3.2.1-Cell Structure And Microscopy

Question 1

Eukaryotic cells

Answer 1

Have a distinct nucleus and membrane bound organelles

Question 2

Cell surface membrane

Answer 2

Plasma membrane made from phospholipids
Partially permeable which controls exchange between the cell and its environment

Question 3

Nucleus

Answer 3

Surrounded by 2 membranes forming nuclear envelope
Has nuclear pores
Contains darker staining area, nucleolus
Creates rRNA
Nuclear pores allow mRNA and rRNA to leave

Question 4

Mitochondria

Answer 4

2 membranes forming envelope
Inner membrane folded to form cristae
Matrix contains protein, lipids, ribosomes, and DNA so can produce its own proteins
Aerobic respiration
Make ATP

Question 5

Endoplasmic reticulum

Answer 5

Ribosomes mean rough
No ribosome means smooth
RER- synthesis of proteins, creates the Golgi apparatus
SER- synthesises, stores and transports lipids and carbohydrates

Question 6

Ribosomes

Answer 6

Free in cytoplasm
Made of RNA and protein
Larger in eukaryotic
Smaller in prokaryotes, mitochondria and chloroplasts
Site of protein synthesis

Question 7

Golgi apparatus

Answer 7

Formed from vesicles from ROUGH endoplasmic reticulum
Breaks down at other end to form Golgi vesicles
Processes, modifies and packages proteins and lipids into vesicles for transport
Make lysosomes

Question 8

Lysosomes

Answer 8

Single membrane
Hydrolytic enzymes
Digest old cell organelles and cells
Hydrolyse pathogen in phagocytes
Release enzymes outside of the cells

Question 9

Cell wall

Answer 9

Algae and plant cell walls made from cellulose
Fungi made from chitin
Provides mechanical strength
Prevents cell from bursting when water enters by osmosis
Freely permeable

Question 10

Large central vacuole

Answer 10

Membrane called tonoplast
Filled with fluid
Tonoplast controls exchange between vacuole and cytoplasm
Makes cells turgid for support

Question 11

Chloroplast

Answer 11

2 membranes forms an envelope
Stroma liquid inside
Thylakoid membrane stacked into grana
Small starch grains and lipid droplets
Photosynthesis

Question 12

Ultrastructure

Answer 12

Detail inside of cells, as revealed by electrons

Question 13

Eukaryotes

Answer 13

Cells have a distinct nucleus and membrane bound organelles

Question 14

Division of labour

Answer 14

Each type of cell organnelle has a specific role within a cell

Question 15

Division of labour

Answer 15

RNA in nucleus with code for proteins
Protein synthesis on ribosomes
Protein transported through RER
Protein molecules pinched off in vesicles to Golgi apparatus
Vesicle fuse with Golgi apparatus
Packages and processes protein molecules ready for release
Proteins pinched off in vesicles from Golgi and transported to plasma membrane
Vesicle fuse with membrane
Protein leaves cell by exocytosis

Question 16

Prokaryotic cells and smaller and have no nucleus of other membrane mound organelles

Answer 16

.

Question 17

Prokaryotic cells structure and function

Answer 17

Cell wall by meurin preventing mechanical damage
Capsule, protects bacteria
Plasma membrane, controls what enters and exits
Flagellum- locomotion
Ribosome- protein synthesis
Circular DNA- contains genetic information
Plasmids- contain DNA to help bacteria survive adverse conditions
Mesosome- creates a large surface area for attatchemnt of enzymes, site of respiration
Pili-attachment of one bacteria to another to transfer genetic information

Question 18

Es

Question 19

Virus structure

Answer 19

Nuclic acids such as DNA or RNA
Capsid protein coat that encloses nucleic acid
Lipid envelope
Attachment protein to bind and attatch to host cell

Question 20

Magnification

Answer 20

How many times bigger the image is compared to the object

Question 21

Resolution

Answer 21

The minimum distance apart that two object can be for them to appear as different objects. The higher the resolution, the greater the clarity

Question 22

Preparing a slide with a light microscope

Answer 22

Add drop of water to glass
Thin sample to float on water
Stain with iodine
Lower cover slip using mounted needle
Press cover slip down firmly so cells don’t overlap and allow light to pass through

Question 23

Maximum resolving power of a microscope

Answer 23

0.2um

Question 24

Submission electron microscope

Answer 24

Electrons on surface
Image is 3D
Resolution= 20nm

Question 25

Maximum resolving power of electron microscopes

Answer 25

0.1-0.2nm

Question 26

Electron microscopes

Answer 26

Electrons have a shorter wavelength than light Electron microscopes distinguish two extremely close objects

Question 27

Transition electron microscope

Answer 27

See internal structures 2D Resolution=0.1nm

Question 29

Magnification equation

Answer 29

Magnification= size of image/ size of real object

Question 30

Eyepiece graticule

Answer 30

Scale has no units

Question 31

Setting up an eyepiece graticule

Answer 31

Stage micrometer onto stage Focus so stage micrometer ruler becomes visible Lineup eyepiece graticule with stage micrometer ruler Determine number of small divisions on the eyepiece graticule there are between a single division on the stage micrometer ruler Determine Scale to determine length of single unit on eyepiece graticule

Question 32

Separating cell components

Answer 32

Cell homogenised/ blended to break open cells. Filter to remove debris smell whole cells Use isotonic solution to prevent damage to organelles Use buffer to prevent enzyme denaturation Keep cold to prevent organelle damage by enzymes Centrifuge at lower speeds to separate nuclei/ cell fragments Pour of liquid (supermatant) and respin at higher speeds Repeate Organelle desired in pellet