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3.2 Cells Flashcards

1
Q

structure + function of cell surface membrane

A
  • phospholipid bilayer with embedded proteins
  • selectively permeable. enables control of passage of substances in/out cell
  • barrier betweeen internal + external environment of cell
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2
Q

structure + function of nucleus

A
  • nuclear envelope, nuclear pores, nucleolus, chromosomes, protein bound linear DNA
  • controls cells activity through transcription
  • nuclear pores allows susbtances to move between cytoplasm + nucleus
  • nucleolus makes ribosomes which are made of proteins + ribosomal RNA
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3
Q

structure + function of mitochondria

A

double membrane - inner membrane folded to form cristae
matrix- contain small 70s ribosomes, small circular DNA + enzymes for aerobic respiration
site of aerobic respiration producing ATP for energu release

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4
Q

what are the proteins on the cell surface membrane for

A

cell signalling

antigens - allowing recognition of self + foreign cells by immune system

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5
Q

structure + function of golgi appparatus

A 
fluid filled membrane bound sacs 
receive protein from RER 
modifies/processes protein 
packages into vesicles for transport 
makes lysosomes
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6
Q

structure + function of lysosomes

A

membrane bound organelles
that releases hydrolytic enzymes
release of hydrolytic enzymes (lysozymes) to break down pathogens/worn out cell components

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7
Q

structure + function of ribosomes

A

free float in cytoplasm/bound to RER
not membrane bound
made from 1 large 1 small subunit
site of protein synthesis

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8
Q

structure + function of RER

A

ribosomes bound by a system of membranes
folds polypeptides to secondary/tertiary structure
packages to vesicles, transport to golgi apparatus

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9
Q

structure + function of chloroplasts

A

thylakoid membranes stacked to form grana
linked by lamellae
they sit in the stroma
surrounded by double membrane
contains starch granules + circular DNA
chlorophyll absorbs light for photosynthesis to produce organic substances

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10
Q

structure + function of cell walls

A

made mainly of cellulose - plants/algae
made mainly of chitin - fungi
rigid structure surrounding cells
prevents cell changing shape/bursting

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11
Q

structure + function cell vacuole

A

contains cell sap- weak solution of sugars and salts
tonoplast membrane
maintains pressure in cell- stops wilting
stores/isolates unwanted chemicals in cells

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12
Q

how do prok cells differ from euk cells

A

prok are smaller
no membrane bound organelles in cytoplasm
smaller ribosomes
no nucleus- single circular DNA thats free in cytoplasm, not associated with proteins
cell wall contains the glycoprotein murein

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13
Q

what do many prok cells have

A

one or more plasmids
capsule surrounding cells
one or more flagella

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14
Q

why are viruses acelluar + non living

A

acelluar - not made of/unable to divide into cells

non living - unable to exist/reproduce without host cells

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15
Q

describe the structure of a virus

A

attachment proteins
capsid
genetic material

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16
Q

how does an optical microscope work

A
  • uses visible light to form 2D image
  • visible light longer wavelength so lower resolution
  • low mag
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17
Q

pros and cons to optical microscope

A 
pros 
-can see liviing organisms 
cons 
-2D image 
-only uses thin specimens 
-low resolution
-low mag
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18
Q

how does a scanning electron microscope work

A

-uses electrons to form 3D image
-beams of electrons scan surface, knocking off electron from surface of specimen, which are gathered in cathode ray tube to form an image
-electrons shorter wavelenghth
higher mag

19
Q

pros and cons to scanning electron microscope

A 
pros
-3D
-high res + mag 
-used on thick specimens 
cons 
-vacuum ; can't see living organisms 
-lower res than TEM
-artefacts 
-no colour
20
Q

how does a transmission electron microscope work

A
  • uses electrons to form 3D image
  • electromagnets focus beams of electrons onto specimen, transmitted, denser =more absorbed=darker appearance
  • electrons shorter wavelength, higher res
  • high mag
21
Q

pros and cons to transmission electron microscope work

A 
pros 
-high res + mag 
cons 
-only thin specimens 
-vacuum
-artefacts
-no colour 
-2D images
22
Q

define magnification

A

how much bigger the image of a sample is compared to the real size

23
Q

define resolution

A

how well distinguished the image between 2 points

24
Q

describe measuring size of an object viewed with an optical microscope

A
  • line up eyepiece graticule with stage micrometer
  • use stage micrometer to calculate size of divisions on eyepiece graticule at a particular mag
  • take micrometer away + use graticule to measure how many divisions make up the object
  • calculate size of object by multiplying no. of divisions by size of division
  • recalibrate eyepiece graticule at diff mag
25
describe temporary mount of specimen on slide
- use tweezers to place thin section of specimen on a water drop on a microscope slide - add a drop of stain - add a cover slip by carefully tilting + lowering it with a mounting needle
26
describe principles of cell fractionation + ultracentrifugation as used to seperate cell componenrs
Homogenise tissue using blender -break open cell/release organelles Place in cold,isotionic,buffered solution -cold ; reduces enzyme activity so organelles not broken down -isotonic ; no osmotic effect so cell not shrivel/burst -buffered ; keeps pH constant so enzymes don't denature Filter homogenate -remove large unwanted debris Ultracentrifugation -centrifuge homogenate in tube at low speed -remove pellet of heaviest organelle + spin supernatant a higher speed -repeat at higher speed till organelles seperated out
27
the order of density of organelles
nuceli-->chloroplasts-->mitochondria-->lysosomes-->ER-->ribosomes
28
describe interphase
S phase - DNA replicates | G1 G2- no. of organelles + cell volume increases, proteins synthesis, ATP content increases
29
describe mitosis
parent cell divides | to form two genetically identical daughter cells,
30
describe prophase
- chromosomes condense, becoming shorter + thicker - two sister chromatids joined at centre by centromere - nuclear envelop breaks down + centrioles move to opposite poles to form spindle network
31
describe metaphase
- chromsomes align along equator | - spindle fibres attach to chromosomes at centomeres
32
describe anaphase
- spindle fibres contract, pulling sister chromatids to opposite poles of cell - centromere divided
33
describe telophase
- chromosomes uncoil= become longer + thinner - nuclear envelope reforms= two nuclei - spindle fibres + centrioles break down
34
describe cytokinesis
division of cytoplasm | producing two new genetically identical daughter cells
35
importance of mitosis
- growth of multicellular organisms - repairing damaged tissues/replacing cells - asexsual reproduction
36
how do cancer treatments stop cancer growth
disrupt cell cycle - prevents DNA replication, prevents mitosis - disrupts spindle activity/formation , chromosomes cant attach to spindle by their centromere, sister chromatids cant be pulled to opposite poles of cells, prevents mitosis
37
describe binary fission
- circular DNA and plasmids replicate - cytoplasm expands, each DNA molecule moves to opposite poles of cell - cytoplasm divides - two daughter cells each with single copy of circular DNA + variable no. of plasmids
38
describe viral replication
- attachment protein binds to complementary receptor protein on surface of host cell - inject nucleic acid into host cell - infected host cell replicated virus particles
39
describe the fluid mosaic model of membrane structure
molecules within membrane can move laterally | mixture of phospholipids, proteins, glycoproteins, glycolipids embedded in membrane
40
structure of cell membrane
phospholipid bilayer - phosphate heads - hydrophilic- attracted to water- orient to aqueous environment - fatty acids- hydrophobic - repelled by water- orient to inside of membrane embedded proteins -channel/carrier glycolipids + glyoproteins cholesterol - bind to fatty acids - restricts movement
41
how are the features of membranes adapt it for other functions
phospholipid bilyaer -maintains diff environment on each side of cell fluid bilayer -can bend to take up diff shapes for phagocytosis/from vesicles surface proteins -cell recognition/act as antigens/receptors cholesterol -regulated fluidity/increases stability
42
the role of cholesterol
- makes membrane more rigid/strable - restricts lateral movement - binds to fatty acids, making them pack more closely
43
describe the cotransport of sodium ions and glucose
- sodium ions actively transported out of epithelial cells lining ileum, into blood, by Na/K pump - creates a conc gradient of Na --> higher in lumen than epithelial cell - Na and glucose move by facillitated diffusion into epithelial cell from lumen via cotransporter protein - creates conc gradient of glucose- higher in epithelial cell than blood - glucose moved out cell into blood, by faciliated diffusion via protein channel

bio (12 decks)

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