Biology Trials Flashcards
Transcription
The process of turning genetic information stored in the DNA into an intermediary molecule (mRNA)
- DNA polymerase binds to the ‘promotor’ which signals the DNA to unwind and allows enzymes to read the bases
- The mRNA molecule is built using the complementary bases
- The mRNA molecule detaches from the DNA strand
Translation
The process where genetic information encoded as mRNA turns into a polypeptide chain
Transcription carries the genetic code in the form of mRNA from the nucleus to the ribosome
- mRNA attaches to a ribosome
- the ribosome attaches the codons and anticodons together
- polypeptide chain forms and grows as amino acids are added
- once a stop codon is reached, the chain detaches
DNA replication
DNA replication is the process by which an existing DNA molecule is copied to produce 2 identical DNA molecules. The enzymes 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 bases break. 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 final 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.
Mitosis model of cell replication
- The nuclear membrane breaks down and nucleolus disappear
- Chromatin condenses into chromosomes that have duplicated into two chromatids held together by a centromere
- Centrosome separate forming spindle
- Chromosomes move to the middle (equator)
- Chromatids pulled by spindle go to opposite poles, becoming chromosomes
- Nuclear membrane reforms
- Cytokinesis
- Two cells identical with the parent
Why is mitosis essential
for growth, repair and asexual reproduction
Meiosis model of cell replication
- The nuclear membrane breaks down and nucleolus disappear
- Chromatin condenses into chromosomes that have duplicated into two chromatids held together by a centromere
- Centrosome separate forming spindle
- Chromosomes move to the middle (equator)
- Homologous pairs come together and crossing over occurs
- Homologous pairs of chromosomes pulled apart by spindle go to opposite poles and cells become haploid
- Nuclear membrane reforms
- Cytokinesis
- Nuclear membrane breaks down
- Chromatin condenses into two chromatids held together by centromeres
- Centrosome separate forming spindle
- Chromosomes move to the middle (equator)
- Chromatids pulled by spindle go to opposite poles, becoming chromosomes
- Nuclear membrane reforms
- Cytokinesis
- Four haploid cells that are genetically unique
Why is meiosis essential
sexual reproduction, gamete production and genetic diversity
Progesterone role in pregnancy
A hormone that is important in pregnancy is progesterone. Progesterone is initially produced by the corpus luteum in the ovary and causes the endometrium to thicken, which helps to support and maintain the pregnancy in the first weeks when the placenta is still developing. The developed placenta then produces progesterone at significantly higher levels to maintain the pregnancy. Prior to birth progesterone levels drop significantly to facilitate labour.
Oestrogen role in pregnancy
Oestrogen support changes during pregnancy, such as the preparation of breasts for lactation and the uterus for contraction of childbirth
Oxytocin role in pregnancy
Oxytocin is the main hormone of birth and causes contractions of the uterus
Relaxin role in pregnancy
Relaxin is a hormone that plays a role in pregnancy and birth by relaxing the pelvis and joints to allow passage of the foetus
How is birth initiated
Birth is initiated because of stress to the foetus, the release of the corticotrophin-releasing hormone and the dominance of estrogen and progesterone
Nucleotide composition, hydrogen bonding and pairing
- DNA is a polymer made up of nucleotide monomers
A nucleotide contains a deoxyribose sugar joined to a phosphate group and a nitrogenous base - The sugar-phosphate chain forms an external backbone for the DNA strand and the nitrogenous bases radiate towards the centre of the helical molecule, joined to the sugar in the backbone
- Two purine bases: Guanine (G) and adenine (A) and two pyrimidine bases - thymine (T) and cytosine (C) - are the nitrogenous bases.
- Hydrogen bonding results in the nitrogenous bases paring A-T and C-G
Aboriginal bush medicine
- A term used to describe the skills and practices used to maintain health, based on indigenous beliefs and practices.
- Use of native flora and fauna, traditionally prepared
- Preventative and diagnostic techniques, including treatments of mental illnesses
- Holistic view of health, emphasising the connections between physical, emotional, social and spiritual aspects of wellbeing
EXAMPLES - Tea tree oil
- Crushed leaves applied as a paste to wounds
- Strong antiseptic
- Used in western medicine to treat fungal infections and acne
EXAMPLES - Eucalyptus oil
- Infusions treat muscle aches, fevers and chills
- Used in western mouthwash and cough lollies
Aboriginal smoke bush
Conospermum, colloquially known as smokebush
- Endemic to south-west Western Australia
- Traditionally used and nurtured by Indigenous peoples of the region for it’s medicinal properties
- 1960s - US National Cancer Institute looking for cancer-fighting molecules, Western Australian Government grants them a licence to collect plant samples and screen them
- 1980s – AIDS epidemic, Smokebush screenedFound 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
- AMRAD gained exclusive licence to develop the patent
- WA government were paid $1.65 million to gain these rights
- Of the $100 million made annually from commercial use of the molecule, none was given to the indigenous population and no credit either
- No consultation of Indigenous community - No royalities or compensation, No acknowledgement
Vaccination antibodies concentration
After initial vaccination, a time delay occurs before antibodies are produced. The antibody level rise to peak then decreases 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.
A booster vaccine ensures the level of antibodies in the blood is 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.
How can variation occur?
- Random segregation
- Crossing over
in the early stages of meiosis random segregation of each member of the homologous pairs of chromosomes results in haploid cells and produces highly varied gametes
Crossing over restructures some chromatids and may produce new combinations of alleles along a chromosome
Both processes result in new combinations of alleles in gametes
How mutagens work:
High-energy electromagnetic radiation
High-energy electromagnetic radiation includes gamma rays, X-rays and some ultraviolet rays
How mutagens work:
Electromagnetic radiation
Electromagnetic radiation passes through tissue to break DNA strands and chromosomes or alter nucleotide bases by changing atoms
How mutagens work:
Chemical mutagens
Chemical mutagens substitute bases and modify the backbone of DNA and often prevent them from replicating. some chemical mutagens break chromosomes
How mutagens work:
Naturally occurring mutagens
Naturally occurring mutagens include viruses, chemicals in plants (alkaloids) and moulds (aflatoxin) and change DNA structure
How mutagens work:
Reactive oxygen species (ROS)
Reactive oxygen species (ROS) interact with other mutagens to break DNA
Types of mutations:
Point mutations
Point mutations involve a change in one nucleotide base. They include:
- Substitution of a nucleotide may result in a different amino acid in a polypeptide chain
- Insertion or deletion of a nucleotide base results in a frameshift that has major harmful impacts on polypeptide synthesis
Types of mutations:
Chromosomal mutations
Chromosomal mutations result in whole sections of chromosomes being deleted, inserted, inverted or translocated to other chromosomes. These rearrangements are usually very harmful to organisms
Types of mutations:
Non-disjunction of homologous chromosomes
Non-disjunction of homologous chromosomes results in a change in chromosome number (aneuploidy) that is usually very harmful to fatal
Stomatic mutations
stomatic (body cell) mutation can result in diseases such as cancer but are not passed on to the next generation
Germ-line mutations
Germ-line mutations can be passed on to offspring and thereby alter allele frequency in the gene pool. Many chromosome mutations in the germ-line result in sterility
Mutations in ‘Coding’ DNA
‘Coding’ DNA segments result in the production of polypeptides so mutations may result from the failure to produce a functional polypeptide
Mutations in ‘non- coding’ DNA
‘Non-coding’ DNA segments may have no known function or regulate gene expression. If regulatory, mutations may result from the failure to produce a functional polypeptide
Genetic variation relating to fertilisation, meiosis and mutation and the effect of the mutation, gene flow and genetic drift on the gene pool of populations
- Fertilisation and meiosis result in recombinations of existing alleles
- Mutations produce new alleles and have the potential to change the gene pool and influence evolution
- Mutation increases variation in the gene pool
- Gene flow from immigrants can increase genetic diversity
- Genetic drift is a random change that mainly impacts. very small populations
Incidence definition
Incidence is the number of new cases of a disease at a. given time
Prevalence definition
Prevalence measures the number or proportion of cases of a disease at a given period
Antivirals treatment
treat a narrow range of viruses and include drugs for the treatment of influenza, HIV, herpes, Hepatitis B and C
Antibiotics treatment
target bacterial pathogens. antibiotics do not work against viral infections such as the cold or influenza
morbidity vs mortality
morbidity refers to the rate of disease in a population
mortality refers to the number of deaths in a population
How Prions cause disease
- Proteinaceous infectious particle
- Abnormally folded protein, transmits misfolded
protein state to other cellular proteins
e.g: Mad cow disease
How viruses cause disease
- non-cellular
- Nucleic acid + protein envelope
- Replicate inside living cells
e. g: COVID-19
How bacteria cause disease
- single-celled, prokaryotic organism
- Reproduce by binary fusion
- Secrete toxins, invade cells, form biofilms
e. g: Tuberculosis
How Protozoa cause disease
- single-celled, eukaryotic organism
- Absorb nutrients from hosts
- Secrete toxins, invade cells, form biofilms
e. g: Malaria
How Fungi cause disease
- Eukaryotic, may be multicellular
- Reproduce by spreading spores
E.g: Athletes foot (tinea pedis)
Macroparasite
- Visible to naked eye
- Ectoparasites – live on organisms
- Endoparasites – live in organisms
E.g: Tapeworm
Robert Koch description
Robert Koch (1843 – 1910)
- German microbiologist
- Identified microbial origins of anthrax, cholera and tuberculosis
- Developed a procedure for isolating and identifying microbes causing disease
- Postulates: links microbial growth as causative agent for disease
Koch’s postulates
- In all organisms with the disease, the microorganisms must be present
- Microorganisms must be isolated, and grown in pure culture
- When a healthy organism is inoculated with the pure culture, it develops the same symptoms as the original sick organism
- Isolate and re-grow microorganisms from newly infected organism. If same, congrats, that’s the cause of the disease
Lous Pasteur description
Louis Pasteur (1822 – 1895)
- French microbiologist
- Disproved theory spontaneous generation
- Proposed germ theory of disease (all things come from pre-existing things)
- Also pasteurization to sterilize food, medical equipment etc
Swan-necked flask experiment
- Take flasks with bent (swan) necks. Particles in the air cannot travel through these necks without getting stuck. Fill with broth
- Apply heat to both flasks, bring to boil. This sterilizes the contents of the flasks
- Break the neck of one flask
- Observe the growth of microorganisms in broth
• Flask with broken neck = microbe growth
• Flask without broken neck = no growth
daptions of different pathogens that facilitate their entry into and transmission between hosts
Cell wall degrading enzymes: Break down cell walls to release intracellular nutrients
Effector proteins: Proteins secreted to suppress host
defences, and aid
entry into cells
- e.g. T3SS
Toxins
- Damage host tissues
- Disable immune system
- e.g. botulinum
Adhesion to host cells:
Adhesion molecules help pathogens stick around cells and colonise tissues and organs
Extremophiles: Pathogens may be able to survive in hostile environments to help their survival inside of organisms
adaptions of different pathogens that facilitate their entry into and transmission between hosts
Protective coverings
- Bacterial capsules: tightly packed polysaccharides giving an extra protective layer
- Viral envelopes: allow longevity outside of host cells and avoidance of immune system
Vectors - Increase efficiency of transmission - Carry pathogens from host to host - E.g. Anopheles mosquitoes for transmission of Plasmodium protozoa, causing malaria
Reservoirs
- Sites both living and non-living where pathogens lay dormant for long periods between outbreaks
- E.g. animals may be reservoirs of human diseases (rabies, cholera)
Rapid species evolution - High rates of mutation during replication allow pathogens to rapidly evolve - Increases pathogenicity - Increased ability to evade host immune responses
Components of the first line of defence
Cilia
Hair-like projections - Line airways
Move in a wave-lie motion to push pathogens away from lungs
Mucous membranes - Cells lining openings of body secrete mucous - Traps pathogens and particles
Secretions
Fluids secreted from sweat glands, hair follicles, urinary tract Flush out pathogens
- antimicrobial
chemical barriers
- stomach acid
- Alkali contents of small intestine
- enzymes in mouth
Skin
- protective layer
- pores secrete anti-microbials
- Outer layer of skin is constantly shedding
The second line of defence
The lymph system
Inflammation
Phagocytosis
Cell death to seal off pathogens
Major Histocompatibility Complex (MHC)
Glycoproteins present on every single cell specifically reserved for presentation of molecules such as antigens and identification
There are TWO TYPES: I and II
MHC I
o Present on all nucleated cells
o Presents the normal proteins it makes AND abnormal ones
o Presents to Tc cells (CD8)
MHC II
o Present on antigen- presenting cells (APCs) ONLY
o Presents the abnormal, pathogenic antigens
o Presents to Th cells (CD4)
Explain how the immune system responds after primary exposure to a pathogen, including innate and acquired immunity
Pathogen enters body detected as foreign due non-self antigens on its surface
2. Inflammation allows increased blood flow to the site
3. Non-specific responses Phagocytosis
4. Macrophages
• engulf pathogens which they encounter
• release cytokines to call other immune cells to the site of infection
• present the foreign antigens on their surface
5. B cells and T helper cells which are recruited to the site by interleukins (cytokine)
6. B and T cells bind to antigen presented on macrophage MCHII molecule
1. B cells via antibodies, T cells via T cell receptors (TCRs)
7. CLONAL SELECTION: Cells selected by binding affinity to antigens
8. B cells differentiate into plasma cells
• secrete pathogen-specific antibodies to immobilise the foreign cells
9. Cytotoxic killer T cells attack pathogenic cells by releasing cytotoxins (e.g. perforin)
10. Memory B and T cells are produced
11. Pathogen is cleared from the site
12. Suppressor T cells dampen the immune response
13. Memory B and T cells remain circulating in the blood to provide long-term immunity.
• Investigate and analyse the wide range of interrelated factors involved in limited local, regional and global spread of a named infectious disease
-Local
1. Immunisation • Herd immunity 2. Personal Hygiene • Washing hands • Covering coughs • Cleaning surfaces 3. Safe Health Practices • Staying home when you’re sick • Contraceptives 4. Public Health Information / programs • Schools • Workplaces
• Investigate and analyse the wide range of interrelated factors involved in limited local, regional and global spread of a named infectious disease
-Regional
1. Monitoring environmental conditions • Sanitation facilities • Food and water supplies • Combatting climate 2. Improving swift identification • Surveillance • Recognition • Diagnosis 3. Creating appropriate responses
• Investigate and analyse the wide range of interrelated factors involved in limited local, regional and global spread of a named infectious disease
-Global
1. Quarantine • Isolating / banning individuals travelling from certain countries 2. Communication • World Health Organization 3. Monitoring affected / potentially affected individuals • Travel cards / documents used to track this data 33
Negative feedback loop
- Feedback systems which counteract changes to normal or homeostatic levels in the body, therefore returning the system to acceptable conditions
- Oppose a stimulus
key elements of negative feedback loops
• temperature
Sensors/receptors: Thermoreceptors - Control centre: Hypothalamus in the brain - Effectors: - Sweat glandsà sweating - Skeletal musclesà shivering - Smooth muscleà vasoconstriction and vasodilation - Muscle cellsà increase or decrease metabolic rates
key elements of negative feedback loops
• glucose
**
Hormones description
- Signalling molecules
- Regulate physiology and behaviour
- Produced by the endocrine system in
the glands - Transported around body using
circulatory system and lymph system
Hormone examples
- Insulin – signals to cells to uptakes glucose
- Glucagon – signals to liver to release glucose
- Leptin – decreases appetite
- Ghrelin – stimulates appetite
- Aldosterone – reabsorption of sodium in kidneys
Hormones: signal transdcution
- Reception Hormones bind to
receptors on the cell surface - Transduction Binding triggers a signaling cascade in cytoplasm
- Response Signalling in the cell
triggers a responseà usually a certain gene is ‘switched on’ or ‘switched off’
Hormones role
By regulating expression of certain cell components, hormones allow the body to coordinate changes to cell structure and function
This can translate to larger changes in tissue and organ responses
Hormones can therefore control processes such as:
- Metabolism - Digestion
- Respiration - Sleep
- Growth
- Development - Reproduction - Mood
Investigate the causes and effects of non-infectious diseases in humans, including but not limted to:
• Genetic diseases
- Single gene disorder – alteration to one specific gene E.g Cystic Fibrosis, Tay-Sachs,
Sickle-cell anaemia, achondroplasia, Cri du chat syndrome, hemochromatosis - Chromosome abnormality – alteration to chromosome structure or number E.g Down
Syndrome, Klinefelter Syndrome - Mitochondrial disorder – alteration to mitochondrial DNA E.g LHON (Leber’s hereditary
optic neuropathy disease) - Multifactorial disorders – combination of genetic and environmental factor influences
E.g Heart Disease, Alzheimer’s, Cancer
Causes of genetic diseases:
- Mutation
- Random
- Error in gamete formation - Exposure to mutagens
- Inheritance from parents
- Acquired changes
CAUSES
- External mutagens
- DNA replication errors - DNA repair system
malfunction
EFFECTS - Silent - Missense - Nonsense - Creation of SNPs - Creation of new alleles - Potentially beneficial or negative
Chromosomal mutations
CAUSES
- Usually a result of errors in meiosis
- Crossing over occurs
incorrectly (chunks of DNA screwed up = structural mutations)
- Sister chromatids incorrectly separated during anaphase (DNA not separated properly = number mutations)
EFFECTS
- Usually severe, because chromosomal mutations involve large changes to a number of genes
- Investigate the causes and effects of non-infectious diseases in humans, including but not limited to:
- Diseases caused by environmental exposure
Environmental diseases: diseases caused as a direct result of an individual’s environment, including exposure to physical and chemical substances
Types:
1. Lifestyle diseases
• E.g. cardiovascular disease, alcoholism, smoking-related diseases 2. Disease caused by physical factors
• E.g. exposure to radiation
3. Disease caused by exposure to chemicals
• E.g. exposure to toxic metals
Disease may be as a result of over-exposure (such as skin cancer or heavy metal poisoning) or under-exposure (for example, deficiency in adequate exercise, vitamin D deficiency)
• Examples:
• Minamata – ingestion of large amounts of mercury
- Investigate the causes and effects of non-infectious diseases in humans, including but not limited to:
- Nutritional diseases
Causes:
1. Excessive nutrient consumption
• May lead to: cardiovascular disease, type 2 diabetes, stroke 2. Insufficient nutrient consumption
• E.g. malnutrition, scurvy (lack of vitamin C), anemia (lack of iron) 3. Problems with digestion
- Investigate the causes and effects of non-infectious diseases in humans, including but not limited to:
- Cancer
- Changes to fundamental molecular functioning of cell uncontrolled and indefinite cell division
- Mutation to normal cell
- Inability to regulate cell growth and division
- Alterations leading to cancer phenotype:
- Indefinite replication
- Evasion of growth suppressors
- Resist cell death
- Induce blood-flow to tumour site (angiogenesis)
- Invade other tissues (metastasis)
- Effects of uncontrolled cell proliferation:
- Reduction in system/organ normal function - Invasion of tissues
- Growth to clog/impede bodily systems
mutations: Electromagnetic Radiation
Highly penetrative waves which interact with and ionize atoms High energy alters DNA bonding, and may cause rearrangement of the structure - - Example: UV light - Radiation from the sun, harmful in high doses - Causes pyrimidine dimers
mutations:
Radioactive agents
- Uranium
- Release radiation, to cause structural disruptions to DNA
Metals
Arsenic, nickel… Affect DNA replication + repair
Intercalating agents
- Ethidium bromide
- Cause frameshift
mutations
Mutations: Naturally Occurring
Viruses
- Replicate by inserting their genetic material into host cells
Bacterial Infections
- Inflammation = reduced repair and increased mutation
Transposons
- Chromosomal mutations
Epidemiology
The branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors relating to health;
The study of diseases that affect a large proportion of the population. It describes the patterns and causes of disease in populations.
• analyse patterns of non-infectious diseases in populations, including their incidence and prevalence, including but not limited to: nutritional disease
Condition in which body becomes resistant to insulin, and gradually is unable to produce insulin. This leads to a build-up of glucose in the blood, which can cause damage to systems in the body.
Causes: increased consumption of unhealthy diets, sedentary lifestyles, genetic factors
INCIDENCE
- 1.4 million new cases every year in U.S.
- Incidence of Diabetes has quadrupled over past 3 decades
- Predicted increases in cases between 2010 – 2030:
- 20% in developed
countries
- 69% in developing
countries
PREVALENCE 1 in 11 adults 20–79 had diabetes in 2015 (415 million) - 90% T2D - Expected to rise to 642 million by 2040 - Epicentre of epidemic: ASIA - China and India top two epicentres of diabetes
MORTALITY 5 million deaths per year - One death every 6 seconds - Mostly due to diabetic complications such as cardiovascular disease - T2D expected to become 7th most prevalent cause of death globally by 2030
Evaluate effectiveness of current disease-prevention methods + develop strategies for prevention of a non-infectious disease, including: genetic engineering
By introducing healthy genetic material, the cell and it offspring may have restored function
METHOD 1. Identify gene causing pathogenesis 2. Engineer/design healthy allele 3. Package the gene • Put into viral genome • Make lots of copies and put into gun • coat inorganic nanoparticle 4. Insertion - This may occur In vivo (within living) or ex vivo (out of living)
DISEASES
- Cystic Fibrosis – correct mutations to the CFTR gene
- Hemophilia – insertion of healthy genes for factor VIII and IX (blood clotting proteins)
- Parkinson’s disease – delivery of genes to restore neural function, reducing disease progression
CRISPR–Cas9
Used to precisely locate and edit parts of the genome and gene drives to increase the frequency of desired alleles.
A gene editing system for accurately introducing point mutations into genomes
METHOD
2 Parts
1. Guide RNA, containing nucleotide sequence
complementary to gene you want to edit 2. Cas9 – endonuclease enzyme, cuts DNA
- The ability to accurately edit genomes gives us unprecedented control over making changes to living cells
- Edit dysfunctional cells in vivo or in vitro
- Improve current genetic therapeutics
- Altering the fundamental genetic cause
of the disease will prevent disease development and inhibit its potential passing onto offspring
Explain a range of causes of disorders by investigating the structures and function of the relevant organs, for example:
• Hearing loss
OUTER EAR
- Pinna, ear canal
- Sound waves enter through ear
canal
MIDDLE EAR - Ear drum, ossicles - Waves vibrate ear drum - Movement of ear drum moves ossicles bones to beat against cochlea
INNER EAR - Cochlea, auditory nerve - Cochlea is filled with fluid, which is moved by knocking from ossicles - Fluid vibrations bend hair cells - Creates electrical impulses - Electrical impulses sent to auditory nerve à brain
ear disorders
conductive hearing loss
Conductive hearing loss
Outer or middle ear damage
Ineffective sound transfer to inner ear
- Ear infections
- Abnormal middle ear bone
growth (otosclerosis) - Ear drum perforation
ear disorders
Sensorineural hearing loss
Inner ear damage
Ineffective sound transfer from middle ear to brain
- Congenital (loss from birth)
- Genetic factors
- Disease during pregnancy
- Acquired due to:
- Age
- Noise
- Physical trauma
- Infections e.g. meningitis
hearing aids: conductive hearing loss
- Magnify sound vibrations entering the ear
- Increase hearing sensitivity
- Worn in or behind the ear - Types:
- Analog
- sound wavesàelectrical signals
àamplificationàsound waves
fed back into ear - Digital - Sound wavesànumerical codes àamplificationàsound waves fed back into ear
Sound energy is converted to electrical energy by a microphone
The electrical signals are sent to an amplifier which produces louder sound waves
A speaker directs the amplified sound waves to the auditory canal
Sound waves travel along the normal pathway through the ear
bone induction implants; Conductive or mixed hearing loss
- Alternative to hearing aids
- Processor placed behind ear
- Sound waves detected by processor
- Processor converts sounds digitally to
vibrations - Vibrations transmitted to implanted section
of device, which stimulates the vibration of the
ear bone - Vibrations transmitted from bone to inner
ear, triggering fluid movement in cochlear àcreation of electrical impulses to the auditory nerve
A summary
transmit a sound from bone to inner ear bypassing the outer and middle ear
Sound processor: Detects sound waves and digitally analyses them > amplifies and converts them into vibrations
Implanted Part: Transmits vibrations through bone and inner ear
When at the inner ear, the movement stimulates the hair cells resulting in electrical impulses. These impulses go to the hearing nerve (auditory) in the brain where it is interpreted as sound.
Cochlear implants: sensorineural hearing loss (inner ear damage)
- Electronic devices which replace damaged inner ears (cochlea)
- Sound received by external transmitter
- Sound turned into digital code
- Code transferred to internal implant
- Code converted to electrical impulses
- àtransferred directly to auditory nerve
A summary
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, bypassing the damaged hair cells and messages are sent along the auditory nerve.
Explain a range of causes of disorders by investigating the structures and function of the relevant organs, for example:
• Visual Disorders
Light enters through cornea
Pupil lets light into the front of the eye
lens focuses light by
shortening or lengthening width
light rays meet at
focal point at the retina
rods and cones are excited by light,
converting signal into electrical impulses
impulses passed to
optical nerve, onto the brain
- Lens and cornea help to refract light – lens can change shape but cornea cannot
- The goal is for the image to land ON the retina – this will then be interpreted by the brain
Eye disorders
MYOPIA
- Near sightedness
- Cornea too curved or eyeball too long
- Objects far away are blurry
HYPEROPIA
- Far sightedness
- Cornea too flat or eyeball too short
- Objects close up are blurry
- Investigate technologies that are used to assist with the effects of a disorder, including but not limited to:
- Visual disorders: spectacles, laser surgery
Change angle at which light hits
cornea
Changes the focal point, restoring normal vision
Myopiaà: concave lens
Hyperopiaà: convex lens
The response of a named Australian plant to a named pathogen
Eucalyptus: phytophthora cinnamomi (fungal pathogen)
Passive defences
Physical barriers: thick cuticle and bark; waxy leaves and dry lead surfaces vertically hanging leaves prevent the formation of moisture which also provides some protection from water moulds
chemical barriers: stored oils function as preformed chemical defences, not only against defoliating animals but also as antifungal and antibacterial agents or for priming defences in both the host and neighbouring plants
Active defences or induced responses: The formation of barrier zones in new tissue produced by the vascular cambium; these zones protect the healthy sapwood by separating it from the adjacent infected or damaged tissue; in some eucalyptus, these zones contain protective wound-sealing gums
periderm separates damaged tissue from healthy tissue and prevents the spread of the disease
Autosomal inhertinece
Autosomal inheritance is the inheritance of genes carried on normal (autosomal) chromosomes that impacts males and females equally
Co-dominance, incomplete dominance and multiple alleles
Alleles can interact in a co-dominant manner in which both alleles are expressed (e.g. roan cattle)
In incomplete dominance, the heterozygous form has an intermediate or a blended phenotype, different from either parent
Multiple alleles is the inheritance of a characteristic in which there are more than two forms of alleles so there is a great variety of possible phenotypes and genotypes (e.g. human blood types may be A or B (co-dominant) or O (recessive to both A and B)
Applications of recombinant DNA technology
Rapidly and predictably produces organisms with known characteristics.
Include insect resistance (Bt cotton, potatoes, maize and rice), herbicide resistance (canola, soybeans, maize, cotton), longer self-life (non-browning apples), increased nutrition (golden rice); disease resistance (papaya, squash); stress tolerance (droughtgard maize)
Passive and active responses of plants
Passive
Physical barriers: for example, thick cell walls, wax
chemical barriers; stored chemical compounds that protect the plant and/ or are released upon infection by a pathogen, for example:
- plant defensins
- pH
Active or induced
Responses activated by injury or exposure to pathogens such as:
- thickening of the cell wall with lignin
- hypersensitive response
Antibodies
When an antigen enters the body the adaptive immune system produces antibodies against it. Each antibody has a unique binding site shape that locks onto the specific shape of the antigen. The antibodies destroy the antigen, which is then engulfed and digested by macrophages
Antibodies work in three ways;
- They neutralise the pathogen by either attaching directly to the surface through the antigen-antibody complex or by attaching to the toxins produced by. the bacteria
- They activate other defence cells such as phagocytes
- They activate the complement system
The innate immune system make up
- the skin and all mucous membranes from external and internal barriers
- defence cells are formed from white blood cells such as phagocytes; macrophages are the first phagocytes to encounter pathogens in the tissue and they are reinforced by neutrophils
- Macrophages and neutrophils recognise pathogens by means of cell-surface receptors that distinguish self from non-self
- various substances circulate in the blood and in body fluids, such as cytokines and antimicrobial peptides called defensins
- complement system involves a system of soluble proteins that activate one another in a chain reaction
- Natural killer (NK) cells specialise in identifying cells infected by a virus or that have been cancerous.
Inflammatory responses, temperature and proteins
There is an increase in the diameter of blood vessels, increasing blood flow and bringing more white blood cells and defence compounds to the infected site
fever and an increase in temperature of the tissues and body temperature help the immune system fight infection
secretions of proteins that bring about blood. clotting help prevent the pathogen from entering the bloodstream and spreading to other parts of the body
Macrophages
Macrophages immediately recognise pathogens which cross-protective barriers and begin replicating
Macrophages then release cytokines which along with other chemicals (e.g. histamine) set up the inflammatory response
Macrophages and neutrophils produce toxins to help kill ingested pathogens
Single nucleotide polymorphisms (SNP)
A single nucleotide polymorphism (SNP) is an alternative form of an allele resulting from a single base substitution (mutation) in the DNA which occurs in at least 1% of the population
Hbs is a SNPof normal haemoglobin (Hba)
90% of human variation in DNA occurs as SNPs are found in ‘non-coding as well as ‘coding’ sections of DNA
Hormonal immune response
The hormonal immune response involves B cells that recognise antigens and produce the plasma cells that make antibodies. The antibodies are released and circulate through the body to ‘attack’ antigens
Cell-mediated immune response
The cell-mediated immune response involves mostly T cells. Cell-mediated immunity. does not involve antibodies
it involves the activation of T lymphocytes and the release of various cytokines in response to an antigen
3 Types of immunity
Passive immunity is provided when a person is given antibodies
Active immunity results when exposure to disease triggers the immune system to produce antibodies. it is long-lasting and sometimes lifelong.
artificial active acquired immunity comes about through vacination
Homeostasis definition
Homeostasis can be explained using a stimulus-response model in which a change in the external or internal environmental conditions is detected and appropriate responses occur
Negative feedback mechanisms
- a stimulus, which is a change in the environment
- a receptor that detects the change in the environment.
- a control centre that controls the response
- an effector that receives the message and carries out the response
- a response that mitigates the original stimulus, hence the negative feedback
Negative feedback
Negative feedback loops that maintain homeostasis for temperature: thermoreceptors detect temperature changes. External temperature changes are detected by receptors in the skin. Internal changes are detected by receptors in the hypothalamus. These inputs are then sent via the nervous system to the appropriate effectors such as muscles and glands. the subsequent response brings about changes depending on whether it is hot or cold.
negative feedback loops that maintain homeostasis for glucose the pancreas produces two hormones, insulin and glucagon and these regulate the amount of glucose in the blood. Insulin lowers blood glucose (blood sugar) levels by facilitating glucose transport from the blood to the cells. Glucagon raises blood glucose levels by metabolising glycogen into glucose.
Plant response to a pathogen
The river red gum can most effectively rid itself of the halo leaf spot canker by dropping its leaves, though this means new leaves will have to be made. The halo leaf spot will prevent the river red gum from being able to photosynthesise if too many leaves are infected and this would kill the tree. The fungal canker stem affects the ability of the lemon‐scented gum to effectively transport material via the xylem and phloem, thus weakening the tree. As the canker affects the lemon‐scented gum’s stem it is not possible to eliminate or ‘drop’ that part of the tree, though if it was on a branch this response could be possible. The lemon‐scented gum must use a method that will isolate the infected area as much as possible, however, it may not be possible to kill the canker completely.
OPTIC NERVE
A bundle of nerve fibres that connect the retina with the brain and help us interpret what we see.
RETINA
The light-sensitive nerve layer that lines the inside of the back of the eye. It creates electrical signals that travel through the optic nerve to the brain.
OPTIC DISC (BLIND SPOT)
A disc on the retina that is the point of entry of the optic nerve. It lacks visual receptors, so it’s also known as the blind spot.
VITREOUS HUMOUR
A clear gel-like substance that occupies the space between the crystalline lens and the retina and transmits initial light waves.
FOVEA
The central part of the macula, necessary for activities where visual detail is important, such as driving or reading.
MACULA
The central part of the retina that allows us to see fine details.
SCLERA
The dense protective tissue of the eyeball that forms the ‘white’ of your eye. Sclera forms over 80% of the surface area of the eyeball, from the cornea to the optic nerve.
CONJUNCTIVA
A clear, thin transparent layer of tissue that covers part of the front surface of the eye and the inner surface of the eyelids.
CORNEA
The clear, dome-shaped front part of the eye that helps your eye focus light, so you can see clearly.
PUPIL
The opening in the centre of the iris that controls the amount of light passing through to the back of the eye.
CRYSTALLINE LENS
The transparent, elastic structure inside the eye that bends to focus light rays onto the retina.
AQUEOUS HUMOUR
The clear, watery fluid in the front of the eyeball made up of water, sugars and various nutrients. It nourishes the cornea and the lens and gives the eye its shape.
IRIS
The coloured part of the eye surrounding the pupil that controls the amount of light that enters into the eye.
Power of accommodation
The ability of the eye lens to increase of decrease its focal length to some extent by ciliary muscles.
How the eyes see objects far away
The ciliary muscles relax so as to decrease the curvature of the lens and it becomes thin and its focal length increases thus the image of far off objects is made on the retina and the eye is able to see distant objects
How the eyes see objects nearby
The ciliary muscles contract to increase the curvature of the lens and it becomes thick, thus the focal length of the eye decreases and able to see nearby objects
Limitation of power of accommodation
the focal length of the eye cannot be decreased below a specific limit, thus the eye cannot see objects clearly below 25cm however there is no such limit for distant objects
Kidneys
Kidneys are complex organs of the excretory system. The main functions of kidneys are to filter the blood of wastes and produce urine without the loss of too much water. Kidneys also helo in the homeostasis of water, glucose and inorganic salts.
Hearing aids
Hearing aids consist of a microphone that picks up sound waves, converts them to electrical signals and sends them to the amplifier which increases the power of the signals and sends them to a speaker
Bone conduction implants
Bone conduction implants are used for conductive hearing loss. A sound processor captures sounds and turns them into vibrations. The vibrations are sent to the implant which transmits the sound through bone vibrations to the inner ear
Cochlear implants
Cochlear implants or bionic ears are used for conductive hearing loss. A sound processor captures the sound and turns them into vibrations. The vibrations are sent to the implant which transmits the sound through bone vibrations to the inner ear
Conductive hearing loss
Conductive hearing loss is due to problems with the ear canal, eardrum, middle ear or ear ossicles and is caused by middle-ear infections and damage to ear ossicles.
Sensorineural hearing loss
Sensorineural hearing loss is due to problems of the inner ear, such as damage to the hairs or nerve cells in the cochlea caused by ageing, or cumulative exposure to excessive noise or certain drugs. When the cells are damaged electrical signals are not transmitted efficiently.
Mixed hearing loss
Mixed hearing loss is a combination of conductive and sensorineural hearing loss to the outer, middle and inner ear or auditory nerve.
Technologies that are used to assist with the effects of loss in kidney function
Haemodialysis is done at least three times a week and. lasts for four to five hours. During haemodialysis, needles are used to access the blood. One needle takes the blood out for treatment and the other needle returns the blood. The blood is taken through a special filter called a dialyzer, which cleans it before it is returned to the body.
Peritoneal dialysis is done in the home and uses a tube that is put into the stomach. Special peritoneal dialysis fluid is used to clean the blood. The fluid must be changed regularly.
A kidney transplant involves surgery where a healthy kidney is taken from one person and surgically placed into someone with end-stage kidney disease.
Technologies to assist the effects of visual disorders
Spectacles and contact lenses are artificial lenses designed to correct the refractive errors of myopia and hyperopia.
Laser surgery is a form of vision correction that involves reshaping the cornea to correct refractive error. The technology uses a cool-temperature laser and LASIK surgery is the most common form
Cataract surgery involves the removal of the opaque lens and its replacement with a clear artificial lens (called an intraocular lens)
Myopia or near-sightedness (short-sighted)
A refractive error caused when the distance between the lens and the retina is too great
Hyperopia or far-sightedness (long-sighted)
A refractive error caused when the distance between the lens and the retina is too short.
Cataracts
A degenerative condition in which the lens of the eye clouds over
Macular degeneration
Progressive deterioration of the macula of the retina (the central lining of the eye)
Glaucoma
Caused by damage to the optic nerve due to increased pressure within the eye
Cytotoxic T
- Destroy cells that are recognised as foreign
- Attach to a cell surface and release chemicals
Helper T
Stimulate the production of plasma cells by activat9ing B lymphocytes and T cells to divide
Suppressor T
Turn off the immune reponse and suppress the production of antibodies
Memory T
- Responsible for the secondary response
- Clone when activated by an antigen after re-expose
Plasma B
- Presence of antigen stimulates cells to differentiate into plasma cells
- Plasma cells produce immunoglobins called antibodies that bind with a specific antigen
Memory B
- Remain in the body after infection to recognise later infections
- Produce secondary responses that is faster
