Cell Biology: Theory, Prokaryotic and Eukaryotic Cells

• The human body is a complex machine

Cell Theory

• All organisms are made of cells
• Cells are the basic units of life
• Cells come from pre-existing cells that have multiplied

Prokaryotic vs Eukaryotic Cells

• Prokaryotic cells lack a nucleus, while eukaryotic cells possess one
• The typical diameter of a prokaryotic cell is approximately 1µm; eukaryotic cells range from 10 to 100 μm
• Prokaryotic cells lack a cytoskeleton, while eukaryotic cells have a cytoskeleton
• Prokaryotic cells lack cytoplasmic organelles; eukaryotic cells present them
• Prokaryotic DNA content ranges from 1 × 10^6 to 5 × 10^6 base pairs; eukaryotic DNA ranges from 1.5 × 10^7 to 5 × 10^9
• Prokaryotic chromosomes consist of a single circular DNA molecule; eukaryotic chromosomes consist of multiple linear DNA molecules

Cells to Organs

• Cells form tissues, which are complex organizational arrangements that fulfill specific functions
• Epithelial tissue provides covering and lining
• Connective tissue such as bone and fat provides support
• Muscle tissue deals with Movement
• Nervous tissue facilitates communication
• Adipose Tissue is involved in fat storing

Beyond Tissues

• Basic tissues form organs
• Organs contain different combinations of tissue types
• Organ systems comprise multiple organs working together
• Cells provide the basis for different organ functions, which contribute to body systems
• The body makes use of: Energy Supply, Scaffold, Propulsion System, Pumps, Ventilation and Plumbing, Purification, Protection, Control Systems, Creation, Construction and Repair.

Cells factoids

• The human body consists of cells and water
• It contains approximately 37 trillion (10^13) cells

Cell mass facts

• Muscle accounts for 44% of total mass, composed of 17 billion muscle cells.
• Fat makes up 28.5% of total mass, consisting of around 50 billion fat cells
• Red blood cells comprise 5.5% of total mass; each cell weighs around 25-35 billionths of a gram
• Skin cells make up 5.5% of total cells
• Skin is composed of approximately 2 trillion cells
• Blood and lymph vessels account for 6.8% of total cells
• The nervous system accounts for 8.3% of total cells
• The nervous system contains roughly 100 billion neurons insulated and supported by 3 trillion glial cells
• Red blood cells make up 70.7% of all cells: approximately 26 trillion

Fluid content

• Average lean adult females: 45% solid, 55% fluid
• Average lean adult males: 40% solid, 60% fluid
• Intracellular fluid (ICF) accounts for 2/3 of total body fluid
• Extracellular fluid (ECF) makes up 1/3; 80% is interstitial fluid, and 20% is blood plasma

Fluid content and controls

• Fluid content is regulated but it can change due to diabetes and renal disease
• Electrolytes / CO2 changes are related to CV disease
• K+ over 7 can be fatal

Balancing Acid and Base

• Respiratory control involves CO2
• Metabolic buffers involve bicarbonate
• Renal regulation involves electrolytes

Fluid Exchange

• The surface area to volume ratio is essential for fluid exchange
• The estimated surface area of the lungs is approximately half a tennis court
• Surface area of the gut can perform same functions as the kidneys

What we know about cells

• The human body develops from a single cell into ~37 trillion cells
• Cells can grow and function independently
• Cells have different types that fulfil distinct functions
• It have common structural and functional features

Cell as Factory

• Plasma Membrane: outer boundary
• Cytoplasm: internal substance
• Nucleus: genetic regulation
• Organelles: functional components

Molecular component of cells

• DNA or RNA (Genome) is transcribed into RNA (Transcriptome)
• RNA (Transcriptome) is translated into Proteins (Proteome)
• Proteins (Proteome) can assist in creating Metabolome

The Genome

• The first human genome mapping took place from 1990-2003
• The cost was approximately $5 billion
• DNA provides the information for replication, growth, and differentiation
• There are approximately ~20,000 genes in the human genome

The Proteome

• Each cell type has a unique set of proteins to perform its functions
• The human body has 60-80,000 unique proteins

Nucleus

• Nucleolus facilitates RNA transcription and ribosome biogenesis
• Rough endoplasmic reticulum facilitates ribosomes
• Proteins synthesis is done within the rough endoplasmic reticulum by folding
• Smooth ER is involved in lipid and steroid hormone production

Golgi Complex

• The Golgi complex processes and sorts proteins from the endoplasmic reticulum for transport
• In this cellular structure proteins are trafficked and sorted for correct destinations

Mitochondria

• The powerhouse of the cell is the mitochondria, which produces ATP
• Mitochondria replicates by fission
• Mitochonria contains its own maternal DNA

Lysosomes

• Lysosomes handle waste disposal

Cytoskeleton

• The cytoskeleton facilitates structure, support, and transport via filaments and tubules

Learning Objectives

• To describe how cells can be thought of as the basic units of life
• To describe how different cell types can provide specialization for a particular organ
• To identify how water plays a key role in regulating the intracellular and extracellular environment
• To identify the key functions of the nucleus, endoplasmic reticulum, golgi, mitochondria, lysosomes, and cytoskeleton