Cells- new Flashcards

Question

Talk about the phospholipid Bilayer.

Answer 1

Individual phospholipids which are a triglyceride consisting of 2 fatty acids and a phosphate group. The hydrophilic heads face outwards and the hydrophobic tails point inwards. This allows lipid soluble molecules to pass through but not water soluble molecules.

Answer 2

Strengthen the membranes to reduce lateral movement of other molecules to make the membrane less fluid at high temperatures and prevent leakages

Answer 3

carbohydrates covalently bonded to lipids in the membrane. The carb extends to act as a cell surface receptor and maintain stability.

Answer 4

Carbohydrate attached to extrinsic proteins act as cell surface receptors help cells attach to each other (forming tissues) and self recognition (ie lymphocytes)

Answer 5

Interspersed throughout the surface of the membrane (intrinsic proteins) or on the surface (extrinsic. some give mechanical support or cell receptors for things like hormones. Others completely span the bilayer creating protein channels allowing water soluble ions to diffuse across. others are carrier proteins which bind to molecules and change shape to move them accross

Answer 6

Movement of small, non-polar molecules from an area of high concentration to an area of low concentration. They move directly through the bilayer.

Answer 7

Large, charged ions and polar molecules that don’t diffuse easily require a channel protein. - Protein Channels, Water filled hydrophilic channels that allow water soluble ions to pass through. They open in the presence of a specific ion. - Carrier Proteins, When a specific molecule like glucose which is specific to the protein, it binds to the protein and change shape to allow them through.

Answer 8

Movement of water from an area of high water potential to an area of low water potential through a partially permeable membrane

Answer 9

The preassure created by water potential, measured in kilopascals In standard conditions of temperature (37) and preassure (100kPa), pure water has a water potential of 0kPa. - adding a solute lowers the potential - the water potential of a solute must always be lower than 0

Answer 10

Hypotonic- Lower solute concentration, more water, less solute. Hypertonic- High solute concentration, more solute, less water. Isotonic- Same solute concentration

Answer 11

Movement of substances like ions from a low to high concentration against the concentration gradient with the help of ATP and carrier proteins through a partially permeable membrane. 1. Ion binds to the carrier protein 2. ATP binds to protein and splits into ADP and a Phosphate Ion. 3. The protein changes shape allowing the ion to move accross 4. The phosphate ion is released and the protein changes back to the original shape

Answer 12

The active transport of sodium ions from the epithelial cell into the blood lowers the sodium ion concentration inside the cell and generates a sodium ion concentration gradient between the ileum and the epithelial cell Sodium ions move into the cell from the ileum by facilitated diffusion, carrying glucose molecules along with them via a cotransport protein The glucose concentration inside the epithelial cell increases, and glucose molecules enter the blood via facilitated diffusion

Answer 13

The immune system is made up of specialised cells that respind to foreign objects and protect an individual from harm. The cells detect: **Toxins-** harmful substances produced by pathogens, detected by immune cells **Cells from other organisms-** Immune cells csn detect the presence of cells from other organisms of the same species, ie, an organ transplant **Pathogens-** Microorganisms which cause disease **Abnormal Body Cells-** Ie. cancerous cells

Answer 14

molecules that are present on the cell surface membrane if all cells that elicit an immune response if they are foreign. Every cell has a specific antigen that binds to complementary receptors

Answer 15

The immune system responds to antigens which are the protein layer around a pathogen which have a specific structure which is unique to each cell. Non-Specific- Non-specific immune responses are innate, immediate, the same for all pathogens and act as a physical barrier. Its less effective Specific- The specific Immune response is antigen specific and produces responses specific to one pathogen only .

Answer 16

PHAGOCYTOSIS- 1. When pathogens enter the body, they release attractants to bring phagocytes closer- chemotaxis 2. Phagocytes have several receptors on their surface that recognize and attach to the chemicals on pathogens 3. They engulf the pathogen into itself and form a vesicle known as a phagosome 4. Lysosomes fuse with the phagosome 5. Enzymes called lysozymes destroy the ingested bacteria via hydrolysis of their cell walls. 6. The soluble products are absorbed into the cytoplasm

Answer 17

B cells: These lymphocytes produce antibodies that recognize and bind to specific antigens on pathogens, marking them for destruction by other cells of the immune system. Involved in the humoral response T cells: They move to the thymus gland where they mature and are involved in cell mediated response. There are two types of T cells involved in the specific immune response. Helper T cells help activate B cells and other immune cells, while cytotoxic T cells directly kill infected cells.

Answer 18

In the cell mediated response, phagocytes engulf pathogens causing them to ingest and process them eventually becoming an antigen presenting cell which is where the invading pathogens antigen is presented on the surface of the WBC’s membrane. Examples include cancer cells, phagocytes, body cells, transplanted cells or viral infected cells. Helper T cells receptors bind to the complementary antigens on the APC’s which activate T cells to rapidly divide via mitosis. These clones can have different functions like: stimulating B cells to produce antibodies, stimulate phagocytosis, become memory cells or cytotoxic T cells (punch holes in infected cells using the chemical perforin to destroy them.

Answer 19

The surface antigens of invading pathogens are taken up by a B cell which processes them and presents them in its surface. Helper T cells attach to the processed antigens activating the B cell causing it to divide by mitosis to give a clone of plasma cells. These plasma cells produce the specific antibody that is complementary to the antigens on the patheogens surface.The antibody attaches to antigens on the pathogen and destroys them, this is the primary immune response. Some B cells develop into memory cells which can respond to future infections by the same patheogen by dividing rapidly and developing into plasma cells that produce antibodies, this is the secondary immune response.

Answer 20

Memory Cells- cells which replicate themselves when exposed to an invading pathogen and remain in the lymph nodes for decades searching for the same antigen resulting in much faster immune response should the individual be infected by the same pathogen again. So during the second exposure to the antigen, memory B cells are present. These respond to the pathogens infection faster by rapidly dividing bby mitosis to make genetically identical plasma cells in larger quantities, this is called clonal expansion Therefore more complementary antigens can be produced at a faster rate to destroy the pathogens.

Answer 21

Antibodies are protein chains forming a Y shape structure which is complementary to only a signle antigen. They work by forming an antigen antibodu complex which serves as markers for phagocytes to destroy attached cells. They clump cells together making it easier for phagocytes to find (agglutination)

Answer 22

Antigenic Shift- occurs when a virus undergos sudden change in genetic makeup creating a completely new strain. It occurs when a non-human virus enters a host and combines with a human virus. This way memory cells dont detect the altered antigens so its no longer effectve Antigenic Drift- occurs when a virus undergoes a gradual change in genetic makeup causing a different but somewhat similar generic makeup to present. Drift occurs when a virus undergoes gradual mutatuons which overtime can lead to the creation of a new virus.

Answer 23

Immunity is the ability of an organism to resist infection. Passive Immunity- Produced by the introducion of antibodies into individuals from an outside source. No dircect contact to the patheogen or its antigen is necessary to induce immunity. As the antibodies are not being produced by the individuals themselves, the antobodies arent replaced when broken down so its short lasting. Examples incude: The Mothers Placenta or milk as a transfer od antivodies, anti-venom or infected antibodies. Active Immunity- Produced by stimulating the production of antibodies by individuals own immune system causing the formation of memory cells. Needs the exposure to a pathogen. Has a lag time however is long-term. Examples include: Natural infection and vaccination

Answer 24

Vaccination is the introduction of the appropriate disease antigens in the form of dead or inactive pathogens into the body by injections. The intention is to stimulate an immune response to form memory cells to allow a greater and more immediate response to a future infection, The result is in the future if a person gets infected again, antibodies can be produced rapidly to overcome the infection quickly. When a sufficiently large proportion of the population have been vaccinated, it is called Herd Immunity. Pathogens are passed from one person to another when in close contact, however if a large amount of the population is immune, it is more difficult for a pathogen to spread. This is good as babies and young children can be protected as they cannot be vaccinated due to their immune system not being developed fully.

Answer 25

- The production and testing of vaccines may be done on animals - The risks of the vaccine (ie side effects) have to be balanced with benefits - Has to be tested on humans - Expensive - Should they be compulsory?

Answer 26

Monoclonal antibodies are made from b lymphocytes which are unspecified. they bind to antigens in the samew w\y as naturally produced antibodies. Due to there being many different types of antigens, each B cell will produce a different complementary antibody. It is therefore medically useful to be able to produce many clones of a single type of antibody

Answer 27

- Direct Therapy- Monoclonal antibodies which are specific to antigens found on the surface of cancerous cells can be used to target and then destroy the cells as part of an immune response - Indirect Therapy- Drugs can be attached to monoclonal antibodieslike a cytotoxic drug. The antibody isb then used to direct the drug toward the cells displaying a particular antigen - Diagnosis- Particular antigens are targeted by antibodies to measure levels of that antigen in the body - Pregnancy- Monoclonal antibodies in home pregnancy tests are specific to the hormone human chrionic gonadotrophin (hCG) in the urine sample:

Answer 28

Human Immunodeficiency Virus is a patheogen that can lead to the disease acquired Immune Dificiency Syndrome (AIDS) It contains:

Answer 29

1. GP120 binds to the protein CD4 found on T-helper cells. 2. The capsid fuses with the cell surface membrane and the RNA and reverse transcriptase enters the cell. 3. The reverse transcriptase converts RNA into DNA 4. Newly made DNA is moved into the nucleus and inserted into the cells DNA 5. The HIV DNA creates mRNA (messenger RNA) with the help of viral enzymes, which contains the instructions for making new viral proteins and RNA. 6. The mRNa passes out of the nucleus through a nuclear pore and uses the cells protein synthesis mechanisms to make HIV 7. These break away forming new HIV particles

Answer 30

HIV causes AIDS by killing ot interfering eith the normal functioning of helper T cells decreasing the number of them. This means the immune system cannot stimulate B cells to produce antibodies and memory cells may become infected or destroyed. As a result, the body is unable to produce adequate immune response and becomes susceptible to other infections and cancers.

Answer 31

Enzyme linked immunosorbant assay. It uses antibodies to detect the presence of a protein in a sample and the quantity. This is used to detect HIV and the pathogens of diseases.

Answer 32

In bacterial cells, water constantly enters via osmosis, this entry of water would normally cause the cell to burst but it doesnt due to the tough murein walls. Antibiotics like penicillin inhibit certain enzymes required for the synthesis and assembly of peptide cross linkages which weakens the walls making them unable to withstand preassure, killing the cells Viruses rely on host cells, therefore lack metabolic pathways and cell structures. Antibiotics are ineffective as there are no metabolic mechanisms or structures for them to disrupt. They also have a protein coat so dont have sites where antibiotics can work

Answer 33

Capsid- A protein coat containing genetic material in the form of DNA or RNA Attachment proteins (glycoproteins- Attached to capsid, help viruses to recognize and bind to cells in the host. Genetic Material (DNA or RNA)- Contains instructions for making new copies of the virus (only inside living host cells) Lipid Envelope- Made from fatty lipid molecules taken from cells in the host â†’ only in some

Answer 34

Viruses depend on a host cell to infect and reproduce, when found outside of host cells, viruses exist as a protein coat or capsid, sometimes in a membrane. It encloses either a DNA or RNA which codes for the virus elements. 1. Attachment- The Virus attaches to the surface of the host cell 2. Entry- Viral genetic info enters host cell 3. Replication- Viral DNA/RNA replicates and new viral proteins are made forming new capsids. 4. Assembly- New viral particles are assembled 5. Release- Host cell lyses (bursts) leaving newly made viruses

Cells- new Flashcards

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