Chapter 2 - Basic Components Of Living Systems

Question 1

How do you calculate magnification, image size and actual size?

Answer 1

Magnification = size of image / actual size

Size of image = magnification * actual size

Actual size = size of image / magnification

Question 2

Define magnification

Answer 2

Magnification is how much bigger the image is compared to the objects or specimens actual size.

Question 3

Microscopy convention calculations

Answer 3

nm = /1000 = μm = /1000 = mm = /10 = cm = /100 = m = /1000 = km (/ changes to * for when going from right to left)

Question 4

Define resolution

Answer 4

Resolution is how detailed the image is. It is how well the microscope can distinguish between two points that are close together.

Question 5

Describe the structure of the nucleus

Answer 5

• A large organelle surrounded by a nuclear envelope (double membrane) which contains many pores. The nucleus contains chromatin (which is made up from DNA and proteins) and a structure called the nucleolus.

Question 6

Describe the functions of the nucleus, nucleolus and nuclear envelope

Answer 6

Nucleus:

• controls all the activity of the cell.
• contains the genetic code of the cell.

Nucleolus:
- site of ribosome production. Composed of RNA and protein.

Nuclear envelope:
- a double membrane which compartmentalises the nucleus and prevents damage. Protects the DNA.

Question 7

Describe the structure of the rough endoplasmic reticulum and smooth endoplasmic reticulum.

Answer 7

Rough ER:

• system of hollow tubes and membrane bound sacs which form sheets called cisternae.
• covered with ribosomes and consists of an interconnected system of flattened sacs.

Smooth ER:
- similar to the RER (above) but lacks ribosomes. It is a system of interconnected tubules.

Question 8

Describe the functions of the rough endoplasmic reticulum and the smooth endoplasmic reticulum.

Answer 8

Rough ER:
- site of protein synthesis. Folds and processes proteins formed at the ribosomes.

Smooth ER:
- responsible for carbohydrate and lipid synthesis and storage.

Question 9

Describe the structure of the Golgi apparatus.

Answer 9

• stack of flattened, membrane bound sacs (cisternae)

- these are continuously formed from the ER at one end and budding off as Golgi vesicles at the other.

Question 10

Describe the function of the Golgi apparatus

Answer 10

• allows internal transport
• collects and sorts molecules (such as new lipids and proteins) and packages them into vesicles.
• these may be secretory vesicles (if the proteins need to leave the cell) or lysosomes (which stay in the cell).

Question 11

Describe the structure of ribosomes.

Answer 11

• a 2 subunit organelle (made up from two smaller parts, like a snowman) made from RNA and protein. Not membrane bound. Very small organelles: about 22nm in diameter. Found free floating in the cytoplasm or attached to the rough ER.

Question 12

Describe the function of ribosomes.

Answer 12

• these are where proteins are made.
• they assemble amino acids into proteins in chains using mRNA.
• they are either attached to the Rough ER or are free floating in the cytoplasm.

Question 13

Describe the structure of mitochondria.

Answer 13

• oval shaped
• surrounded by two membranes (double membrane)
• the inner membrane forms finger like structures called cristae. The solution inside is called a matrix.

Question 14

Describe the function of mitochondria.

Answer 14

• carry out the later stages of aerobic respiration.

- as a result of respiration they make ATP energy (energy carrier in cells)

Question 15

Describe the structure of lysosomes.

Answer 15

• a single membraned, spherical sac.

- contains hydrolytic (digestive) enzymes known as lysozymes.

Question 16

Describe the function of lysosomes

Answer 16

• digests unwanted structures (e.g. Cell organelles, storage molecules or while cells when it dies.)
• head of sperm cells and white blood cells contain lysosomes.

Question 17

Describe the structure of centrioles

Answer 17

• a component of the cytoskeleton, composed of many microtubules.
• small hollow cylinders that occur in pairs next to the nucleus in animal cells.
• each centriole contains a ring of microtubules.

Question 18

Describe the function of centrioles

Answer 18

• makes a copy of itself during cell division and then helps to form the spindle in cell division.