Cells

Question 1

Describe the structure of mitochondria:

Answer 1

Oval-shaped.They have a double membrane- the inner one is folded to form cristae.Inside is the matrix, which contains enzymes involved in respiration.

Question 2

Function of mitochondria

Answer 2

They are the site of aerobic respiration where ATP is produced.

Question 3

Function of chloroplasts:

Answer 3

Site where photosynthesis takes place.

Question 4

Function of Golgi apparatus:

Answer 4

It processes and packages lipids and proteins.It also makes lysosomes.

Question 5

Function of Golgi vesicle:

Answer 5

Stores lipids and proteins made by the golf apparatus and transports them out of the cell via the cell membrane

Question 6

Function of lysosome:

Answer 6

Contains digestive enzymes called lysozymes.These can be used to digest invading cells or to break down worn out components of the cell.

Question 7

Function of the ribosome:

Answer 7

The site where proteins are made.

Question 8

Function of the rough endoplasmic reticulum:

Answer 8

Folds and processes proteins that have been made at the ribosomes.

Question 9

Function of the smooth endoplasmic reticulum:

Answer 9

synthesises and processes lipids.

Question 10

Function of the vacuole:

Answer 10

Helps maintain pressure inside the cell and keep the cell rigid this stops plants wilting.Also involved in the isolation of unwanted chemicals inside the cell

Question 11

Describe optical (light) microscopes:

Answer 11

• They use light to form an image.
• They have a maximum resolution of 0.2 micrometers.This means you can’t see ribosomes,ER and lysosomes.
• The maximum magnification is x1500

Question 12

Describe electron microscopes:

Answer 12

• They use electrons to form an image.
• they have a higher resolution ( 0.0002 micrometers)
• magnification is about x1500000

Question 13

Describe transmission electron microscopes:

Answer 13

• use electromagnets to focus a beam of electrons, which is then transmitted through the specimen.
• denser parts of the specimen absorb more electrons which makes them look darker on the image
• high resolution- can see structure of organelles
• but can only be used on thin specimen

Question 14

Describe scanning electron microscopes:

Answer 14

• scan a beam of electrons across the specimen.This knocks electrons from the specimen which are gathered in a cathode ray tube to form an image.
• the images you end up show the specimen and they can be 3d
• can be used on thick specimen
• but give lower resolution than TEMs

Question 15

Describe cell fractionation:

Answer 15

1) Homogenisation- breaking up the cells. can be done using a blender or by grinding the cells.The solution must be kept ice cold to reduce activity of enzymes that break down organelles.Solution should be isotonic to [revent osmosis.A buffer solution should be added to maintain the pH
2) Filtration-the solution is filtered through a gauze to separate any large debris.
3) Ultracentrifugation-the cell fragments are poured into a tube and then into a centrifuge which spins slowly, the heavy organelles like the nucleus sink to the bottom to form a pellet.The top part is drained of and then spun at a higher speed the heavier organelles sink this time the mitochondria. the process in repeated at a higher and higher speed