cell structure

Question 1

what is magnification?

Answer 1

number of times larger an image appears is compared with the actual size of the object.

Question 2

what is resolution?

Answer 2

the ability to clearly distinguish between two points in an image. clarity of an image.

Question 3

state types of microscope

Answer 3

optical microscope
Laser microscope
electron microscope( transmission and scanning electron microscopes)

Question 4

optical microscope details?

Answer 4

mag of x1500
wavelength 400-700nm(resolution)
creates photomicrographs

Question 5

laser scanning microscope image formation?

Answer 5

objects are scanned point by point using lasers which are then assembled and displayed on the screen.
has depth selectivity

Question 6

what are electron microscopes?

Answer 6

resolution-0.004nm mag- X125000

electrons are fired from a cathode and focused using magnets on photographic plates

Question 7

transmission electron microscope image formation?

Answer 7

beam of electron passes through the specimen which has been fixed with metal salts and then focused on photographic plates. images are in 2D and called electron micrographs.
mag- X20miliion
resolution-

Question 8

scanning electrons microscopes image formation?

Answer 8

specimen coated with heavy metal causes the electrons to bounce off the specimen forming 3D images in a vacuum. specimen has to be dead
mag- X200000
resolution-

Question 9

describe nucleus, nuclear envelope, nucleolus stating their function.

Answer 9

nucleus is surrounded by the double membrane nuclear envelope which contains pores though which large materials such as mRNA move out of the nucleus.
-nucleolus makes ribosomes
nucleus does
-contains DNA coiled around chromatin into chromosomes
-controls cellular processes such as semi-conservative replication, mRNA transcription, mitosis.

Question 10

describe the rough endoplasmic reticulum stating function

Answer 10

system of membrane containing continuous cisternae. coated with ribosomes

• provides large surface area for ribosomes to assemble amino acids into proteins
• transport system, cisternae transports substances from one area to another.

Question 11

describe and state the function of the smooth endoplasmic reticulum

Answer 11

system of membrane containing continuous cisternae with no ribosomes.
-contains enzymes that catalyses reactions like
*synthesis of cholesterol, lipids/phospolipids and steroids
involved in transport, synthesis and absorption of lipids

Question 12

describe and state the function of the cell membrane

Answer 12

fluid mosaic with phospholipid bi layer with extrinsic and intrinsic proteins

• isolates cytoplasm from external environment
• used in cell signalling
• selectively permeable to allow transport of some substances out of the cell

Question 13

explain the role of cholesterol, glycoproteins and glycolipids in the cell membrane

Answer 13

cholesterol: steroid molecules connects phospholipids and regulates fluidity of membranes
glycoproteins and glycolipids: act as cell receptors for cell signalling and communication. They also act as cell antigens for cell recognition.

Question 14

structure and function of Golgi apparatus

Answer 14

stack of membrane bound organelles.

modify and packs proteins which are then pinched off

Question 15

structure and function of mitochondrion

2-5um long

Answer 15

double membrane bound organelle with fluid filled cavity called cristae. inner membrane is fluid filled matrix.

• sites for ATP production during aerobic respiration
• self replicating. more abundant where more metabolism takes place

Question 16

chloroplasts structure and function

4-10um

Answer 16

double membrane with envelope. inner membrane with continuous stacks of thylakoids. each stack is called grana fluid filled matrix is the stroma.
-sites for photosynthesis

Question 17

structure and function of the vacuole

Answer 17

surrounded by a membrane called tonoplasts
-filled with water and solute help maintain cell stability
when full, water pushes the cell wall making plants turgid
-turgidity gives support to plants.

Question 18

lysosome structure and function

Answer 18

small bags from the Golgi apparatus surrounded by single membrane. contains strong hydrolytic enzymes and neutrophils and macrophages.

• keep the hydrolytic enzymes from the rest of the cell
• engulfs old cell organelles and digest them and return for reuse.

Question 19

cilia and undulipodia structure and function

Answer 19

formed from centrioles consists of microtubules

-for movement

Question 20

structure and function of ribosome

20nm

Answer 20

made of rRNA. made in the nucleolus.

• ribosomes at the RER used for synthesizing proteins
• free ribosomes in the cell used to assemble proteins for cell usage.

Question 21

centrioles structure and function

Answer 21

made of 200 microtubules at right angles. microtubules made of tubulin proteins.

• help in cell division
• formation of cilia and undulipodia

Question 22

cytoskeleton structure and function

Answer 22

microfilaments: gives support and mechanical strength.
intermediate filaments: anchor the cells within cytoplasm and enable cell signalling.
microtubules: gives shape and support and help organisms move through the cytoplasm.

Question 23

cellulose cell wall structure and function

Answer 23

outside of plasma membrane

• provide strength and support
• maintain cells shape
• contributes to strength
• selectively permeable

Question 24

examples of non-membrane bound organelles

Answer 24

-ribosome
-cell wall
-cilia and undulipodia
-centriole
-cytoskeleton
THE REST ARE MEMBRANE BOUND

Question 25

differences between prokaryotic and eukaryotic cells

Answer 25

• they do not have membrane bound organelles
• they do not have true nucleus
• don’t have well developed cytoskeleton
• have small ribosomes
• have free naked DNA not wound around histone proteins.