is represented with a bar graph
Quantitative data
Quantitative data is numerical data e.g. 10 seconds and is represented as a line graph or histogram
Independent Variable
The independent variable is a factor that is changed or manipulated in an experiment to determine its effect on the dependent variable.
Dependent Variable
The dependent variable is measured to determine if the change or manipulation of the independent variable had any effect.
Control Variable
Something that is kept constant throughout the experiment.
Control group
A control group is where the factor affecting change is removed to provide a baseline for a comparison against the experimental group.
Experimental method scaffold
There will be two ….
In the experimental group………… will be changed by ………………….
Add …… to a test tube.
Add…..
Add….
The ……………..will be measured by ……………………after
All other variables will be kept the same e.g. ………………………
Repeat the above for the other ….*not relevant if it is an all or nothing.
For the control group repeat the above but with no ……………….
Repeat the experiment ………….
If ……………. then …………………
Accuracy
The accuracy of a measurement relates to how close it is to the ‘true’ value of the quantity being measured.
Improve accuracy
Accuracy can be improved by using a better measuring tool that is being used to measure the dependent variable or collecting quantitative data instead of qualitative data
Precision
Precision is how closely a set of measurement values agree with each other.
Improve precision
To improve the precision, you can make sure everything else is controlled and repeat your experiment more to spot anomalies and variation within the results.
Reproducibility
The closeness of the agreement between the results of measurements of the same quantity being measured, carried out under changed conditions of measurement. These different conditions include a different method of measurement, different observer, different measuring instrument, different location, different conditions of use, and different time.
Repeatability
The closeness of the agreement between the results of successive measurements of the same quantity being measured, carried out under the same conditions of measurement. These conditions include the same measurement procedure, the same observer, the same measuring instrument used under the same conditions, the same location, and repetition over a short period of time.
Cellular respiration
The release of energy from glucose in cells.
Aerobic cellular respiration
the release of energy from glucose in the presence of oxygen
Aerobic cellular respiration word equation
Glucose + oxygen –> carbon dioxide + water
Aerobic cellular respiration stages and locations
Glycolysis (cytosol)
Krebs cycle (mitochondrial matrix)
Electron transport chain (mitochondrial cristae)
Draw a mitochondria
Describe glycolysis
Glucose is broken down into two pyruvate molecules and two loaded co-enzymes
Inputs to glycolysis
Glucose, 2 NAD+, 2 ADP + Pi
Outputs of glycolysis
Pyruvate, 2 NADH, 2 ATP
Describe the Kreb’s cycle
Removal of H+ ions from pyruvate creating, ATP, loaded co-enzymes and CO2
Inputs Kreb’s Cycle
Pyruvate, 8 NAD+, 2 ADP + Pi
Outputs Kreb’s Cycle
Carbon dioxide, 8 NADH, 2 ATP
Describe electron transport chain
H+ ions are used to create a concentration gradient to drive the synthesis of ATP. Oxygen is the final hydrogen ion and electron acceptor to form water.
Inputs electron transport chain
Oxygen, 10 NADH, 26-28 ADP + Pi
Outputs electron transport chain
Water, 26-28 ATP, 10 NAD+
Co-enzyme
In general, these are molecules that assist enzymes that have loaded or unloaded forms which go between reactions in a cell in a cyclical manner.
Role of NADH
Coenzymes assist enzymes, NAD+ carries hydrogen ions and electrons by forming NADH and moves from glycolysis and Krebs cycle to the electron transport chain in a cyclical manner.
Role of ATP in aerobic cellular respiration
Coenzymes assist enzymes, ADP + Pi carries energy by forming ATP it moves between glycolysis, Krebs cycle and the electron transport chain from parts of the cell in a cyclical manner.
Net ATP output aerobic cellular respiration
30-32 ATP
Evolution
change in allele frequency over time.
Allele
Variation of a gene at a particular gene locus.
Natural selection scaffold
VA – There is variation in the phenotypes in the __ population due to random mutations as ___
ST – All organisms face a daily struggle to survive and reproduce. The ___ struggle because _____ which is the selection pressure
SE – The ____ have a selective advantage as ___
IN – The organisms that have a selective advantage (___), survive, reproduce and their offspring inherit the alleles for the trait of ___
E – Evolution occurs by natural selection and there is a change in allele frequency over time and the ___ population becomes better suited to its environment.
Speciation
the formation of a new species
Gene flow
The movement (migration) of an individual into or out of a population changing allele frequency.
Why could speciation not occur?
Gene flow between populations
Similar selection pressures
Not enough time for mutations to accumulate and cause change
How do new alleles arise in a population
Mutations
Allopatric speciation
The formation of new species (speciation) due to a permanent geographical barrier
Allopatric speciation scaffold
Two populations of ______ are geographically isolated by a permanent geographical barrier of _______.
There is no gene flow.
There are different selection pressures (e.g. _____) acting on each population of ____and those with a selective advantage for (____________) survive and reproduce.
Mutations accumulate over many generations in each population.
Eventually they can no longer interbreed to produce fertile and viable offspring and would be considered 2 separate species.
Example of species for allopatric speciation
Galapagos Island finches
Pathogen
disease-causing agent
What makes a cellular pathogen?
pathogens that can reproduce independently and undertake independent metabolic processes (like cellular respiration and protein synthesis)
Examples of cellular pathogens
Bacteria, fungi, protozoa, parasites
What makes a non-cellular pathogen?
pathogens that can’t reproduce independently and cannot undertake independent metabolic processes (like cellular respiration and protein synthesis)
Examples of non-cellular pathogen.
Virus, prion
Antigen
An antigen is a unique molecule or part of a molecule that can initiate an immune response.
Which antigen will initiate an immune response.
Non-self
Advantage and disadvantage of innate immune system.
Advantage: Quick to respond
Disadvantage: Does not form a memory of the pathogen
What is a leukocyte?
A white blood cell
Name the white blood cells (leukocytes) in the innate immune system.
Phagocytes (macrophages, dendritic cells, neutrophils)
Natural killer cells
Mast cells
Eosinophils
Name the two roles of a phagocyte.
Phagocytosis
Antigen presentation (dendritic cells and macrophages only)
Phagocytosis overview
Recognise, engulf and digest foreign material, such as pathogens.
Phagocytosis steps
Phagocyte recognises a non-self-antigen and engulfs pathogen forming a phagosome
Phagosome fuses with lysosome forming a phagolysosome
Pathogen destroyed by digestive enzymes (lysozymes) in lysosome
Destroyed pathogen removed from the cell by exocytosis
Antigen presentation
Antigen presenting cells (macrophage or dendritic cells). This means that they will move from the site of infection to the lymph node to present non-self-antigens on MHCII to T and B cells to initiate the adaptive immune response.
MHCII marker
Dendritic cells and macrophages (antigen presenting cells) have MHCII markers on their surface. These are markers that allow the cells to carry the non-self-antigen to the lymph node.
Site of clonal selection
Lymph node
Signs of inflammation
Redness
Heat
Swelling
Pain
Process of inflammation
Damaged cells/tissues release cytokines. These attract neutrophils to the site of infection and activate mast cells to release histamine.
Histamine causes vasodilation which is more blood flow to the area. This means that there will be more macrophages, neutrophils and dendritic cells brought to the site of infection and cause redness and an increase in temperature.
Histamine also causes an increase in membrane permeability. This means that more tissue fluid leaks out causing swelling and pain and means that the phagocytes can reach the tissues and help eliminate the pathogen by phagocytosis.
Function of a mast cell
Release histamine, initiating inflammation and allergic responses
Cause of redness and heat during inflammation
Histamine causes vasodilation which is more blood flow to the area. This means that there will be more macrophages, neutrophils and dendritic cells brought to the site of infection and cause redness and an increase in temperature.
Cause of pain and swelling during inflammation
Histamine also causes an increase in membrane permeability. This means that more tissue fluid leaks out causing swelling and pain and means that the phagocytes can reach the tissues and help eliminate the pathogen by phagocytosis.
Extracellular pathogens initiate which adaptive immune response?
Humoral
Intracellular pathogens initiate which adaptive immune response?
Cell-mediated
Advantage and disadvantage of adaptive immune system
Advantage: Produces a memory of the pathogen
Disadvantage: Takes time to respond
Lymphocyte
White blood cell (leukocyte) involved in adaptive immune response
Clonal selection
Clonal selection occurs. This means that the antigen presenting cell that has moved from the site of infection to the lymph node to present a non-self-antigen on an MHCII marker to a B cell and T helper cell which causes the T helper cell to release cytokines to activate the naive B cell.
Clonal expansion and clonal differentiation
Clonal differentiation and expansion occurs. This means that the B cell divides by mitosis forming a B memory cell and a plasma cell.
Function of plasma cell
secrete specific, complementary and free-floating antibodies.
Function of B memory cell
remain in circulation to provide long term immunity.
Humoral immune response steps
Clonal selection occurs. This means that the antigen presenting cell that has moved from the site of infection to the lymph node to present a non-self-antigen on an MHCII marker to a B cell and T helper cell which causes the T helper cell to release cytokines to activate the naive B cell.
Clonal differentiation and expansion occurs. This means that the B cell divides by mitosis forming a B memory cell and a plasma cell. The plasma cell then secretes specific, complementary and free floating antibodies.
The B memory cell remains in circulation to provide long term immunity.
Protein level of an antibody
Quaternary this means that there are two or more polypeptide chains (4) joined together
Draw and label an antibody
Function of an antibody
Antibodies have specific and complimentary antigen binding sites to __, they attach to the antigen and then
Agglutinate the pathogen /
Neutralise the pathogen /
Opsonise the pathogen /
Activate complement proteins /
… so that phagocytosis is made easier
Agglutination by antibodies
Agglutination of ____ pathogens occurs. This means that there are less pathogens circulating and makes phagocytosis of more pathogens easier.
Neutralisation by antibodies
Neutralisation of ____ toxins/ ____ virus occurs. This means that they become inactive and will reduce the severity of disease.
Opsonisation by antibodies
Opsonisation occurs by antibodies attaching to ____pathogens. This means that phagocytosis is more likely as they have been marked for destruction.
Activation of complement proteins by antibodies
Activate complement proteins. This means that the complement proteins produce a membrane attack complex which destroys the pathogen by lysing the plasma membrane.
Monoclonal antibody
Monoclonal antibodies (mAb) are laboratory produced antibodies that can bind to specific and complementary antigens on a cell.
What diseases can monoclonal antibodies be used for?
Autoimmune and cancer. But also some pathogens.
Bispecific monoclonal antibody
a mAb with two different antigen binding sites
Conjugated monoclonal antibody
mAb connected to a chemotherapy drug or radioactive particle
Function of a monoclonal antibody
Monoclonal antibodies have specific and complimentary antigen binding sites to __, they attach to the antigen and then
Flag the cell for phagocytosis by a macrophage /
Activate natural killer cells /
Activate complement proteins /
Deliver a toxic drug, if conjugated
Outline the function of CRISPR in a bacteria.
Primitive adaptive immune system this means that
Invading viral DNA is cut and stored as spacers in the CRISPR array providing a memory of viral infections
If the same virus reinfects the bacteria, gRNA is transcribed and attached to a Cas9 endonuclease forming a gRNA-Cas9 complex
gRNA guides Cas9 to the viral DNA and Cas9 recognises the PAM sequence and then cuts the viral DNA, preventing destruction of the bacteria.
What is photosynthesis?
Photosynthesis converts light energy into chemical energy as glucose.
Word equation photosynthesis
Carbon dioxide + water –> glucose + oxygen (sunlight, excess water and chlorophyll on arrow)
Chloroplast drawing
Describe light dependent reaction
Light energy is used to split water (photolysis) into hydrogen ions and electrons.
Describe light independent reaction
Reduction of carbon dioxide (using the enzyme Rubisco) where carbon dioxide gains hydrogen ions and electrons to form glucose.
Inputs LDR photosynthesis
Water, ADP + Pi, NADP+, light
Inputs LIR photosynthesis
Carbon dioxide, ATP, NADPH
Outputs LDR photosynthesis
Oxygen, ATP, NADPH
Outputs LIR photosynthesis
Glucose, ADP + Pi
NADP+
Role of NADP in photosynthesis
Coenzymes assist enzymes, NADP+ carries hydrogen ions and electrons by forming NADPH and moves from the light dependent reaction to the light independent reaction in a cyclical manner.
Role of ATP in photosynthesis
Coenzymes assist enzymes, ADP carries energy by forming ATP and moves from the light dependent reaction to the light independent reaction in a cyclical manner.
Rubisco function
Catalyses the light independent reaction (Calvin cycle)
Photorespiration
Oxygen competitively inhibits Rubisco , reducing photosynthesis and glucose formed
How do C4 plants prevent photorespiration?
Separate light independent reaction by location.
Partly in mesophyll cell and partly in bundlesheath cell
Why is preventing photorespiration an advantage?
More photosynthesis = more glucose = more growth
Enzymes involved in C4 photosynthesis
Rubisco and PEPCase
Role of PEPCase in C4 photosynthesis
Convert carbon dioxide into a C4 molecule in the mesophyll cell
Why does C4 photosynthesis prevent photorespiration?
Rubisco is in a different location (cell) to the light dependent reaction, so any oxygen produced in the LDR cannot bind to Rubisco
Similarities of C3 and C4 photosynthesis
Both do the same light dependent reaction during the day in the mesophyll cell
Both use Rubisco for the calvin cycle
Both do the light independent reaction completely during the day
Which environment are C3 plants suited to?
Wet, cool
Which environment are C4 plants suited to?
Hot
Which environmental factor increases photorespiration?
Temperature (heat)
WHich part of the cell does the LIR of photosynthesis occur
stroma of chloroplast
Which part of the cell does the LDR of photosynthesis occur
THylakoid membrane of grana in chloroplast
