cell specialisation

Sperm cells

•  join with an ovum. this is called fertilisation
• contain genetic information in nucleus.but its only half the genetic info of a normal adult cell
• have long tail which allows them to swim to ovum. theyre also streamlined to make this easier
• packed wih mitochondria which provide the energy needed for swimming
• contain enzymes which allows them to digest their way to the outer layer of ovum

Nerve cell

• send electrical impulses around the body
• have long axon which carries electrical impulses from one part of body to another. Axon is covered wth myelin which speeds up transmission of nerve impulses
• end of axon has syapses. they are junctions which allow impulse to pass from 1 nerve cell to another
• cell body is covered with dendrites that increase surface area so that other nerve cells can connect easily

Muscle cells

• can contract (get shorter)
• to do this they contain protein fibres which can change their length. when a muscle cell contracts, these protein fibres shorten. decreasing length of cell
• also packed full of mitochondra to provide energy for muscle contraction
• muscle cells work together to form muscle tissue

root hair cells

• roots are covered with hairs that increse surface area of root, so it can absorb water and dissolved mineral more effectively 
• do not contain chloroplasts as theyre underground and do not need to photsynthesise

xylem cells

• found in plant stem, and form long tubes, these tubes carry water and dissolved minerals from roots to leaves
• have very thick walls containing lignin. this provides support to plant. but this causes xylem cells to die
• end walls between the cells have broken down. this forms a long tube so water and dissolved minerals can flow easily
• no nucleus, cytoplasm, vacuole or chloroplast (internal structures) making it easier for water and minerals to flow

Phloem cells

• carry dissolved sugars up and down plant
• contain two different types of cells - phloem vessel cells have no nucleus and only limited cytoplasm. the end walls of these cells have pores called sieve plates. both these features allowes dissolved sugars to move through the cell interior. They dont have many mitochondria so each phloem vessel cell has a companion cell connected by pores
• mitochondria in companion cell provide energy to phloem vessel cell