biology cape
CELLS
All living things are made of cells, and cells are the smallest units that can be alive. Life on Earth is classified into five kingdoms, and they each have their own characteristic kind of cell. However the biggest division is between the cells of the prokaryote kingdom (the bacteria) and those of the other four kingdoms (animals, plants, fungi and protoctista), which are all eukaryotic cells. Prokaryotic cells are smaller and simpler than eukaryotic cells, and do not have a nucleus.
Prokaryote = without a nucleus
Eukaryote = with a nucleus Eukaryotic Cells
Cytoplasm (or Cytosol). This is the solution within the cell membrane. It contains enzymes for metabolic reactions together with sugars, salts, amino acids, nucleotides and everything else needed for the cell to function.
Nucleus. This is the largest organelle. Surrounded by a nuclear envelope, which is a double membrane with nuclear pores - large holes containing proteins that control the exit of substances such as RNA from the nucleus. The interior is called the nucleoplasm, which is full of chromatin- a DNA/protein complex containing the genes. During cell division the chromatin becomes condensed into discrete observable chromosomes. The nucleolus is a dark region of chromatin, involved in making ribosomes.
Mitochondrion (pl. Mitochondria). This is a sausage-shaped organelle (8µm long), and is where aerobic respiration takes place in all eukaryotic cells. Mitochondria are surrounded by a double membrane: the outer membrane is simple, while the inner membrane is highly folded into cristae, which give it a large surface area. The space enclosed by the inner membrane is called the matrix, and contains small circular strands of DNA. The inner membrane is studded with stalked particles, which are the site of ATP synthesis.
Chloroplast. Bigger and fatter than mitochondria, chloroplasts are where photosynthesis takes place, so are only found in photosynthetic organisms (plants and algae).
All living things are made of cells, and cells are the smallest units that can be alive. Life on Earth is classified into five kingdoms, and they each have their own characteristic kind of cell. However the biggest division is between the cells of the prokaryote kingdom (the bacteria) and those of the other four kingdoms (animals, plants, fungi and protoctista), which are all eukaryotic cells. Prokaryotic cells are smaller and simpler than eukaryotic cells, and do not have a nucleus.
Prokaryote = without a nucleus
Eukaryote = with a nucleus Eukaryotic Cells
Cytoplasm (or Cytosol). This is the solution within the cell membrane. It contains enzymes for metabolic reactions together with sugars, salts, amino acids, nucleotides and everything else needed for the cell to function.
Nucleus. This is the largest organelle. Surrounded by a nuclear envelope, which is a double membrane with nuclear pores - large holes containing proteins that control the exit of substances such as RNA from the nucleus. The interior is called the nucleoplasm, which is full of chromatin- a DNA/protein complex containing the genes. During cell division the chromatin becomes condensed into discrete observable chromosomes. The nucleolus is a dark region of chromatin, involved in making ribosomes.
Mitochondrion (pl. Mitochondria). This is a sausage-shaped organelle (8µm long), and is where aerobic respiration takes place in all eukaryotic cells. Mitochondria are surrounded by a double membrane: the outer membrane is simple, while the inner membrane is highly folded into cristae, which give it a large surface area. The space enclosed by the inner membrane is called the matrix, and contains small circular strands of DNA. The inner membrane is studded with stalked particles, which are the site of ATP synthesis.
Chloroplast. Bigger and fatter than mitochondria, chloroplasts are where photosynthesis takes place, so are only found in photosynthetic organisms (plants and algae).