Cells and Cells transport

Question 1

Electron vs light microscope

Answer 1

Radiation source:
Electron vs Light

Wavelenght:
About 0.005nm vs 400-700nm

Max resolution:
0.05nm vs 200nm

Max magnification:
Over a million vs 1500

Lenses:
Electromagnets vs Glass

Speciment:
Dead, dehydraded, small and thin vs Living or dead

Image:
Black and white vs Coloured

Question 2

Advantages and disadvantage of electron microscope?

Answer 2

Adv:

Higher magnification

Higher resolution(due to shorter wavelenght)

Dis:

Vaccum so dead specimens

Difficult process and produce artefacts

Expensive and training required to use

Black and white image only

Question 3

Transmission electron microscope?

Answer 3

A beam of e- transmitted through specimen

Specimen stained by heavy metal

Substances deflect e- but pattter remaining e- produce create image

Adv: Higher resolution, internal structure observed

Dis: Very thin specimen, not 3D, specimen deteriorates

Question 4

Scanning electron microscope?

Answer 4

Specimen is coated with thin film of heavy metal

e- beam is scann specimen

e- reflected from surface are collected and produce image

Adv: Surface structure shown, 3D image, thick section examined

Dis:Lower resolution, only surface can be viewed

Question 5

What is required for a homegenic solution?

Answer 5

Ice cold, isotonic and buffer solution

Ice cold - so enzymes dont damage organelles

Isotonic - so no osmosis which causes burst or shiver

Buffer - so no damage to enzymes or organelles

Question 6

Describe homogenisation and centrifugation?

Answer 6

Break open tissue in homogenous solution using a blender

Filter to remove debris

Put it into tube and centrifuge at low speed

Cell debris e.g. cell wall would form pellets at bottom

Supernatant would be removed and spun at higher speed

Heavier organelles would form sediment e.g. nuclei

Continue process until desired organelle obtained, as continue density decrease

Usually, order is nuclei, chloroplasts, mitochondria, ER, and ribosomes

Question 7

List organelles found in eukaryotic?

Answer 7

Nucleus, centrioles, mitochondria, golgi body, lysosomes, RER, SER, chloroplasts, ribosome

Question 8

Nucleus?

Answer 8

Contain DNA

Nuclear envelope has nuclear pole that allows mRNA to communicate with cytoplasm

Nucleoplasm contains chromatin and nucleoli

In dividing cell chromatin is chromosomes

Controls cell process e.g. division, protein synthesis and ribosome synthesis

Question 9

Centrioles?

Answer 9

Produce spindle fibre for chromosome separation in mitosis and meiosis

Hollow cylinder contains 9 triplets of microtubules

Question 10

What is rough endoplasmic reticulum?

Answer 10

Has ribosomes that produce proteins that are transported through the cisternae

Usually secretory proteins and sent to golgi body

Question 11

What is smooth endoplasmic reticulum?

Answer 11

Lacks ribosomes and is involved in the production and transport of lipids

Question 12

what is golgi body function?

Answer 12

Production of glycoproteins e.g. mucin

Packaging and secretion of proteins e.g. enzymes

Formation of cell walls in plant cells.

Formation of lysosomes

Lipid biosynthesis

Question 13

Structure of chloroplast?

Answer 13

Thylakoid form stack called grana

Stroma liquid

Ribosome

Question 14

Palisade mesophyll cells structure?

Answer 14

Possess numerous chloroplasts

Have relatively thin cell walls to allow carbon dioxide to diffuse in at a faster rate

Are cylindrical (columnar) with a relatively large surface area increasing the rate of gaseous diffusion

There are with few air spaces in between so that maximum light can be absorbed

Question 15

Epithelial cells structure?

Answer 15

Shape called squamous, cuboidal and columnar used to categories

Numerous mitochondria

Microvill

Question 16

What is totipotent cell?

Answer 16

Embryonic cell that can differentiate into any cell

This include placenta

Occur for limited time in mammalian embryo

Question 17

What is pluripotent cell?

Answer 17

Embryonic stem cell that can differentiate into any cell except extra embryonic cell

Able to differentiate into all the cells that arise from the three primary germ layers; the ectoderm, endoderm, and mesoderm

Question 18

What is multipotent cell?

Answer 18

Adult stem cells that can differentiate into limited number of cell

Small number in body

Question 19

Structure of cell membrane?

Answer 19

Phospholipid bilayer, phosphate outwards and fatty acids inwards

Unsaturated fatty acids increase the permeability of the membrane whereas saturatedfatty acids decrease its permeability

Question 20

Ficks law?

Answer 20

Rate of diffusion is proportional to

surface area x concentration gradient / diffusion distance

Question 21

Channel protein involved?

Answer 21

Facilitate diffusion

Question 22

Carrier diffusion involved?

Answer 22

Facilitate and active transport?

Question 23

Whatis pinocytosis?

Answer 23

The material taken up is in liquid form

Vesicles formed are often extremely small, in which case the process is known as micropinocytosis and the vesicles as micropinocytotic vesicles