cells and organelles a level

• rough ER has ribosomes attached to it, smooth ER does not have any ribosomes on its surface
• plasma membranes are found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells
• plasma membranes are made of mainly lipids and proteins
• plasma membrane regulates the movement of substances into and out of the cell. It also has receptor molecules on it, which allow it to respond to chemicals like hormones
• A cell wall has a rigid structure that surrounds plant cell.
• cell walls are mainly made of the carbohydrate cellulose
• cell walls support and strengthen the plant cells
• A Nucleus is a large organelle surrounded by a nuclear envelope (double membrane),which contains many pores
• The nucleus contains chromatin and a structure called the nucleolus
• chromatin is made from DNA and proteins
• The nucleus controls the activities of the cell by controlling the transcription of DNA. DNA contains instructions to make proteins.
• Lysosomes are round organelle surrounded by a membrane, with no clear internal structure
• Lysosomes contain digestive enzymes. These are kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down worn out components of the cell.
• A ribosome is a very small organelle that either floats free in the cytoplasm or is attatched to the rough endoplasmic reticulum.
• Ribosomes are made up of proteins and RNA. It is not surrounded by a membrane
• Ribosomes are the site where proteins are made
• Rough endoplasmic reticulum is a system of membranes enclosing a fluid-filled space. The surface is covered with ribosomes.
• The rough endoplasmic reticulum folds and processes proteins that have been made at the ribosomes
• The smooth endoplasmic reticulum is a system of membrane enclosing a fluid-filled space but the surface is not covered with ribosomes
• A vesicle is a small fluid-filled sac in the cytoplasm, surrounded by a membrane
• Vesicles transport substances in and out of the cell and between organelles.
• Golgi-apparatus is a group of fluid-filled,membrane- bound, flattened sacs. Vesicles are often seen at the edges of the sacs.
• The golgi apparatus processes and packages new lipids and proteins it also makes lysosomes
• Mitochondrion are usually oval-shaped. They have a double membrane - the inner one is folded to form structures called cristae. Inside is the matrix, which contains enzymes involved in respiration
• The mitochondrion is the site of the aerobic respiration, where ATP is produced. They're found in large numbers in cells that are very active and require a lot of energy
• A chloroplast is a small, flattened structure found in plant cells. It's surrounded by a double membrane, and also has membranes inside called thylakoid membranes. It contains chlorophyll which absorbs the light needed for photosynthesis
• Centrioles are small, hollow cylinders, made of microtubules
• Centrioles are found in animal cells, but only some plant cells
• Centrioles are involved with the separation of chromosomes during cell division
• Cilia are small, hair-like structures found on the surface membranes of some animal cells. In cross-section, they have an outer membrane and a ring of nine pairs of protein microtubules inside, with two microtubules in the middle