Biology Chapter: Cell Structure and Function

Order of Cells

• Cells are the basic unit of life.
• Cells have evolved over time to adapt to different environments.
• Cellular processes are regulated by complex feedback mechanisms.
• Cells respond to changes in their environment to maintain homeostasis.
• Cells require energy to function.
• Cells reproduce to create new cells.
• Cells process information from their environment.
• Cells grow and develop over time.

Cells: A "Sac"

• Cells have a cell membrane that acts as a barrier, regulating what enters and leaves the cell.
• The membrane is composed of lipids and proteins.
• Lipids are made up of fatty acids, which contain carbon, hydrogen, and oxygen.
• Proteins are made up of amino acids, which provide structural support.

Modern Cell Theory

• All living organisms are composed of cells.
• New cells arise from pre-existing cells through cell division.
• Cells contain DNA, which is passed from parent cell to daughter cell during division.
• Cells are made up of six main elements: carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.
• Energy flow, or metabolism, occurs within cells.
• The plasma membrane allows selective passage of molecules into the cell.
• Transport proteins embedded within the cell membrane facilitate the passage of specific molecules.

Major Components of A Cell

• Water is the most abundant molecule in cells.
• Cells contain inorganic ions and carbon-containing molecules.
• Nucleic acids, such as DNA and RNA, are essential for genetic information storage and transfer.
• Proteins perform a wide variety of functions in cells, including structural support, enzyme activity, and transport.
• Carbohydrates provide energy and structural support.
• Lipids are involved in energy storage, cell signaling, and membrane formation.

Organelles

• Organelles are specialized structures within cells that perform specific functions.
• Mitochondria are responsible for energy production in animal cells.
• Chloroplasts are responsible for photosynthesis in plant cells.

Different Types of Cells

• Two main types of cells: prokaryotic and eukaryotic cells.
• Prokaryotic cells lack a nucleus and other membrane-bound organelles.
• Eukaryotic cells have a nucleus and other membrane-bound organelles.
• Prokaryotes include bacteria and archaea.
• Eukaryotes include plants, animals, fungi, and protists.
• Prokaryotic and eukaryotic cells share some similarities, including the presence of chromosomes, DNA as genetic material, ribosomes, cytoplasm, a plasma membrane, and vacuoles.

Types of Microorganisms

• Microorganisms are tiny living organisms that can only be seen with a microscope.
• Microorganisms include bacteria, fungi, viruses, prions, parasites, and protozoans.

The Evolution of the Cell

• Natural selection is a process that drives the evolution of organisms.
• Natural selection involves two key processes: random variation and selection.
• Random variations are passed down from parent to offspring.
• Selection favors individuals with traits that increase their chances of survival and reproduction.

From Molecules to the First Cells

• Organic molecules, such as amino acids, sugars, purines, and pyrimidines, are essential building blocks of cells.
• DNA, RNA, and proteins are composed of hydrogen, carbon, nitrogen, oxygen, sulfur, and phosphorus.
• Amino acids and nucleotides combine to form polymers, such as polypeptides (proteins), polynucleotides (DNA and RNA), and polysaccharides (carbohydrates).
• Polynucleotides have the ability to self-replicate.
• Self-replicating molecules are subject to natural selection.
• RNA can act as a catalyst for biochemical reactions.
• Information flows from polynucleotides (DNA and RNA) to polypeptides (proteins).
• DNA serves as the hereditary material in cells.
• Proteins are made up of 20 different types of amino acids.
• Phospholipids are essential components of cell membranes.
• Phospholipids have a hydrophilic head (attracted to water) and a hydrophobic tail (repelled by water).
• The nucleus is enclosed by an outer nuclear membrane (ONM) and an inner nuclear membrane (INM), and it is surrounded by cytoplasm, which contains organelles.

How are cells studied

• Microscopes are essential tools for studying cells.
• Electron microscopes provide higher magnification and resolution than light microscopes, allowing for greater detail in cell structure.
• Robert Hooke was the first to observe cells using a microscope.

Classifications of Living Things: Domains of Life

• All living organisms are classified into three domains: bacteria, archaea, and eukarya.
• Bacteria are single-celled prokaryotes.
• Archaea are single-celled prokaryotes that are often found in extreme environments.
• Eukarya include four kingdoms: fungi, plants, animals, and protists, which are typically single-celled eukaryotes.