cells unit 2

Question 1

what is the structure of a nucleus?

Answer 1

• nuclear envelope
• nuclear pores
• nucleoplasm
• chromosomes
• nucleolus - site of RNA production

Question 2

what is the function of the nucleus?

Answer 2

• site of DNA replication and transcription
• contains the genetic code for each cell

Question 3

what is the structure of the endoplasmic reticulum?

Answer 3

• rough and smooth both have folded membrane’s called cisternea
• rough have ribosomes on the cisternae

Question 4

explain the structure of the Golgi apparatus and vesicles

Answer 4

• folded membranes making cisternae
• secretary vesicle pinch off from the cisternae

Question 5

explain the functions of the golgi apparatus and vesicles?

Answer 5

• add carbohydrates to portions to form glycoproteins
• produce secretory enzymes
• secrete carbohydrates
• transport, modify and store lipids
• form lysosomes
• molecules are ‘ labelled’ with their destination
• finished products are transported to cell surface in golgi vesicles where they fuse with the membrane and the contents in released.

Question 6

explain the structure of lysosomes?

Answer 6

bags of digestive enzyme - can contain 50 different enzymes

Question 7

explain the function of lysosomes?

Answer 7

• hydrolyse phagocytic cells
• completely break down dead cells
• exocytosis - release enzyme to outside of cell to destroy them
• digest worn out organelles for reuse of materials

Question 8

describe the structure of mitochondria?

Answer 8

• double membrane
• inner membrane called the cristae
• fluid centre called the mitochondrial matrix
• loop of mitochondria DNA

Question 9

explain the function of mitochondria?

Answer 9

• site of aerobic respiration
  -site of ATP production
• DNA to code for enzymes needed in respiration

Question 10

describe the structure of ribosomes?

Answer 10

• small
• made up of protiens and rRNA

Question 11

describe the functions of ribosomes?

Answer 11

• site of protein synthesis

Question 12

describe the structure of a vacuole

Answer 12

• filled with fluid surrounded by a single membrane called a tonoplast

Question 13

describe the functions of the vacuole

Answer 13

• make cells turgid and therefore provide support
• temporary store of sugars and amino acids
• the pigments may colour petals to attract pollinators

Question 14

describe the structure of chloroplasts

Answer 14

• surrounded by a double membrane
• contains thylakoids ( folded membranes with pigments )
• fluid filled stroma contains enzymes for photosynthesis
• found in plants

Question 15

describe the functions of chloroplasts

Answer 15

site of photosynthesis

Question 16

describe the structure of a cell wall

Answer 16

plants - made of microfibrils of the cellulose polymer
fungi - made of chitin, a nitrogen- containing polysaccharide

Question 17

describe the function of a cell wall

Answer 17

provide structural strength to the cell

Question 18

describe the structure of the plasma membrane

Answer 18

• found in all cells
• phospholipid bilayer- molecules embedded within and attached on the outside

Question 19

describe the function of the plasma membrane

Answer 19

• controls the entrance and exit of molecules

Question 20

what are the key differences between prokaryotic cells and eukaryotic cells?

Answer 20

• the cells are much smaller in P
• no membrane bound organelles in P
• smaller ribosomes
• no nucleus
• cell wall is made of murrain

Question 21

whats the structure of a virus?

Answer 21

• genetic material
• capsid
• attachment protein

Question 22

where do viruses replicate?

Answer 22

inside of host cells

Question 23

what are the three main types of microscopes?

Answer 23

• optical light microscope
• transmission electron microscopes
• scanning electron microscopes

Question 24

define magnification

Answer 24

how many time larger the image is compared to the object.

Question 25

define resolution

Answer 25

the minimum distance between two objects in which they can still be views as separate.

Question 26

describe the optical light microscope?

Answer 26

• a beam of light is condensed to create an image
• poor resolution due to light having a long wave length
• lower magnification
  colour images can be seen
• can view living samples

Question 27

describe the electron microscope

Answer 27

• a beam of electrons is condensed to create an image
• higher resolving power as electrons have a short wavelength
• higher magnification
• black and white images
• sample must be non-living

Question 28

difference between transmission electron and scanning electron microscope

Answer 28

• TEM - extremely thin specimens are used and electrons pass through the specimen
• SEM - specimens do not need to be thin and 3D images can be uncovered. electrons are beamed onto the surface and scattered in different directions.

Question 29

how do you calculate magnification?

Answer 29

image size = actual size x magnification
I=AM

Question 30

converting units

Answer 30

metre (M) -> millimetere (mm) -> micrometre (um) -> nanometre (nm)

Question 31

what is the purpose of the eye piece graticule?

Answer 31

can be used to measure the size of objects you are viewing under the microscope

Question 32

what is the reason for cell fractioning ?

Answer 32

• used to isolate different organelles so they can be studied
• this enables individual organelle structure and functions to the studied.