cells Flashcards

Question

what is the rate of mitosis controlled by?

Answer 1

-environment -growth factors -genes

Answer 2

-made up of a phospholipid bilayer -it is permeable (has channel and carrier proteins) -controls the movement of substances in and out of the cell

Answer 3

-cytoplasm -phospholipid -carbohydrate -extracellular fluid -glycolipid -glycoprotein -transmembrane protein (channel, carrier) -peripheral protein -cholesterol -filaments of cytoskeleton

Answer 4

-phosphate head which is hydrophilic (attracting water), facing outwards -fatty acid tails which are hydrophobic (hating water), facing inwards -forms a bilayer that allows lipid soluble molecules to enter/exit -prevents water soluble substances entering/leaving -membrane is flexible and self sealing

Answer 5

-span the membrane channel= -water filled pore allowing diffusion of water soluble ions -facilitated diffusion carrier= -bind ions or other molecules causing a conformational change so that the molecule can move across the membrane -facilitated diffusion and active transport

Answer 6

-does not span the entire membrane

Answer 7

-adds strength to the membrane -hydrophobic, helps to prevent loss of water and dissolved ions -pulls fatty acid tails together, limits movement but still fluidity

Answer 8

-carbohydrate covalently bonded to a lipid -cell to cell adhesion -cell recognition -blood types

Answer 9

-cell to cell adhesion -cell recognition -cell surface receptors for hormones and neurotransmitters

Answer 10

fluid= -phospholipid molecules can move -allows flexibility, ability to change shape and gain/lose molecules mosaic= -proteins vary in size, shape and pattern

Answer 11

most molecules do not freely diffuse across the membrane because: -they are too large to pass through channels -not lipid soluble -charged (polar) -repelled by protein channels due to the charge on them

Answer 12

-doesn't require energy from an external source -the kinetic energy that the particles possess means that they are constantly in motion -motion is random -diffusion, facilitated diffusion and osmosis are passive

Answer 13

-net movement of molecules or ions from a region of where they are more highly concentrated to one where their concentration is lower until evenly distributed

Answer 14

-net movement of molecules from an area of higher concentration to an area of lower concentration using transmembrane proteins such as channel or carrier proteins -charged ions and polar molecules would enter the cell in this way

Answer 15

-passage of water from a region where it has a higher water potential to a region where it has a lower water potential through a selectively permeable membrane

Answer 16

-pressure created by water molecules -measured in kilopascals (kPa)

Answer 17

-movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using ATP and carrier proteins

Answer 18

1. sodium ions actively transported out of cells by the sodium potassium pump into the blood, taking place in a carrier protein 2. maintains a much higher concentration of sodium ions in the lumen of the intestine than inside the cell 3. sodium ions diffuse into the cells down the concentration gradient through facilitated diffusion 4. as the sodium ions diffuse in through the second carrier protein, they carry either amino acid molecules or glucose molecules into the cell with them 5.the glucose/amino acids pass into the blood plasma by facilitated diffusion using another type of carrier

Answer 19

-microvilli= increases surface area of the wall to maximise the rate of absorption of digested food -increased number of channel/carrier proteins= maximise the rate of absorption of nutrients

Answer 20

-non specific -specific

Answer 21

-immediate response -same for all pathogens -some examples are: physical barriers (skin) and phagocytosis

Answer 22

-slower response -longer lasting effects -specific to each pathogen -some examples are: cell mediated response (T lymphocytes) and humoral response (B lymphocytes)

Answer 23

-every cell (self/non self) will have markers on its surface -proteins are used as antigens as they have specific shapes and varied sizes -allow cells of the immune system to recognise: pathogens, toxins, none self cells from organisms of the same species, abnormal cells

Answer 24

transmission electron microscope (TEM)= -beam of electrons passes through a thin part of specimen from below, this absorbs the electrons therefore appearing dark scanning electron microscope (SEM)= -beam of electrons through the specimen from above (doesn't have to be thin)

Answer 25

-phagocyte is attracted to the pathogen by chemical products of the pathogen -it moves towards the pathogen along a concentration gradient

Answer 26

-the phagocyte has several receptors on its cell surface membrane that attach to chemicals on the surface of the pathogen

Answer 27

-lysosomes migrate towards the phagosome formed by engulfing the pathogen

Answer 28

-the lysosomes release their lysozymes into the phagosome where they hydrolyse the bacterium

Answer 29

-the hydrolysis products of the bacterium are absorbed by the phagocyte

Answer 30

-they are produced by stem cells in the bone marrow -T lymphocytes and B lymphocytes -T lymphocytes mature in the thymus gland and is a cell mediated response -B lymphocytes mature in bone marrow and is a humoral response

Answer 31

-they will only respond to antigens that are presented on the outside of the cell -phagocytes that have engulfed a pathogen and presented its antigen on its surface -a cell that has been infected by a virus, cell puts viral antigen on its surface -transplanted cells -cancer cells

Answer 32

1. pathogens invade body cells or are taken in by phagocytes 2. phagocytes places antigens from the pathogen on its cell surface membrane 3. receptors on a specific helper T cell fit complimentary onto these antigens 4. this attachment activates the T cell to divide rapidly by mitosis and form a clone of genetically identical cells 5. the cloned T cells: -become memory cells -stimulates phagocytes -stimulates B cells to divide and produce antibodies -activate cytotoxic cells (Tc)

Answer 33

-produce a protein called perforin -makes holes in the cell membrane of infected cells, leading to water moving in and cell swells (lysis)

Answer 34

-hydrolyse material ingested by phagocytic cells -release enzymes to the outside of the cell in order to destroy material around the cell -digest worn out organelles so that the useful chemicals made out of it can be re used -break down cells after they have died

Answer 35

-site of protein synthesis -speed up the time of reactions -80s= found in eukaryotic cells -70s= found in prokaryotic cells, mitochondria and chloroplasts

Answer 36

-contains cellulose -provides mechanical strength in order to prevent the cell bursting under the pressure created by osmosis -to give mechanical strength to the plant as a whole -allow water to pass along it and so contribute to the movement of water through the plant

Answer 37

-fluid filled sac bounded by a single membrane called a tonoplast -it contains sugars and amino acids acting as a temporary food store -support herbaceous plants, by making cells turgid

Answer 38

algae= -made up of both cellulose and glycoproteins fungi= -made up of a mixture of chitin, glycan and glycoproteins

Answer 39

-binary fission

Answer 40

-replication of the circular DNA and of plasmids -division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids

Answer 41

-pathogens -toxins -abnormal cells

Answer 42

1. the surface antigens of an invading pathogen are taking up by a B cell 2. the B cell processes the antigens and presents them on the surface 3. helper T cells attach to the processed antigens on the B cell thereby activating the B cell 4. the B cell is now activated to divide by mitosis to give a clone of plasma cells or memory cells 5. the cloned plasma cells produce and secrete the specific antibody that exactly fits the antigen on the pathogen's surface 6. the antibody attaches to antigens on the pathogen and destroys them 7. the B cells that develop into memory cells respond to future infections by the same pathogen by dividing rapidly and developing into plasma cells that produce antibodies. This is the secondary immune response.

Answer 43

-proteins with specific binding sites -the antibody binding sites are complimentary to a specific antigen, forming an antigen-antibody complex -made up of 4 polypeptide chains (2 light, 2 heavy) -the binding site is different on different antibodies and is therefore called the variable region -the rest of the antibody is known as the constant region, this is the same on every antibody

Answer 44

-antibody produced from a single clone of cells -can be used to target specific substances and specific cells -one type they target is cancer cells -antibodies are given to a patient and attach themselves to the receptors on their cancer cells and block the chemical signals

Answer 45

-produced by stimulating the production of antibodies by the individual's own immune system -direct contact with pathogen/antigen -takes time to develop -long lasting -two types of active immunity: natural active, artificial active

Answer 46

-results from an individual becoming infected with a disease under normal circumstances -body produces its own antibodies

Answer 47

-forms the basis of vaccination -involves inducing an immune response, without them suffering the symptoms of the disease

Answer 48

-limited resolution -lower magnification compared to other microscopes

Answer 49

-image is not in colour -living specimens can not be observed -specimens need to be extremely thin

Answer 50

-high resolution -high magnification

Answer 51

-act as a control centre of the cell -retain the genetic material of the cell in the form of DNA and chromosomes -manufacture ribosomal RNA and ribosomes

Answer 52

-involves killing dividing cells by blocking a part of the cell cycle -drugs used to treat cancer usually disrupt the cell cycle by: -preventing DNA from replicating -inhibiting the metaphase stage of mitosis by interfering with spindle formation

Answer 53

-produced by the introduction of antibodies from an outside source -no direct contact with pathogen -no memory cells formed -antibodies not replaced when broken down -immunity is acquired immediately -no long lasting immunity -examples are: anti venom, mother to foetus in utero

Answer 54

-an antigen is a protein on a cell surface membrane that triggers an immune response

Answer 55

-few side effects -economically available in sufficient quantities to immunise the majority of the vulnerable population -equipment to be able to produce, store and transport the vaccine -has to be administered properly at the correct time -needs to be able to immunise the majority of a population in order to provide herd immunity

Answer 56

-when a large proportion of the population has been vaccinated to make it difficult for a pathogen to spread within that population

Answer 57

-pathogen may mutate frequently which can cause antigenic variability -vaccination might not cause immunity in some people -too many varieties of pathogen -pathogen 'hiding' from the immune system -objections to vaccinations -individuals could develop the disease soon after being vaccinated but before the immunity has developed to a high enough level

Answer 58

-use of animals -trials and testing -side effects causing long term harm -trialling new vaccines with unknown health risks in countries where the targeted disease is common -should they be compulsory? -should expensive programmes continue even when a disease is almost eradicated?

Answer 59

-human immunodeficiency virus -targets helper T cells (Th) -treats symptoms using antiretroviral drugs

Answer 60

-genetic material (RNA) -integrase= integrates viral DNA into host cell DNA -lipid envelope= made of cell membrane/phospholipid bilayer -capsid -matrix -attachment proteins= attaches to a CD4 receptor in Th cell -revers transcriptase= reverse transcription (produce DNA from RNA)

Answer 61

1. following infection, HIV enters the bloodstream and circulates around the body 2. a protein on the HIV readily binds to a protein called CD4 3. the lipid envelope fuses with the cell surface membrane. The RNA and enzymes of HIV enter the helper T cell 4. the HIV reverse transcriptase converts the virus' RNA into DNA 5. the newly made DNA is moved into the helper T cell's nucleus where it is inserted into the helper T cell's DNA 6. the HIV DNA in the nucleus creates messenger RNA using the cell's enzymes. This mRNA contains the instructions for making new viral proteins and the RNA to go into the new HIV 7. the mRNA passes out of the nucleus through a nuclear pore and uses the cell's protein synthesis mechanisms to make HIV particles 8. the HIV particles break away from the helper T cell with a piece of its cell surface membrane surrounding them which forms their lipid envelope

Answer 62

-HIV reduces the number of Th cells, therefore: -reduced stimulation of phagocytosis -reduced stimulation of B cells -reduced activation of Tc cells -reduced memory cells

Answer 63

-enzyme linked immunosorbent assay -uses antibodies to detect the presence of HIV

Answer 64

1. apply sample to a surface (blood on a slide) to which all the antigens in the sample will attach 2. wash surface several times to remove any unattached antigens 3. add the antibody that is specific to the antigen we are trying to detect and leave the two to bind together 4. wash the surface to remove excess antibody 5. add a second antibody that binds with the first antibody. This second antibody has an enzyme attached to it 6. add the colourless substrate of the enzyme. The enzyme acts on the substrate to change it into a coloured product (positive result) 7. the amount of the antigen present is relative to the intensity of colour that it develops

Answer 65

-cause agglutination of the bacterial cells. Clumps of bacterial cells are formed, making it easier for the phagocytes to locate them as they are less spread out within the body -then serve as markers that stimulate phagocytes to engulf the bacterial cells to which they are attached