Animal Cell Model Diagram Project Parts Structure Labeled Coloring and Plant Cell Organelles Cake: Animal Cells Functions Animal Cell Model Diagram Project Parts Structure Labeled Coloring and Plant Cell Organelles Cake

Animal Cells Functions Biography

Source:- Google.com.pk

Give the name and function of the 2 special animal cells below. Label and explain the parts of each cell concerned with that special function.

Motor neuron

cell name: [motor] neurone (nerve cell)

cell function : to transmit nervous impulses [to muscle/gland]

[fatty sheath - insulates & speeds up messages]

Sperm cell

cell name:sperm cell

cell function : to fertilise egg cell

Both animal cells and plant cells share the same 3 features. However, plant cells usually have the following features in addition:

A cell wall - normally composed of cellulose- on the outside of the cell. This is rigid, so it gives the plant cell its shape. It is made of several layers of parallel fibres, and the gaps are filled in with jelly-like substances, e.g. pectin. This means it is usually freely permeable to many molecules, especially gases and water. In some parts of a plant it may be impregnated with other substances e.g. lignin for strength in wood, or suberin for waterproofing in bark.

The cell wall gives most plant cells a fairly regular many-sided outline. The cellulose is secreted by the cytoplasm when a cell divides and it gradually thickens up as more materials are added. It stays soft and extensible until the cell stops growing, then it becomes tougher. It is non-living and not part of the cytoplasm. Normally, the cell membrane is pushed tightly against the inside of it, so that it is practically invisible, but it may be seen when the cytoplasm shrinks.

A vacuole is a cavity, usually in the centre of the cell, containing a liquid, known as cell sap. This may be a store of water and dissolved substances, e.g. sugars and metabolic by-products. The vacuolar membrane is similar to the cell membrane. Sometimes it is said that animal cells have a vacuole, but these are usually much smaller and only temporary.

Because it has a vacuole, the cytoplasm in a plant cell is usually pushed to the outside of the cell, so that it forms a thin layer inside the cell wall. The nucleus is also displaced to the edge.

Chloroplasts may be present in the cytoplasm, in different numbers, e.g. cells of leaves contain more than stems, and roots usually contain none at all. Chloroplasts are green, due to the pigment chlorophyll, and are said to be the site of photosynthesis, which only goes on in green plants. Label the diagrams below, and colour in as appropriate.

Name and note the functions of the cells, and explain their specialisations.

palisade mesophyll cell

Cell name : palisade mesophyll cell

Function : to carry out photosynthesis

Specialisations : many chloroplasts containing chlorophyll - regular columnar shape enabling close packing for efficient absorption of light and water

root hair cell

Cell name : root hair cell

Function : to absorb water and mineral ions from soil

Specialisations : projecting section has large surface area for absorption of water and minerals from soil water - no chloroplasts

CELL SPECIALISATION

In both plants and animals, individual cells cannot get much bigger than a certain size. Therefore, in order to grow, an organism must increase the number of cells it is made up from. This is done by cell division, i.e. by individual single cells dividing repeatedly so that each one gives rise to two cells.

At the same time, cells may become specialised according to the tasks they have to perform. These specialisations usually involve some modifications of the structure described above, and the process of changing is called differentiation.

Many similar cells may be grouped together to form tissues. These may then be combined to make organs which have major functions , and several of these work together to form organ systems.

So an individual living organism (plant or animal) is said to be made up from all these sub-units.

Name at least 3 types of cells from the human body, and briefly mention any special characteristics that enable them to perform their functions. One has been done for you.

Cell type Specialisation Function

lining cell (epithelium)

e.g. from inside cheek flattened shape

interlocking edges to fit together to make a

thin covering layer

> red blood cell > disc shaped > to carry oxygen

> white (blood)

cell > can change

shape > to attack invading

microorganisms ("germs")

> nerve cell

(neuron) > long thin

fibres > to conduct nervous impulses

> muscle cell > can contract

(tighten) or relax > cause movement

Name 2 types of cells from a green plant, and briefly describe their structural specialisations and the functions they perform. One has been done for you.

Cell type Specialisation Function

leaf palisade layer (photosynthetic tissue) many chloroplasts - closely packed to make food by photosynthesis

(trapping the energy of sunlight)

> stem (xylem is composed not of typical cells but vessel elements to be more precise) > no end walls leaving hollow lumen (channel through middle) - also thick cell walls to withstand pressure

> carry water

> stem (phloem) > vertical strands of

cytoplasm > carry products of photosynthesis

("foods")

What is the difference between an organ and an organelle? > an organ is a part of the body of an organism whereas

> an organelle is part of a cell

NUCLEUS TRANSPLANTATION EXPERIMENTS

In a series of experiments, nuclei were removed by being sucked out carefully from fertilised frogs' eggs (at the one cell stage), and in some cases they were either replaced with nuclei from other frogs' eggs, or their original nuclei were restored. Some of the transplanted nuclei were from frogs of different colour varieties. After this, the eggs were usually able to develop normally, and tadpoles hatched out and grew into adult frogs. Some of the results are shown graphically alongside.

frog spawn nucleus transplantation expts

What is another name for a fertilised egg (one cell stage)? > zygote

What are the very next couple of stages (in normal development) composed of?

> 2 cells

> 4 cells

Why does this progression not continue evenly after a while?

> Different cells are needed in different quantities in embryo

What do the results above tell you about the role of the nucleus?

> necessary for development

> controls colour of organism - i.e. expression of characteristic

What contribution do you think the cytoplasm makes in the normal development of fertilised cells turning into frogs?

> provides nutrition, energy,etc, for growth