Cells - Biology - Naba, Aaliya, Maryam, and Zainab

 Another overdue post but finally.

2. Cells

2.1 Cells

Nucleus, Cytoplasm, Mitochondria, and Ribosomes are always found in cells.

Cell Membrane:

• Made up of protein and fat

• Partially permeable

• Pressed tightly to the cell wall.

Cell Wall:

• located outside the cell membrane

• found in cells of plants, fungi and bacteria

• made of cellulose

Cytoplasm:

• Clear and jelly

• 70% water with proteins and other minerals.

• Metabolic reactions take place

Vacuole:

• a fluid-filled space inside a cell

• It contains cell sap

• Animal cells have smaller vacuoles called vesicles

Nucleus:

• Genetic information is stored (On chromosomes made of DNA)

Chloroplasts:

• only found in some plant cells

• contains the green pigment called chlorophyll

• It also contains starch grains

Mitochondria (aka gob babies)

• Mitochondria provide energy for the cells.

• found in plant and animal cells

Ribosome

• Makes protein (made up of long chains of amino acids)

2.2 Bacterial Cells

• It's a unicellular organism

• Bacterial cells have cell walls that aren't made up of cellulose.

• It doesn't have a nucleus or a mitochondrion

• The cell walls protect the cell from bursting due to excessive water.

• Since they don't have a nucleus with genetic information, they have a circular strand of DNA that gives instructions for making proteins.

• Bacterial cells have plasmids, small, circular molecules of DNA.

2.3 Specialised cells

• Not all cells have the same features

• They are meant to perform specific acts

• One example of specialised cells is tissues. There are a group of cells which are tissues that line the stomach and help you digest food.

• A group of tissues make up an organ. (stomach, heart, leaf, onion bulb)

• A group of organs working together is called an organ system. (stomach, large intestines, small intestine, liver, etc., work together.)

• A lot of these organ systems make up an organism.

2.4 Size of specimens.

• Cells are very small, and so we can't see them without a microscope. The photographs are so much bigger than the object.

• We need to find the magnification to see how much bigger the image is than the object.

• The magnification = size of an image/size of the actual image.

• actual size = image size/magnification

• Image size =  actual size * magnification

• Some objects are very tiny and millimetres are bigger than them, and so we use micrometres. 1 µm = 1 × 10^-6 m

• 1 m = 10^6 µm

Have a marvelous day and never stop learning,

Naba, Aaliya, Maryam, and Zainab

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