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cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

cell surface membrane

A
  • found in all cells
  • phospholipid bilayer
  • controls the entrance and exit of molecules
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2
Q

nucleus

A
  • double membrane (nuclear envelope)
  • nuclear pores
  • nucleoplasm
  • chromosomes (protein-bound, linear DNA)
  • nucleolus (site of rRNA production)
  • site of DNA replication and transcription
  • contains genetic code for each cell
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3
Q

mitochondria

A
  • double membrane
  • inner membrane is called the crista
  • mitochondrial matrix
  • loop of mitochondrial DNA
  • site of aerobic respiration and ATP production
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4
Q

chloroplasts

A
  • double membrane
  • thylakoids that stack to make grana
  • stroma containing photosynthetic enzymes
  • found in plants
  • site of photosynthesis
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5
Q

golgi appartus and golgi vesicles

A
  • folded membranes making cisternae
  • secretary vesicles pinch off cisternae
  • form glycoproteins
  • form lysosomes
  • transport, modify and transport lipids
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6
Q

lysosomes

A
  • bag of digestive enzymes
  • hydrolyse phagocytic cells
  • autolysis (break down dead cells)
  • exocytosis (release enzymes outside cell to destroy)
  • digest worn out organelles for reuse of materials
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7
Q

ribosomes

A
  • rRNA and protein
  • 80s ribosomes in eukaryotes
  • 70s ribosomes in prokaryotes, mitochondria and chloroplasts
  • site of protein synthesis
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8
Q

rough endoplasmic reticulum

A
  • folded membranes called cisternae
  • ribosomes on cisternae
  • site of protein synthesis
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9
Q

smooth endoplasmic reticulum

A
  • folded membrane called cisternae
  • synthesis and stores lipids and carbohydrates
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10
Q

cell wall

A
  • in plant and fungi
  • in plants the wall is made of cellulose
  • in fungi the wall is made of chitin
  • provides structural strength to the cell to prevent bursting
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11
Q

cell vacuole

A
  • filled with cell sap
  • single membrane called tonoplast
  • makes cells turgid for support
  • temporary store of sugars and amino acids
  • pigments attract pollinators
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12
Q

specialised cells

A

cells into tissues, tissues into organs and organs into systems

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13
Q

structure of prokaryotic cells

A
  • cell wall (murein)
  • cell surface membrane
  • cytoplasm
  • capsule
  • plasmids
  • flagella
  • ribosomes
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14
Q

eukaryotic vs prokaryotic

A
  • cytoplasm that lacks membrane-bound organelles
  • smaller ribosomes (eukaryotes=80S and prokaryotes=70S)
  • no nucleus; instead they have a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins
  • a cell wall that contains murein, a glycoprotein
  • prokaryotes are much smaller
  • may contain plasmids, a capsule and flagella
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15
Q

structure of viruses

A
  • genetic material (RNA)
  • capsid (protein shell enclosing RNA)
  • attachment proteins
  • lipid envelope
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16
Q

optical microscope

A
  • a microscope that uses light to form an image
  • poorer resolution due to light having longer wavelength of light
  • lower magnification
  • images are in colour
  • can view living samples
  • small organelles such endoplasmic reticulum, lysosomes and ribosomes are not visible
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17
Q

transmission electron microscope

A
  • TEMs use electromagnets (shorter wavelength) to focus a beam of electrons, which is then transmitted through the specimen.
  • denser parts of the specimen absorb more electrons, which makes them look darker on the image you end up with.
  • TEMs are good because they give high resolution images, so you see the internal structure of organelles like chloroplasts
  • 2D image
  • thin specimens
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18
Q

scanning electron microscope

A
  • SEMs scan a beam of electrons (shorter wavelength) across the specimen. this knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image.
  • sample must be in a vacuum
  • must be stained
  • the images you end up with show the surface of the specimen and they can be 3D
  • SEMs are good because they can be used on thick specimens.
  • they give lower resolution images than TEMs
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19
Q

magnification

A

how many times larger the image is than the actual size of the object being viewed

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20
Q

resolution

A

the minimum distance apart that two objects can be in order for them to appear as separate items.
the resolution in an optical microscope is determined by the wavelength of light, and the wavelength of the beam of electrons determine the resolution in an electron microscope.

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21
Q

formula for magnification

A

magnification = size of image/size of real object

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22
Q

cell fractination

A
  • used to isolate organelles so they can be studied
  • homegenisation used to break cells apart using a blender or vibration
  • placed in cold, isotonic buffer solution
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23
Q

order of cell fractination

A

nuclei, chloroplasts, mitochondria, lysosomes, ER, ribosomes

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24
Q

cell ultracentrifugation

A
  • centrifuge spins at high speeds and the centrifugal forces causes pellets of the densest organelle to form at the bottom
  • supernatant is removed and spun at increasingly faster speeds
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25
Q

phases of mitosis

A

(interphase) prophase, metaphase, anaphase and telophase (cytokinesis)

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26
Q

interphase

A

G1 (gap phase 1) - cell grows and new organelles and proteins are made
S (synthesis) - cell replicates its DNA ready to divide
G2 (gap phase 2) - cell keeps growing & proteins needed for cell division are made

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27
Q

prophase

A
  • DNA supercoils
  • nuclear envelope disintergrates
  • centrioles divide and move to poles
  • spindle fibres form
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28
Q

anaphase

A
  • centromeres spilt
  • chromatids move to separate poles
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29
Q

metaphase

A
  • centromere attaches to spindle fibres
  • chromosomes line up at equator
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30
Q

telophase

A
  • chromosomes lengthen
  • spindle fibres disintergrate
  • nucleus starts to reform
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31
Q

cytokinesis

A

causes cell to split into two disntinct daughter cells with idenitcal nuclei

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32
Q

binary fission

A
  • replication of circular DNA and plasmids
  • division of cytoplasm
    -produces 2 daughter cells
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33
Q

virus replication

A
  • virus attaches to host cell receptor proteins
  • genetic material is released into host cell
  • genetic material and proteins are replicated by host cell ‘machinery’
  • viral components assemble
  • replicated viruses released from host cell
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34
Q

phospholipid bilayer properties

A

allows movement of non-polar, lipid soluble and small molecules to pass through the membrane

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35
Q

fluid mosaic model

A

fluid
- membrane can change shape as molecules can move
mosaic
- phospholipids, proteins, glycoproteins, glycolipids, cholesterol

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36
Q

simple diffusion

A
  • net movement of particles
  • passive process (no ATP)
  • high concentration to low concentration
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37
Q

facilitated diffusion

A
  • net movement of particles
  • passive process (no ATP)
  • high concentration to low concentration
  • through use of intrinsic proteins
38
Q

osmosis

A
  • movement of water
  • area of high water potential to an area of low water potential
  • across partially permeable membrane
39
Q

active transport

A
  • active process (ATP)
  • low concentration to high concentration
  • uses carrier proteins
  • ATP binds to carrier protein and is hydrolysed, changes shape
40
Q

co-transport

A
  • coupled movement of molecules through carrier (cotransporter) protein
  • combination of AT and FD
41
Q

co-transport of glucose and sodium ions

A
  • sodium ions actively transported out of the epithelial cell into blood
    -reduces sodium ion concentration in epithelial
  • sodium ions can the diffuse from lumen down their concentration gradient into epithelial cell
  • does this through a co-transporter protein
  • glucose or amino acids are actively transported
  • glucose moves by facilitated diffusion from the epithelial cell to the blood
42
Q

identified by the immune system

A
  • pathogens
  • cells from other organisms of the same species
  • abnormal body cells
  • toxins
43
Q

antigen

A

foreign protein that stimulates an immune response

44
Q

antigen variablility

A

pathogenic DNA can frequently mutate so previous immunity is no longer effective as memory cells have memory of old antigen shape

45
Q

phagocytosis

A
  • phagocytes detect antigen and bind
  • phagocyte changes shape and engulfs pathogen
  • pathogen is contained in phagosome vesicle
  • lysosome fuses with phagosome
  • lysozyme released into phagosome which hydrolyses pathogen
46
Q

controls cell-mediated response

A

t-lymphocytes

47
Q

controls humoral response

A

b-lymphocytes

48
Q

cell-mediated response

A
  • once pathogen has been destroyed, the antigens are positioned on the cell surface (antigen-presenting cell)
  • helper T cells have receptors which bind to antigens on APC
  • this activates helper T cell to divide by mitosis to make clones that diffrentiate into different cells
  • remain as helper T cells
  • cytotoxic (killer) T cells
  • memory T cellls
  • stimulate macrophages
49
Q

helper T cells

A

stimulate B cells to divide and secrete antibodies

50
Q

killer T cells

A

destroy abnormal cells by releasing perforin protein which makes a pore in membrane so substances can’t leave or enter cell

51
Q

memory T cell

A

remain in the blood to provide long term protection

52
Q

humoral response

A
  • antigens in blood collide with complementary antibody on B cell
  • B cell takes in antigen by endocytosis and presents it on its cell surface membrane
  • B cell collides with helper T cell
  • B cell divides by mitosis and diffrentiates
  • makes memory B cells or plasma cells
53
Q

plasma cells

A

secrete antibodies

54
Q

memory B cells

A

remain in blood and divide by mitosis to make plasma cells

55
Q

antibody

A

protein specific to an antigen which is secreted by plasma cells

56
Q

antibody structure

A
  • immunoglobins
  • quaternary structure with two heavy polypeptide chains and two light polypeptide chains
  • bonded by disulphide bonds
  • contstant and variable region
  • variable region has antigen-binding site
57
Q

antigen-antibody complexes

A

antibody attaches to antigen at variable region

58
Q

agglutination

A

antibodies are flexible and can clump multiple antigens together, making it easier for phagocytes to locate them

59
Q

vaccines

A

small amounts of dead or weakened pathogens introduced to the body to stimulate the humoral response

60
Q

herd immunity

A

arises when a sufficiently large proportion of the population has been vaccinated which reduces the risk of a pathogen spreading

61
Q

active immunity

A

involves the production of antibodies and the development of memory cells, antibodies appear 1-2 weeks after exposure

62
Q

natural active immunity

A

producing antibodies in reponse to pathogenic infections

63
Q

artifical active immunity

A

producing antibodies in reponse to exposure of attenuated pathogen (e.g. vaccine)

64
Q

passive immunity

A

acquisition of antibodies from another source so memory cells are not created, response is immediate

65
Q

natural passive immunity

A

receiving antibodies from another organism (e.g. antibodies from breast feeding)

66
Q

artifical passive immunity

A

receiving manufactured antibodies via external delivery (e.g. blood transfusion of monoclonal antibodies)

67
Q

structure of HIV

A

core- 2 RNA strands and reverse transcriptase enzyme
capside- outer protein coat
lipid envelope- extra outerlayer taken from host cell’s membrane
attachment proteins- help attach HIV to host cell

68
Q

retrovirus

A

makes DNA from RNA using reverse transcriptase

69
Q

replication of HIV

A
  • attachment proteins attach to receptors on helper T cell
  • RNA enters the cell
  • reverse transcriptase converts RNA to DNA
  • viral DNA is incorported into helper T cell nucleus
  • DNA transcribed into viral mRNA
  • translated into HIV proteins
70
Q

AIDS

A
  • HIV causes helper T cells to die
  • B cells no longer activated and decreased phagocytosis
  • no antibodies produced
  • body cannot fight off infections
71
Q

monoclonal antibody

A

antibodies artificially derived from a single B cell clone

72
Q

monoclonal antibodies for targeting medication to specific cell types by attaching a therapeutic drug to an antibody

A
  • monoclonal antibodies with antibody complementary to antigens on outside of cancer
  • antibodies with drugs on attach to cancer cells
  • drugs delivered directly to cancer and kill them
73
Q

monoclonal antibodies for medical diagnosis

A

pregnancy test, influenza, hepatitis, chlamydia

74
Q

ELISA test (HIV)

A
  • HIV antigens bound to bottom of reaction vessel
  • blood sample added
  • HIV-specific antibodies bind to antigens (primary antibodies)
  • unbound antibodies are washed out
  • secondary antibody with enzyme attached binds to primary antibodies
  • reaction vessel washed out again
  • coloured substrate added which binds to secondary antibody
  • reaction vessel changes colour if individual hs HIV
75
Q

ethical issues of vaccines

A
  • animal testing
  • human testing
  • side effects
  • epidemics (difficult to decide who gets vaccine first)
76
Q

ethical issues of monoclonal antibodies

A
  • animal testing
  • side effects
77
Q

why is the soultion cold?

A

to reduce enzyme activity

78
Q

why is the solution isotonic?

A

prevents osmosis which could cause organelles to shrivel or burst

79
Q

why is the solution buffered?

A

prevent damage from pH change (dentauration)

80
Q

mitotic index

A

number of cells undergoing mitosis/total number of cells

81
Q

purpose of mitosis

A

one round of division
- creates 2 genetically identical daughter cells
- creates diploid cells
- asexual reproduction
- growth and repair

82
Q

how can cancer treatments control the rate of cell division?

A
  • prevent DNA replication
  • disrupt spindle fibre formation
83
Q

conversion of centimetres to millimetres to micrometres to nanometres

A

x10, x1000, x1000

84
Q

why are viruses non-living?

A

they are acellular, have no metabolism and cannot self replicate

85
Q

role of cholesterol

A

steroid molecule that binds to fatty acid tails to restict movement and reduce fluidity

86
Q

role of glycoproteins/lipids

A

cell signalling and cell recognition

87
Q

why does the membrane form a phospholipid bilayer?

A

hydrophillic phosphate (-ve) heads attract water and hydrophobic fatty acid (no charge) tails repel water

88
Q

factors that affect membrane permeability

A

temperature, pH and use of a solvent

89
Q

carrier protein

A

binding site of carrier protein changes shape to allow large molecules to diffuse down

90
Q

channel protein

A

water filled gated pore that allow charged substances to diffuse down

91
Q

factors that affect transport

A

concentration/water potential gradient
diffusion distance
surface area
amount of intrinsic proteins
temperature

biology (21 decks)

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