2 - Basic components of living systems

Question 1

Development of Cell Theory

Answer 1

1665 - Cell first observed.
1674 - First living cell observed.
1832 - Evidence for the origin of new pant cells.
1833 - Nucleus first observed.
1837 - The birth of a universal cell theory.
1845 - Evidence for he origin of new animal cells.
1860 - Spontaneous generation disproved.

Question 2

Light Microscope

Answer 2

2 lenses : objective lens, eyepiece lens.
Cheap
Easy to use
Portable and light
Able to be used to study whole living specimens
Allow x1500
Electromagnetic spectrum wave = 400-700 nm. So the closer structures are together they will appear as on object

Question 3

Scanning Electron Microscope

Answer 3

3D image with a magnification from x15 up to x200000.
Image is black and white
Specimen still has to placed in a vacuum and is often coated with a fine film of metal.

Question 4

Transmission Electron Microscope

Answer 4

Specimen has to be chemically fixed by dehydrated and stained.
Beam passes through the specimen, which is stained with metal salts.
2D black and white image this image is called an electron micrograph

Question 5

Laser Scanning Microscope

Answer 5

They use laser light to scan an object point by point and assemble.
Images are high resolution and show high contrast.
They can be used to observe whole specimens as well as cells.

Question 6

Magnification

Answer 6

The number of times larger an image appear, compared with the size of the object.

Question 7

Resolution

Answer 7

The clarity of an image; the highest the resolution, the clearer the image.

Question 8

Dry Mount

Answer 8

Solid specimens are viewed whole or cut into very thin slices with a sharp blade.
Place the specimen on the plate and cover with a cover slip over the sample.

Question 9

Wet Mount

Answer 9

Specimen are suspended in a liquid such as water immersion in oil. A cover slip placed on from an angle.

Question 10

Squash Slides

Answer 10

A wet mount is first prepared, then a lens tissue used to gently press down the cover slip. Depending on the sample squashing it could damage the sample. Squash sample need soft sample.

Question 11

Smear Slides

Answer 11

The edge of a slide, creating a thin even coating on another slide.

Question 12

Gram stain technique

Answer 12

Crystal violet is first applied to a bacterial on a slide, then iodine which fixes the dye. Then the slide is washed alcohol.

Question 13

Acid-fast technique

Answer 13

A lipid solvent is used to carry carbolfuchsin dye into the cells being studied.

Question 14

Calculating magnification

Answer 14

image size/actual size = magnification

Question 15

Eyepiece graticule

Answer 15

A measuring device. It is placed in the eyepiece of a microscope and acts a ruler when you an object under the microscope

Question 16

Stage graticule

Answer 16

A precise measuring device. It is a small scale that is placed on microscope and used to calibrate the value of eyepiece divisions at different magnifications

Question 17

Animal Cell

Answer 17

Shape = Round 
Nucleus = Present
Cilia = Present
Cell wall = Absent
Vacuole	 = Present
Centrioles = Present 
Cytoplasm = Present
Ribosomes = Present
Mitochondria = Present
Plastids	= Absent
Chloroplast = Absent
Endoplasmic Reticulum (Smooth and Rough) = Present
Golgi Apparatus = Present
Microtubules/ Microfilaments =	Present
Plasma Membrane = Only cell membrane

Question 18

Plant Cell

Answer 18

Shape = Rectangular
Nucleus	 = Present
Cilia = Absent Cell wall = Present 
Vacuole = Present
Centrioles = Present 
Chloroplast = Present 
Cytoplasm = Present
Ribosomes = Present	
Mitochondria = Present	
Plastids	= Present 
Endoplasmic Reticulum (Smooth and Rough) = Present
Golgi Apparatus	= Present
Microtubules/ Microfilaments = Present
Plasma Membrane = Cell wall and a cell membrane

Question 19

The Cytoskeleton

Answer 19

Microfilaments - contractile fibres formed from actin. Responsible for cell movement and also cell contraction during cytokines.
Microtubles - Globular tubulin protein polymerise to form tubes that are used to form scaffold- like structures that determine the shape of the cell.
Intermediate fibres - these fibres give mechanical strength to cells and help maintain there integrity

Question 20

Production and secretion of a protein.

Answer 20

The gene is transcribed into a length of mRNA.
Many copies of this mRNA are made and they are passed out of the nuclear pores to the ribosomes.
At the ribosomes the instructions are translated and insulin molecules are assembled.
These insulin molecules pass into the cisternae of the RER
Vesicles pinch of a go to the GA
The vesicles fuse with the GA
Vesicles pinch off and pass to the plasma membrane,where the vesicle fuses with the plasma membrane
Plasma membrane opens up to release insulin molecules outside

Question 21

Prokaryotic Cell vs Eukaryotic Cells (Similarities)

Answer 21

Prokaryotic cells are similar to eukaryotic cells : they have a plasma membrane cytoplasm ribosomes and DNA

Question 22

Prokaryotic Cell vs Eukaryotic Cells (Differences)

Answer 22

Prokaryotic cells are different to eukaryotic cells: as they are smaller, have a less developed cytoskeleton they do not have a nucleus and they do not have mitochondria

Question 23

Binary fission

Answer 23

Prokaryotic cells divide through binary fission