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cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what organelles are in an animal cell? (15)

A

cell membrane, cytoplasm, ribosomes, mitochondria, nuclear envelope, nuclear pores, nucleoplasm, nucleolus, chromatin, centrioles, lysosomes, ventricles, golgi apparatus, rough endoplasmic reticulum, smooth endoplasmic reticulum

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2
Q

what organelles are in a plant cell? (16)

A

chloroplasts, amyloplasts, mitochondria, cell membrane, cell wall, ribosomes, tonoplast, vacuole, rough endoplasmic reticulum, smooth endoplasmic reticulum, golgi apparatus, nuclear envelope, nuclear pores, nucleoplasm, nucleolus, chromatin

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3
Q

what is the structure of a mitochondria?

A

-cristae= extensions of the inner membrane, that help attachment of enzymes. Increases SA
-outer membrane
-inner membrane
-matrix= contains proteins, lipids, ribosomes and DNA
-contains DNA + ribosomes= proteins needed for respiration

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4
Q

what is the structure and function of a chloroplast?

A

-thylakoid= coin/disc stacked up to make grana or granum
-grana/granum= stack(s) of thylakoids, stacks increase SA
-intergranal lamella= connects each grana to each other
-outer membrane
-inner membrane
-stroma is the sight of light independent reaction of photosynthesis
-thylakoid membrane is the sight of light dependant reaction
-circular DNA and ribosomes to produce proteins needed for photosynthesis

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5
Q

what is the structure and function of golgi apparatus?

A

-add carbohydrate to proteins to form glycoproteins
-produce secretory enzymes
-secrete carbohydrates
-transport, modify and store lipids
-form lysosomes
–series of flattened sacs that extend from the endoplasmic reticulum

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6
Q

what is the structure and function of the nucleus?

A

-nuclear envelope= controls entry and exit of materials
-nuclear pores= allows passage of large molecules
-nucleoplasm= gel like material that makes up the bulk of the nucleus
-nucleolus= site of ribosomal RNA where ribosomes are assembled (RNA + protein)
-chromatin= contains DNA + protein

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7
Q

what is the structure and function of the smooth/rough endoplasmic recticulum?

A

smooth:
-lacks ribosomes
-functions are to synthesise, store and transport lipids and carbs
-double membrane
rough:
-ribosomes= provide a large SA for the protein synthesis, provide a pathway for the transport of materials
-cisterna
-double membrane

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8
Q

what are the steps of differentiation?

A

-egg + sperm= zygote
-zygote goes through mitosis and becomes an embryo
-embryo differentiates/specialises into a type of cell (sperm, nerve etc)
-over 200 cell types

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9
Q

what organelles are in a prokaryotic cell?

A

ribosomes, plasmids, circular DNA, cytoplasm, cell membrane, cell wall (murein), mucilaginous capsule, flagella

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10
Q

what are the organelles that are not always found in prokaryotes?

A

plasmids, flagella, mucilaginous capsule

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11
Q

what is the prokaryotic cell division?

A

binary fission

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12
Q

what organelles are in a virus cell? (3)

A

genetic material, protein capsid, attachment proteins

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13
Q

how do you prepare for cell fractionation?

A

-the solution needs to be placed in a solution that is:
1. cold= reduces enzyme activity as enzymes could break down organelles
2. isotonic= prevents osmosis which could lead to organelles bursting/shrivelling
2. buffered= maintains pH as could affect organelle structure or enzyme activity

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14
Q

what are the steps of cell fractionation?

A

-cut up tissue and keep it in a cold, isotonic, buffered solution
-further cut up tissue in a homogeniser (cells broken and organelles are released)
-homogenate (fluid) is filtered to remove any remaining whole cells or tissue debris
-place filtered homogenate into a centrifuge tube
-homogenised tissue is spun in a centrifuge tube at a low speed for 10 minutes
-result of being spun at low speed (1000x gravity)= sediment 1 (nuclei) and supernatant 1
-result of being spun at medium speed (3500x gravity)= sediment 2 (mitochondria) and supernatant 2
-result of being spun at high speed (16500x gravity)= sediment 3 (lysosomes) and supernatant 3

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15
Q

what are the features of an electron microscope?

A

-high magnification (ability to enlarge an image of an object through lenses multiple times larger than the actual object)
-high resolution (ability to distinguish between two separate points)
-small wavelength
-can see sub-cellular structures

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16
Q

what are the limitations of the electron microscope?

A

-whole system in a vacuum
-high cost
-inability to observe live specimens
-bulky type of equipment

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17
Q

what are the stages of cell division?

A
  1. interphase
    -DNA replication
    -synthesis of organelles
  2. nuclear division (mitosis/meiosis)
    -chromosomes divided
  3. cytokinesis
    -division of cell membrane to produce 2 or 4 cells
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18
Q

what are the stages of mitosis? (6)

A

interphase, prophase, metaphase, anaphase, telophase, cytokinesis

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19
Q

what happens in the interphase stage?

A

-new cell organelles are synthesised and DNA replication occurs
-the chromosomes are unravelled to allow access to the genetic material for replication and protein synthesis

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20
Q

what happens in the prophase stage?

A

-chromosomes condense becoming shorter and thicker
-nucleolus and nuclear envelope break down, signalling the end of this stage
-the centrioles move to opposite poles of the cell and the spindle fibres start to develop

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21
Q

what happens in the metaphase stage?

A

-the chromosomes’ centromeres attach to the microtubules
-the chromosomes are pulled along the spindle apparatus and line up at the middle of the cell

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22
Q

what happens in the anaphase stage?

A

-the centromeres split and the spindle fibres shorten
-one chromatid from each chromosome is pulled to opposite poles of the cell
-mitochondria gather around the spindle fibres and provide energy for the process

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23
Q

what happens in the telophase stage?

A

-the chromosomes reach their respective poles and unravel to form chromatin and the nuclear envelope reforms
-two sets of genetic information become enclosed in separate nuclei
the spindle fibres disintegrate and the nucleolus reform

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24
Q

what happens in the cytokinesis stage?

A

-the cell surface membrane constricts around the middle of the cell until it meets the middle and creates two new cells

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25
Q

what is the rate of mitosis controlled by?

A

-environment
-growth factors
-genes

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26
Q

what are the structure and functions of the cell membrane?

A

-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

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27
Q

what are the features of the cell membrane? (10)

A

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

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28
Q

what does a phospholipid consist of in a cell membrane?

A

-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

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29
Q

what does a transmembrane protein consist of in a cell membrane?

A

-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

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30
Q

what does a peripheral protein consist of in a cell membrane?

A

-does not span the entire membrane

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31
Q

what does cholesterol consist of in a cell membrane?

A

-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

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32
Q

what do glycolipids consist of in a cell membrane?

A

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

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33
Q

what do glycoproteins consist of in a cell membrane?

A

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

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34
Q

why is a cell membrane known as a fluid mosaic model?

A

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

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35
Q

what is the permeability of the cell membrane?

A

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

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36
Q

what is passive transport?

A

-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

37
Q

what is diffusion?

A

-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

38
Q

what is facilitated diffusion?

A

-charged ions and polar molecules would enter the cell in this way
-uses transmembrane proteins such as channel or carrier proteins

39
Q

what is osmosis?

A

-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

40
Q

what is water potential?

A

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

41
Q

what is active transport?

A

-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

42
Q

what are the steps of co transport?

A
  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 a different type of protein carrier in the cell surface membrane
  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
43
Q

what is the structure and function of the small intestine?

A

-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

44
Q

what are the two defence mechanisms?

A

-non specific
-specific

45
Q

what is the non specific defence mechanism?

A

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

46
Q

what is the specific defence mechanism?

A

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

47
Q

what are antigens?

A

-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

48
Q

what is the 1st stage of phagocytosis?

A

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

49
Q

what is the 2nd stage of phagocytosis?

A

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

50
Q

what is the 3rd stage of phagocytosis?

A

-lysosomes migrate towards the phagosome formed by engulfing the pathogen

51
Q

what is the 4th stage of phagocytosis?

A

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

52
Q

what is the 5th stage of phagocytosis?

A

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

53
Q

what are lymphocytes?

A

-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

54
Q

what will lymphocytes respond to in the cell mediated response?

A

-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

55
Q

what are the steps of the cell mediated response?

A
  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)
56
Q

what is a Tc (T killer cell)?

A

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

57
Q

what is the structure and function of lysosomes?

A

-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

58
Q

what is the structure and function of ribosomes?

A

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

59
Q

what is the structure and function of the cell wall? (plant)

A

-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

60
Q

what is the structure and function of the vacuole?

A

-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

61
Q

what is the structure of the cell wall? (algae and fungi)

A

-made up of either cellulose or glycoproteins, or a mix of both (algae)
-does not contain cellulose but made up of a mixture of chitin, glycan and glycoproteins (fungi)

62
Q

what is prokaryotic cell division?

A

-binary fission

63
Q

what are the steps of binary fission in prokaryotic cells?

A

-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

64
Q

what will lymphocytes respond to in the humoral response?

A

-pathogens
-toxins
-abnormal cells

65
Q

what are the steps of the humoral response?

A
  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.
66
Q

what are antibodies?

A

-proteins with specific binding sites
-the antibody binding sites are complimentary to a specific antigen
-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
-each antibody has a specific binding site that fits very precisely onto a specific antigen to form an antigen-antibody complex

67
Q

what are monoclonal antibodies and how are they used for treatments?

A

-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

68
Q

what is active immunity?

A

-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

69
Q

what is natural active immunity?

A

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

70
Q

what is artificial active immunity?

A

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

71
Q

what is a limitation of the light/optical microscope?

A

-limited resolution
-lower magnification compared to other microscopes

72
Q

what is a limitation of the transmission electron microscope and the scanning electron microscope?

A

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

73
Q

what is an advantage of using an electron microscope?

A

-high resolution
-high magnification

74
Q

what are the functions of the nucleus?

A

-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

75
Q

what is the treatment of cancer?

A

-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

76
Q

what is passive immunity?

A

-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

77
Q

what is an antigen?

A

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

78
Q

what are the features of a successful vaccination programme?

A

-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

79
Q

what is herd immunity?

A

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

80
Q

why can vaccinations not eliminate a disease?

A

-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

81
Q

what are the ethics surrounding vaccinations?

A

-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?

82
Q

what is HIV?

A

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

83
Q

what is the structure of HIV? (7)

A

-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)

84
Q

what is the replication of HIV?

A
  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
85
Q

how does HIV cause the symptoms of AIDS?

A

-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

86
Q

what is the ELISA test?

A

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

87
Q

what are the steps of the ELISA test?

A
  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
88
Q

how does an antibody lead to the destruction of an antigen?

A

-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

biology (3 decks)

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