Biology F/R-009: Cell Types and Life Characteristics

Biology (F/R-009) - Types of Cells and Cellular Organelles of Eukaryotes

• The course will cover distinguishing prokaryotic and eukaryotic cells.
• Students will learn the structure and function of cellular organelles.
• Mitochondria's role in metabolism will be explored.
• Functions of cell membranes will be detailed.
• Animal cells in various tissues will be studied.
• The role of nucleic acid in genetics and cellular communication will be explained.

Characteristics of Life

• Life is composed of cells.
• Reproduction is a characteristic of life.
• Growth and development are characteristics of life.
• Metabolism is the process of obtaining and using energy
• Responding to the environment is a characteristic of life.
• Homeostasis is a characteristic of life.
• DNA is the universal genetic code.
• Evolution and adaptation are hallmarks of life.

Levels of Organization

• Atoms, molecules, cells, tissues, organs, organ systems, and organisms are progressive levels of organization.
• Levels of organization can be extended to communities, ecosystems, and finally the biosphere.

Cell Structure and Types

• A cell is the basic unit of life.
• Cells come from pre-existing cells.
• Unicellular organisms consist of a single cell.
• Multicellular organisms have many specialized cells grouped together into tissues.
• Tissues are collections of similar cells with a common embryonic origin.

Reproduction

• Asexual reproduction involves a single parent producing genetically identical offspring, often with rapid reproduction.
• Sexual reproduction involves two parents creating genetically unique offspring increasing genetic diversity.

Growth and Development

• Single-celled organisms grow by increasing in size.
• Multicellular organisms undergo extensive development from a fertilized egg, undergoing cell division and differentiation (changing shape/structure).

Obtaining and Utilizing Energy

• All living things obtain energy from their environment and use for growth, reproduction, and excretion.
• Metabolism combines anabolism (synthesis, energy-expenditure) and catabolism (decomposition, energy-release).
• Chemical reactions within organisms maintain their life processes.

Responding to the Environment

• Organisms respond to stimuli (signals).
• Responses can be to internal or external stimuli.
• Examples of internal stimuli: blood glucose level, hunger, tiredness.
• Examples of external stimuli: light, touch, sound.

Homeostasis

• Homeostasis describes the self-regulating processes that maintain suitable body conditions for life, reacting to internal and external conditions.

DNA as the Universal Genetic Code

• All life is based on DNA determining inherited traits.
• DNA is a nucleic acid stored in a double helix structure.
• DNA has the ability to duplicate itself and transmit genetic information.

Evolution and Adaptation

• Evolution is the ability of a group of organisms to change over time, pivotal for survival in changing environments.
• Adaptation is a characteristic that helps an organism to survive and reproduce in its environment.

The Cell (General)

• A cell is the lowest level of organization capable of life functions.
• All cells are enclosed by a membrane and utilize DNA for genetic information.
• Eukaryotic cells possess membrane-bound organelles, the most significant being the nucleus.
• Prokaryotic cells have a simpler structure, lacking a nucleus and other membrane-bound organelles.

The Cell Theory

• Cells were named by Robert Hooke in 1665.
• The cell is the basic unit of structure and function.
• Living things are made of one or more cells.
• All cells come from pre-existing cells.

Types of Cells

• Prokaryotic cells are the most primitive cell type, lacking a nucleus and other membrane-bound organelles. Bacteria are the only prokaryotes.
• Eukaryotic cells are found in most organisms (plants & animals), with a nucleus containing the genetic material and numerous membrane-bound organelles.

Animal Cell - Organelles

• Various organelles (e.g. mitochondria, endoplasmic reticulum, Golgi apparatus), are identified in diagrams and descriptions.

Cell Membrane

• The cell membrane protects the cell and allows passage of certain molecules.
• Properties like selective permeability are key functions of cell membranes.
• Mechanisms like Endocytosis, exocytosis, and facilitated diffusion are part of the membrane's functioning.

Passive Transport Across Cell Membranes

• Diffusion is the net movement of molecules from high to low concentration.
• Facilitated diffusion is diffusion aided by proteins across the membrane .

Active Transport

• Active transport requires ATP to move molecules against their concentration gradient. Diagrams highlight typical mechanisms.

Passive Transport - Osmosis

• Osmosis is the movement of water across a selectively permeable membrane from a hypotonic (lower solute) to a hypertonic (higher solute) solution, until equilibrium (isotonic).
• Different solutions (hypotonic, hypertonic, isotonic) affect cells differently.
• Erythrocytes (red blood cells) provide examples illustrating this.

Cell Lysis

• Cell lysis is the bursting of a cell due to increased internal pressure in hypotonic solutions.

Permeability

• Molecules have different permeabilities through biological membranes based on size and charge.

What are Mitochondria?

• Mitochondria are organelles ("powerhouses" of the cell) responsible for generating a form of energy called ATP, via biochemical reactions known as cellular respiration.
• They are found within the cytoplasm of most eukaryotic cells. Their double-membrane structure is crucial.

Structure of Mitochondria:

• Mitochondria consist of an outer membrane, inner membrane, and a matrix (gel-like material).
• Cristae are folds in the inner membrane that increase surface area. Porins are prominent proteins in the outer membrane.

Functions of Mitochondria

• Mitochondria play a vital role in producing energy.
• They play a role in cell multiplication, detoxification, apoptosis, maintaining calcium levels, and cellular activities (differentiation/signaling).
• They regulate metabolic activity.

Mitochondrial DNA

• Mitochondria have their own DNA (mtDNA).
• This DNA is different from the nuclear DNA, mostly similar to bacteria.
• mtDNA holds the instructions for some proteins and support equipment (about 37 genes). Its lineage is often traced maternally.

Producing Energy

• ATP is the critical source of energy for metabolic processes.
• The citric acid cycle (Krebs cycle) in mitochondria is a key step in most ATP generation.
• The process of oxidative phosphorylation is how mitochondria generate ATP.

Cell Death (Apoptosis)

• Apoptosis, or programmed cell death, is an integral part of life.
• Mitochondria play a role in deciding which cells will undergo apoptosis.
• Release of cytochrome C is a key event triggering this process.

Storing Calcium

• Mitochondria play a role in storing calcium in the cell.
• This stored calcium has various cellular functions, including neurotransmitter release and other biological processes.

Krebs Cycle

• A series of chemical reactions, the Krebs cycle takes place in the mitochondria.
• The Krebs cycle contributes to producing cellular energy.

Net Results of Glycolysis and Krebs Cycle

• Glycolysis produces ATP and other necessary chemicals.
• The Krebs Cycle further produces ATP and chemicals to drive ATP creation through phosphorylation.

Symptoms of Mitochondrial Diseases

• Symptoms can range from poor growth to muscle weakness, problems with senses, development delays, some organ or neurological problems, etc.