Cell Structure. Cells: What we Already Know All living things are made of 1 or more cells....
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Transcript of Cell Structure. Cells: What we Already Know All living things are made of 1 or more cells....
Cells: What we Already Know
• All living things are made of 1 or more cells.
• Single-celled organisms include Paramecium, amoeba, chlamydomonas and yeast.
• These can carry out all the functions of living things.
• Cells vary in shape.
Cells: What we Already Know
• Cells are small because diffusion of substances in and out becomes very difficult when they become larger.
• Also it is easier for a single nucleus to handle a smaller cell.
• Cells can be divided into 2 types:– Prokaryotes – before the nucleus– Eukaryotes – true nucleus
General Characteristics of Cells
• Cytoplasm and Nucleoplasm– a jelly-like substance surrounded by a
membrane. – The portion of jelly outside the nucleus
is called cytoplasm.– The portion inside the nucleus is called
nucleoplasm.
General Characteristics of Cells
• Size and Shape– These are related to function.– Some cells like white blood cells can
change shape as they move about.
General Characteristics of Cells
• Cell Structure– Suspended in the cytoplasm are various
organelles. – Intracellular fluid, called cytosol, consists
mainly of water. In this are dissolved amino acids, sugars and other substances used to make bigger molecules.
– Structural proteins, enzymes and ions used to maintain a balanced biochemical environment are also present.
General Characteristics of Cells
• Organelles– The inside of cells are divided into small
compartments so different functions can go on at specific places in the cell at the same time.
– The compartments are called organelles, each has a different function.
Animal Cells Plant Cells•Plasma Membrane•Microvilli•Nucleus •Endoplasmic reticulum•Ribosomes•Golgi body•Lysosomes •Vacuoles•Peroxisomes•Mitochondria•cytoskeleton
•Centrioles•Cilia•Flagella
•Plastids•Chloroplasts•Cell walls•Large vacuole
Cell Membrane
• This separates the cell from the environment and maintains stable cell environment by controlling entry and exit of substances.
• It is selectively/partially permeable
Cytoplasm
• A jelly-like substance found between the cell membrane and the nuclear membrane.
• Holds the organelles in place• Contains dissolved substances and is
the site of many chemical reactions.
Golgi Apparatus
• This modifies proteins made by the ribosomes then packages them up and secretes them.
Endoplasmic Reticulum
• A transport network within the cell • Smooth ER is the site for lipid
synthesis (sER) • Rough ER is the site for protein
synthesis. (rER)
Ribosomes
• These can be associated with ER to form rough ER or free in the cytoplasm.
• The site of protein synthesis.
Nucleus
• This is the control centre for cell – it contains genetic material.
• Surrounded by a nuclear membrane.• The nuclear membrane has a
number of nuclear pores so substances can enter and leave the nucleus.
• Contains a nucleolus where RNA is made.