3.4 Eukaryotic Cell structure

Question 1

What is meant by the ultrastructure of a cell

Answer 1

The specific internal structure of a cell that makes it suited for its job

Question 2

What is the function of the nucleus

Answer 2

1. Act as a control centre of the cell through the production of mRNA and tRNA and hence protein synthesis
2. Retain the genetic material of the cell in the form of DNA
3. Manufacture ribosomal RNA and Ribosomes.

Question 3

What is the function of the nucelus’ nuclear envelope

Answer 3

It is a double membrane that surrounds the nucleus. Its outer layer is continuous with the ER of the cell and has ribosomes on its surface.

It controls the entry and exit of materials in and out of the nucleus

Question 4

What is the function of the nucleus’ nuclear pores

Answer 4

They allow the passage of large molecules, like mRNA.

Question 5

What is the function of the nucleoplasm inside the nucleus

Answer 5

It is a jelly-like granular material that makes up the bulk of the nucleus

Question 6

What is the function of chromosomes

Answer 6

To consist of protein-bound, linear DNA

Question 7

What is the function of nucleolus’ in the nucleus

Answer 7

To manufacture ribosomal RNA and assemble the ribosomes. There may be more than one

Question 8

What is the function of mitochondrias

Answer 8

To act as the site of the aerobic stages of respiration

Question 9

What is the function of a mitochondrias double membrane

Answer 9

To control the entry and exit of materials. The inner of the two membranes form extensions known as cristae

Question 10

What is the function of mitochondrial cristae

Answer 10

To provide a large surface area for the attachment of enzymes and other proteins involved in respiration. They are extensions of the inner-membrane

Question 11

What is the function of the mitochondrial matrix

Answer 11

They make up the rest of the mitochondria. They contain protein, lipids, ribosomes and DNA that allow the mitochondria to control the production of some of their own proteins

Question 12

What is the function of chloroplasts

Answer 12

To act as the site of photosynthesis

Question 13

What is the chloroplast envelope

Answer 13

A double plasma membrane that surrounds the organelle. It controls what enters and leaves the chloroplasts

Question 14

What is the grana of the chloroplast

Answer 14

Stacks of thylakoids. Inside a thylakoid is the photosynthetic pigment chlorophyll

Question 15

What is the stroma of the chloroplast

Answer 15

A fluid-filled matrix where the second stage of photosynthesis takes place.

Question 16

How are chloroplasts adapted to their function of harvesting sunlight

Answer 16

1. The granal membranes provide a large surface area for the attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis.
2. The fluid of the stroma possesses all the enzymes needed to make sugars in the second stage of photosynthesis
3. Chloroplasts contain both DNA and ribosomes so they can quickly make the required proteins for photosynthesis

Question 17

What is the endoplasmic reticulum

Answer 17

A sheet of membranes that are continuous with the outer nuclear membrane.

Question 18

What is the rough endoplasmic reticulum

Answer 18

A sheet of membranes with ribosomes embedded in it.

Question 19

What are the functions of the RER

Answer 19

1. Provide a large surface area for protein synthesis and glycoproteins
2. Produce a pathway for the transport of materials, especially proteins, throughout the cell

Question 20

What are the functions of the SER

Answer 20

1. Synthesise, store and transport lipids

2. Synthesise, store and transport carbohydrates

Question 21

What are the functions of the golgi apparatus

Answer 21

1. Add carbs to proteins to form glycoproteins
2. Produce secretory enzymes, such as those secreted by the pancreas
3. Secrete carbs, such as those in making cell walls in plants
4. Transport, modify, and store lipids
5. Form lysosomes

Question 22

Where are golgi apparatuses specifically well developed

Answer 22

In secretory cells, like epithelial cells that line the intestines.

Question 23

What are the functions of lysosomes

Answer 23

1. Hydrolyse material ingested by phagocytic cells, like white blood cells and bacteria
2. Release enzymes to the outside of the cell in order to destroy material around the cell
3. Digest worn out organelles so that the useful chemicals they are made of can be re-used
4. Completely break down cells after they have died (autolysis)

Question 24

Where are lysosomes abundant

Answer 24

Secretory cells, like epithelial cells and phagocytic cells

Question 25

What are the two types of ribosomes

Answer 25

80s ribosomes - eukaryotic cells

70s ribosomes - prokaryotic cells

Question 26

What are ribosomes made up of

Answer 26

Ribosomal RNA and protein

Question 27

What is the function of ribosomes

Answer 27

Protein Synthesis

Question 28

What does a cell wall consist of

Answer 28

Microfibrils of cellulose

Question 29

What is the function of cell walls

Answer 29

1. To provide mechanical strength in order to prevent the cell bursting under osmotic gain or loss
2. To give mechanical strength overall
3. To allow water to pass along it and contribute to the movement of water within the plant

Question 30

What are the cell walls of algae made up of

Answer 30

Cellulose or glycoproteins

Question 31

What are the cell walls of fungi made up of

Answer 31

Chitin, glycan and glycoproteins

Question 32

What is a vacuole

Answer 32

A fluid-filled sac bounded by a single membrane called a tonoplast

Question 33

What are the components present in the vacuoles solution

Answer 33

Mineral salts, sugars, amino acids, wastes and pigments such as anthocyanins