3. Eukaryotes

Question 1

What features do eukaryotic cells share with prokaryotes?

Answer 1

Plasma membrane cytoplasm and ribosomes

Question 2

What are the functions of the nucleus?

Answer 2

• Location of most of the cells DNA and the site of DNA replication
• It is the site where gene transcription is turned on or off
• The nucleolus is where ribosomes begin to be assembles from RNA and proteins

Question 3

What is the function of the nuclear envelope?

Answer 3

It separates the genetic material from the cytoplasm

-It separates DNA transaction which occurs in the nucleus from translation (which occurs in the cytoplasm)

Question 4

What is the nuclear lamina?

Answer 4

Network of filaments inside the nuclear envelope. Interacts with chromatin and helps support the envelope to which it is attached

Question 5

Where are the nuclear pores located?

Answer 5

At the site where the inner membrane curls around to become the outer membrane.

Question 6

What is the endomembrane system?

Answer 6

An interconnected system of membrane enclosed compartments

Question 7

What does the endomembrane system consist of?

Answer 7

the plasma membrane. the nuclear envelope, the endoplasmic reticulum, the golgi apparatus and lysosomes

Question 8

What is the smooth endoplasmic reticulum?

Answer 8

Site for lipid synthesis and chemical modification of proteins

Question 9

What are the steps in the transfer of materials in the endomembrane system?

Answer 9

1. Protein containing vesicles from the endoplasmic reticulum transfer substances to the cis region of the golf apparatus
2. The golgi apparatus chemically modifies proteins in its lumen
3. Proteins shipped to destinations elsewhere in the cell enclosed within vesicles that punch off from the RER

Question 10

What is the function of smooth endoplasmic reticulum?

Answer 10

1. certain proteins that are synthesised in the rough ER are chemically codified within the lumen of the smooth er
2. Chemical modificationof toxic small molecules taken in by the cell, making them more polar so they are more water soluble and easily removed
3. Site for glycogen degradation in animal cells
4. Lipids and steroids are synthesised
5. stores calcium ions, which trigger cellular responses when released

Question 11

What are the major functions of intracellular membranes?

Answer 11

1. Provide a surface for biochemical reactions
2. Establish a number of compartments to prevent mixing
3. Provide for transport of materials within the cell, from the cell to its exterior or from the cell to an adjacent cell

Question 12

What are the 2 compartments that the golgi apparatus consists of?

Answer 12

1. Flattened membranous sacs called cistern

2. Small membrane enclosed vesicles

Question 13

What are the functions of the golgi apparatus?

Answer 13

1. Receives protein containing vesicles from the rough ER
2. Collection, packaging and distribution of molecules synthesised elsewhere in the cell
3. Adds carbs to proteins and modifies other carbs that were attached to proteins in the Rough Er
4. Synthesises polysaccharides for the plant cell wall

Question 14

What are the three regions of the cistern of the golgi apparatus?

Answer 14

1. Cis region lies nearest to the nucleus or a patch of RER
2. The trans region lies closest to the plasma membrane
3. The medial region lies in between

Question 15

How do protein containing vesicles interact with each part of the rough ER

Answer 15

1. They fuse with the cis membrane
2. Release cargo into the lumen of the yogi cistern
3. Vesicles bud off from the trans region carrying their contents away from the golgi apparatus

Question 16

What are the functions of the cytoskeleton?

Answer 16

1. It supports the cell and maintains its shape
2. It holds cell organelles and other particles in position within the cell
3. It moves organelle and other particles around in the cell
4. Involved with movements of the cytoplasm, called cytoplasmic streaming
5. Interacts with extracellular structures, helping anchor the cell in place

Question 17

What are the three main components of the eukaryotic cytoskeleton?

Answer 17

1. Actin filaments 7nm (actin protein)
2. Microtubules (tubular protein) 25nm
3. Intermediate filaments (vimentin protein) 10nm filament diameter

Question 18

What are the major roles of the microfilaments?

Answer 18

• They help the entire cell or parts of the cell move

- They determine and stabilise cell shape

Question 19

What are the motor elements of the cytoskeleton?

Answer 19

• Actin filaments interact with myosin motors
• Microtubules interact with kinesis or dynein motors
• Intermediate filaments are predominantly static

Question 20

What do actin filaments do?

Answer 20

They interact with myosin motors and are responsible for muscle contractions and cytoplasmic streaming

Question 21

What are the two roles of microtubules in the cell?

Answer 21

• They form a rigid internal skeleton for some cells

- They act as a framework along which motor proteins can move structures within the cell

Question 22

What are microtubules composed of?

Answer 22

Assembled from dimers of the protein tubulin. The tubulin protein forms protofilament.
13 protofilaments form cylinder

Question 23

What is the difference in movement of eukaryotic flagella and prokaryotic?

Answer 23

Eukaryotic flagella beat while prokaryotic flagella rotate.

Question 24

What does eukaryotic flagella consist of?

Answer 24

Microtubules and dynein motors

Question 25

How does dynein create the movement of eukaryotic flagella?

Answer 25

• Dynein binds between two neighbouring microtubule doublets and can line one microtubule against another.
• Microtubules are fixed at one end which creates the curvature

Question 26

What does kinesin do?

Answer 26

Carries protein laden vesicles or other organelles from one part of the cell to another.

Question 27

How does kinesis carry out its function?

Answer 27

The proteins bend to the organelle/vesicle and walk it along a microtubule by a repeated series of shape changes.