Animal Cell Structure and Functions

• Cells are the structural and functional units of life, and determine an organism's activities.
• Animal cells are eukaryotic, containing membrane-covered organelles, a nucleus, and mitochondria.
• Animal cell shapes and sizes vary based on their function, such as concave red blood cells or elongated nerve cells.

Animal Cell Structure and Functions

• The outer cell membrane separates the cell from the external environment and can be modified for specific functions like movement and feeding.
• Cytoplasm is a jelly-like fluid filling the cell, housing organelles.
• Organelles perform specific jobs within the cell.
• The nucleus is the control center, containing DNA and regulating cell activities like metabolism, growth, and reproduction.
• Mitochondria are responsible for cellular aerobic respiration.
• Lysosomes digest and recycle toxic substances and waste.
• Animal cells lack a cell wall.
• Animal cells provide structure, absorb nutrients, convert nutrients to energy, enable movement, and store/transfer hereditary material.

Plasma Membrane

• Composed of a phospholipid bilayer, separating the cytoplasm from cell organelles.
• Selectively permeable, controlling substances entering and exiting organelles to maintain homeostasis.

Nucleus

• The control center and regulates cellular activities, including growth and cell division
• Contains DNA, the cell's genetic material.
• DNA and histone proteins form chromosomes, which pass genetic information.
• The nuclear membrane separates the nucleus from the rest of the cell.
• Contains the nucleolus, where ribosomal RNA associates with proteins to form ribosomes.

Cytoplasm

• The watery interior of the cell contains ions, and proteins, allowing cells to maintain turgidity
• Most cellular activities take place in the cytoplasm.
• Organelles are suspended in the cytoplasm.
• Contains molecules and enzymes for waste breakdown, metabolic activities, and glycolysis (first step in cellular respiration).
• Cytosol, within the cytoplasm, lacks organelles but contributes to cell shape.

Cell Organelles

• Structures performing various jobs within the cell to maintain balance and keep the cell alive.
• Include the nucleus, mitochondria, ribosomes, lysosomes, vacuoles, endoplasmic reticulum, and Golgi apparatus.

Mitochondria

• Converts oxygen and nutrients into energy via aerobic respiration.
• The number of mitochondria varies depending on the cell type such as heart cells needing more mitochondria
• Oblong organelles with inner and outer membranes and a matrix.
• The inner membrane folds to form cristae.
• Membranes are made of proteins and phospholipid layers separated by the intermembrane space.

Ribosomes

• Synthesize proteins needed by the cell, aiding in cellular repair, growth, and enzyme formation.
• Composed of small (mRNA) and large ribosomal subunits, which bind to mRNA to facilitate protein synthesis.

Golgi Apparatus

• Packages and secretes proteins.
• Receives proteins from the endoplasmic reticulum (ER).
• Comprises compartments called cisternae (flattened, disk-shaped, stacked pouches).
• Ribosomes can be scattered or attached to the ER such as the rough ER possessing ribosomes
• Proteins are packaged in vesicles and sent to different cell organelles from the Golgi body
• Smooth ER lacks ribosomes, synthesizes lipids and fats, and acts as the cell's detoxification center.