foundations in biology- 2 basic components

Question 1

What does a microscope do?

Answer 1

allow you to magnify objects hundreds, thousands, and hundreds of thousands of times
open worlds of unicellular organisms and see how their structures relate to functions.

Question 2

What was the first microscope? When was it invented

Answer 2

light
16-17 c

Question 3

What happened by the mid-19th century?

Answer 3

Scientists had access to microscopes with a high enough mag to see individual cells, and cell theory was developed

Question 4

What does the cell theory state

Answer 4

-Plant and animal tissues are composed of cells

-Cells are basic units of life

-Cells only develop from existing cells

Question 5

What are the positives of/ why are light microscopes important?

Answer 5

-easily available

-cheap

-can be used in the field

-observes dead and living specimens

Question 6

How does a compound light microscope work? consists of?

Answer 6

has 2 lenses- objective(closest to specimen), eyepiece.

The objective provides a magnified image that’s further magnified again by the eyepiece, which provides a higher magnification and reduces chromatic aberration than a simple one

illumination provided from below the specimen and above if the specimen is opaque

Question 7

What are the different ways to prepare a sample

Answer 7

-dry mount
-wet mount
-squash slides
-smear slides

Question 8

How is dry mount prepared? Examples used to view

Answer 8

-specimens viewed as a whole or cut into thin slices(sectioning).

-Specimen placed on the slide’s centre and coverslip over it.

-hair, pollen, dust, and insects as a whole. muscle tissue and plants are sections by sectioning

Question 9

How is a wet mount prepared? Examples used to view

Answer 9

-specimens suspended in liquid

-Cover slip placed at an angle

-aquatic samples

Question 10

How are squash slides prepared? Examples used to view

Answer 10

-Wet mount first prepared, lens tissue used to gently press down the cover slip
-damage to the slip was prevented by squashing the sample between two microscope slides
-good for soft samples
-care needed, sothe cover slip is not broken when pressed

-root tips squashed to look at cell division

Question 11

How are smear slides prepared? Examples used to view

Answer 11

-The edge of the slide is used to smear the sample, creating a thin, even coating over another slide
-Cover slip placed over the sample

-blood sample- see blood cell

Question 12

what is brightfield microscopy

Answer 12

When the sample is illuminated from below and viewed from the top

Question 13

what is wide-flied microscopy

Answer 13

When the whole sample is illuminated at once

Question 14

why are most stained samples low contrast

Answer 14

Most cells don’t absorb a lot of light

Question 15

what is resolution limited by in staining

Answer 15

wavelength and diffraction of light as it passes through the sample

Question 16

What does staining do

Answer 16

increases contrast as different components take up stains to different degrees, allowing components to become more visible so they can be identified

Question 17

how do you prep a sample for stainibg

Answer 17

Place the sample on the slide and allow air dry

Heat treat it by passing it through an open flame

The specimen will then adhere to the slide and take up stains

Question 18

what do pos chareged dyes do? example of dye

Answer 18

are attracted to neg charged material in cytoplasm staining the negative components

crystal violet, methylene blue

Question 19

what do neg charged dyes do? example of dye

Answer 19

They are repelled by neg charged cytosol, they stay out of the cell, leaving the cell unstained, letting them stand out against the stained background

Nigrosin, Congo red

Question 20

whats differential staining

Answer 20

The way of distinguishing between the two types of organisms is otherwise hard to identify.

can also distinguish between the two types of organelles of an organism within a tissue

Question 21

what is gram staining

Answer 21

searate bacteria into 2 grps - fran pos a d gram neg

Cytol violet was applied to the bacterial specimen on a slide, then iodine fixing dye.

Slide washed with alcohol

gram pos retain dye and appear blue, neg have these walls a loose dye

Neg then dyed with safirin dye (counterstained)

This appears red

gram pos susceptible to penicillin, inhibiting formation of walls

Neg have thin walls, not susceptible to penicillin

Question 22

what is the acid-fast technique for staining used for

Answer 22

to differentiate species of Mycobacterium from other bacteria

lipid solvent used to carry carbol fuchsin dye in the cells

Cells were washed with a dilute acid-alcohol solution

Mycobacterium retains dye, which is bright red

other bacteria exposed to methylene blue

Question 23

what are thec stages of prepping slides? what is involbes

Answer 23

fixing- chemicals used to preserve specimens

sectioning- specimens dehydrated with alcohol and placed in wax or resin till hard and then sliced thinly with a microtome

staining- specimens often treated with many stains showing different structures

mounting- specimen secured to microscope slide anda cover slip on top

Question 24

what is magification

Answer 24

How many times larger is the image than the object viewed

Question 25

what is resolution

Answer 25

The ability to see individual objects as separate entities.

Question 26

what limits resolution

Answer 26

diffraction of light as it passes through the sample and the lens, so structures are are no longer seen as separate

Question 27

what is diffraction

Answer 27

tendency of light waves to spread and pass close to physical structures

Question 28

how can resolution e increased

Answer 28

using electron beams

Question 29

whats the calc for magnuficatioj

Answer 29

image size/actual size

Question 30

how to calibrate

Answer 30

1. Set up the eyepiece graticule and stage micrometre 2. Align the eyepiece graticule and stage micrometre 3. Calculate the value of the ocular units in micrometres 4. Repeat the process for your other objective lenses

Question 31

how does electron microscopy work

Answer 31

beam of electrons with wavelength of <1nm used to illuminate the specimen more details of cell ultrastructure as smaller wavelengths

Question 32

magnification of Electron microscope

Answer 32

up to x500000

Question 33

disad of electro microscopy

Answer 33

expensive Specimens can be damaged by the electron beam and complex prep, so the problem of artefact only in labs

Question 34

what are the two typres oc electrom microscopy

Answer 34

transmission EM scanning EM

Question 35

What is TEM 'what resolution

Answer 35

a beam of electrons transmitted through the species and focused to produce an image 2D reslvig powr of 0.5nnm

Question 36

what is SEM 3D what resolution

Answer 36

beam electron sent across the surface and collected. 3-10nm

Question 37

differences of LM and EM

Answer 37

LM- cheap to buy and operate small, portable simple sample prep sample prep does not normally lead to distortion vacuum not required natural colour of sample up to 2000x mag res 200nm specimen dead or live EM- expensive Large, needs installing complex sample prep Sample prep can lead to distortion vacuum requires b and w over x500000 msg res of TEM o.5, SEM 3-10nm dead specimen

Question 38

what is an artefact?

Answer 38

visible detail caused by processing specimens

Question 39

what us laser scanning confocal microscopy used for

Answer 39

a microscope moving a single point of focused light across the specimen(point illumination) cause fluorescence from the components dyed. emitted light fromthe specimen if the filter is passed through a pinhole aperture Only light from focal plane detected used instead of LM for higher intensities high res asvlight from elsewhere removed 2D when moved across specimwn, 3D when at difff focal planes noninvasive- used to diagnose eye disease- can see distribution of molecules in cells- help develop new drugs

Question 40

whats the function and structure of nucleus

Answer 40

contaon genetic info as DNA which directs synthesis of all proteins required by cell, which means DNA controls metabolic activity of cell as many of these proteins are enzymes needed for metabolism DNA in double membrane called the nuclear envelope protecting it, envelope contains pores allowing molecules to move in and out, DNA is too large to leave, so transcribed into RNA

Question 41

wsr does DNA do

Answer 41

associates with histones(protein) forming chromatin, which coils nd condenses to form chromosomes

Question 42

whats the function and structure of nucleolus

Answer 42

produce ribosomes in nucleus composed of protein and RNA

Question 43

whats the function and structure of mitrochondria

Answer 43

site of final stage cellular reproduction, the energy stored in bonds of complex, organic molecules is made available for cells to use by the production of ATP double membrane: inner = folded structure called cristae fluid interior=matrix

Question 44

whats the function and structure of ventricles

Answer 44

membranous sacs with storage and transport roles A single membrane with fluid inside

Question 45

whats the function and structure of lysosomes

Answer 45

Specialised vesicle with a hydrolytic enzyme brak down waste in cells, old organelles, pathogens(whch are englufed by phagocytic cells and involved in apoptosis

Question 46

whats the function and structure of sytoskeleton

Answer 46

network of fibres needed in shape, and stability of cell-hold organelles in place, and control cell movement and organelle movement

Question 47

cytoskeleton contains

Answer 47

microfilaments microtubles intermedate fibres

Question 48

whats the function and structure of microfilaments

Answer 48

Contractile fibres are formed from actin cell movement and contraction during cytokinesis

Question 49

whats the function and structure of mictotubles

Answer 49

globular tubulin proteins polymerise, forming tubes used to form scaffold-like structures, determining the shape of the cell act as tracks for the movement of organs mamy make spindle fibres

Question 50

whats the function intermediate fibres

Answer 50

mechanical strength and integrity

Question 51

whats the function and structure of centrioles

Answer 51

composed of microtubules 2 form centrosomes involved in the assembly and organisation of spindle fibres in cell division positioning role in structures like flagella and cilia

Question 52

What's the function and structure of flagella

Answer 52

whip-like, protrudes from the cell moves the cell and detects chemical change

Question 53

whats the function and structure of cillia

Answer 53

Hair like extension of a cell contain 2 microtubules, surrounded by 9 pairs of microtubules creates a current

Question 54

What is the endoplasmic reticulum structure What are the SER and RER functions

Answer 54

network of membranes enclosing flattened sacs (cisternae), connected to the nuclear membrane of the nucleus SER- lipid and carb synthesis and storage RER- ribosomes bound to surfaces - synthesis and transport protein

Question 54

whats the function and structure of ribosomes

Answer 54

free float or attached to the rer, no membrane, constructed of RNA Site of protein synthesis

Question 55

whats the function and structure of golgi apparatus

Answer 55

compact structure of cisternae and NO ribosomes modifies and packs proteins into vesicles

Question 56

how are proteins produced?

Answer 56

1-protein synthesised on the ribosome is bound to the ER 2- Pass into cisterae and are packaged into transport vesicles 3- Vesicles containing these proteins move to the Golgi via the cytoskeleton 4-vesicles fuse with the cis face of Golgi, and proteins enter. Proteins are modified before leaving Golgi in a vesicle from the transface 5-secretory vesicles carry proteins that need to be released from the cell, move to and fuse with the plasma membrane releasing contents by exocytosis, some vesicles become lysosomes