StarterQuiz:

1. What are the beating hairs for movement of a unicellular organism called?

2. What organism uses these?3. These structures also help with feeding by

moving food into a specialised area, what is this called?

4. Amoeba use extensions of the flexible cell membrane to move, what do we call this?

5. Which unicellular organisms can photosynthesise?

StarterQuiz:

1. What are the beating hairs for movement of a unicellular organism called? Cilia

2. What organism uses these? Paramecium3. These structures also help with feeding by

moving food into a specialised area, what is this called? Cilia

4. Amoeba use extensions of the flexible cell membrane to move, what do we call this? Pseudopods

5. Which unicellular organisms can photosynthesise? Euglena

4. Specialised Cells

Explain why cells which are

specialised contain different

organelles.

Cell Specialisation

There are hundreds of different types of plant and animal cells. Each focus on a certain “job” in the organism in which they are found. It is said that they are specialised, or differentiated, for that function.

https://www.youtube.com/watch?v=UgT5rUQ9EmQ

When a sperm and egg are fertilised…

• The cells are unspecialised (identical)• After several cell division cycles have

occurred, they start to differentiate.• This occurs as some genes are

turned on in some cells only which cause certain proteins to be made which give the cell a particular shape or number of organelles.

Similarities and differences in Size of Cells.

Size: All cells are microscopic. When a cell

gets too big it divides, so its SA to volume ratio goes up.

Plant cells are larger than animal cells. They have a vacuole so cytoplasm pushed closer to membrane for diffusion of gases and nutrients

Similarities and differences with Shape

Shape: Shape relates to function e.g. nerve

cells long and thin to carry impulsesCells that are specialised for diffusion

tend to be long and thin to decrease the distance to travel across a cell and to increase surface area (root hair cell, villi cells in intestine)

Plant cells tend to be more regular in shape as the rigid cell wall dictates shape.

Similarities and differences in Organelles

Number of a certain organelle can be an indicator of the function of a cell

Many ribosomes and rough ER- high rate of protein synthesis, also have prominent nucleoli.

Smooth ER – make lipids, metabolises CHO, detoxifies other drugs, make steroids eg sex hormones so gonads rich in smooth ER. Liver also.

Golgi Bodies - Cells specialised for secretions Many mitochondria - Cells with high energy

requirement –(liver and muscles)Many chloroplasts – high photosynthesis rate.

Red Blood Cells• Contain haemoglobin which transports

oxygen to other cells and around the body• Biconcave shape for maximum surface area

to allow more oxygen to be absorbed efficiently.

• Biconcave shape also allows for a flexible framework which means cells can squeeze through the thinnest of capillaries.

• Cells have a thin outer membrane allowing oxygen to diffuse through easily.

• Have no nucleus so there is more room for oxygen to be carried in the cell and hence around the body.

Sperm cell• The tail (flagella) of the sperm cell

enables it to swim to the ovum and fertilise it.

• The head is streamlined also to aid swimming

• The head contains genetic information and a nucleus and has an enzyme to help penetrate the egg cell membrane to allow fertilisation.

• The middle section immediately behind the head is packed with mitochondria to provide energy.

Nerve cell• Transmit electrical nerve impulses

and so carry information from one part of the body to another ie from receptor to an effector.

• Dendrites extend from the cell body to make connections with other neurones.

• Have a long axon (nerve fibre) to carry the impulse to the target organ.

• End plate forms a synapse with an effector (a muscle or a gland).

Muscle cells

• Long thin cells• Have many

mitochondria due to energy requirements

Plant cell - Xylem

• Long and tube-like hollow vessels to carry the water from roots to leaves.

• Cells have no end walls between them so they form a 'pipeline' to carry the water.

• Spirals and rings of lignin in the cell walls strengthen them to withstand pressure of water.

Plant cell – root hair• Located in the root epidermis and in

direct contact with the soil • Thin walls make up-take of water

easier. • Wall nearest the soil has a long

'finger-like' projection with very thin walls into the soil. This projection increases the surface area for more efficient absorption of water and ions.

• no chloroplasts as no photosynthesis occurs (no light); No mitochondria - active transport

Plant cell – palisade cell

• Typical plant cell• Packed with chloroplasts which

contain the light absorbing pigment chlorophyll.

• Regular shaped closely packed cells forming a continuous layer for efficient and maximum absorption of sunlight

Cell sort – group activity

• In groups of 4 match up the cell names with the cell pictures with clues underneath. Make sure everyone in your group agrees. There are 12 animal cells and 12 plant cells.

• You have 5 minutes then we will mark as a class.

Compare the following cells

In terms of cell function explain why these cells have different shape and organelles:– Root hair cell and plant palisade cell

– Muscle cell and nerve cell