Cells

=Differences between plant and animal cells= Gives the cell shape and protection, as well as regulates movement of substances into and out of the cell
 * **Factors** || **Plant cells** || **Animal Cells** ||
 * **Structure** || Fixed shape || No fixed shape ||
 * **Components and their functions** || Plasma Membrane:

Golgi Apparatus: Packages macromolecules in membrane-bound vesicles at the periphery to be transported somewhere else in the cell

Nucleus: Contains chromatin/ DNA responsible for providing the cell with its unique characteristics

Nucleolus: Produces ribosomes

Ribosomes: Synthesizes protein

Rough endoplasmic reticulum: Collect the proteins synthesized on ribosomes for transport throughout the cell

Smooth endoplasmic reticulum: Plays different functions according to cell type: e.g. lipid and steroid hormone synthesis, breakdown of lipid-soluble toxins in liver cells, etc

Mitochondroin: The cristae in the mitochondroin increase surface area for sugar to be combined with oxygen to produce ATP - the primary energy source for the cell

Centrosomes: (or known as microtuble organizing centre, MTOC) where microtubles are produced. They replicate during cell division and move to opposite ends of the nucleus, dividing the centrosomes. The microtubles grow into a "spindle" responsible for separating the replicated chromosomes into the two daughter cells. (only present in lower plant forms)

Cilia and flagella: Move liquid past the surface of the cell

Cytoskeleton: Helps to maintain cell shape. Primary importance of the cytoskeleton is in cell mortility. The internal movement of cell organelle, as well as cellocomotion and muscle fiber contraction could not take place without the cytoskeleton.

Cell junctions: - Tight junctions: bind cells together, forming a barrier that is leak-proof. E.g. tight junctions form the lining of the digestive tract, preventing the contents of the intestine from entering the body. - Anchoring/ adhering junctions: link cells together, enabling them to function as a unit and forming tissue, such as heart muscles or the epithelium that comprises skin.

- Communicating/ gap junctions: allow rapid and electrical communication between cells. They consist of channels that connect the cytoplasm of adjacent cells.

Cytoplasm: The site of translation in the cell.

Lysosome and food vacuole: (Lysosomes are l ess common in plant cells) Food vacuole is generally large and central in plant cells, whereby the main functions are to store nutrients and waste products, increase cell size during growth, and regulate tugor pressure (water) in cell. Without sufficient water, the tugor pressure will drop and the plant will wilt.

Chloroplast: Contains the green pigment called chlorophyll, which convert energy of sun, water and carbon dioxide to synthesize sugar during photosynthesis

Cellulose cell wall: Provides and maintains the shape of plant cells and serves as a protective barrier. Fluid collects in the plant cell vacuole and pushes out against the cell wall. This tugor pressure is responsible for the crispness of fresh vegetables. (this would also explain why plant cells do not burst even when they undergo plasmolysis, whereas animal cells would burst if they were submerged in a hypotonic solution for too long) Plastids: Involved in photosynthesis, gravity perception, and biogenesis of micro-and macromolecules. All kinds of plastids develop from proplastids, which are small bodies found in plants growing in the dark as well as in the light || Plasma Membrane: Gives the cell shape and protection, as well as regulates movement of substances into and out of the cell

Golgi Apparatus: Packages macromolecules in membrane-bound vesicles at the periphery to be transported somewhere else in the cell

Nucleus: Contains chromatin/ DNA responsible for providing the cell with its unique characteristics

Nucleolus: Produces ribosomes

Ribosomes: Synthesizes protein

Rough endoplasmic reticulum: Collect the proteins synthesized on ribosomes for transport throughout the cell

Smooth endoplasmic reticulum: Plays different functions according to cell type: e.g. lipid and steroid hormone synthesis, breakdown of lipid-soluble toxins in liver cells, etc

Mitochondroin: The cristae in the mitochondroin increase surface area for sugar to be combined with oxygen to produce ATP - the primary energy source for the cell

Centrosomes: (or known as microtuble organizing centre, MTOC) where microtubles are produced. They replicate during cell division and move to opposite ends of the nucleus, dividing the centrosomes. The microtubles grow into a "spindle" responsible for separating the replicated chromosomes into the two daughter cells. (for animal cells they are present in pairs).

Cilia and flagella: Move liquid past the surface of the cell

Cytoskeleton: Helps to maintain cell shape. Primary importance of the cytoskeleton is in cell mortility. The internal movement of cell organelle, as well as cellocomotion and muscle fiber contraction could not take place without the cytoskeleton.

Cell junctions: - Tight junctions: bind cells together, forming a barrier that is leak-proof. E.g. tight junctions form the lining of the digestive tract, preventing the contents of the intestine from entering the body. - Anchoring/ adhering junctions: link cells together, enabling them to function as a unit and forming tissue, such as heart muscles or the epithelium that comprises skin.

- Communicating/ gap junctions: allow rapid and electrical communication between cells. They consist of channels that connect the cytoplasm of adjacent cells.

Cytoplasm: The site of translation in the cell.

Lysosome and food vacuole: (Lysosomes are highly common in animal cells) Food vacuoles are generally small in animal cells, whereby the main functions are to store nutrients and waste products, increase cell size during growth. ||

=Differences between prokaryotic and eukaryotic cells =

**Factors ** || **Prokaryotic cells ** || **Eukaryotic cells ** || Types of organisms || Simple cells without a distinct, membrane-bound nucleus, e.g. viruses and bacterial cells || More complex, e.g. fungal cells, protistan cells, animal cells and plant cells || Cell size || Relatively small cells, most are 1-10 micrometers across || Relatively large cells, with most animal cells being 10-30 micrometers across, and most plant cells being 10-100 micrometers across || Cell components and functions || Nucleoid region: Storage of genetic information, the site of DNA replication

Cytoplasm: The site where many metabolic reactions occur

Ribosomes: <span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Synthesize proteins

<span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Mesosome: <span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Permeable boundary the allows for entry and exit of nutrients and waste, and may play a role in DNA replication

<span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Cell wall: <span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Protects against mechanical and hypertonic stress

<span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Pili: <span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Assist in adhesion and sexual conjugation

<span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Flagella: <span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Assist in movement and may play a role in sexual conjugation

<span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Simple chromatophores: <span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%; letter-spacing: 0px;">Photosynthesis (unlike more complex chloroplasts in plant cells) and respiration || <span style="font-family: 'Lucida Console',Monaco,monospace; font-size: 130%;">Plasma membrane Nucleus and nucleolus Golgi apparatus Lysosomes and food vacuoles Mitochondroin Smooth/ rough ER Ribosomes Cell junctions Cytoskeleton Centrosome Cilia and flagella (Cellulose cell wall) (Chloroplast) || = =