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biology!🌺🌱 > cell structure > Flashcards

cell structure Flashcards

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1
Q

cell-surface membrane (eukaryotic cells)

A
  • phospholipid bilayer
  • function –> extracellular substances enter & waste leaves the cell (sometimes requires active transport or membrane proteins)
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2
Q

smooth endoplasmic reticulum

A
  • (membrane forms flattened sacs –> called cisternae)
  • site of lipid synthesis, toxin modification & glycogenesis
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3
Q

rough endoplasmic reticulum

A
  • (membrane forms flattened sacs –> called cisternae)
  • has large no. of ribosomes attached to the surface
  • folds & processes proteins made on the ribosomes
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4
Q

nucleus
(eukaryotic cells)

A
  • nuclear envelope has a double membrane & nuclear pores to export mRNA n ribosomes into cytoplasm
  • contains chromatin –> consists of DNA bound to histone proteins
  • contains nucleolus –> site of ribosome production
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5
Q

ribosomes

A

-either free or on R.E.R
-eukaryotes have 80s ribosomes –> consists of 2 subunits, 60s & 40s
-70s ribosomes found in prokaryotes, mitochondria & chloroplasts
-site of translation (during protein synthesis)

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6
Q

golgi apparatus
(eukaryotic cells)

A
  • stack of membrane-bound flattened sacs
  • proteins modified in cis-face
  • role in ‘packaging’ & ‘secretion’ of proteins
  • digestive enzymes placed into lysosomes
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7
Q

golgi vesicles
(eukaryotic cells)

A

export modified proteins to fuse with the cell membrane (leave through trans-face)

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8
Q

mitochondria
(eukaryotic cells)

A
  • site of aerobic respiration
  • double membrane
    >inner membrane folds to form cristae (gives it large S.A –> increases rate of aerobic resp.)
  • small circular pieces of DNA found in the matrix
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9
Q

centrioles
(eukaryotic cells)

A
  • hollow cylinders
  • produce spindle fibres for cell division
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10
Q

lysosome
(eukaryotic cells)

A
  • small, membranous vehicle
  • has hydrolytic enzymes –> destroys pathogens/gets rid of unwanted cells & organelles
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11
Q

vacuoles (only in plant cells)

A
  • membrane-bound organelle found in all plant cells
  • surrounded by tonoplast
  • turgid –> helps cells stay rigid
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12
Q

chloroplasts (only in plant cells)

A
  • site of photosynthesis (light-dependant stage takes place in the thylakoid membranes, light-independant stage takes place in the stroma)
  • membrane-bound thylakoids containing chlorophyll stack to form grana
    –> grana joined tg by lamellae
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13
Q

plant cell wall

A
  • provides structural support (made of cellulose)
  • plasmodesmata (narrow threads of cytoplasm) connect the cytoplasm of neighbouring plant cells)
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14
Q

epithilial cell

(specialised eukaryotic cell)

A
  • villi increase S.A for absorption
  • mitochondria releases energy to waft things away/transport digested food molecules
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15
Q

erythrocyte

(specialised eukaryotic cell)

A

no nucleus & biconcave disc shape –> maximises S.A –> can carry more oxygen

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16
Q

sperm cell

(specialised eukaryotic cell)

A
  • acrosome enzyme to penetrate egg
  • long midpiece –> lots of mitochondria –> releases lots of energy for swimming
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17
Q

how is bacteria digested?

(exam q)

A

lysosomes fuse with the vesicle & release hydrolytic enzymes

18
Q

organelles in prokaryotic cells

A

1) plasma membrane
2) peptidoglycan cell wall
3) capsule (outer gel coating)
* flagella
* pili (for attachment to other cells, involved in reproduction)
* plasmid DNA
* circular DNA
* ribosomes (not membrane bound!!)

19
Q

what is the name for the types of organelles eukaryotic cells contain but prokaryotic cells don’t contain?

A

membrane-bound organelles!

20
Q

difference between DNA in eukaryotes & DNA in prokaryotes

A
  • eukaryotes –> linear, long, associated w histone proteins, contains introns
  • prokaryotes –> circular, short, not associated w histone proteins, no introns
21
Q

parts of virus particle

A

-attachment proteins
-genetic material
-capsid

22
Q

process of viral replication

A
  1. virus injects nucleic acid into host cell
  2. infected host cell replicates the virus
23
Q

process of binary fission

A
  1. circular DNA & plasmids replicated in bacterial cell
  2. circular DNA & plasmids move to opp. poles of cell
  3. cytoplasm divides
  4. two daughter cells prod. –> each contains 1 copy of circular DNA (but can have multiple plasmids)
24
Q

define ‘resolution’

A

minimum distance at which 2 very close objects can be distinguished

25
Q

light microscope –> preparation

A
  • cut thin layer of specimen
  • add drop of water & potassium iodide/stain onto specimen
  • put coverslip on top
26
Q

light microscope –> pros

A
  • images are colourful
  • living tissue can be viewed
27
Q

light microscope –> cons

A
  • long wavelength of light makes resolution low
  • max. magnification only x1500
28
Q

scanning electron microscope

A
  • beam of electrons scatters across surface of specimen, knocking electrons off –> electrons form 3D image
  • lower resolution than TEM (but higher than optical)
29
Q

transmission electron microscope

A
  • beam of electrons passes through specimen
    –> areas that absorb electrons = darker on micrograph
    –> internal image prod.
30
Q

electron microscopes –> cons

A
  • in vacuum environment –> living objects can’t be viewed
  • specimens must be very thin
  • specimens must be dehydrated & stained w heavy metals
  • complex staining process may intorduce artefacts
31
Q

why do electron microscopes have a vacuum environment?

A

so particles in the air don’t deflect electrons out of the beam alignment

32
Q

define ‘cell fractionation’

A

technique which separates organelles according to their density

33
Q

stages of cell fractionation

A
  1. homogenisation
  2. filtration
  3. ultracentifugation
34
Q

homogenisation

A

place cells in cold, isotonic & buffered solution –> blend to release organelles
* cold –> reduces enzyme activity as some enzymes may break down organelles
* isotonic –> solution needs same w.p as organelles so osmosis doesn’t occur (organelles would burst/shrink)
* buffered –> maintains constant pH (proteins in organelles can be denatured by change in pH)

35
Q

filtration

A

removes any tissue debris

36
Q

ultracentrifugation

A
  • filtrate spun at diff. speeds
  • heaviest organelles sink to bottom of tube, forming pellet
  • fluid above the supernatant is removed and spun again in centrifuge at higher speed
  • process continues until desired organelle is obtained
    (nuclei would be 1st, ribosomes would be last)
37
Q

stages of cell division

A
  1. interphase
  2. mitosis
  3. cytokinesis
38
Q

interphase

A
  • G1 –> protein synthesis
  • S –> DNA replication
  • G2 –> DNA checked over
39
Q

mitosis

A
  • prophase –> chromosomes condense & become visible, spindle fibres form, nuclear membrane breaks down
  • metaphase –> chromosomes line at up equator & attach to the spindle fibres via centromere
  • anaphase –> spindle fibres contract, centromere splits, sister chromtids pulled to opp. poles of cell
  • telophase –> nucleus begins reforming
40
Q

cytokinesis

A

2 gentically identical, diploid cells produced

41
Q

what is mitosis used for?

A
  • growth & repair
  • asexual reproduction

biology!🌺🌱 (14 decks)

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