Cellular structure and transport

what are the two types of cells?
Prokaryotic and eukaryotic cells
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Key features of prokaryotes?
smaller than eukaryotes which allows them to reproduce rapidly, the cells DNA is in a nucleoid region-it has no nucleus as theres no cell membrane, its the oldest type of cell, single celled and single circular chromosome.
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Key features of eukaryotes?
contains a membrane bound nucleus, it evolved from prokaryotes, it's larger and more complex, it's either single celled or multicellular, it has multiple linear chromosomes.
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what is the definition of a prokaryote?
a cell of an organism which belongs to the kingdom prokaryotae that is characterised by lacking a nucleus.
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What is the definition of a eukaryote?
an organism consisting of a cell/cells which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus- lives in all living organisms.
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What is the role of the pilus?
For movement like a flagella.
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What is binary fission?
the division of parent body into 2 to produce2 identical cells. It is used fpr bacteria.
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What is generation time?
the time required for a cell to double/divide into 2.
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what does the term acellular mean? Give an example.
it means they are non-living particles. eg. viruses
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What do viruses contain?
nucleic acids as RNA and DNA as genetic material.
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Why is it hard to kill viruses?
Because they work inside our body cells which makes it difficult to destroy without damaging our cells.
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Why are viruses classed as acellular?
They cannot carry out the living processes and they only survive by living in cells.
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What are attachment proteins?
present on the outside of a virus cell which involves in binding other proteins to cell structures.
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What are the 2 types of defence mechanisms?
specific and non specific response
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What is specific response?
it is slower and specific to the pathogen eg antibodies, b-lymphocytes. It is the specific immune response.
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What is non-specific response?
It is an immediate response and the same for all pathogens eg physical barriers.
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Give examples of non specific immune response.
skin, cilia, stomach acid, mucus, nose hairs.
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What is the role of cytokines?
it communicates to other phagocytes to tell bacteria is near.
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what are the first 3 steps of phagocytosis?
The receptors on the phagocyte detects the bacteria and enters the phagocyte by endocytosis and engulfs it. Then a vesicle is formed called a phagosome. The phagosome then fuses with a lysosome to form a phagolysosome.
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what are the last 2 steps of phagocytosis?
The lysosome has enzymes (lysozyme) which digests the bacteria down. This then leaves soluble debris which is taken out of the cell by exocytosis.
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What kind of cell is a major histocompatibility complex (MHC)?
an antigen present cell (apc)
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What do T helper cells do to B cells?
They activate them which then bind to the b cells displaying antigens in the same way as phagocytes.
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What do t helper cells release once activated?
They release cytokines which are proteins that stimulate the division of B cells and cytotoxic T cells.
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What is the cell mediated response?
It is where T-lymphocytes only respond to antigens that are displayed on the surface of our body cells. When they join to the foreign antigens it triggers other lymphocytes.
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What is an antigen?
It is a protein which allows your body to recognise cells that are not self cells eg. foreign cells.
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What is the importance of MHC's?
They are antigens on out WBC which helps our immune system to identify pathogens.
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Give an example of what MHCs do?
In pregnancies the placenta blocks the antigens from passing onto the baby and destroying it as it is a non self cell.
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What are the steps of binary fission?
1. The cell replicates its DNA and the cytoplasmic membrane elongates which separates out the DNA molecules. 2. cross walls form which makes membrane invaginate 3. the cross walls form completely 4. daughter cells are produced.
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What do B-lymphocytes do?
defend against specific diseases, circulate in the blood and lymph.
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What are the two types of B-lymphocytes?
Memory B cells and effector/ plasma B cells.
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What are memory cells?
they are dormant versions which means they await infection.
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What are effector/ plasma cells?
they actively produce the antibodies.
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First 3 processes of humoral immunity?
B cells recognise the foreign antigen and forms a phagosome which matches its receptors. The antigen is kept on surface for t helper cell to be attracted to b lymphs to activate it. Antigens are activated so ready to be cloned.
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Last 3 processes of humoral immunity?
The cloning of antigens occur by mitosis which makes genetically identical memory and plasma cells. The antibodies are released from plasma and memory cells. The antibodies attach to antigens on pathogens and are engulfed.
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What do memory cells do after infection is gone?
they circulate in the blood and tissue fluid to respond to future infections from the same pathogen by dividing into plasma cells that produce antibodies.
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What are monoclonal antibodies?
They are antibodies which are cloned from a single group of identical white blood cells. They are made to bind to a a specific target antigen eg. cancer cells.
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What are some ethical issues on monoclonal antibodies?
expensive, use of animals.
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How can monoclonal antibodies help treat cancer?
they can carry toxic drugs or radioactive substances that bind to and kill the cancer cells. They can bind to antigens on the cancer cells that will stop the cancer cells from being able to grow and divide.
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What are the main cells involved in humoral immunity?
B -lymphocytes
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What are the main cells involved in humoral immunity?
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How are monoclonal antibodies produced?
A mouse is vaccinated and its b cells are removed. The WBC called B-lymphocytes produce the antibodies. Tumor cells are fused with cell to make hybridoma which make specific antibodies which then copy themselves.
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What hormone is present when a women is pregnant?
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What are the 3 main windows on a pregnancy stick?
test,reaction and control site.
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what does the test site do?
the test site is where the urine moves up the stick and the hormone hcg would bind to the antibodies in the test site and this would cause a colour change because of an enzyme reaction.
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why is the colour change from the control site important?
because it only shows that the kit is working and hasnt got any problems.
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What happens at the reaction site?
It has mobile monoclonal antibodies where the hcg hormone would bind to it and are binded to coloured beads.
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What is inside a vaccine?
a weakened/ dead pathogen
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What are the 4 types of vaccines?
live attenuated, active, DNA, subunit.
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What is a live attenuated vaccine?
It is where the full, live pathogen is injected but it is a weakened version. They're difficult to make and are bad for weak immune systems.
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What are inactive vaccines?
This is where the pathogen is dead but these vaccines don't last long so require boosters.
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What are DNA vaccines?
This is where you inject DNA from antigens to initiate the response. You are likely to have fewer symptoms.
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What are subunit vaccines?
This is where you're injected with the pathogens antigens which is better for those who have weak immune systems.
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What is herd immunity?
this is where most of the population has been vaccinated so the disease wont spread as much and this also protects those who haven't got immunity as those who were vaccinated around them wouldn't spread and catch it.
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How does the body defend itself from invasion?
By being able to distinguish what is self cells and what is non self cells like pathogens.
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How do cytotoxic cells kill infected cells?
They bind to infected cells and make a protein called perforin which makes pores in the cells membranes. The pores makes the cell freely permeable to all substances which make ions and water flow in which causes it to swell and burst which is lysis.
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After lysis occurs in pathogens when being destroyed, what happens?
The pathogen is then labelled by antibodies from B-cells for destruction by phagocytes.
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What is endocytosis?
The inward transport of large molecules through the cell surface membrane.
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what is exocytosis?
The outward bulk transport of materials through the cell surface membrane.
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What are some ethics of using vaccines?
The use of animals are often seen as harming the animal which makes it unacceptable, the side effects may cause long term harm,
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Why are some parents reluctant to giving their child the MMR vaccine?
because there have been many links to peoples children gaining autism after having this injection.
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Card 2


Key features of prokaryotes?


smaller than eukaryotes which allows them to reproduce rapidly, the cells DNA is in a nucleoid region-it has no nucleus as theres no cell membrane, its the oldest type of cell, single celled and single circular chromosome.

Card 3


Key features of eukaryotes?


Preview of the front of card 3

Card 4


what is the definition of a prokaryote?


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Card 5


What is the definition of a eukaryote?


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