Biology HSC exam Flashcards
(103 cards)
1
Q
Transcription
A
The process of turning genetic information stored in the DNA into an intermediary molecule mRNA.
- RNA polymerase binds to a ‘promoter’, which signals the DNA to unwind, and allows the enzyme to read the bases.
- Thew mRNA molecule is built, using complementary bases.
- mRNA detaches from the DNA strand.
2
Q
Translation
A
The process of turning information encoded as mRNA into a polypeptide chain.
- mRNA attaches to a ribosome.
- The ribosome matches the codon and anticodons together.
- A polypeptide bond is formed, and continues to grow as amino acids are added
- Once a stop sequence is reached, the chain detaches and then folds.
3
Q
DNA replication
A
DNA replication is the process by which an existing DNA molecule is copied to produce 2 identical DNA molecules.
· The enzyme topoisomerase relaxes the DNA from its coiled structure.
· The enzyme helicase unwinds & unzips the DNA molecule at a particular point (an origin of replication) making two template strands of DNA available.
· The hydrogen bonds between the nitrogenous base’s breaks.
· The enzyme primase synthesizes short RNA primers to start each new DNA strand or fragment. One of the strands is in the 3’ to 5’ direction, which is called the leading strand; the other is in the 5’ to 3’ direction and is called the lagging strand.
· The enzyme DNA polymerase catalyses the synthesis of the new DNA strands.
· DNA Polymerase helps the DNA nucleotides (which are readily available in the cell) match up with their complementary base on the template DNA (A&T, C&G). DNA polymerase continues to bond free nucleotides to the exposed bases according to the complementary base pairing rule until there are no more exposed bases.
· DNA ligase (enzyme) seals the two strands of DNA into double strands.
The result of DNA replication is two identical DNA molecules, made up of one old and one new strand which automatically coil back into a double helix.
4
Q
Internal vs external fertilisation
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Internal fertilisation involves the fusion of male and female gametes within a parent’s body. Internal fertilisation tends to occur between terrestrial animals.
External fertilisation involves the fusion of male and female gametes outside a parent’s body. External fertilisation tends to occur between aquatic animals.
5
Q
Sexual vs asexual reproduction
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Sexual reproduction, such as meiosis, is the process of forming a new organism from the fusion of the offspring’s parents’ gametes. Comparatively, asexual reproduction, such as mitosis, is the process of producing offspring from just one parent through cell division or mitosis.
The offspring as a result of sexual reproduction does not have genetic material that is identical to its parents. The offspring from asexual reproduction is a clone of its parent, meaning it has the same allele combinations as its parent.
6
Q
components of the first line of defence
A
Skin: Tightly pack cells that form a protective layer.
Mucous membrane: Cells lining the opening of the body (respiratory tract, urinary and reproductive system) secrete a protective layer of mucous. It traps pathogens and foreign particles
Cilia: Hair-like projections which line the air-passages (nose and throat). Movement of the structures pushes pathogens away.
Chemical barriers: Substances such as stomach acid, the conditions in the small intestine and enzymes in the mouth all act to destroy pathogens.
Secretions: Fluids are routinely secreted from sweat glands, hair follicles and open passages in the body.
7
Q
Phagocytes
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These are leukocytes that engulf and break down pathogens in a process known as phagocytosis. Phagocytes include: • Neutrophils • Macrophages • Monocytes • Dendritic cells
8
Q
phagocytosis
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In phagocytosis, the phagocyte engulfs the foreign material, forming a phagosome. A lysosome fuses with the phagosome forming a phagolysosome. Within the phagolysosome the enzyme breaks down the foreign material into smaller pieces. The enzyme fragments are expelled from the phagocyte by exocytosis.
9
Q
Natural Killer Cells
A
Natural Killer Cells are cells that attack viral-infected body cells. They are able to recognize cell surface markers (antigens) on body cells and destroy them by producing chemicals called perfins which are able to bind with foreign cell antigens on the surface and form pores (holes) that cause the cell to lyse (release cell contents). After the NK cell detects an infected or tumour cell, it induces programmed cell death, or apoptosis. Phagocytic cells then come along and digest the cell debris left behind.
10
Q
The complement system
A
The complement system is a set of more than 30 different proteins which float around in the blood that assist other defence molecules in destroying pathogens. The complement proteins can stimulate phagocytes to become more active, attract phagocytes to the site of infection or destroy the membranes of invading pathogens.
11
Q
inflammatory response
A
The inflammatory response is responsible for releasing several types of chemicals that enable the activation of phagocytes and other white blood cells to fight foreign substances. The body sends blood and fluid to the site of injury or infection, making it red, hot and swollen., allowing more blood flow to the site of infection and increasing access for phagocytes to enter.
12
Q
naive B cells
A
After formation and maturing in the bone marrow, naive B cells move into the lymphatic system to circulate throughout the body. When a naive B cell encounters an antigen that fits its membrane-bound antibody, it quickly divides in order to become either a plasma B cell or a memory B cell.
13
Q
naive T cells
A
Once formed in the bone marrow, naïve T cells migrate to the thymus (hence the name “T cell”) to mature. Each T-cell has a unique receptor that can fit with only one kind of antigen like a lock that can fit with only one shape of key. The antigens are bound to certain receptor molecules, called Major Histocompatibility Complex class 1 (MHCI) “SELF” and class 2 (MHCII) “NON-SELF”.
14
Q
Cytotoxic T
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Destroy cells that are recognised as foreign
Attach to a cell surface and release chemicals
15
Q
Helper T
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Stimulate the production of plasma cells by activating B lymphocytes and T cells to divide
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Q
Suppressor T
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Turn off the immune response and suppress the production of antibodies
17
Q
Memory T
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Responsible for the secondary response
Clone when activated by an antigen after re-exposure
18
Q
Plasma B
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Presence of antigen stimulates cells to differentiate into plasma cells
Plasma cells produce immunoglobulins called antibodies that bind with a specific antigen
19
Q
Memory B
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Remain in the body after infection to recognise later infection
Produce secondary response that is faster
20
Q
Pathogen
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- When a pathogen enters the body, it is detected as foreign due to the presence of non-self-antigens on its surface
- Inflammation allows increased blood flow to the site. Increased permeability of blood vessels allow WBCs to migrate from the blood to infected tissue
- Non-specific responses, including phagocytosis, occur. Macrophages engulf pathogens and release cytokines to call other immune cells to infection.
- The macrophages present foreign antigens on their surface for recognition by B cells and helper T cells which are recruited to the site by interleukins (type of cytokine)
- B and T cells specific to the pathogen are selected by the antigens (clonal selection)
- B cells differentiate into plasma cells and secrete pathogen-specific antibodies to immobilise the foreign cells.
- Cytotoxic killer T cells attack pathogenic cells by releasing cytotoxins
- Memory B and T cells are produced
- Pathogen is cleared from the site
- Suppressor T cells dampen response and suppress killer T cells once the infection has passed
- Memory B and T cells remain circulating in the blood to provide long term immunity
20
Q
Pathogen
A
- When a pathogen enters the body, it is detected as foreign due to the presence of non-self-antigens on its surface
- Inflammation allows increased blood flow to the site. Increased permeability of blood vessels allow WBCs to migrate from the blood to infected tissue
- Non-specific responses, including phagocytosis, occur. Macrophages engulf pathogens and release cytokines to call other immune cells to infection.
- The macrophages present foreign antigens on their surface for recognition by B cells and helper T cells which are recruited to the site by interleukins (type of cytokine)
- B and T cells specific to the pathogen are selected by the antigens (clonal selection)
- B cells differentiate into plasma cells and secrete pathogen-specific antibodies to immobilise the foreign cells.
- Cytotoxic killer T cells attack pathogenic cells by releasing cytotoxins
- Memory B and T cells are produced
- Pathogen is cleared from the site
- Suppressor T cells dampen response and suppress killer T cells once the infection has passed
- Memory B and T cells remain circulating in the blood to provide long term immunity
21
Q
Bacteria example
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Bacteria – Vibrio cholerae
Disease: cholera (a diarrheal infection)
Symptoms: diarrhea, vomiting, leg cramps, dehydration
Treatment: Oral Rehydration Solution (ORS) mixture of salt and sugar with 1 litre of water and drunk in large amounts. Other treatments include intravenous fluid replacement and antibiotics.
Vaccine: Vaxchora
Prevention: drink and use safe water; wash hands often with safe water; cook food well, peel fruits and vegetables.
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Q
Fungi example
A
Bacteria name: dermatophytosis
Disease: Tinea
Symptoms: darkening of the skin, peeling, red rashes, or scaly patches, blisters, cracking of the skin
Treatment: The treatment for ringworm is an antifungal medication
Vaccine: Ringvac
Prevention: maintain hygiene, keep skin dry, avoid sharing towels, avoid public swimming pools
Mode of transmission = direct contact, skin to skin contact, surfaces e.g. shower floor
Examples of types of tinea include athlete’s foot, ringworm
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Q
Protozoa example
A
Protozoa – Plasmodium falciparum
Disease: Malaria (transmitted via Anopheles mosquito)
Symptoms: fever, headache, chills, sweating; gastrointestinal (diarrhea, vomiting, nausea); pain in abdomen and muscles.
Treatment: prescription drugs to kill the parasite; antimalarial drugs are currently being researched and developed.
Vaccine: Mosquirix vaccine (RTS,S)
Prevention: avoid mosquito bites by using insect repellant; use mosquito net.
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Protozoa example
Protozoa – Plasmodium falciparum
Disease: Malaria (transmitted via Anopheles mosquito)
Symptoms: fever, headache, chills, sweating; gastrointestinal (diarrhea, vomiting, nausea); pain in abdomen and muscles.
Treatment: prescription drugs to kill the parasite; antimalarial drugs are currently being researched and developed.
Vaccine: Mosquirix vaccine (RTS,S)
Prevention: avoid mosquito bites by using insect repellant; use mosquito net.
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parasite example
Bovicola ovis
Disease: sheep lice
Symptoms: excessive itching and unwarranted wool loss, damaged wool.
Treatment: shearing fleece to remove lice
Prevention: stock-proof fences to prevent sheep from straying and catching lice (known as biosecurity); isolating infected sheep; stock introduced in farm should be quarantined and inspected for lice.
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virus example
Virus – Severe Acute Respiratory Syndrome Coronavirus 2
Disease: coronavirus disease (COVID-19)
Symptoms: fever, dry cough, tiredness, conjunctivitis, diarrhea, aches and pains, shortness of breath
Treatment: rest, drink lots of fluids, and eat nutritious foods; self-isolate and visit the doctor.
Prevention: wear mask, sanatise, cough into elbow, maintain safe distance, stay home if feeling unwell.
Vaccine: Moderna, Pfizer
Prevention: quarantine, PPE
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prion example
Prions – Bovine spongiform encephalopathy (BSE)
Disease: Mad cow disease (also Variant Creutzfeldt-Jakob disease through contaminated food – zoonotic disease in humans)
Symptoms: dementia, problems with coordination, psychosis, unresponsiveness, weight loss and drop in milk (for cattle), behavioural changes, trembling.
Treatment: no cure; treatment focuses on keeping patients as comfortable as possible.
Prevention: avoid feeding cattle rendered material from slaughtered animals and to isolate and destroy all infected animals.
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Virus structure
Virus is classified as a non-cellular pathogen as they have living and non-living features. They are not made up of cells but rather they have a protein coat containing genetic information in the form of DNA or RNA. This means that they are able to pass on their genetic information via DNA/RNA replication and produce more virus via protein synthesis.
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bacteria structure
Bacteria are unicellular, microscopic organisms without membrane-bound organelles. This means that they are prokaryotes and do not have cell membrane. They undergo asexual reproduction via the binary fission process.
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Protozoan structure
Protozoans are unicellular, eukaryotic organisms. They mean that they have cell membranes although they don’t have cell wall. Similar to bacteria, they asexually reproduce via binary fission and have DNA as their genetic material.
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fungi structure
Although fungi can be unicellular (e.g. yeast) or multicellular (e.g. mushroom), they are all eukaryotes. This means that they have membrane-bound organelles. They also have a rigid cell wall made from chitin. Unlike bacteria and protozoan, they are not motile (non-mobile). They reproduce via spores and spores rely on wind for transportation which germinates upon landing on a surface in a favourable environment such as presence of moisture and preferably cool temperatures. Fungi can either be living on dead tissue (known as saprophyte) or be parasites (thrive on living tissue).
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prion structure
Prions are classified as non-cellular pathogen as they do not contain any DNA or RNA
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Design and conduct a practical investigation relating to the microbial testing of water OR food samples
Equipment:
• Food sample (e.g. bread, yogurt and cheese)
• 6x Agar plates
• 1x Incoulating loop
• 1x Bunsen Burner
• sanitiser
• 3x Test tubes
• Pen & Labels
• Sticky tape
Procedure:
Step 1: Sterilise table surfaces using sanitizer
Step 2: Sterilise your inoculating loop by heating it in the flame of bunsen burner. (making sure it turns orange)
Step 3: Transfer small quantities of three different food sample into three test tubes with 2mL of distilled water and gently mash up the food samples.
Step 4: Dip your sterilised inoculating loop into the food sample in one of your test tube and wipe the food gently on the surface of your agar.
Step 5: Put on the agar plate lid and seal the plate using the sticky tape then label the food type on the lid.
Step 6: Heat your inoculating loop again and repeat
Step 7: Leave sealed agar plates as your control.
Step 8: Observe the number of microbial colonies that are formed in each agar plate and record observations.
Safety:
• Wear gloves to avoid being infection by bacteria.
• When you have sealed the agar plate, do not open it again.
• Take care of using the bunsen burner and hot inoculating loop.
• Wash your hands thoroughly using water and hand-wash solution before leaving the laboratory.
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How do ears work:
When sound waves in the ear canal reach the ear drum, it vibrates at the same frequency. It passes these vibrations on to the middle ear bones. The ossicles receive vibrations from the ear drum. They amplify these vibrations and pass them on to the fluid in the inner ear. The organ of Corti in the inner ear contains hair cells that can detect vibrations. The movement of the hair cells causes their cilia to vibrate. These vibrations are converted into electrical nerve impulses that can be sent along the cochlear nerve to the brain to be interpreted as sound.
Hair cells in the inner ear can be damaged by exposure to noise. The hair cells for higher pitches are the first to encounter sound waves, and so experience more stress over time from noise exposure. This causes them to degenerate earlier than hairs for lower pitches.
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hearing aids
Hearing aids receive sound through a microphone, which then converts the sound energy to electrical energy. The amplifier increases the loudness of the signals and then converts the electrical energy back to sound. This sound leaves the hearing aid through a speaker which directs the sound down the auditory canal.
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Cochlear implant
A cochlea implant is an electronic device used for conductive hearing loss. Sound is detected by a microphone and transferred to a speech processor which sends a digital signal to the implant via the transmitter. The implant transforms the signal into electrical impulses. Electrodes stimulate the nerves in the cochlea, by passing the damaged hair cells and messages are sent along the auditory nerve.
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Bone conduction implants
A bone conduction system consists of a small titanium implant, abutment and sound processor. Sound is transmitted as vibrations from the sound processor to the implant, through the bone to the inner ear.
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How do the eyes work
- Light enters eye and passes through thin conjunctiva.
- Light passes through cornea, which refracts (bends) the light
- Light passes through pupil
- Optic nerve carries electrical impulses from retina to brain
- Retina detects and converts light impulses into electrical stimuli
- Light passes through lens, which refracts (bends) light to focus it on the retina
- Brain interprets electrical impulses to create an image
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Myopia vs Hyperopia
Myopia – the eyeball is too long, and the light focuses in front of the retina, causing the image seen to be blurred/ not sharp.
Hyperopia – either the eyeball is too short, or the lens is not able to retract light sufficiently and the focal point of light entering the eye is behind the retina, again causing the image seen to be blurred/ not sharp
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glasses and contact lenses
glasses and contact lenses correct vision by changing the angle at which light hits the cornea which adjusts for misshapen corneas that cause the focal point to deviate from the norm.
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laser eye surgery
1. A thin flap of the cornea is cut and folded back.
2. A laser is used to reshape the cornea to a more suitable shape.
3. The fold of skin is then folded back into place.
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How do kidneys work
- Blood enters the glomerulus in the nephron via the renal artery. It is filtered based on size by Bowman's Capsule.
- Small substances from blood can enter the nephron, e.g. water and dissolved materials.
- Filtrate travels along the kidney tubule, where most substances are reabsorbed.
- After reabsorption is complete, the remaining substances are transported as urine.
- Urine exits nephrons to travel via ureter to the bladder.
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dialysis definition
Kidney dialysis is a life-prolonging treatment for people with kidney failure. The dialyser allows the blood to be ‘cleaned’ and helps to regulate the homeostasis of water and ion concentration.
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Haemodialysis
waste filtered from blood outside of the body in the dialyser machine. Blood was drawn out of the patient's arm and passed through a series of semi-permeable membranes. Toxins are removed from blood into dialysis fluid and clean blood returns to the body.
4 hours 3x a week at the hospital and make dietary changes
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Peritoneal dialysis
Cleansing fluid enters the peritoneal cavity in the abdomen by catheter. Wastes filtered into the cavity from blood. Fluid and wastes drawn from abdomen and discarded. Can be performed at home or whilst travelling. More flexible and independent.
Peritoneal dialysis is done in the home and uses a tube that is put into the stomach. 30 minutes 4x a day (portable, Self-control)
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kidney transplant
The preferred treatment in most cases of kidney failure is a kidney transplant. However, transplant organs need to be carefully matched to recipients to prevent host immune responses destroying the introduced organ
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Epidemiological studies
Epidemiological studies are used to find the causes of health outcomes and diseases in populations and are vital in our understanding of non-infectious diseases and how to address them.
Epidemiological studies can determine the causation of a disease. By conducting descriptive studies, cohort studies and control studies, strong correlations between particular factors and the incidence of a disease can be discovered and explored to try and establish causation. Once the causation of a particular disease is understood, strategies for preventing it and/or limiting its incidence and/or mortality rates can be developed. Descriptive studies can allow epidemiologists to discover what groups within a population are most likely to be affected by a non-infectious disease. This allows any interventions made, e.g, by government health departments to be more efficient because they are being targeted at the groups in society who most need it. One downfall of epidemiological studies is that the quality of the data they produce very much depends on the quality of the study and design and biases.
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Genetic technologies
Benefits of the continued use of genetic technologies used for the direct modification, removal or transfer of gene/s or other genetic material microorganisms and plant-based substances are now being manipulated using genetic technologies to benefit society via medical treatments. For example, mRNA technologies have enabled the production of vaccines, such as the COVID-19 vaccines. The mRNA encodes a key protein of SARS-COV-2; once the mRNA gets inside our cells, our bodies produce this protein. That acts as the antigen, the foreign molecule that triggers an immune response. Genetic technologies have also enabled the creation of bacterial-medicated cancer therapies to assist in the treatment of various cancers by using the bacteria as vectors for therapeutic cancer medication.
Both medical examples have positive benefits to society via increasing the health of individual (and therefore their ability to contribute positively to society) and through the reduction in the healthcare and societal costs associated with disease.
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Artificial pollination and artificial insemination
It involves a male sperm cell being inserted into a female’s reproductive tract. The fusion of the sperm and egg cell results in fertilisation of the egg cell, producing zygote. Artificial insemination is primarily used to produce offspring with favourable characteristics, a mix of both male and female parents. Artificial insemination is a form of selective breeding because it allows the sperm cell of a selected male to fertilise the egg cell of a selected female.
Artificial Pollination involves the manual transfer of pollen into the stigma of another plant to combine with the egg cell (ovule) of the plant.
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Genes + environment = phenotype
The term genotype means genetic makeup. It may refer to the makeup of a pair of specific alleles for a specific characteristic. The term phenotype refers to the manifestation of the genotype as a physical or physiological trait, such as eye colour in humans or blood type. The phenotype results from the expression of the genotype and the interaction with the environment of the organism.
The organism’s diet or availability of food/water: Pea plants that have limited availability of water would be shorter than pea plants that have access to abundant volumes of water, provided their pea plants are genetically identical.
pH of soil: Hydrangeas exhibit pink and blue colours depending on the pH of the soil. If the soil pH is less than 6, the hydrangeas will be blue. If the pH is greater than 7, they are pink. Hydrangeas colour are dependent on the concentration of aluminium ions in the soil where ion availability is affected by pH.
emperature of ambient environment: Himalayan rabbits are found to have different fur colour based on temperature affecting their gene expression in producing fur pigments. Above thirty five degrees celsius, they have white fur (better at reflecting heat). Below thirty degrees celsius, they have black fur (better at absorbing and trapping heat).
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DNA sequencing and profiling
DNA sequencing determines the order of nucleotide bases (adenine, thymine, cytosine, and guanine) for all of the DNA (genome) of an organism. DNA profiling is also called DNA fingerprinting as it works in a similar way to fingerprinting. The process involves matching samples but, unlike fingerprinting, only a sample of the more variable parts (the lengths of short tandem repeats or variable number of tandem repeats) of the genome DNA are compared so the result is a statement of probability that the two samples were of the same origin, or in some cases were genetically related.
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Aboriginal medicines
Traditional knowledge is often exploited, and indigenous cultural and intellectual property rights are often not recognised. For example, aboriginal people are concerned that their cultural knowledge of plants, animals and the environment is being used by scientists, medical research, nutritionists, and pharmaceutical companies for commercial gain.
The indigenous traditional bush medicine of Eucalyptus oil has been utilised in contemporary medicine as it contains anti-inflammatory and antibacterial agents which are effective in reducing disease duration. For example, Eucalyptus oil has been used in throat lozenges combined with other drugs to effectively “soothe” the throat and provide an anti-inflammatory effect which shortens the duration of the cough. Ethical considerations of using indigenous bush medicines include recognition of their practices, cultural recognition of their discoveries and ethical consideration of using their plants (eucalyptus) for contemporary medicine.
For example, the Kakadu Plum is an important bush food for people in northern Australia; the fruits and seeds were eaten raw and used to treat colds and flus. Scientists have discovered that the Kakadu Plum fruit contains the highest recorded level of natural vitamin C of any plant globally, more than 100 times that of oranges and therefore has enormous potential for use in dietary supplements and health foods.
In the 1960s, the US National Cancer Institute while looking for cancer-fighting molecules were granted by the Western Australian Government a licence to collect plant samples and screen them. In the 1980s, during the AIDS epidemic, Smokebush was screened and found to contain conocurovone, a molecule able to combat the HIV virus in low concentrations. US Department of Health and Human Services filed a patent for exclusive rights.
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HOMEOSTASIS
the process by which the body maintains a constant internal environment
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Biotechnology
Biotechnology is any technology that is developed from biological processes. Genetically Modified foods have had their genomes altered through genetic engineering technology. This technique is used to introduce favourable traits. GM foods like Golden Rice and Transgenic Salmon were developed for a purpose. Golden Rice was developed to add Vitamin A to diets that were deficient in the vitamin by the addition of a gene to code for beta-carotene. This reduced the health burden on society and the salmon provided a source of food that had a higher yield in a shorter time. Producing foods that have a higher yield or disease resistance are of benefit to society and the environment. There is less reliance on herbicides and pesticides which impact on the environment. New developments are always treated with suspicion and it takes time for them to be accepted by society. Some areas are slowly gaining acceptance. Genetically modified foods are gradually gaining acceptance as people see the benefits outweighing the risks to both themselves and the environment.
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Vaccines
After initial vaccination, a time delay occurs before antibodies are produced. The antibody level rise to peak, then decrease to below the concentration required for immunity. A booster vaccination quickly increases antibody level and the remaining antibody level after a decline is sufficient to provide immunity for a longer period of time and a larger concentration. A booster vaccine ensures the level of antibodies in the blood are high enough to provide immunity. The memory B and T cells formed after an initial vaccination quickly recognise an antigen on re-exposure to it in a booster vaccine and so rapidly reproduce a large number of antibodies.
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point mutation
Point mutations are changes that occur in a single nucleotide. These changes can be substitution with the wrong nucleotide, an extra nucleotide added (addition) or a nucleotide not included (deletion).
The point mutation may have no effect on the protein produced as the change may still enable a triplet code for the same amino acid, or the change of one amino acid might not have a significant effect on the resulting protein.
The point mutation may mean that the triplet code initiates a stop sequence, in which case the protein will not be produced.
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A frameshift point mutation
A frameshift point mutation is caused by an addition or deletion. Every triplet on the DNA after the point mutation is affected. This can radically change the protein product of the cell.
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Chromosomal mutations
Chromosomal mutations involve large sections of the chromosome breaking off completely (deletion), or breaking off and reassembling in reverse order (inversion) or breaking off and adhering to another chromosome (translocation).
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diseases caused by point mutations
point mutations: cystic fibrosis, sickle cell anaemia
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chromosomal mutations
Down’s syndrome, Turner’s syndrome.
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Structural adaptations
Structural adaptations refer to physical characteristics of an offspring. An example of this may include the long ears of Red Kangaroos that aid cooling.
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Physiological adaptations
Physiological adaptations refer to the biochemical processes that an organism is able to perform to allow it to tolerate its ambient environment’s selective pressures. An example of this is how echidna can decrease its heart rate to reduce the oxygen it consumes per minute when they are swimming to escape floods.
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Behavioural adaptations
Behavioural adaptations refer to how an organism moves to respond to a threat, need or any other event to ensure the continuity of the species. An example of a behavioural adaptation is how snakes seek shade (e.g. under rocks) during a hot summer day to prevent overheating.
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genetic diversity
During meiosis, the processes of independent assortment, crossing over, random segregation, mismatch of nitrogenous bases during DNA replication as well as the random fusion of gametes contribute towards the genetic variation in a species’s population.
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Crossing over
During prophase 1 crossing over occurs are maternal and paternal chromosomes line up along side one another. The arms of the chromosomes intercept is called chiasmata, in chiasmata the genetic information swaps ‘synapsis’ and this increases variation occurring with new allele combinations.
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Independent assortment
Independent assortment of chromosomes means that homologous pairs of chromosomes randomly segregate to opposite poles of the spindle during meiosis. The result is a large number of different chromosome combinations possible in each gamete. Because independent assortment happens in meiosis in both parents the genotype of the offspring could be highly varied.
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Codominant vs incomplete dominance
Co-dominance occurs when both alleles for a trait are expressed at the same time without blending of the trait that each allele specifies. This occurs when there is no recessive alleles for the trait. An example of co-dominance is when a cow have both red and white colour patches on its skin. These cows are known as roan cows. (spotty)
Incomplete dominance is similar to co-dominance in that both alleles for a given gene are expressed meaning that neither of the two alleles have complete dominance over the other. However, for traits that are incomplete dominant, there is a blending of the two parents’ es which that visible in the offspring’s phenotype. E.g: red and white flower creating a pink flower
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Koch’s postulates
1. The pathogen must be associated or responsible for all causes of the disease.
2. The pathogen must be able to be isolated from the affected host, grown in a pure culture and recorded for its characteristics.
3. When the newly cultured pathogen is inserted into a new, healthy (unaffected) host, it must result in the new healthy host in developing the same disease (e.g. same symptoms)
4. The pathogen must be able to be isolated from the newly affected host and shown to be same pathogen (e.g. same characteristics) that was isolated from the original affected host.
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Robert Koch
Robert Koch developed many agar techniques including one to culture microorganisms. He also demonstrates that specific microorganisms are responsible for causing specific disease.
- Identified the bacteria responsible for causing anthrax
- Identified the bacterium responsible for causing tuberculosis and cholera
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Pasteur's experiments on microbial contamination
Louis Pasteur was responsible for identifying microbes as the agents responsible for spoilage. Pasteur managed to disprove the theory of spontaneous generation by demonstrating that all microorganisms come from pre-existing organisms (germ theory of disease).
His work significantly changed the way that we treat and prevent infectious diseases. Modern medical approaches to disease, including using antiseptics and hygiene practices to reduce exposure to microorganisms are results of the findings of Pasteur’s work.
This led to the development of pasteurisation. pasteurisation is the process of heating up and cooling down food, eliminating pathogens. This finding contributed significantly to our understanding of the disease, as the scientific community began to accept that infectious diseases must be a result of microorganisms, originating from one external source.
His work led to:
- Developing a vaccine for chicken cholera
- A vaccine against anthrax (using Koch’s work) and used it on sheep for the first time
· Swan neck flask - Broth placed in swan neck flask, boiled to get rid of micro-organisms, one flask was broken, and one was normal. Broken one had spoiled (proves that bacteria don’t just generate randomly, they come from exposure to the air)
Anthrax experiment - had 2 vaccinations: one was regular pathogen and one was a weaker version. Those given regular died, those given weaker survived. Led to creation of vaccinations.
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Types of proteins:
Structural proteins are responsible for support for cells and their organelles and also provide support to major structures such as cartilage and hair. Examples include collagen and keratin. Functional proteins are involved in biochemical reactions and help maintain normal immune function. Examples include enzymes (e.g. avidin) and immunoglobulins.
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Access the causes and effects of plant and/or animal diseases on agricultural production
Infectious diseases impede a plants ability to function normally and therefore has a significant impact on the yield and quality. Plant diseases cost millions each year and impacts our ability to trade (locally and internationally). It is estimated that pathogens cause 12.5% crop loss globally. The Tomato Spotted Wilt (Tomato- first recorded in tomato plants) is a prime example of a plant disease. The disease is caused by a virus pathogen which is transported to the plant’s surface via thrips (a black-coloured insect). Therefore, when the virus makes contact with the plant when the insect feeds on it. Within a cell, the virus’s genetic material (RNA or DNA) is replicated and after some time, replicated virus can breakthrough cell membrane and spread to other cells in the plant or exit the plant and infect other plants. This process degrades the fruit or crop’s quality and should not be consume due to potential of viral infection. The symptoms experienced by the plant that is affected by the tomato spotted wilt virus include: wilting of leaves and ringspots on leaves and fruit. This reduces the yield of agriculture, causing a reduction in revenue for farmers and passing on higher costs for consumers, reducing their disposable income. Furthermore, countries may lose international competitiveness and therefore reduce trade due to increased prices, particularly if competitor prices are cheaper.
Bovine spongiform encephalopathy (BSE) or mad cow disease is an animal disease that causes a progressive neurologic disease of cows. BSE is caused by a protein called a prion. A cow gets BSE by eating feed contaminated with parts that came from another cow that was sick with BSE. People can get a version of BSE called variant Creutzfeldt-Jakob disease (vCJD). It is believed that people got the disease from eating food made from cow’s sick with BSE. Mad Cow disease is a direct consequence on agriculture as it reduces the quantity of cattle acceptable for sale, similarly as the plant disease, reducing income for farmers. Furthermore, the disease can have direct impacts on the health of individuals.
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Health campaign
In order to prevent the spread of the disease large-scale quarantine measures must take place to minimise community transmission, as the disease is infectious. Epidemiology studies must be done to trace the spread within the community. As the incubation period is 2-21 days people must isolate if exposed to disease for 21 days then get tested and at the end of this period before re-joining the community. Avoiding sharing needles/ body fluids. Preventative measures such a fly screams and sprays should be used to prevent direct contact with fruit bats that can transmit the disease. These measures must be taken to minimise prevalence as it has a high fatality ratio until vaccines can be developed and distributed to the community.
The combined use of quarantine and vaccination programs is more effective way of controlling disease than using exclusively because the herd immunity resulting from effective vaccination programs can be backed up by isolation of discrete occurrences of the disease.
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Describe the prevalence, symptoms, cause, and treatment/ management of a named non-infectious disease.
Cystic Fibrosis is a genetically acquired disease. It is non-infectious and patients are born with the disease. An individual is more likely to have cystic fibrosis if he/she has a family history of cystic fibrosis. Cystic fibrosis is caused by a mutated CFTR (cystic fibrosis transmembrane conductance regulator) gene on chromosome 7. The inheritance of cystic fibrosis is autosomal recessive. In Australia, one in 2 500 babies are born with cystic fibrosis. The gene is unable to produce a functioning protein that would normally act as a membrane channel controlling the movement of chloride ions into the cell. Thus, CF causes mucus-secreting organs to produce abnormally thick mucus symptoms include problems with digestion and breaking). There is currently no cure for cystic fibrosis. Patients learn to manage the disease from birth. Management involves, intensive daily physiotherapy of the chest to clear the lungs of mucus and enzyme replacement capsules with food to aid digestion.
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Polypeptide vs protein
A polypeptide is a chain of specific amino acids joined together by peptide bonds. Secondary and tertiary polypeptide structures result from folding and twisting the amino acid chain. A protein consists of at least one polypeptide chain that has a specific conformation. The shape of the combination of polypeptide chain (called quaternary structure) is the result of the interacting forces between the chains. The resultant protein structure is significant for its function.
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Differences and SNPs
The comparison genetic similarities and differences between humans can be achieved by comparing the genomes of each species using DNA sequencing. The level of variation within each species needs to be taken into account when comparing the variation between species.
Analysis of single nucleotide polymorphisms (SNPs) is another tool for comparing genetic similarities and differences. Single nucleotide polymorphisms are differences in one nucleotide base on a DNA sequence, often originating from a substitution point mutation. The number of SNPs within a population is used as an indicator of the level of genetic diversity. SNPs can occur in coding and non-coding regions of DNA, so their impact on phenotype varies greatly.
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Bacteriophage treatment
An advantage of using bacteriophage treatment is that antibiotic resistance could be avoided as no antibiotics are used in the treatment of the disease, thereby preventing overuse or misuse of antibiotics. A second advantage of using bacteriophage treatment is that each bacteriophage is specific to a particular bacterium. If introduced into an infected patient the bacteriophage can destroy the pathogenic bacteria as they use them to reproduce. Ince the pathogenic bacteria are destroyed the bacteriophage would also reduce in numbers as they would no longer have a suitable host to complete their life cycle.
A possible disadvantage of using bacteriophage treatment is the unknown effect of residual bacteriophage may have on the body until it completely disappears and the possibility that may evolve to use other host cells, other than the original bacteria it was used to destroy.
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Distinguish between active and passive immunity
Active immunity occurs when a pathogen triggers an immune response, and this can occur through, natural infection or injection with vaccination. Passive immunity occurs when a person is given antibodies: IgG bodies can be passed from mother to unborn child, through a mother’s milk. Furthermore, a person may be given immunoglobulin protection for a specific disease (for example, immunodeficiency diseases).
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Phagocytosis
The process by which phagocytes engulf and destroy foreign or unwanted material (e.g. pathogens). Phagocytes are white blood cells, or leukocytes. The phagocyte engulfs the foreign material, forming a phagosome. A lysosome fuses with the phagosome, forming a phagolysosome. Within the phagolysosome the enzymes break down the foreign material into smaller pieces. The small waste fragments are expelled from the phagocyte by exocytosis.
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Infectious vs non-infectious vaccines
Vaccines for infectious diseases contain either killed or weakened versions of the virus that causes the disease. When you get a vaccine, your immune system recognises these as foreign. It responds by creating memory cells and antibodies that protect you against future infection. Instead of containing a killed or weakened version of a virus, vaccines for non-infectious diseases such as cancer are made up of cancer cells removed from the patient’s own immune cells in a lab and re-exposed to these substances in the vaccine to signal the body’s immune system to kill the cancer cells in the body. When someone has cancer, the body attacks its own cells which it misreads for foreign invading cells. The vaccine displays the protein from the cancer cell as the antigen so the body will attack the cancer cells and body cells.
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Plant defences
Eucalyptus have thick bark and leaves with thick waxy cuticles, both of which form a physical barrier against infection by pathogens. Stored oils in the leaves have antibacterial and antifungal properties. If the leaf tissue is damaged by a pathogen the surrounding cell can die (programmed cell death or apoptosis) and produce an impenetrable barrier to prevent the rest of the plant from becoming infected.
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crispr-Cas-9
CRISPR is a tool for editing genomes, meaning it allows researchers to easily alter DNA sequences and modify gene function. It cuts and splices DNA at precise locations. It has many potential applications, including correcting genetic defects, treating and preventing the spread of diseases, and improving the growth and resilience of crops.
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Disease caused by exposure to the environment
Asbestos is a harmful substance that causes mesothelioma. The incidence of mesothelioma in Australia is between 700 and 800 new cases per year. The mortality rate is approximately 94%. Wearing protective clothing and masks on work-sites that have asbestos would ensure that people would not breath in the asbestos dust that damages lungs. Initially those responsible for producing the materials containing asbestos denied any knowledge of the danger. This meant that it was harder to prove that it was the building material causing the disease. Epidemiology provided evidence of the link between exposure the asbestosis and the incidence of mesothelioma. Link between disease and work.
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Population genetics
Population genetics is the study of genetic differences within and between populations, it largely involves the tracking of genes and their alleles across space and time.
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natural selection
Variation occurs within a population as a result of mutation
Environmental pressure is applied to the population
Phenotypes best suited to the change in environment survive
Surviving organisms reproduce, this gradually changes the frequency of population traits
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gene flow
transfer of genetic variation (different alleles) from one population to another
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genetic drift
when the relative frequency of alleles within a population change, due to the disappearance of particular genes as a result of natural selection
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bottlenecking
when there is an abrupt reduction in the number of individuals in a population (as the result of a sudden and severe selection pressure), causing a loss of biodiversity in the gene pool
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founder effect
when a new population is established by a small number of individuals separated from a larger population, there will be a loss of genetic variation within the new group. This may lead to new speciation events and evolutionary pathways
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artificial insemination
injection of semen through the cervix into the uterus without sexual intercourse for the purpose of achieving fertilisation
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In vitro fertilisation
when an egg is fertilised by sperm outside of the body, usually in a test tube
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artificial pollination
when pollen is purposefully taken from one plant and placed on the stigma of another flower
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Therapeutic cloning
cloning techniques developed in order to produce therapies for the disease. this involves the production of stem cells genetically identical to the donor which may be used to treat diseases such as diabetes and Parkinson's.
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Recombinant DNA technology
methods to join together DNA from two different species, in order to produce new genetic combinations
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gene therapy
the correction of genetic disorders by introducing normal, functional genes into cells
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Crispr-cas9
a gene-editing system where point mutations are accurately introduced to genomes
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central nervous system
brain and spinal cord
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peripheral nervous system
nerves branching form the CNS throughout the body
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polymerase chain reaction
a form of vector DNA cloning
amplifies a particular DNA sequence and makes multiple copies that can be used in various research and analysis techniques
three processes are denaturing, annealing and extension to make multiple copies of the segment of DNA
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Recombinant DNA
DNA that contains genes from two or more sources
1. Isolation: DNA fragments are extracted from their natural sources
2. Digestion: DNA fragments are cut using a restriction enzyme
3. Insertion: sticky ends bind, so that the target gene is inserted into the DNA scaffold
4. DNA ligase seals the backbone to produce recombinant DNA molecule
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Gel electrophoresis
A technique commonly used to separate molecules like DNA, RNA and proteins according to their size
an electric current is applied across the cell
shorter strands of DNA move more quickly through the gel than longer strands resulting in the fragments being arranged in order of size
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dialysis compensate for the loss of a function of the kidney
Loss of kidney function may result in a failure to remove urea from blood. In dialysis, blood from the patient passes through selectively permeable dialysis tubing. Because the urea diffuses from the high concentrations in the blood to the low concentrations in the dialysate, the urea is removed from the blood.
