Cell Biology Sub topic 2: Cell differentiation and specialist.

Question 1

What is a specialised cell?

Answer 1

`- A cell that performs a dedicated purpose/function.

• Most cells in a organism is specialised.
• A cell’s structure helps it carry out its function.
• So depending on what job it does it can look very different from each other.

Question 2

What is differentiation?

Answer 2

• The process by which a cell changes to become specialised and adapt to its function and purpose.
• In result of differentiation, the sub-cellular structures of the cells changes.
• Most differentiation occurs as a organism develops.
• In most animal cells the ability to fulfil this process is lost once a cell becomes specalised.
• Lots of plant cells don’t loose this ability.

Question 3

Example of a Specialised cell 1: Sperm Cell.

Answer 3

• Sperm cells are specialised for reproduction.
• Function: Carry the Male DNA to the female egg.

Features:
Contains genetic information in the nucleus.
Sperm contains half the genetic information of a normal adult cell.

Long Tail:

• Allows them to swim to the ovum.
• Also streamlined to make this easier.

Packed with mitochondria:- Provides energy needed for swimming.

Enzymes: Allows them to digest through the ovums cell wall.

Question 4

Example of a specialised cell 2: Nerve cells.

Answer 4

• Specialised to carry electrical impulses across the body.
• Axon: Carries the electrical impulses from one part of the body to another.
• Myelin insulates the axon and speeds up the transmission of nerve impulses.
• Synapses:
• Junctions that allow that allow impulses to pass from one nerve cell to another.
• Dendrites:
• Increase surface area, other nerve cells can connect easily.

Question 5

Example of a specialised cell 3: Muscle cells:

Answer 5

Muscle cells are specialised to contract easily.

• Contain protein fibres which can change their length.
• When a muscle contracts:
• Protein fibres shorten to decrease the length of the cell.
• Packed with mitochondria to provide the energy needed for contraction.

Question 6

Example of a specialised 4: Root hair cells.

Answer 6

• Root hairs are specialised for absorbing minerals and water.
• Covered in hairs.
• Increases the surface area of the root so it can absorb water dissolve minerals more effectively.
• ## (DO NOT CONTAIN CHLOROPLASTS)>

Question 7

Example 5:Xylem cells.

Answer 7

Function: carry water and dissolved minerals from the roots to the leaves.

• Features:
• Very thick walls containing lignin= Provides support to the wall.
• End walls between the cells have completely broken down: Forms a long tube so that water and dissolved minerals can flow easily.
• Have no nucleus, vacuole, cytoplasm or chloroplasts.
• Easier for water + dissolved minerals to flow.

Question 8

Phloem Cells:

Answer 8

• Carries dissolved sugars up and down the plants.
• has no nucleus and only limited cytoplasm.
• End walls have pores called sieve plates.
• Features allow dissolved sugars to move through the cells interior.
• Each phloem vessel cell has a companion cell connected by pores.
• ## Has mitochondria to provide energy to the Phloem vessel cell.