Cells

Question 1

What is the preparation stage

Answer 1

Tissue was placed in … solution
Cold = prevent enzyme activity
Isotonic (same con.) = prevent osmosis
Buffered = maintain a constant pH

Question 2

What is the homogenisation stage

Answer 2

Tissue is placed in the blender = break up cell
Then fluid is extracted (homogenate)
And filtered = remove whole cells and debris

Question 3

What is ultracentrifugation

Answer 3

Homogenate is placed in an ultra centrifuge
Spun at low speed = creates a density gradient
Sediment in the base and supernatant at the top
Extract supernatant
Repeat with medium and high speeds

Question 4

What is the supernatant

Answer 4

The solution at the top of the homogenate that is collected ( contains cell organelle)

Question 5

What order are cell organelles collected from cell fractionation

Answer 5

Nuclei
Mitochondria
ribosomes

Question 6

What are the features of a light microscope

Answer 6

Uses light
Long wavelength
Low magnification
200nm resolution
In colour 
2D
Not in a vacuum
Thin sample-single layer 
No complex staining

Question 7

What are the features of TEM (transmission electron microscope)

Answer 7

Uses electrons
Short wavelength
High(est) magnification
0.1nm resolution
Not in colour
2D
Thin samples 
In a vacuum
Complex staining

Question 8

What are the features of an SEM (scanning electron microscope)

Answer 8

Uses electrons
Short wavelength
High magnification
10–20nm resolution
Not in colour
3D
Thin sample
In a vacuum
Complex staining

Question 9

What is cell fractionation

Answer 9

A method to remove the organelle from cells

1. Preparation
2. Homogenisation
3. Ultracentrifugation

Question 10

How do you work out magnification

Answer 10

Size of object

Question 11

Role of cell wall

Answer 11

Gives structure

Stops cell collapsing

Question 12

Role of chloroplast

Answer 12

Site of photosynthesis

Absorb light

Question 13

Role of smooth endoplasmic reticulum

Answer 13

Forming and transporting lipids

Question 14

Role of Mitochondria

Answer 14

Produces ATP-> leads to energy release

Double membrane
Matrix- produces lipid fluid
Lots of enzymes
Cristae- LSA

Question 15

Role of Ribosomes

Answer 15

Protein synthesis

Question 16

Role of nucleus

Answer 16

Makes RNA and ribosomes

Question 17

Roles of lysosomes

Answer 17

Contains enzymes 
Digests substances (Eg. Old non-useful structures)

Question 18

Role of Nuclear pores

Answer 18

Allows passage of large molecules (mRNA)

Question 19

Role of nucleoplasm

Answer 19

Contains chromotin

Question 20

Role of rough endoplasmic reticulum

Answer 20

Contains ribosomes

Forming and transporting proteins

Question 21

Roles of Golgi body

Answer 21

Modified proteins
Makes glycoproteins
Produces secretory enzymes
Secretary carbohydrates

Question 22

Role of Golgi vesicles

Answer 22

Contains enzymes

Question 23

Role of cell membrane

Answer 23

Controls movement of substances in and out of cells

Question 24

Role of cytoskeleton

Answer 24

Transporting

Structure

Question 25

Role of the pilli

Answer 25

Exchange of substances

Question 26

Role of flagella

Answer 26

Used for movement

Question 27

Role of cell wall

Answer 27

Structure

Question 28

Features of a eukaryotic cell

Answer 28

``` Cell wall Cytoskeleton Cell membrane Golgi vesicles Golgi body Rough and smooth endoplasmic reticulum Mitochondria ribosomes Centrioles Nucleus Lysosomes Nucleus pores Nuclear Nucleoplasm Chloroplast Vacuole ```

Question 29

Features of a prokaryotic cell

Answer 29

``` Slime capsule Cell wall Cell membrane Nucleoid Pili Ribosomes Flagella Plasmid ``` Very few organelles Smaller ribosomes No membrane-bound organelles

Question 30

Features of a cell surface membrane

Answer 30

``` Glycoprotein Glycolipid Extrinsic protein Intrinsic protein Cholesterol Phospholipids Hydrophilic head Hydrophilic tails ```

Question 31

Role of glycoproteins

Answer 31

Cell recognition and interaction | Hormones attach

Question 32

Role of extrinsic proteins

Answer 32

Molecules bind and pass through cell

Question 33

Role of intrinsic proteins

Answer 33

Allows large and charged molecules to pass through

Question 34

Role of cholesterol

Answer 34

Provides structural support

Question 35

Role of phospholipids

Answer 35

Allows lipid soluble substances in/out of cell

Question 36

What is the fluid-mosaic model

Answer 36

Individual phospholipids can move relative to each other | Proteins embedded in phospholipid layer