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Module 2 - Foundations In Biology > Cell Structure > Flashcards

Cell Structure Flashcards

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1
Q

Name the parts of a light microscope

A

Eye piece, objective lens, stage, lamp, coarse-focusing knob, fine-focusing knob.

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2
Q

How does a light microscope works?

A

Has two lenses- objective and eyepiece. Objective lens produces a magnified image which is magnified again by the eyepiece lens. The sample is illumination usually by a light source underneath the sample.

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3
Q

Eye piece lens

A

Used to view image formed after light has passed through the objective lens

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4
Q

Coarse focusing wheel

A

Wheel on a microscope that moves parts of the microscope to get the image into focus (bigger wheel)

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5
Q

Fine focusing wheel

A

Wheel on a micrscope that moves parts of the micrscope a small amount to get the image into focus (smaller wheel)

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6
Q

Objective lens

A

Alters the magnification

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7
Q

Condenser lens

A

Used to control the illumination entering the objective lens

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8
Q

What can you see with a light microscope

A

Nuclei, cytoplasm, cell membranes, cell wall

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9
Q

How does an electron microscope work

A

Uses a beam of electrons to illuminate the specimen. Electrons have a much shorter wavelength than light so greater resolution can be achieved

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10
Q

What is the magnification of electrn micrscopes

A

up to x500,000

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11
Q

what can you see with an electron microscope

A

the cell ultrastructure

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12
Q

Transmission electron microscope

A

electron bream is transmitted through the specimen. The final image is 2D. produces a cross sectional image. Has a resolving power of 0.5nm

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13
Q

Scanning electron microscope

A

Electron beam scattered across the surface of an object which produces a 3D image. has a resolving power of 3-10nm

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14
Q

What is the formula for magnification

A

Magnification = image size/actual size IAM triangle

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15
Q

Define resolution

A

The degree to which its possible to distinguish between 2 objects that are very close together. The higher the resolution the greater detail you can see

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16
Q

Advantages of light microscopes

A

cheap
easy to use
wide range of specimens can be viewed including live organisms

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17
Q

disadvantages of light microscopes

A

specimen needs to be thin and transparent
max magnification - 1500
max resolution - 200nm

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18
Q

advantages of TEM

A

greater resolution (0.05-1nm)
produces more detailed 2D images showing the cell ultrastructure
greater magnification - x500,000

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19
Q

disadvantages of TEM

A

electron beams are deflected by air particles therefore sample needs to be in a vacuum which kills living cells
very expensive
requires a skilled operator

20
Q

advantages of SEM

A

high resolution (3-10nm)
Produces more detailed 3D images
Shows cell ultrastructure
Greater magnification x100,000
Produces 3D images that can show cell and tissue arrangements

21
Q

disadvantages of sem

A

has to be done in a vacuum which kills all living cells
very expensive
needs a skilled operator

22
Q

advantages of laser scanning confocal

A

wide range of specimens can be viewed including living organisms
can give 2d and 3d images
greater resolution
can focus at different depths within a specimen

23
Q

disadvantages of laser scanning confocal

A

specimen needs to be thin and transparent
requires a skilled operator

24
Q

how does a laser scanning confocal microscope work

A

moves a single spot of focused light across a specimen. this causes fluorescence from the components labelled with a dye. the emitted light from the specimen is filtered through a pinhole aperture. only light radiated from very close to the focal plane is detected

25
Q

what would light emitted from other parts of the specimen do on a laser scanning confocal microscope

A

reduce the resolution and cause blurring. this unwanted radiation does not pass through the pinhole and is not detected

26
Q

How are 2d and 3d images produced with a laser scanning confocal microscope

A

A spot illuminating the specimen is moved across the specimen and a 2d image is produced. A 3d image can be produced by creating images at different focal planes

27
Q

What can laser scanning confocal micrscopes be used for

A

currently used in the diagnosis of diseases in the eye and is also being developed for use in endoscopic procedures.
since it can be used to see the distribution of molecules within cells its also used in the development of new drugs

28
Q

what are the rules for a good scientific drawing

A

title
state magnification
use a sharp pencil
labels shouldnt have arrowheads
white unlined paper
use as much of the paper as possible
smooth continuous lines
no shading
draw clearly defined structures
ensure proportions are correct
label lines should be parallel to the top of the page and drawn with a ruler

29
Q

how to calibrate a microscope

A

you do this by comparing a stage micro meter and eyepiece graticule to work out what one unit on the eyepiece graticule is in micrometres

30
Q

function of cell membrane

A

controls the exchange of materials between the internal cell environment and the external cell environment
partially permeable
formed from a phospholipid bilayer of phospholipids

31
Q

function of cell wall

A

found in plant cells not animal cells
offer structural support
plants - cellulose
bacteria - peptidoglycan

32
Q

function of nucleus

A

present in all eukaryotic cells
large and separated from cytoplasm by a double membrane (nuclear envelope) containing pores
pores allow mRNA and ribosomes to travel out of the nucleus
contains chromatin (material from which chromosomes are made)
chromosomes are made of sections of linear dna tightly would around proteins called histones
contains nucleolus which is the site of ribosome production

33
Q

function of mitochondria

A

site of aerobic respiration within all eukaryotic cells
surrounded by double membrane with the inner membrane folded to form cristae
the matrix formed by the cristae contains enzymes needed for aerobic respiration, producing atp
small circular pieces of DNA (mitochondrial dna) and ribosomes are found in matrix

34
Q

function of chloroplasts

A

found in plant cells
larger than mitochondria and surrounded by a double membrane
site of photosynthesis
membrane bound compartments called thylakpids containing chlorophyll stack to form structures called grant
contain small circular pieces of DNA and ribosomes used to synthesise proteins needed in chloroplast replication and photosynthesis

35
Q

function of ribosomes

A

all cells
freely in cytoplasm or as part of the rough endoplasmic reticulum in eukaryotic cells
80s ribosomes are found in eukaryotic cells
70s ribosomes are found in prokaryotic mitochondria and chloroplasts
site of protein synthesis

36
Q

function of rough endoplasmic reticulum

A

found in plant and animal cells
surface covered in ribosomes
formed from continuous folds of membrane with nuclear envelope
processes proteins made by ribosomes

37
Q

function of smooth endoplasmic reticulum

A

found in plant and animal cells
no ribosomes on surface
involved in the production processing and storage of lipids carbohydrates and steroids

38
Q

function of golgi apparatus

A

found in plant and animal cells
flattened sacs of membrane similar to the SER
modifies proteins and lipids before packaging them into golgi vesicles
vesicles then transport proteins and lipids to their required destination
proteins that go through the golgi apparatus are usually exported such as hormones like insulin, put into lysosomes or delivered to membrane bound organelles

39
Q

large permanent vacuoles

A

sac in plant cells surrounded by the tonoplast, selectively permeable membrane
vacuoles in animal cells are not permanent and small

40
Q

function of vesicle

A

plant and animal cells
membrane bound sac for transport and storage

41
Q

function of lysosomes

A

specialist forms of vesicles which contain hydrolytic enzymes (enzymes that break down biological molecules down)
break down waste material such as worn out organelles
used extensively by cells of the immune system and in apoptosis (programmed cell death)

42
Q

function of centriole

A

hollow fibres made of microtubules
two centrioles at right angles to search other form a centrosome, which organises the spindle fibres during cell division
not found in flowering plants and fungi

43
Q

function of microtube

A

found in all eukaryotic cells
makes up the cytoskeleton of the cell ab 25nm in diameter
made of alpha and beta tubulin combined to form dimers, the dimers are then joined into protofilaments
13 protofilaments in a cylinder make a microtubule

44
Q

function of cytoskeleton

A

provide support and movement of cell

45
Q

structure of microvilli

A

specialised animal cells
cell membrane projections
increases surface area to increase the rate of exchange of substances

46
Q
A

Module 2 - Foundations In Biology (7 decks)

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