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Biology > 2.1 Cell structure > Flashcards

2.1 Cell structure Flashcards

1
Q

preparation of mounted tissue

A
  1. obtain thin section
  2. place plant tissue in drop of water
  3. stain tissue
  4. add coverslip using mounted needle at 45 degrees to avoid air bubbles
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2
Q

how do light microscopes work

A
  1. lenses focus rays of light and magnify
  2. different structures absorb different amount of wavelengths of light
  3. reflected light is transmitted to the observer via eyepiece
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3
Q

how do TEMs work

A
  1. pass high beam of electrons through thin slice of specimen
  2. more dense structures appear darker since they absorb more electrons
  3. focus image onto fluorescent screen using magnetic lenses
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4
Q

how does SEMs work

A
  1. focus beam if electrons onto a specimens surface using electromagnetic lenses
  2. reflected electrons hit a collecting device and are amplified to produce an image on a photographic plate
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5
Q

how do laser scanning microscopes work

A
  1. focus laser beam onto a small area using objective lens
  2. fluorophores in the sample smith photons
  3. photomultiplier tube amplifies the signal onto a detector.
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6
Q

microscopy equation

A

image size = actual size x magnification

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7
Q

magnification

A

factor by which the image is larger than the actual specimen

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8
Q

resolution

A

smallest separation distance at which 2 separate structures can be distinguished from one another

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9
Q

mag and res of light microscope

A

mag= x2000
res= 200nm

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10
Q

mag and res of TEM

A

mag= x2 000 000
res= 0.2 nm

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11
Q

mag and res of SEM

A

mag= x200 000
res= 10nm

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12
Q

calibrating an eyepiece graticule

A
  1. place micrometer on stage
  2. line up scales and count how many graticule divisions are in 1mm of the micrometer
  3. calculate the length of 1 eyepiece division= 1mm/ number of divisions
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13
Q

nucleus structure

A
  • surrounded by a nuclear envelope, a semipermeable double membrane
  • nuclear pores allow substances to enter/exit
  • dense nucleolus made of RNA + proteins assembles ribosomes
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14
Q

nucleus function

A
  • contains DNA coiled around chromatin into chromosomes
  • controls cellular processes:
    site of mRNA transcription
    mitosis
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15
Q

RER structure

A
  • system of membranes, containing fluid-filled cavities (cisternae)
  • coated with ribosomes
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16
Q

RER function

A
  • cisternae: network of tubules and flattened sacs extends from cell membrane + connects to nuclear envelope
  • large SA for ribosomes
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17
Q

SER structure

A

-system of membranes, containing fluid-filled cavities (cisternae)
- no ribosomes

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18
Q

SER function

A
  • contains enzymes that catalyse reactions involves with lipid metabolism:
    synthesis of cholesterol, lipids, steroid hormones
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19
Q

Golgi Apparatus structure

A
  • Planar stacks of membrane-bound, flattened sacs
    (looks like a stack of pancakes)
20
Q

Golgi Apparatus function

A

-proteins modified by adding: sugar,lipids or folding into 3D shape
- proteins being packaged into vesicles

21
Q

Mitochondrion structure

A

-surrounded by a double membrane with a fluid filled space between
- inner membrane= highly folded into cristae
- inner layer of mitochondrion= fluid-filled matrix

22
Q

Mitochondrion function

A
  • site of ATP production during aerobic respiration
    -self-replicating so more can be made if more energy is needed
23
Q

Chloroplast structure

A

-surrounded by a double membrane or envelope
- inner membrane= thylakoids(stacks of flattened membrane sacs) each stack is called a granum
- contains loops of DNA and starch grains

24
Q

Chloroplast function

A

site of photosynthesis
1. light energy trapped by chlorophyll = used to make ATP, occurs in grana
- water also splits to supply hydrogen ions
2. hydrogen reduces CO2, using energy from ATP
- makes carbohydrates: occurs in stroma

25
Q

Vacuole structure

A
  • surrounded by a membrane: tonoplast
  • contains fluid
26
Q

Vacuole function

A
  • plants= large, permanent vacuole
  • filled with water and solutes, maintains cells stability
  • when full, pushes against cell wall making it turgid
27
Q

Lysosomes structure

A
  • formed from Golgi apparatus: single membrane
  • contain powerful hydrolytic enzymes
28
Q

lysosomes function

A
  • keeps the enzymes separate from rest of cell
  • engulf old cell organelles and foreign matter
  • digest them and return digested components to cell for reuse
29
Q

Cilia and undulipodia structure

A
  • protrusions from the cell: surrounded by the cell surface membrane
  • contain microtubules and formed from centrioles
30
Q

Cilia and undulipodia Function

A
  • epithelial cells= move band of mucus
  • act as an antenna: receptors allowing cells to detect signals about the environment
  • spermatozoon is the only cell with undulipodia
31
Q

Ribosomes structure

A
  • spherical and made of ribosomal DNA
  • made in nucleus: pass through nuclear envelope into cell cytoplasm as two separate subunits and then combine as it leaves
  • some remain free in the cytoplasm, some attach to RER
32
Q

Ribosomes Function

A
  • bound to exterior of RER= synthesising proteins that will be exported outside the cell
  • free in the cytoplasm= site of assembly of proteins
  • large subunit= joins to amino acids
  • small subunit= mRNA binding site
33
Q

Centrioles structure

A
  • two bundles of microtubules at right angles
  • microtubules= made of tubular protein subunits which are arranged to form a cylinder
34
Q

Centrioles Function

A
  • before a cell divides: spindle(made of tubulin) forms from centrioles
  • chromosomes attach to the middle part of the spindle and motor proteins walk along tubulin threads, pulling chromosomes to opposite ends
  • cilia and undulipodia: centrioles multiply and line up beneath cell surface membrane, microtubules then sprout outwards
35
Q

cellulose cell wall structure

A
  • made of bundles of cellulose fibres
36
Q

cellulose cell wall function

A
  • provide mechanical strength and support
    -maintains cell shape
  • permeable to allow solutions to pass through
37
Q

microfilaments structure

A
  • made up of protein (actin)
38
Q

microfilament function

A
  • gives support and mechanical strength to the cell
  • keeps the shape of cell stable
  • allows cell movement
39
Q

microtubules function

A

-provide shape and support
- form the track for motor proteins ( dynein + kinesin) to walk along
- form the spindle before a cell divides
- makes up cilia + undulipodia + centrioles

40
Q

intermediate filaments function

A
  • anchor the nucleus within the cytoplasm
  • extends between cells enabling signalling and allowing cells to adhere to a membrane
41
Q

All-purpose stains

A
  • methylene blue
42
Q

Acetic Orcein

A

binds to DNA and stains purple-red

43
Q

Eosin

A

stains cytoplasm pink

44
Q

Sudan red

A

stains lipids red

45
Q

iodine

A

stains cellulose yellow
stains starch blue/black

Biology (2 decks)

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