Cell Structure

Question 1

Define Magnification

Answer 1

How many times bigger the image observed is in comparison to the actual size

Question 2

Define Resolution

Answer 2

The ability to distinguish between two points

Question 3

What is the equation for magnification ?

Answer 3

Image size = Actual Size x Magnification

Question 4

How do light microscopes work ?

Answer 4

Lenses focus rays of light and magnify the view of a specimen
Reflected light is transmitted to the observer via the objective lens and eyepiece

Question 5

How do transmission electron microscopes work ?

Answer 5

Projects an electron beam through a sample. An electromagnetic beam of electrons is projected onto the sample, and a 2D image is formed.

Question 6

How do scanning electron microscopes work ?

Answer 6

Scanning Electron Microscopes directs an electron beam across a sample. SEM is different from TEM in that it projects electrons across a specimen instead of simply passing electrons through it. Electrons from the specimen which are captured in a special instrument known as a cathode ray tube. Can be used to produce a 3D image

Question 7

Why do samples need to be stained for light microscopes ?

Answer 7

Coloured dye binds to the structures, which facilitates the absorption of wavelengths of lights to produce an image. Staining allows for the differentiation between features

Question 8

What is the magnification and resolution of a Light microscope ?

Answer 8

Resolution - 200 nm
Magnification - x1500

Question 9

What is the magnification and resolution of a Transmission Electron Microscope ?

Answer 9

Resolution - 0.5 nm
Magnification- x500,000

Question 10

What is the magnification and resolution of a Scanning Electron Microscope ?

Answer 10

Resolution - 5 nm
Magnification - x500,000

Question 11

Describe the structure of the nucleus

Answer 11

Surrounded by a nuclear envelope, double membraned
Contains nuclear pores
Nucleolus made of RNA

Question 12

What is the function of the nucleus ?

Answer 12

Controls the activities of the cells by controlling transcription

Question 13

What is the structure of the Rough Endoplasmic reticulum ?

Answer 13

Formed from continuous folds of membrane
Contains Ribosomes

Question 14

What is the Function of the Rough Endoplasmic Reticulum ?

Answer 14

Involved in Processing and packaging Proteins into vesicles

Question 15

What is the structure of the Smooth Endoplasmic Reticulum ?

Answer 15

Formed from continuous folds of membrane
Doesn’t contain ribosomes

Question 16

What is the function of the Smooth Endoplasmic Reticulum ?

Answer 16

Involved in the production, processing and storage of lipids

Question 17

What is the structure of the Golgi ?

Answer 17

Flattened sacs of membrane

Question 18

What is the Function of the Golgi ?

Answer 18

Modifies proteins and lipids before packaging them into vesicles

Question 19

What is the Structure of Ribosomes ?

Answer 19

Two Subunits of RNA

Question 20

What is the function of Ribosomes ?

Answer 20

The Main site of protein synthesis

Question 21

How are Proteins produced ?

Answer 21

DNA is transcribed into mRNA
The mRNA exits the nucleus via nuclear pores
mRNA travels to Ribosomes located on the Rough Endoplasmic Reticulum
The Rough Endoplasmic reticulum packages them into vesicles
The Vesicles are transported to the Golgi where they’re modified and repackaged into vesicles
The vesicles travel to the plasma membrane where they fuse with it and exit the cell vis exocytosis

Question 22

What is the structure of the mitochondria ?

Answer 22

Double membraned with the inner membrane folded to cristae
The matrix formed by the cristae contains enzymes needed for aerobic respiration

Question 23

What is the Function of the mitochondria ?

Answer 23

Produces ATP as a result of aerobic respiration

Question 24

What is the structure of the chloroplast ?

Answer 24

Double membraned

Question 25

What is the function of Chloroplast ?

Answer 25

The main site of photosynthesis

Question 26

What are lysosomes ?

Answer 26

Membrane bound sac containing digestive enzymes which break down waste materials such as organelles

Question 27

Describe the structure and function of the plant walls ?

Answer 27

Made of cellulose to provide strength and prevent cell from bursting when water enters the cell

Question 28

What are vesicles ?

Answer 28

Membrane bound sac for transport and storage

Question 29

What are bacterial and fungal cell walls made of ?

Answer 29

Fungi : Chitin Bacteria : Peptidoglycan

Question 30

What are centrioles ?

Answer 30

Hollow fibres made of microtubules Two centrioles at right angles to each other form a centrosome, which organises the spindle fibres during cell division Not found in flowering plants and fungi

Question 31

What is the plasma membrane ?

Answer 31

The plasma membrane controls the exchange of materials between the internal cell environment and the external environment The membrane is partially permeable Plasma membrane is formed from a phospholipid bilayer

Question 32

What is the flagella ?

Answer 32

Made of longer microtubules Contracts to provide cell movement

Question 33

What is the Cillia ?

Answer 33

Hair-like projections made from microtubules Allows the movement of substances over the cell surface

Question 34

Why is the cytoskeleton important ?

Answer 34

Provides mechanical strength Aids transport within cell Enables cell movement

Question 35

What are similarities between eukaryotes and prokaryotes ?

Answer 35

Both have; Cell Membrane Cytoplasm Ribosomes

Question 36

Differences between eukaryotic and Prokaryotic

Answer 36

Prokaryotes have no membrane bound cells or nucleus Prokaryotes have small (70s) Ribosomes and Eukaryotes have (80s) Prokaryotes have Circular DNA