Cells

Question 1

What is the structure of the cell surface membrane?

Answer 1

Phospholipid bilayer with embedded proteins.

Question 2

What is the function of the cell surface membrane?

Answer 2

Regulates movement of substances in and out of the cell.

Question 3

What is the structure of the nucleus?

Answer 3

Surrounded by a nuclear envelope which contains pores.
It contains chromosomes.
It contains one or more nucleolus.

Question 4

What is the function of the nucleus?

Answer 4

Controls the cell’s activities.
DNA codes for proteins.
The pores allow substances to move between the nucleus and the cytoplasm.
The nucleolus makes ribosomes.

Question 5

What is the structure of the mitochondria?

Answer 5

Double membrane
Inner membrane folds to form cristae.
Matrix is the gel-like fluid that contains DNA.
Contain DNA
Contain ribosomes

Question 6

What is the function of the mitochondria?

Answer 6

Produces ATP from aerobic rerespiration.

Question 7

What is the structure of the rough endoplasmic reticulum?

Answer 7

Fluid-filled sacs that have ribosomes attached to them.

Question 8

What is the function of the RER?

Answer 8

Syntheis and transport of proteins made at the ribosome.

Question 9

What is the structure of the ribosome?

Answer 9

Membrane-free
Made up of ribosomal RNA and proteins

Question 10

What are the ribosomes in prokaryotic cells called?

Answer 10

70S ribosomes

Question 11

What is the function of the ribosome?

Answer 11

Responsible for protein synthesis.

Question 12

What is the structure of the SER?

Answer 12

Fluid-filled sacs.

Question 13

What is the function of the SER?

Answer 13

Synthesises and transports lipids.

Question 14

What is the structure of the Golgi apparatus?

Answer 14

A group of fluid-filled, membrane-bound sacs.

Question 15

What is the function of the Golgi apparatus?

Answer 15

Processes and packages new lipids and proteins into vesicles.
Modifies and processes proteins.
Forms lysosomes.

Question 16

What is the function of a vesicle?

Answer 16

Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell.

Question 17

What is the structure of a lysosome?

Answer 17

Contains hydrolytic enzymes, aka lysozymes.

Question 18

What is the function of a lysosome?

Answer 18

Digests invading cells and breaks down worn out components

Question 19

What is the structure of the cell wall?

Answer 19

Surrounds cells in plants, algae and fungi.
Plants and algae- cellulose
Fungi- chitin

Question 20

What are the 3 functions of cell membranes?

Answer 20

To control the transport of substances entering and leaving the cell- partially permeable
To act as a receptor site to recognise chemicals that need to enter the cell or organelles
To separate the cell from the environment + act as a barrier between organelles and the cytoplasm

Question 21

Describe the structure of a chloroplast

Answer 21

Double membrane
Stroma- fluid
Thylakoid membrane
DNA
70S ribosomes

Question 22

What is the function of a chloroplast?

Answer 22

Where photosynthesis occurs
Thylakoid membranes contain chlorophyll and also have a large surface area to absorb more light
Stroma- contains enzymes needed for photosynthesis

Question 23

Why are viruses acellular?

Answer 23

They cannot undergo cell division

Question 24

What components do viruses contain?

Answer 24

Genetic material
Capsid
Attachment protein

Question 25

Define magnification

Answer 25

The number of times bigger the image appears to its actual size

Question 26

Define resolution

Answer 26

The minimum distance between two points in which they can be seen as separate

Question 27

Why do light microscopes have a low resolution?

Answer 27

Light has a long wavelength so has a low resolution

Question 28

Why do electron microscopes have a high resolution?

Answer 28

Electrons have a shorter wavelength than light

Question 29

What are the two types of electron microscopes?

Answer 29

Transmission Electron Microscope (electrons are transmitted through specimen) Scanning Electron Microscope (electrons bounce off specimen)

Question 30

Compare TEM to SEM

Answer 30

TEM- higher resolution, requires thin specimen, produces black and white image SEM- lower resolution than TEM, 3D image, shows the external image of the cell

Question 31

What are the advantages of using an electron microscope over a light microscope?

Answer 31

Higher resolution, higher magnification, more detailed images

Question 32

What are the advantages of using a light microscope over an electron microscope?

Answer 32

Produces coloured images, can view live specimens, simple preparation

Question 33

Describe the process of isolating organelles from a cell

Answer 33

Homogenise the sample- breaks apart cell membranes allowing for organelles to be released Filter to remove cell debris Add to an ice cold, isotonic and pH buffered solution Centrifuge (spin at low speeds) the solution to produce a pellet of organelles- the denser organelles will be separated first

Question 34

Why does the solution need to be isotonic?

Answer 34

To prevent osmotic lysis of organelles

Question 35

Why does the solution need to be ice cold?

Answer 35

Stop lytic enzymes to prevent digestion of organelles

Question 36

Why does the solution need to be pH buffered?

Answer 36

Maintain constant pH to prevent denaturation of enzymes