2.2 Cells

• The nucleus controls all cell activity.
• The nucleus regulates transcription of genes and directs protein synthesis.
• The nucleus is the largest organelle.
• The nucleus consists of DNA and nucleolus.
• The nucleus is surrounded by a nuclear membrane.
• The nucleolus is composed of RNA and proteins.
• The nucleolus is responsible for the synthesis of ribosomal RNA (rRNA) and the assembly of ribosomes.
• The mitochondrion is the site of aerobic respiration, which synthesises ATP molecules and provides energy for the cell.
• The mitochondria consists of a double membrane.
• The inner membrane of the mitochondrion is folded into a cristae to increase surface area.
• The mitochondrion contains its own circular DNA (mtDNA)
• The chloroplast is the site of photosynthesis, usually in the leaves of a plant.
• The chloroplast produces glucose and oxygen for plants and other organisms.
• The chloroplast consists of a double membrane.
• The stacks of internal membrane structures in a chloroplast is called grana, which contain the pigment chlorophyll.
• Chloroplasts contain their own circular DNA (cpDNA)
• The Golgi body is a stack of flattened membranes that are not connected which is involved in the modification and packaging of proteins.
• The ribosome is the site of translation (protein synthesis).
• Ribosomes can be found on Rough Endoplasmic Reticulum or free floating in the cytoplasm.
• Rough Endoplasmic Reticulum increases surface area for cellular processes.
• Attached ribosomes synthesise proteins that RER packages into vesicles and secretes into the Golgi body.
• Endoplasmic reticulum is a network of interconnected flattened membrane sacs that span from the nucleus to the cell membrane.
• Rough Endoplasmic Reticulum contains ribosomes attached to the surface.
• Smooth Endoplasmic Reticulum do not contain ribosomes.
• The vacuole stores water in plant cells.
• Vacuoles can be used to store nutrients.
• Vacuoles can store and dispose of waste products.
• Lysosomes destroy foreign bodies (such as bacteria) and recycle cellular materials (like non-functional organelles)
• Lysosomes are membrane bound vesicles containing digestive enzymes (lysozymes).
• In animal cells, the cytoskeleton helps to maintain the cell shape.
• Centrioles are small structures composed of protein microtubules.
• Centrioles duplicate prior to cell division so each daughter cell receives a centriole.
• Microtubules extent from centrioles at opposite poles of cells to attach to centromeres of chromosomes and align them along metaphase plate.