Studied by 37 people
prokaryotic
organisms whose cells lack a nucleus and other organelles
eukaryotic
any cell or organism that possesses a clearly defined nucleus
nucleus
controls the activities of the cell
mitochondria
where aerobic respiration takes place
cytoplasm
where most of the chemical reactions take place
cell membrane
controls the passage of substances into and out of the cell and contains receptor molecules
ribosomes
where protein synthesis occurs
cell wall
surrounds the plasma membrane of plant cells and provides strength and protection
chloroplasts
absorb light (using chlorophyll) to make food by photosynthesis
permanent vacuole
filled with cell sap to help keep the cell turgid
bacteria
prokaryotic, have cytoplasm and a cell membrane and wall, no nucleus, genetic material found in a DNA loop and rings of DNA plasmids
tissue
a group of cells that have similar structure and that function together as a unit
centi
0.01m
milli
0.001m
micro
0.000001m
nano
0.000000001m
µm
micron, 1/1000000 of a meter
exothermic reaction
chemical reactions that release energy
what is cellular respiration?
the process of converting glucose into a form of energy that can be used by cells
aerobic
with oxygen
anaerobic
without oxygen
respiration in cells can..
take place aerobically or anaerobically to transfer energy
aerobic respiration equation
glucose + oxygen → carbon dioxide + water + energy release
anaerobic respiration equation
glucose → lactic acid
As the oxidation of glucose is incomplete in anaerobic respiration..
much less energy is transferred than in aerobic respiration
during exercise the human body..
reacts to the increased demand for energy
The heart rate, breathing rate and breath volume increase during exercise to supply the muscles with more oxygenated blood..
This enables increased cellular respiration so more energy is transferred to meet the demands of the muscle cells.
If insufficient oxygen is supplied, anaerobic respiration takes place in muscles..
The incomplete oxidation of glucose causes a build-up of lactic acid and creates an oxygen debt. During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.
Blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose..
Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells.
what are the similarities of aerobic and anaerobic respiration?
both are catabolic processes that takes place in all cells and releases energy and carbon dioxide
what are the differences of aerobic and anaerobic respiration?
one needs oxygen, one doesn’t and they produce different products
Water may move across cell membranes via osmosis. Osmosis is..
diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
What are the effects of osmosis on plant and animal cells?
it allows for the absorption of water, making the cells turgid. The water can also carry dissolved ions and chemicals
the heart
an organ that pumps blood around the body in a double circulatory system
What is the double circulatory system?
Heart to lungs to heart, heart to rest of body to heart
right ventricle
pumps blood to the lungs where gas exchange takes place
left ventricle
thicker wall with more muscle to generate a higher pressure to pump blood a longer distance to the rest of the body
The natural resting heart rate is controlled by..
a group of cells located in the right atrium that act as a pacemaker.
The structure and function of the veins
large diameter, thin outer layer, has elastin and contains valves to stop blood from flowing in the wrong direction, carries deoxygenated blood back to the heart to be pumped to the lungs for oxygen
The structure and function of the arteries
thick wall, doesn’t stretch, carries oxygenated blood away from the heart at a high pressure
The structure and function of the capillaries
narrow, thin cell walls to allow for fast and easy substance exchange, large surface area, gets blood to areas of the body required for ‘exchange’
red blood cells contain haemoglobin which..
binds to oxygen to transport it from the lungs to the tissues.
In coronary heart disease, layers of fatty material build up inside the coronary arteries..
narrowing them, reducing the flow of blood and resulting in a lack of oxygen to the heart cells.
Stents
used to keep the coronary arteries open
Statins
used to reduce blood cholesterol levels which slow down the rate of fatty material deposit.
In the case of heart failure, a donor heart or heart and lungs can be transplanted..
artificial hearts are occasionally used to keep patients alive whilst waiting for a transplant or allow the heart to rest as an aid to recovery.
photosynthesis equation
carbon dioxide + water → glucose + oxygen
photosynthesis is an..
endothermic reaction where light energy is transferred from the environment to the chloroplasts by light
What are the effects of light intensity on the rate of photosynthesis?
the rate of photosynthesis will increase because there is more light available to fuel the reactions of photosynthesis
What are the effects of temperature on the rate of photosynthesis?
As temperature increases the number of collisions increases, therefore the rate of photosynthesis increases
What are the effects of carbon dioxide concentration on the rate of photosynthesis?
carbon dioxide is one of the reactants in photosynthesis so if the concentration of carbon dioxide is increased, the rate of photosynthesis will increase
What are the effects of the amount of chlorophyll on the rate of photosynthesis?
light is an agent required for photosynthesis and leaves with more chlorophyll are better able to absorb light, therefore the rate of photosynthesis increases with the presence of more chlorophyll
pathogens are microorganisms that..
cause infectious diseases: viruses, fungi, bacteria and protists
pathogens may infect plants or animals and can be spread by..
direct contact, water or air
bacteria reproduce rapidly inside the body and may..
produce toxins that damage tissues and make us feel ill.
bacterial diseases:
Salmonella -food poisoning spread by bacteria ingested in food, or on food prepared in unhygienic conditions. Symptoms of fever, abdominal cramps, vomiting and diarrhoea are caused by the toxins secreted by the bacteria. In the UK, poultry are vaccinated against Salmonella to control spread.
Gonorrhoea -STD causing symptoms of thick yellow or green discharge from the vagina or penis and pain when urinating. Easily treated with the antibiotic penicillin. Spread can be controlled by using barriers methods of contraception
protist diseases:
Malaria -symptoms of recurrent episodes of fever, which can be fatal. Spread is controlled by preventing the mosquito vectors from breeding and by using mosquito nets to avoid being bitten.
Bacteria can be grown in a nutrient broth solution or as colonies on an agar plate..
Uncontaminated cultures of microorganisms are required for investigating the action of disinfectants and antibiotics.
How do you prepare an uncontaminated culture using aseptic techniques?
Petri dishes and culture media must be sterilised before use.
Inoculating loops used to transfer microorganisms to the media must be sterilised by passing them through a flame.
The lid of the petri dish should be secured with adhesive tape and stored upside down to prevent condensation damaging the agar.
In school labs, cultures should generally be incubated at a maximum of 25℃ to prevent growth of harmful microorganisms.
What are the effects of antiseptics on bacterial growth?
antiseptics destroy or inhibit the growth of microorganisms and prevents the growth of bacteria
Phagocytosis
Phagocytes engulf and digest pathogens
Lymphocytes
Lymphocytes release antibodies which attach to antigens on a pathogen/cell
Antitoxin production
neutralises toxic substances produced by the pathogen
Memory cells divide and release antibodies quickly..
in response to a second infection by the same pathogen
Vaccination involves introducing small quantities of dead or inactive forms of a..
pathogen into the body to stimulate white blood cells to produce antibodies.
Antibiotics such as penicillin are medicines that help cure bacterial diseases by killing infective bacteria inside the body..
Antibiotics can’t kill viral pathogens and specific bacteria should be treated by specific antibiotics .
Nitrate deficiency
stunted growth as nitrate ions are needed for protein synthesis
Magnesium deficiency
discolouration as magnesium ions are needed to make chlorophyll
Where does the heart drug digitalis originate from?
foxgloves
Where does the painkiller aspirin originate from?
willow
Where does penicillin originate from?
Penicillium mould
New medical drugs have to be tested and trialled before use to check..
toxicity, efficacy and dose
results of testing and trials are only published after scrutiny by..
peer review to help prevent false claims.
Defects from the immune system can mean that an individual is..
more likely to suffer from infectious diseases
viruses living in cells can be the trigger for..
cancers
immune reactions initially caused by a pathogen can trigger..
allergies such as skin rashes and asthma
severe physical ill health can lead to..
depression and other mental illnesses
How are monoclonal antibodies produced?
Mouse lymphocytes stimulated to produce a specific antibody.
Lymphocytes combined with a tumour cell to form hybridoma cells.
Hybridoma cells both divide and make the antibody.
Single hybridoma cells are cloned to produce many identical cells that all produce the same specific antibody.
A large amount of the antibody can be collected and purified.
monoclonal antibodies are specific to one binding site on one protein antigen..
they can therefore target a specific chemical or type of cell within the body.
How are monoclonal antibodies used in pregnancy tests?
They are attached to the end of a pregnancy test stick onto which a woman urinates. If she is pregnant, HCG will be present in her urine and will bind to the monoclonal antibodies on the test stick. This will cause a change in colour or pattern which will indicate pregnancy.
How are monoclonal antibodies used in research?
To identify the presence of proteins or for purification of the target protein. When linked with fluorescent tags, monoclonal antibodies are used to analyse cell types in blood/tissue or for isolation of cells.
How are monoclonal antibodies used to treat cancer
Cancerous cells have antigens on their surface. Monoclonal antibodies can be designed to bind specifically with these antigens. When injected into a person's body, the monoclonal antibodies will bind with these cancer cells and clump them together. This makes it easier to identify a cancerous tumour, which can then be treated or removed. The antibodies can be made slightly radioactive to allow the cancerous cells to be detected in the body, for example using a PET scanner.
Monoclonal antibodies have also been designed to treat cancer by:
Carrying drugs that have been attached to them, to the tumour. This means that the drugs specifically target the cancer cells and can allow smaller doses of chemotherapy drugs to be used. This can reduce the side effects and reduce risk to healthy cells.
Encouraging your immune system to attack the cancer cells directly.
How are monoclonal antibodies used in labs?
Monoclonal antibodies can be produced to be able to target specific things in the blood, such as certain hormones, drugs and pathogens. Labs use them to run investigations about the levels of different substances in the blood so they can diagnose diseases and hormone imbalances and carry out drug tests.
How are monoclonal antibodies used to treat blood clots?
Monoclonal antibodies can be made to bind to antigens on blood clots. The monoclonal antibodies can be attached to dyes that will glow fluorescently under UV light or attached to radioactive elements which can be detected with special cameras. This can make locating the clot much easier and can help to speed up how quickly a patient is treated.
What are the three stages of the cell cycle?
interphase, mitosis and cytokinesis
What is interphase?
Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome.
What is mitosis?
One set of chromosomes is pulled to each end of the cell and the nucleus divides.
What is cytokinesis?
The cytoplasm and cell membrane divides to form two identical cells
Meristem tissue in plants can..
differentiate into any type of plant cell, throughout the life of the plant.
What are the uses of stem cells from meristems in plants?
Produce clones of plants quickly and economically.
Rare species can be cloned to protect from extinction.
Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.
Asexual reproduction involves only one parent and no fusion of gametes. There is no mixing of genetic information..
This leads to genetically identical offspring. Only mitosis is involved.
The formation of gametes involves what?
meiosis
Why is peer review helpful?
they provide a trusted form of scientific communication and confirmation and make sure no mistakes have been made repeatedly
reports of scientific developments in the popular media are not subject to peer review so they..
may be oversimplified, inaccurate or biased.
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