Cell Structure

Question 1

how would you prepare a dry mount

Answer 1

cut a thin slice of the specimen, use tweezers to place on slide, place cover slip on top

Question 2

how would you prepare a wet mount

Answer 2

Pipette a drop of water onto the slide, tilt and lower cover slip on top avoiding bubbles, add a stain to one edge of cover slip then a paper towel on the opposite edge to draw stain under slip across the specimen

Question 3

name two common stains

Answer 3

eosin and methylene blue

Question 4

how do you use a microscope

Answer 4

place slide on the stage
selective lowest power objective lens
use coarse adjustment knob to move stage
look down eyepiece and use coarse adjustment knob to get image inn focus
adjust with fine adjust knob until a clear image appears
swap to higher powered objective lens if needed

Question 5

how do you use an eyepiece graticule

Answer 5

place it in the eyepiece, it is a transparent ruler with numbers but no units

Question 6

how do you use a stage micrometer

Answer 6

placed on stage, has an accurate scale, used to work out value of divisions on the eyepiece graticule at a particular magnification

Question 7

what is the formula for magnification

Answer 7

image size/ object size

Question 8

what is magnification

Answer 8

how much bigger the image is than the specimen

Question 9

give the resolution, magnification and brief description of light microscopes

Answer 9

resolution: 0.2 micrometres
magnification: x1500
use light

Question 10

what is resolution

Answer 10

how well a microscope can distinguish between two points

Question 11

give a brief description of laser scanning confocal microscopes

Answer 11

laser beam I focused through a lens which splits the beam and some light is directed to the specimen, giving it a fluorescent tag, light is then focused through a pinhole to a detector which produces a computer image
3d images

Question 12

place nanometers, milli stres and micrometers in order from smallest to largest

Answer 12

nanometres, micrometres, millimetres

Question 13

give a brief description, magnification and resolution of a transmission electron microscope

Answer 13

use electromagnets to focus bars of lights to produce 2d images
resolution 0.0002
mag: x 1,000,000

Question 14

give brief description magnification and resolution of a scanning electron microscope

Answer 14

scans a beam of electrons across specimen which knocks off electrons that gather in a cathode tube, can be 3D
resolution: 0.002
mag: x500,000

Question 15

give the description and function of the nucleus

Answer 15

large organelle, nuclear envelope containing pores, contains nucleolus
controls cell activity by controlling transcription

Question 16

give the description and function of a lysosome

Answer 16

round organelle, no clear internal structure
contains digestive enzymes which breaks down inactive organelles

Question 17

give the description and function of the RER

Answer 17

system of membranes enclosing fluid-filled space, covered with ribosomes
folds and processes proteins

Question 18

give the description and function of the SER

Answer 18

system of membranes enclosing a fluid-filled space, no ribosomes
synthesis and process of lipids

Question 19

give the description and function of the Golgi apparatus

Answer 19

fluid filled, membrane-bound, flattened sacs
processes and packages lipids and proteins also makes vesicles

Question 20

give a description and the function of ribosomes

Answer 20

small organelle, free floating or attached, made up of preteens and RNA, no membrane
site of protein synthesis

Question 21

give a description and function of mitochondria

Answer 21

oval-shaped, double membrane
site of aerobic respiration and where ATP is produced

Question 22

give a description and function of chloroplasts

Answer 22

double membrane, thylakoids which form grana, linked by lamellae
site of photosynthesis

Question 23

give the function and description of a centriole

Answer 23

small cylinders made of microtubules
involved in separation of chromosomes during cell division

Question 24

give the function and a description of the cell wall

Answer 24

made of cellulose
provides support and structure for the cell

Question 25

give the function and a description of cilia

Answer 25

small hair like structures, have an outer membrane and nine pairs of micortbulus with a single pair in the middle
allows substances to be moved along cell surface

Question 26

give the function and a description of flagellum

Answer 26

stick out from cell and surrounded by plasma membrane, two tubule in centre and nine round edge
used to propel cells forward

Question 27

what are the five main functions of the cytoskeleton

Answer 27

supports organelles, keeping them in position
strengthen cell and maintain its share
movement of chromosomes
cell movement
transport of organelles within the cell

Question 28

describe the interelationship between organelles in synthesis and secretion of proteins

Answer 28

DNA contains the gene which codes for an amino acid sequence of a protein
proteins are then synthesised at the ribosomes
they are folded and processed at the RER and transported to the Golgi in vesicles, then lave the cell via vesicles and merge with cll plasma membrane

Question 29

give some similarities and differences between prokaryotic and eukaryotic cells

Answer 29

similarities: both have a cytoplasm and a cell membrane, both perform protein synthesis through ribosomes

differences: DNA is circular in P and linear in E, P are smaller (2 micrometres compared to 10-100) few organelles none with membranes in p, flagella in p arranged in a helix, 70s ribosomes in p, no nucleus in p