cells Flashcards
Cell membrane
- Phospholipids are a major component of biological molecules.Due to the nature of phospholipids. The cell membranes made up of two layers of phospholipid- phospholipid bilayer
- besides the phospholipid bilayer, the cell membrane also contains various proteins, carbohydrate chains, and cholesterol attached to or embedded within the phospholipid bilayer
Cell membrane ( fluid mosaic model)
- The fluid mosaic model is used to describe the structure of the cell membrane.
- the cell membrane is fluid in that phospholipids and proteins are not stationary but can move rapidly the across surface of the membrane
- the cell membrane is a mosaic in that many different protein molecules are randomly scattered and embedded throughout the phospholipid bilayer
Nature of cell membrane
- Due to the nature of phospholipids, only small hydrophobic molecules can pass through the phospholipid bilayer. As such, for hydrophilic or water soluble molecules which are unable to pass through the cell membrane, transport proteins are required
- hence, the cell membrane is partially permeable, allowing only certain substances to pass through it. it functions to separate and protects a cell from its surrounding environment and controls how substances move in and out of the cell
Stuff cytoplasm contains
- Cytosol: aqueous solution of essential ions, soluble proteins and soluble organic compounds such as sugars and amino acids
- cytoskeleton: network of protein fibers that give support, motility and regulation to the cell
- organelles: structures with specialized functions, suspended in cytosol
Cytoplasmic streaming
Cytoplasmic streaming takes place in the cytoplasm of cells.it is the movement of the fluid substance (cytoplasm) within a plant or animal cell. Cytoplasmic streaming aids in the transport of materials and organelles around the cell.
Nucleus structure
- Largest organelle within the eukaryotic cell, usually spherical
- consist of the nuclear envelope which separates nucleus from the cytoplasm
- contains nucleolus which synthesizes ribosomes
- contains DNA
- found on almost all eukaryotic cells except matured red blood cell
Nucleus function
Contains the hereditary material (DNA) and controls the activities of the cell
Rough endoplasmic reticulum structure
- A system of flattened membrane-bound sacs
- appears “rough” under electron microscope because of the presence of ribosomes on its surface
Rough endoplasmic reticulum function
Protein synthesis. The polypeptide chain synthesized by the ribosomes will be folded in the RER
Smooth endoplasmic reticulum structure
Consists of fine tubules
Smooth endeplasmic reticulum function
- Lipid synthesis
- detoxification of drugs and poisons (liver)
- storage and release of calcium ions
Golgi apparatus structure
Consist of stacks of flattened membrane-bound sacs
Golgi apparatus function
Chemically modifies products receive from the ER and packages them, before sending them to destinations inside or out of the cell using vesicles
Lysosomes structure
- Small, spherical vesicles surrounded by a single membrane
- Contain hydrolytic enzymes such as lipases, proteases, and nucleuses
Lysosomes function
- To digest materials made in the cell or take in from outside by phagocytosis
- to digest worn-out organelles in the cell, a process known as autophagy
Animal vacuoles structure
- Fluid-filled sac bound by a single membrane
- formed either by the pinching-off part of the cell membrane, or by enlargement of a vesicle from the Golgi apparatus
- Usually relatively smaller and exist temporarily
Animal vacuoles function
Food vacuoles: formed by phagocytosis
Plant vacuoles structure
- In mature plant cells, the large central vacuole is permanent and occupy over 80% of the cell volume
- enclosed by single, partially permeable membrane called the tonoplast
- filled with cell sap, a solution of dissolved such as sugars, ions, waste products and pigments
Plant vacuoles function
- Storage of nutrients such as protein storage in seeds and inorganic ions
- disposal sites for metabolic by-products that would endanger the cell if they accumulated in the cytosol
- may contain pigments that color the cells
Mitochondria structure
- Rod-shaped or cylindrical
- bounded by double membrane
Mitochondria function
- Involved in aerobic respiration
- ATP is the “energy” molecule in living organisms
- abundant in metabolically active cells
Chloroplasts structure
- Bounded by a double membrane
- contain chlorophyll
- Contain thylakoids and stroma
Chloroplasts function
Site of photosynthesis
Ribosomes structure
- Small, round structures found in all cells
- may occur as free ribosomes suspended in the cytosol or bound to the RER
Ribosomes function
- Sites of polypeptide synthesis
- free ribosomes generally make proteins that will function within the cytosol
- bound ribosomes generally make proteins that are destined for insertion into membranes, for packaging within certain organelles such as lysosomes, or for export from the cell
Centrioles structure
- Small, hollow cylinders that occur in pairs
- found in animal cells but absent in plant cells
Centrioles function
Centrioles play a roll in cell division in animal cells
Plant cell vs animal cell (cell wall)
Plant cell - surrounded by the cell wall in addition to the cell membrane
Animal cell - cell wall is absent, only surrounded by the cell membrane
Plant cell vs animal cell (chloroplasts)
Plant cell- chloroplasts are present in large numbers in photosynthetic cells
Animal cell-absent
Plant cell vs animal cell (centrioles)
Plant cell - absent
Animal cell - present
Plant cell vs animal cell (vacuole)
Plant cell- present as a single, large and central vacuole
Animal cell- vacuoles are small and numerous
