Cells Flashcards

Question

interphase

Answer 1

when cell increases in mass and size preps cell for division by synthesising proteins and replicating its DNA G1 phase- cells make RNA enzymes and proteins required for growth, in this phase a signal is received telling cell to divide again S phase- Repicated DNA semi Conservatively resulting In 2 sister chromatids G2 phase- continues to grow I'm prep for mitosis e.g. form mitotic spindles and DNA is checked for errors

Answer 2

prophase- chromosomes condense and are visible these consist of 2 identical sister chromatids that are joined at centrometer 2 centrioles moved towards opp poles of cell nuclear membrane breaks down into small vesicles spindle fibres begin to emerge from centrioles

Answer 3

chromosomes line up at the equator of the cell chrosomes attach to spindal fibres by their centeomeres

Answer 4

spindle fibres shorten and centromere splits this pulls the sister chromatids to the opp poles of the cell

Answer 5

chromosomes arrive at opp poles and begin to uncoil the spindle fibres break down nuclear envelope begin to reform around each set of chromosomes

Answer 6

final step in cell cycle cytoplasm divides forming 2 genetically identical daughter cells After mitosis( propahse metaphase anaphase and telophase)

Answer 7

growth of multicellular organisms- enables unicellular zygote to grow to multicellular organisms growth can be across whole body or confined to certain areas Replacement of cells and repair of tissues- damaged tissues can be repair as cells are constantly dieing and need to be replaced by genetically identical ones happens rapidly on skin and gut lining some animals can even regenerate whole body parts asexual reproduction- single parent organisms creates genetically identical offspring in unicellular cell division results in reproduction of geneticaly identical offspring in multicellular organisms new grow from parent organism and then detach from parent in diff ways

Answer 8

prophase- chromosomes condense and are visible but are all over the place nuclear envelope is breaking down metaphse- chromosomes limed up along the middle of the cell anaphase- moving away from the middle towards opp poles V formation telophase- arrive at opp poles begin to uncoil and nuclear envelope is reforming looks like an 8 cytokenisis-cleavage furrow forms and seperate 2 cells

Answer 9

proportion of cells undergoing mitosis mitotic index = no of cell with visible chromosomes ÷ total no of cells ×100 to get percentage

Answer 10

arise due to uncontrolled mitosis cancer cells divide rapidly and uncontrollably, forming a tumour (abnormal mass of cells) start when these is a mutation in genes that controlled cell division, these 2 genes are called Oncogene (proto-oncogene) and tumor supresser gene mutation common most dont cause cancer either result in early cell death or cell being killed by immune system most cells can be replaced so this rarely effects the body mutations that result in gens of cancerous cells don't result in death allowing mutationbto pass on to cell decendants by the time tumour are detected the containbmillions of these cells carcinogenesis are any agents that may cause cancer benign tumours don't spread so don't cause cancer some spread these are called malignent and cause cancer

Answer 11

almost 50% of people with cancer have a mutated p53 gene that helps control cell growth but other reasons cause it so there is no single treatment most work by controlling rate of mitosis methotrexate- inhibits synthesis of DNA nucleotides in cell Vincristine and taxol- prevent formation of mitotic spindles

Answer 12

process of cell division in prokaryotic cells and is much simpler due to them not having nucleus, chromosomes, membrane bound organelles or spindle fibres 1.single circular DNA molecule undergoes DNA replication 2.Any plasmids undergo DNA rep 3.Parent cell divides in 2 with cytoplasm roughly halfed between 2 daughter cells 4.The 2 daughter cells each contain a single copy of the circular DNA molecules and a variable no of plasmids

Answer 13

controls what enters and exits the cell it is semi permeable consists of proteins, glycoproteins, phosolipids, carbohydrates and cholesterol phosolipids form a bilayer fluid-bilayer constantly moving relavtive to everything in it mosaic- proteins are unevenly distributed throughout membrane, diff shapes and sized selectively permeable- determined by type and distribution of transport proteins and phosolipid molecules present

Answer 14

phosolipid bilayer channel protein carrier proteins glycoproteins glycolipids enzymes cholesterol

Answer 15

Can- small non polar lipid soluble can't- large polar water soluble

Answer 16

have specific tertiary structure that span membrane and make hydrophilic tunnel across it selective will one accept on or a few close types of molecules for transport facilitated diffusion- small charge molecules e.g. ions and polar molecules aquaporins- specifically water via osmosis some are open all the time and some are gated so can open and close in response to signal

Answer 17

specific tertiary structure and allow transport of ions and polar molecules by facilitated diffusion or A transport change shape to move target molecules from one side of membrane to the other typically selective for 1/ a few substances often change shape in response to binding of their target molecules with the shape change moving it to opp side

Answer 18

shape of A site is comp and specific to its substrate e.g. Maltase enzyme is found in the cell membrane of small intestine

Answer 19

other protein molecules act as specific receptors for hormones with comp shape attach to binding sites and allow a cell to respond e.g. insulin

Answer 20

glycolipids- composed of carbohydrates attached to phospholipids within the membrane they are important for cell recognition glycoproteins- composed of carbs and protein these are on the outer surface of the membrane and are important in cell rec, sometimes act as antigens

Answer 21

decreases permeability and increases the stability of the membrane by restricting movement of other molecules diff types of cells have diff amount of cholesterol causes fatty acid chains to pack close together, reducing permeability and increases stability of membrane

Answer 22

ph- denatured enzymes creating holes in the membrane which makes it more permeable temp- denatured proteins creating holes in the membrane making it more permeable fatty acid tails become less rigid and more moment which increases permeability ethanol- breaks down lipids ad they are soluble in it (dish soap is same)

Answer 23

diffusion rate= (SA× conc gradient)/ diffusion distance or pathway

Answer 24

passive process when there are an equal no of molecules on either side (equilibrium) there is no more net movement only allowance non polar small and lipid soluble molecules Diffusion is the net movement of particals from a higher to lower concentration until evenly distributed

Answer 25

temp- increase k energy faster movement of molecules causing faster rate of diffusion SA- more cell surface membrane to pass through so faster diffusion e.g. Alveoli Conc gradient- and conc gradient increases rate of diffusion is faster diffusion Distance- thinner surface/Distance the faster the rate of diffusion (cause it need less energy?)

Answer 26

proteins help molecules pass through membrane down comc gradient polar molecules can't pass between tails of bilayer as they are non polar and repel polar so they move in through channel or carrier proteins these have specific tertiary structures and only transport molecules with comp shapes to their binding sites it is passive still from higher to lower conc

Answer 27

Net movement of water molecules from a higher Water potential to a lower water potential across a partially permeable membrane water is polar so uses aquaporin to move down water potential gradient

Answer 28

pressure exerted by water molecules colliding with things measure in KPa more free moving water molecules higher wa p pure water every molecule is free moving so it has the highest wa P possible so it has a value of 0 adding solute makes it more negative as water is a dipole and attract charges on molecules causing no of free loving water molecules to decrease water moves down conc form high to low Wa P so from more to less free water molecules hypotonic- solution has higher Wa P than cell so water moves into cell causing it to swell Hypertonic- solution has a lower Wa P so water moves out of cell into solution causing it to shrink Isotonic- same Wa P inside and outside of cell so no net movement of water

Answer 29

transport of membranes against their conc gradient, from a low to high conc only uses carrier proteins with specific tertiary structures and comp binding sites requires ATP energy produces from its hydrolysis cause carrier proteins to change shape and push the molecule through the membrane into an area of higher conc

Answer 30

co transporters are a type of carrier protein, bind to 2 molecules at a time conc gradient of 1 molecule is used to move the other against its own conc gradient e.g. glucose plus A acid absorption

Answer 31

each type of cell has a specific molecule on its cell surface membranevthat help to identify it allows immune system to identify self and non self molecules- antigens these come from pathogens, cells from other organism of the same species, abnormal body cells and toxins

Answer 32

An antigen is a foreign molecule- usually a protein- that stimulates an immune response that results in the production of a specific antibody they have a specific shape and tertiary structure that is complimentary to an antibody or receptor of an immune cell if not recognized bu immune system then it will be treated as non self and immune response will initiate glycolipids and glycoproteins act as antigens

Answer 33

phagocytes- A group of white blood cells which can distinguish via receptors on their cell surface between cells that display self antigens and which don't e.g Neutrophils (most common type) they will destroy any cell with non self antigen in phagocytosis phagocytosis- 1) early in infection phagocytes move to site and engulf pathogen, forming a vesicles called a phagosome 2) phagocytes contain many lysosomes which fuse to phagosome 3)hydrolytic enzymes called lysozymes destroy pathogen, debris realised by exocytosis

Answer 34

phagocytes also play key role as antigen presenting cells after phagocytosis the display part of pathogen (antigen) on cell membrane allows for the activation of other immune cells e.g T and B cells which can mount a specific immune response to help remove pathogen more efficiently.these have specific receptors complimentary shape to antigen presented

Answer 35

involves immune cells becoming activated in response to presence of specific antigen, large amounts of specific immune cells are produced to provide Large response, typically removing entire pathogen and creating immunity as memory cells are produced so large and faster response when reinfected split into Cellular response- involves cells humorless response- produces antibodies these can be activated either by antigen directly via receptors on surface or indirectly via antigen presentation

Answer 36

antigen presentation initiates the cellular response 1)T helper cells have a receptor which is comp in shape to a specific antigen 2)upon binding T helper cell becomes activated and divide by mitosis to create many clones 3) also release cytokines-chem messengers- affects stim B cells to divide my mitosis stim phagocytes- phagocytosis stim cytotoxic T cell- contain receptors which bind to antigens on surface of virally infected or cancer cells, upon binding release performing which makes holes in cell membrane leads to apologise and being destroyed 4)once activated some helper T cells become memory cells and stay in blood helping for faster immune response on re infection

Answer 37

involves antibodies B cells can be stimed directly by antigen binding to receptors on their surface or indirectly by release of cytokines from T helper cells upon stim they divide by mitosis to produce clones some differentiate into plasma cells which produce and release large quantities of monoclonal antibodies secrete into the blood this is primary response some B cells became memory cells, which persist in blood (years) and help mount a father immune response on reinfection

Answer 38

monoclonal antibodies have some Tertiary structure produced by intentional or cloned plasma cells they are an example of quaternary protein 4 polypeptide chains( 2 heavy 2 light) are joined by disulphate bridges. Form a Y shape each antibody will have specific tertiary structure with 2 antigen binding sites that are comp to only 1 antigen function- binds to antigen via binding site form antigen antibody complex, due to the 2 antigen binding sites allowing antibodies to bind to antigens and clump them together-agglutination. This marks the antigen and helps attract phagocytes to infection, leads to destruction via phagocytosis

Answer 39

human immunodeficiency virus Causes acquired immune deficiency symdrome like all viruses it is A cellular-no cell surface membrane and can't rep independently. key features: RNA genome Reverse transcriptase allows production of a copy of DNA from viral RNA called Reverse transcription Genome surrounded by protein coat called Capsid lipid envelope contains attachment proteins enable virus to specifically bind to and infect T helper cells

Answer 40

Attachment proteins on HIV bind to specific receptors on T helper cells viral RNA and reverse transcriptase enter cell reverse transcrpitase converts RNA to DNA using host nucleotides, reverse transaction Viral DNA into nucleus and is inserted into host cell genome (DNA)person is now infected transcription of HIV DNA into HIV mRNA which translated to produce HIV proteins Infected T helper cells starts to assemble new virus particals virus paritcald are released from the T helper cells over time this leads to a reduction in the no of T helper cells and is the driving force behind AIDS

Answer 41

by replicating using body's T helper cells HIV reduces an individuals ability to respond to pathogens as cell mediated response and humoral response is compromised as overtime no of T cells decrease as the are destroyed by infection HIV doesn't kill directly but by reducing no of T cells it leave people vulnerable to secondary diseases, this is why HIV leads to AIDS Many AIDS suffers develop infections of lungs intestines or brains and eyes also experience weight loss and diarrhea.Also develop rare cancers that would normally be destroyed uninfected have 800- 1200 T cells per mm³ of blood but someone with AIDS has as few as 200 AIDs can be screened for by checking no of T helper cells or by using ELISAs to measure conc of HIV antibodies

Answer 42

work by preventing bacteria for synthesising murein cell walls or by directly damaging the cell wall, leads to bacteria being destroyed as they are susceptible to osmotic damage some also inhibit binary fission by preventing DNA rep and protein synthesis as viruses have capsids rather than a marine cell wall they don't work for them also because viruses spend most of the time within host cell they are also out of reach of antibiotics

Answer 43

Dead or weakened or specfic antigen (attenuated) form of the pathogen that stimulates an immune response typically infected intramuscularly contains antigen but never live form of pathogen Covid 19 vaccine contained mRNA used by ribsomes to make spike protein( antigen) used by SARS-COV-2 to attach and infect lung cells

Answer 44

both cellular and humoral response start after taking it.Focus on humoral, stim of B cells lead to differentiation into plasma cells + production of small no of antibodies Memory cells also produced and upon actual infection memory cells will coordinate secondary response producing higher conc of antibodies and faster can also replicate sec response by 2 or 3rd vaccine/ booster

Answer 45

High rate of immunization unvaccinated individual are also protected as vaccinated recover from infection quickly and so are less likely to spread the pathogen to unvaccinated

Answer 46

natural selection selects for pathogens that can vary their antigens and evade detection due to this these random mutations mean T cells and antibodies aren't complimentary to antigen anymore viruses are experts at this on reason flu vaccine updates every year

Answer 47

side effects new vaccines developed and tested using animals and cell cultures, may show positive effects here but doesn't mean they will have same + effect in humans- Common limitation Harm may occur to animals during vaccine research, can be argue that it's okay as it stops human suffering and allows drug development If it causes lots of harm to animals the Vet would stop the experiment to minimize suffering, could be repeated at lower conc to reduce side effects

Answer 48

ones body producing antibodies and memory cells upon antigen exposure. primary response is slower and it can take days to build up high enough conc to destroy pathogen, due to memory cells u get long term immunity natural- infection artificial- vaccine

Answer 49

pre-made antibodies are recieved from elsewhere rapid acting and quickly destroys the antigen being targeted your body doesn't produce antibodies so no memory cells only short term protection natural- maternal antibodies from breast milk artificial- monoclonal antibodies (antivenom/antiserum)

Answer 50

have same tertiary structure produced by identical or cloned plasma cells can also be made in lab artificial antibodies can be used target therapeutic drugs as the antibody is specific to 1 antigen drug is attached to antibody can also be used as medical diagnosis in ELISA tests

Answer 51

side effects cost animal welfare potential limited effectiveness in humans often produced by introducing tumour to mice which are genetically engineered to produce large quantities of monoclonal antibodies

Answer 52

Enzyme-linked immune system assay These tests use monoclonal antibodies to detect a specific antigen in a sample M antibodies are fixed to bottom of test well A sample potentially containg antigen is added to well and will Bind to antigen binding site on antibody due to comp shape well is washed to remove unbound second monoclonal antibody is now added which is attached to enzyme will bring to another part of the antigen if it is present well washed again so unbound washed away last substrate is added and the enzyme on 2nd m antibody will convert this to coloured product colour change= + result and confirms antigen presence

Cells Flashcards

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