RAG Rated - RED Flashcards
Test for Sugar
Benedict’s Reagent - add it to a sample and heat it to a water bath that is at 75C. If positive, the test will change from blue to brick red.
Test for Proteins
Biuret Test - add drops of Potassium Hydroxide solution to make the solution alkaline. Then add some copper sulphate (blue). The solution will stay blue if no protein, however it will turn purple if there is
Lipids/fats test -
Emulsion Test - Shake the test substance with ethanol for around a minute until it dissolves, then pour the solution into the water. If lipids are present, they will precipitate and the solution will show as a milky emulsion.
Starch test -
Add iodine solution. If starch is present, then the solution changes from brown-orange to blue-black. If nothing, it stays brown-orange.
Catalyst
A substance which increases the speed of the reaction without being used up or changed in the reaction.
Active Transport
The movement of particles across a membrane against a concentration gradient using energy transferred during respiration.
Osmosis
The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
Interphase
The cell is growing and the number of sub-cellular structures (ribosomes/mitochondria) is increasing. The DNA of the cell is duplicated. X-Shaped chromosomes are formed.
Prophase
The chromosomes condense, getting shorter and fatter. The membrane around the nucleus breaks down and the chromosomes lie free in the cytoplasm.
Metaphase -
The chromosomes line up at the centre of the cell.
Anaphase
Spindle fibres pull the chromosomes apart. The chromatids line up at opposite ends of the cell
Telophase -
Membranes form around each of the sets of chromosomes. These become the nuclei of the new cells.
Cytokinesis
The cytoplasm and cell membrane divide to form two new, genetically identical diploid sex daughter cells.
Stem Cells
These are undifferentiated cells.
Embryonic stem cells
Can divide and produce any kind of cell. Stem cells are important for growth and development.
Adult stem cells
Used to replace damaged cells.
Stem cells in medicine - Advantages
Sickle cell anaemia can be cured with a bone marrow transplant. Extracting stem cells from embryos and growing them into specialised cells. Creating specialised cells to replace those which have been damaged by disease or injury.
Disadvantages of stem cells
Rejection - If not grown using the patient’s own stem cells, the patient’s body may recognise the cells as foreign and trigger an immune response to try and get rid of them.
Tumour development - If scientists cannot control the rate of division, then a tumour can develop.
Disease transmission - If donor stem cells are infected with a virus, then it could be passed on to the recipient and make them sicker.
Ethical issues of stem cells
Human embryos shouldn’t be used because each one is a potential human life. However some think that curing people who are alive is more important than potential life.
The Nervous System
Made up of neurones (nerve cells) which go to all parts of the body.
Stimuli
- The body has lots of sensory receptors (cells that detect a change in the environment AKA a stimulus).
- When a stimulus is detected by receptors, the information is converted to a nervous (electrical) impulse and sent along sensory neurones to the CNS (brain+spinal cord).
Neurones - have….
- All have a cell body with a nucleus.
- The cell body has Extensions that connect to other neurones.
- Neurones can be long which speeds up the impulse.
The CNS
- The CNS co-ordinates the response. Impulses travel through the CNS along relay neurones.
- The CNS sends information to an effector (muscle or gland) along a motor neurone. The effector then responds - muscle contracts or gland secretes hormone.
Reaction time
The time taken to react to a stimulus is your reaction time.
Axons
axons Carry nerve impulses away from the cell body.
Dendrites and dendrons
dendrites and dendrons carry nerve impulses towards the cell body
Myelin sheath
Some axons are surrounded by a myelin sheath which acts as an electrical conductor, speeding up the electrical impulse
Types of Neurone
Sensory, motor, relay
Sensory Neurones
One long dendron carries nerve impulses from receptor cells to the cell body which is located in the middle of the neurone. One short axon carries nerve impulses from the cell body to the CNS.
Motor Neurones
Many short dendrites carry nerve impulses from the CNS to the cell body. One long axon carries nerve impulses from the cell body to effector cells.
Relay Neurone
Many short dendrites carry nerve impulses from sensory neurones to the cell body. An axon carries nerve impulses from the cell body to motor neurones.
Synapses
The connection between two neurones.
Nerve signals are transferred by…
Are transferred by chemicals called neurotransmitters which diffuse across the gap. They then set off a new electrical signal in the next neurone. The transmission is slowed at the synapse because the diffusion of neurotransmitters takes time.
Reflexes are.. Reflex arc? Where do their neurones go?
Automatic, rapid responses to a stimuli. The passage of information in a reflection is called a reflex arc. The neurones in reflex arcs go through the spinal cord.
Short summary of reflexes (bee sting)
- Bee stings finger.
- Stimulation of pain receptors.
- Impulses travel along a sensory neurone.
- Impulses are passed along a relay neurone, via a synapse.
- Impulses travel along a motor neurone, via a synapse.
- When impulse reaches muscle, it contracts.
Cerebrum
Right hemisphere controls muscles on left side of body, vice versa. Different parts are responsible for: movement, intelligence, memory, language and vision.
Cerebellum
Muscle co-ordination and movement
Medulla oblongata
Unconscious activities like breathing, heart rate.
PET Scans
Use radioactive chemicals to show which parts of the brain are active. Very detailed and can investigate the structure + function of the brain in real time. Can show if parts of the brain are unusually inactive or active.
CT Scans
Uses X-Rays to produce an image of the brain. Shows the main structures of the brain but doesn’t show the functions. If a CT scan shows damaged brain structures, the function can be worked out.
Treating problems in the CNS
- Hard to repair damage to the nervous system.
- Can be difficult to surgically remove tumours in parts of the brain that aren’t easy to access.
- Can lead to permanent damage.
Cornea
Refracts light into the eye.
Iris
Controls how much light enters the pupil
Lens
Also refracts light, focusing it onto the retina.
Retina
Light-sensitive, covered in receptor cells called rods and cones which detect light.
Rods
More sensitive in dim light but can’t sense colour.
Cones
Sensitive to different colours but not good in dim light.
Information from light
Converted into electrical impulses. The optic nerve carries these impulses from the receptors to the brain.
Colour-blindness
Red-green is when red or green cones in the retina don’t work properly. No cure as cone cells can’t be replaced.
Cataract
Cloudy patch on the lens, stops light from entering the eye normally. Blurred vision. Less vivid colours. Difficulty seeing in bright light. Can be treated by replacing the lens with an artificial one.
To look at close objects
The ciliary muscle contracts, which slackens the suspensory ligaments. The lens becomes more rounded so light is refracted more.
To look at distant objects
The ciliary muscle relaxes, which allows suspensory ligaments to pull light. This pulls the lens into a less round shape so light is refracted less.
Long-sightedness
Lens is wrong shape, doesn’t bend light enough/eyeball too short. Light from near objects is brought behind the retina. Convex lens.
Transcription
- RNA polymerase binds to a region of non-coding DNA in front of a gene.
- The two DNA strands unzip and the RNA polymerase moves along one of the strands of the DNA.
- It uses the coding DNA in the gene as a template to make the mRNA. Base pairs between the DNA and RNA ensure that the mRNA is complementary to the gene.
- Once made, the mRNA molecule moves out of the nucleus and joins with a ribosome
Near-sightedness
Lens wrong shape, bends light too much/eyeball too long. Light from distant objects brought in front of the retina. Concave lens.
Translation
- Amino acids are brought to the ribosome by another RNA molecule called tRNA.
- The order which amino acids are brought to the ribosome match the order of the base triplets (codons) in mRNA.
- An anticodon is complementary to the codon for the amino acid. This pairing ensures that the amino acids are brought to the ribosome in the correct order.
- The amino acids are joined together by the ribosome. This makes a polypeptide,.
Mutations affect Phenotype
Mutations can happen in non-coding regions of DNA. The ability of RNA polymerase to bind to the DNA can be affected if there is a mutation in the DNA. How well it can bind to the DNA affects how much mRNA is transcribed, therefore how much protein is produced.
Mendel
- Characteristics in plants are determined by hereditary units.
- These are passed on to offspring unchanged from both parents, one unit from each.
- Can be dominant or recessive.
Sex-Linked disorders
Y chromosome smaller than X > carries fewer genes. Males only have an X chromosome so they often only have one allele for each gene. Because of this, the characteristics of this allele are shown even if it’s recessive.
HGP
Find every human gene.
Fossils
Any trace of an animal or plant that lived a long time ago. Found in rocks. Deeper rock, older fossil. Place in chronological order
Ardi
4.4 million yrs old. Feet structure > climbed trees (ape-like toe). Long arms, short legs > like an ape. Same brain size as chimpanzee.
Lucy
3.2 million. Arched feet, slightly larger brain than Ardi.
Tools
Have become sharper, more complex + sophisticated over time
Dating
Carbon dating. Stratigraphy (study of rock layers). Simpler tools > older.
Pentadactyl Limb
- Limb with 5 digits.
- In mammals, reptiles, amphibians.
- Has a similar bone structure but different function in each.
- Provides evidence that we all had a common ancestor (same bone structure).
Classification
Three Domain - Archaea (look similar to bacteria but different), Bacteria (true bacteria), Eukarya (plants, fungi, animals, protists)
Selective breeding
Breeding desired characteristics.
Uses of selective breeding
Agriculture - cattle have higher meat yield.
Medical research - rats with a strong/weak preference for alcohol.
Disadvantages of selective breeding
Reduces gene pool > more chance of harmful genetic defects. Not much genetic variation, so less chance of resistance alleles being present to defend against disease.
Plant tissue culture
Remove small pieces of tissue from plant. Grow it in a growth medium containing nutrients. Under aseptic conditions.
Animal tissue culture
Extract tissue from animal. Separate the cells using enzymes. Place in a culture vessel and bath in a growth medium containing nutrients.
Genetic Engineering
Modifying an organism’s genome to introduce desirable characteristics.
Benefits of GE.
Crops > resistant to pesticides.
Useful proteins into sheep and cows. Animals for organ transplants.
Risks of GE -
Transplanted genes may get out into the environment or that these crops could affect human health. Hard to predict what affect GE has on animals > some have health issues or don’t survive after.
Stages of Genetic Engineering
- The DNA you want to insert is cut out with a restriction enzyme. The vector DNA is then cut open using the same restriction enzyme. The vector DNA and DNA you’re inserting are left with complimentary sticky ends. These are mixed together with ligase enzymes. The Ligases join the pieces of DNA together to make recombinant DNA. This is inserted into other cells e.g bacteria. You can now use the gene you inserted to make the gene you want.
Ebola - VIRUS
- A virus.
- Causes a fever with bleeding.
- Spread via body fluids.
- Reduce transmission by isolating infected people and sterilising any areas where the virus may be present.
Chalara Ash Dieback - FUNGAL
- Caused by a fungus that infects ash trees.
- Symptoms are leaf loss and bark lesions.
- Fungus carried through the air by wind.
- Reduce transmission by removing young, infected trees and replacing with different species or restricting the movement or importation of ash trees.
Malaria - PROTIST
- Protist.
- Damage to red blood cells, liver.
- Mosquitoes act as animal vectors - they pass on the protist to the humans but don’t get malaria themselves.
- Mosquito nets and insect repellent can be used
Cholera, TB, Stomach Ulcers - BACTERIA
Cholera - causes diarrhoea. Spreads via contaminated water sources. Make sure people have access to clean water supplies.
TB - causes coughing and liver damage. Spread through air when people cough. Avoid crowds, sleep alone, practise good hygiene.
Ulcers - Stomach pain, nausea, vomiting. Oral transmission. Clean water supplies and hygienic living conditions.
Lytic Pathway
- Virus attaches itself to a specific host cell and injects its genetic material.
- The virus uses proteins and enzymes in the host cell to replicate its genetic material and produce the components of new viruses.
- The viral components assemble.
- The host cell splits open, releasing the new viruses, which infects more cells.
Lysogenic pathway
- Injected genetic material is incorporated into the genome of the host cell.
- The viral genetic material gets replicated along with the host DNA every time the cell divides - but the virus is dormant and no new viruses are made.
- Eventually a trigger causes the viral genetic material to leave and enter the lytic pathway.
Plant PHYSICAL BARRIERS
- Leaves/stems have a waxy cuticle, which provides a barrier to stop pathogens entering them. Stops water collecting on the leaf.
- Cell walls are made from cellulose. Physical barrier against pathogens.
Plant CHEMICAL DEFENCES
- Antiseptics kill bacteria/fungal pathogens.
- Chemicals to deter pests.
Human PHYSICAL BARRIERS
- Skin - acts as a barrier to pathogens and blood clots seal cuts.
- Hairs and mucus in the nose trap particles that could contain pathogens.
- Cells in the trachea and bronchi produce mucus, which traps pathogens.
- Cilia are hair-like structures that waft mucus to the back of the throat to be swallowed.
Human CHEMICAL DEFENCES
- Stomach produces hydrochloric acid which kills most pathogens that are swallowed.
- Eyes produce a chemical called lysozyme in tears which kills bacteria on the surface of the eye.
Immune Response
B-lymphocytes are a type of white blood cell that produce antibodies when they come across an antigen on a pathogen. Antibodies bind to the new invading pathogen so it can be destroyed by other white blood cells. The antibodies produced are specific to that pathogen so they won’t lock on to any other pathogens. The antibodies are then produced rapidly and flow around the body to find similar pathogens.
Memory lymphocytes
remember specific antigens.
Immunisation
Injecting dead/inactive pathogens into the body. They carry antigens so your body makes antibodies to destroy them. This triggers the production of memory lymphocytes. So, they will remember the antigen and produce a response if the live pathogen attacks > secondary immune response.
Pros of immunisation
Epidemics can be prevented as herd immunity will happen.
Small pox has been eradicated by immunisation programs.
Cons of immunisation
Doesn’t always work. Can have a bad reaction to a vaccine.
Monoclonal Antibodies
- Antibodies are produced by B-lymphocytes.
- Monoclonal antibodies are produced from lots of clones of a single type of B-lymphocyte. All antibodies are identical and target one specific protein antigen.
- Tumour cells can be grown easily as they divide rapidly.
- You can fuse a mouse B-lymphocyte with a myeloma tumour cell to create a hybridoma.
- These can be cloned to create lots of identical cells. These can divide rapidly to produce the same antibodies. These can be collected and purified.
Pregnancy testing kits
Pregnancy Test Kits - HCG is found in pregnant woman’s urine. the part of the stick where you urinate on has antibodies to the hormone, with blue beads attached. The test strip also has some more antibodies stuck onto it. If you’re pregnant - the hormone binds to the antibodies on the blue beads, the urine then moves up the stick carrying the hormone and the beads. The beads and hormone bind to the antibodies on the strip. The blue beads get stuck on the strip turning it blue.
Other uses of monoclonal antibodies -
Find blood clots, target cancer cells, diagnose cancer, target drugs for cancer cells
Stages in medicine
- Preclinical (human cells and tissues in the lab).
- Testing on animals.
- Human volunteers in a clinical trial (first healthy, then ill).
- Approved by a medical agency.
CVD
Too much cholesterol in the blood causes fatty deposits to build up in the arteries, restricting blood flow. Deposits occur where the artery wall has been damaged. The deposits can cause blood clots to form > can block blood flow completely > stroke or heart attack.
Lifestyle changes for CVD
Eat a healthy, balanced diet. Exercise. Stop smoking.
Drugs to reduce CVD risk
- Statins reduce the amount of Cholesterol in the blood stream > slows down the rate at which fatty deposits form > reducing the risk of a heart attack. Can cause aching muscles or liver damage, though.
- Anticoagulants are drugs which make blood clots less likely to form. However, can cause excessive bleeding if the person is hurt.
- Antihypertensives reduce blood pressure. Prevents damage to blood vessels and reduces the risk of fatty deposits forming. However, they can cause headaches and fainting.
Surgical Procedures for CVD
- Stents are tubes that are inserted inside arteries > keep them open > blood passes through > lowers risk of heart attack. Patient must take drugs to stop blood clotting on the stent.
- If part of a blood vessel is blocked then a piece of healthy vessel taken from somewhere else can be used to bypass the blocked section. (CBS)
- The heart can be replaced with a donor heart. It does not however always start pumping properly and drugs must be taken to stop the body rejecting it. The drugs can make you more vulnerable to infections.
Any heart surgery is a major risk and there is a risk of bleeding, clots and infection.
