Cells

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Cell Structure and Organization

(Credits to Mustafa Asif)

Notes

Cells

Made up of:

-protoplasm

- cellulose cell wall (non-living and only in plants)

Protoplasm consists of:

- nucleus which controls cellular activities and consists of

- nuclear envelope

- nucleoplasm

- chromatin (made up of DNA)

- nucleolus

- cytoplasm which surrounds the nucleus and where most life processes occur and consists of

- mitochondria - sites of energy release

- vacuoles - contain water and food substances

- chloroplasts - in plant cells only

- centrioles - in animal cells

- cell surface membrane which is the partially permeable, outer covering enclosing the cytoplasm

Plant and Animal cells

Both plant and animal cells have

- nucleus

- cytoplasm

- cell membrane

- mitochondria - energy is released here by respiration

Only plant cells have

- cell wall

- large vacuole

- chloroplasts

Specialised cells

1. Root hair cell in plants is adapted to do its job of taking in water and nutrients by having

- a large surface area

- a thin cell membrane

2. Red blood cell which carries oxygen around the body have

- no nucleus and a large surface area (concave shape) - allows maximum area for oxygen carriers

- have haemoglobin to carry oxygen

3. White blood cell which fights disease and some make antibodies - their adaptations:

- irregular shape and they can change shape to squeeze out of blood vessels and get to the site of infection

- others have cytoplasm which can flow making it possible for the cell to change shape and hence surround and engulf bacteria

Cells, tissues, organs and systems

Tissue: a group of cells make up a tissue

eg heart muscle tissue

Organ: a group of tissue makes up an organ

eg heart

System: a group of organs makes up a system

eg circulatory system

Organism: a group of systems make up an organism

eg Humans