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Biology > Chapter 2 - Basic components of living organisms > Flashcards

Chapter 2 - Basic components of living organisms Flashcards

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1
Q

Cell surface membrane

A
  • Physical barrier
  • Controls what moves in and out the cell
  • Enables cell to communicate with surroundings
  • formed from phospholipid bilayer - diameter of 10nm
  • partially permeable
  • all cells
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2
Q

Cell wall

A
  • Made of peptidoglycan (murein) in bacterial cells and cellulose in plants
  • Provides strength and rigidity
  • Narrow threads of cytoplasm called plasmodesmata connect the cytoplasm of neighbouring plant cells
  • freely permeable
  • plant cells NOT animal
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3
Q

Nucleus

A
  • double membrane = has pores
  • contains chromatin
    ↳ chromosomes are made of sections
    of linear DNA tightly wound around
    proteins called histones
  • DNA stored replicated and copied into messenger RNA
  • all eukaryotic EXCEPT RBC

- -> via transcription

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4
Q

Mitochondria

A
  • aerobic resp within ALL eukaryotic cells
  • Surrounded by double membrane = inner membrane folded to form cristae
  • matrix formed by cristae contains enzymes needed for aerobic resp
  • small circular pieces of DNA and ribosomes found in matrix
  • Rod shaped
  • In cytoplasm
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5
Q

Chloroplasts

A
  • larger than mitochondria
  • membrane bound compartments called thylakoids containing chlorophyll stack to form grana
  • grana joined together by lamellae
  • light-dependent stage takes place in the thylakoids
  • light-independent stage (Calvin Cycle) takes place in the stroma
  • plant cells
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6
Q

Ribosomes

A
  • freely in cytoplasm or as part of RER
  • complex of ribosomal RNA (rRNA)
  • 80S (60S small and 40S large subunits) in eukaryotic
  • 70S (30S small and 50S large subunits) in prokaryotes, mitochondria and chloroplasts
  • site of translation
  • all cells

- Involved in process of translation, proteins synthesised from mRNA

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7
Q

Endoplasmic reticulum

A

ROUGH ER:
- studded with ribosomes, site where proteins are made folded and moved to golgi
- formed from continuous folds of membrane continuous with the nuclear envelope
- Plant and animal cells
SMOOTH ER
- lipid and steroid synthesis and drug detoxification
- plant and animal cells

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8
Q

Golgi apparatus

A
  • flattened sacs of membrane similar to SER
  • Modifies packages and directs newly made proteins & lipids into golgi vesicles
  • vesicles transport to destination
  • plant and animal cells
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9
Q

Large permanent vacuoles

A
  • sac in plant cells surrounded by tonoplast, selectively permeable membrane
  • vacuoles in animal cells are not permanent and small
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10
Q

Vesicles

A
  • found in plant and animal cells
  • membrane-bound sac for transport and storage
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11
Q

Lysosomes

A
  • specialist form of vesicles
  • Contains hydrolytic enzymes (to break down waste materials such as worn out organelles)
  • used by cells in immune system and in apoptosis
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12
Q

Centrioles

A
  • Hollow fibres made of microtubules
  • Two centrioles at right angles to each other form a centrosome, which organises the spindle fibres during cell division
  • Not found in flowering plants and fungi

- Organises microtubules into spindles on which chromosomes are separated when cell divides

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13
Q

Microtubules

A
  • Makes up the cytoskeleton of the cell about 25 nm in diameter
  • Made of α and β tubulin combined to form dimers, the dimers are then joined into protofilaments - 13 protofilaments in a cylinder make a microtubule
  • Moves organelles and cytoplasm using molecular motors
  • all eukaryotic cells
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14
Q

Microvilli

A
  • cell membrane projections
  • increase SA to increase rate of exchange of substances
  • specialised animal cells
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15
Q

Cilia

A
  • Hair-like projections made from microtubules
  • Allows the movement of substances over the cell surface
  • push mucus towards stomach
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16
Q

Flagella

A
  • Rigid whip like tails that contract to move
  • Prokaryotes —> made from flagellin protein
  • Eukaryotes —> made from tubulin and surrounded by cell membrane
  • specialised cells
17
Q

The importance of the cytoskeleton

A
  • strength and support = mechanical strength = provides scaffolding to maintain shape of cell
  • supports the organelles, keeping them in position
  • cytoskeleton aids transport within cells by forming ‘tracks’ along which organelles can move (endocytosis & exocytosis)
  • enables cell movement via cilia and flagella
18
Q

Plasmids

A
  • small loops of DNA, separate to main circular DNA molecule
  • contain genes that can be passed between prokaryotes (in antibiotic resistance)
19
Q

Slime Capsule

A
  • Outermost layer of the prokaryotic cell (like bacteria)
  • protects bacteria from drying out and attacked by immune system cells
20
Q

Microfilaments

A
  • Made from repeating actin subunits
  • Responsible for Cell movement
    &
    Change in shape
    &
    Muscle contraction
  • Thinnest component of cytoskeleton
21
Q

Pili

A
  • Appendages –> smaller than flagella
  • for attachment to other cells or surfaces in sexual reproduction

- can ‘fix’ the cell to a surface and can aid the exchange of genetic info between cells like bacteria

22
Q

Extracellular Matrix

A
  • Material between cells that hold tissue together
  • Made: scaffolding proteins e.g collagen
  • Important for cell to cell signalling
23
Q

Nucleoid region

A
  • Region of the cytoplasm containing circular DNA

- Viewed by e- microscope

24
Q

Optical Microscopes

A

➜ light limits resolution
➜ max res = 0.2 µm (micrometres )
➜ max mag = x1500
Good:
- cheap
- easy to use for schools
- portable
- study live specimen
Bad:
- magnification weak compared to e- microscope

25
Q

Laser scanning microscope (confocal microscope)

A

➜ cells being viewed must be stained with fluorescent dyes
➜ Multiple depths of the tissue section/organisms are scanned to produce an image
Good:
- high resolution and contrast
- can focus on structures at different depths within specimen
- can be used on thick or 3D specimen
Bad:
- slow process
- laser can cause photodamage to cells

26
Q

Electron microscope

A
  • uses fast travelling e-
  • great resolution (0.0002 µm or 0.2 nm)
    ➜ max mag = x1,500,000
  • e- fired from cathode and focused by e- magnets on to screen/photographic plate
  • 2 types SEM and TEM
  • image produced: micrograph
  • specimen has to be chemically fixed by being dehydrated and stained
27
Q

Electron microscope - SEM

A

Good:
- 3D image
- artificial colour can be added via computer tech
- can be used on thick or 3D specimens
- magnification of 500,000 +
Bad:
- black and white image
- Lower res than TEM
- specimen must be kept in vacuum - no live
- specimen must be coated in metal film

28
Q

Electron microscope - TEM

A

Good:
- magnification from 500,000 to 2 million
- potential new ones going to 50 million
- resolution very good
- can see internal structures
Bad:
- 2D imaging only
- black and white image
- specimen must be kept in vacuum and dead and very thin
- tedious and large and bulky
- temp control
- expensive and technical training required to handle

29
Q

Optical slide production 1

A

1.) FIXING
↳ ꜰᴏʀᴍᴀʟᴅᴇʜʏᴅᴇ ᴛᴏ = ʀᴇᴛᴀɪɴꜱ ɴᴇᴜʀᴀʟ ꜱᴛᴀᴛᴇ

2.) SECTIONING
↳ ᴅᴇʜʏᴅʀᴀᴛᴇᴅ ᴡɪᴛʜ ᴀʟᴄᴏʜᴏʟ, ɪᴍᴘʀᴇɢɴᴀᴛɪɴɢ ɪᴛ ɪɴ ᴘᴀʀᴀꜰꜰɪɴ/ʀᴇꜱɪɴ ꜰᴏʀ ꜱᴜᴘᴘᴏʀᴛ, ᴘʟᴀᴄᴇᴅ ɪɴ ᴡᴀx ᴍᴏᴜʟᴅ ᴀɴᴅ ꜱʟɪᴄᴇᴅ ᴡɪᴛʜ ᴍɪᴄʀᴏᴛᴏᴍᴇ

3.) STAINING
↳ ᴘᴀʀᴀꜰꜰɪɴ ʀᴇᴍᴏᴠᴇᴅ ᴀɴᴅ ɢʀᴀᴍ ꜱᴛᴀɪɴɪɴɢ ᴏʀ ᴀᴄɪᴅ ꜰᴀꜱᴛ

4.) MOUNTING
↳ ꜱᴇᴄᴜʀᴇ ᴛᴏ ꜱʟɪᴅᴇ ᴜꜱɪɴɢ ʀᴇꜱɪɴ ᴀɴᴅ ᴄᴏᴠᴇʀꜱʟɪᴘ ᴏɴ

30
Q

Optical slide production 2

A

∘ ꜰʀᴇᴇᴢᴇ ᴛʜᴇ ꜱᴘᴇᴄɪᴍᴇɴ ɪɴ ᴄᴀʀʙᴏɴ ᴅɪᴏxɪᴅᴇ ᴏʀ ʟɪQᴜɪᴅ ɴɪᴛʀᴏɢᴇɴ
∘ ᴄᴜᴛ ᴛʜᴇ ꜱᴘᴇᴄɪᴍᴇɴ ɪɴᴛᴏ ᴛʜɪɴ ꜱʟɪᴄᴇꜱ ᴜꜱɪɴɢ ᴀ ᴄʀʏᴏꜱᴛᴀᴛ
∘ ᴘʟᴀᴄᴇ ᴛʜᴇ ꜱᴘᴇᴄɪᴍᴇɴ ᴏɴ ᴛʜᴇ ꜱʟɪᴅᴇ ᴀɴᴅ ᴀᴅᴅ ᴀ ꜱᴛᴀɪɴ
∘ ɢᴇɴᴛʟʏ ᴘʟᴀᴄᴇ ᴀ ᴄᴏᴠᴇʀꜱʟɪᴘ ᴏɴ ᴛᴏᴘ ᴀɴᴅ ᴘʀᴇꜱꜱ ᴅᴏᴡɴ ᴛᴏ ʀᴇᴍᴏᴠᴇ ᴀɴʏ ᴀɪʀ ʙᴜʙʙʟᴇꜱ

31
Q

Gram staining

A

Positive:

  • crystal violet followed by iodine
  • washed with alcohol
  • gram positive = retains dye
  • purple under microscope

Negative:

  • lose dye
  • stained with safranin dye (counterstain)
  • appears red/pink
32
Q

Acid fast

A
  • Differentiates species of mycobacterium
  • lipid solvent = carries carbolfuschin dye
  • washed with dilute alcoholic solution
  • mycobacterium are not affected by the acid alcohol and retain the bright red dye
  • other bacteria lose stain and then stained with methylene blue
33
Q

Types of slides

A

Dry mount
- hair, pollen

Wet mount

  • aquatic samples, living organisms
  • add drop of water/immersion oil

Squash slides
- soft samples e.g root tip squash

Smear slides
- A drop of blood and use slide to smear

34
Q

CELL THEORY

A
  • BOTH plant and animal tissue is composed of cells
  • Cells are the basic unit of life
    Cells only develop from existing cells
35
Q

Magnification = Eyepiece magnification × objective magnification

A

Magnification = (Image size)/(object or actual size)

36
Q

Magnification

A

how many times bigger the image of a specimen observed is in compared to the actual size of the specimen

37
Q

Resolution

A

the ability to distinguish between two separate points

Biology (25 decks)

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