Cell Structures and Functions

• A cell membrane is a flexible covering that protects the inside of a cell from the outside environment.
• All cells have a cell membrane.
• A cell wall is a stiff structure outside the cell membrane, present only in plant cells.
• Cytoplasm is the fluid inside a cell that contains salts and other molecules.
• A eukaryotic cell is defined by having its DNA stored within a nucleus.
• A prokaryotic cell lacks a nucleus.
• Organelles are specialized structures within eukaryotic cells, often membrane-bound.
• The nucleus directs cell activities and holds genetic information in DNA.
• Chloroplasts, found in plant cells, conduct photosynthesis, using light energy to produce glucose and oxygen from water and carbon dioxide.
• Mitochondria release stored energy from ATP through cellular respiration in all cells.

Cell Shape and Movement

• Cells are composed of structures that function together to maintain life.
• Cell membranes are mainly phospholipids and proteins.
• Cell walls are present in plant, fungal, and some bacterial cells.
• Cell appendages like flagella and cilia facilitate movement.
• Flagella are long, tail-like appendages that whip back and forth to move a cell.
• Cilia are short, hairlike structures that move cells or molecules.

Cell Types - Prokaryotic and Eukaryotic

• Cells are grouped into prokaryotic and eukaryotic types.
• Both cell types have cell membranes and cytoplasm.
• Prokaryotic cells lack a membrane-bound nucleus, with genetic material in the cytoplasm.
• Most unicellular organisms are prokaryotes.
• Eukaryotic cells have DNA enclosed in a nucleus.
• Plants, animals, fungi, and protists consist of eukaryotic cells.
• Most multicellular organisms are eukaryotes.
• Eukaryotic cells contain membrane-bound organelles with specialized functions.

Cell Organelles

• The nucleus directs cell activities using DNA.
• The number of chromosomes in a nucleus varies by species.
• Humans typically have 23 pairs, totaling 46 chromosomes.

Manufacturing Molecules

• Proteins are assembled in ribosomes.
• Ribosomes are found in the cytoplasm or on the endoplasmic reticulum (ER).
• Rough ER contains ribosomes for protein synthesis.
• Smooth ER produces lipids like cholesterol.

Processing Energy

• Energy is released via cellular respiration in mitochondria.
• The released energy is stored in ATP, which fuels cell processes.
• Chloroplasts use light energy to convert water and carbon dioxide into glucose through photosynthesis.

Processing, Transporting, and Storing Molecules

• The Golgi apparatus modifies and packages proteins into vesicles.
• Vesicles transport substances within the cell.
• Lysosomes, found in animal cells, break down and recycle cell components.
• Vacuoles store food, water, and waste.
• Plant cells have a large central vacuole, while animal cells have smaller vacuoles.

Structures

• Plant cells have cell walls, a central vacuole, and chloroplasts, unlike animal cells.
• Animal cells have lysosomes.
• Plants obtain energy from the sun.
• Animals obtain energy by consuming plants or other animals.
• Chloroplasts in plant cells create sugars used by both plants and animals for energy.

Cell as Factory

• Raw materials are input.
• Various processes transform the materials.
• Waste and products are output.
• Nucleus: contains all the information a cell needs to function (DNA)
• Ribosomes: uses information from the nucleus to gather the materials a cell needs to build important molecules called proteins (protein construction team)
• Chloroplasts: organelles that use the energy from sunlight to make sugar in plant cell only (the process is photosynthesis)
• Mitochondria: organelles that release stored energy (powerhouse) (the process is cellular respiration)
• Rough and smooth endoplasmic reticulum: processes materials it gets from the ribosome and uses them to make proteins and lipids like cholesterol (manufacturing dept.)
• Golgi apparatus: finishes processing materials (proteins and lipids) from the ER and packages them into ball-like structures called vesicles (distribution & shipping dept. for stuff made in ER)
• Vesicles: transport processed materials around the cell
• Cell wall: a tough outer covering that lies right outside the cell membrane in plant cell only
• Cell membrane: a protective covering enclosing the entire cell (plastic bag with tiny holes or a screen door)
• Cytoplasm: a thick fluid inside the cell membrane
• Lysosome: vesicles that break down materials and old cell parts in animal cell only (little enzyme package)
• Central vacuole: large vacuole that stores water and other materials in a plant cell only