SBI3U1P-1 Unit One: Cellular Biology

Cell Theory (three statements)

1. All living things are composed of one or more cells

2. Cells are the basic structural and functional units of life

3. All cells arise from the division of other cells

Cell Membrane

A thin flexible film that separates the contents of the cell from the extracellular fluid and controls the movement of fluids in and out of the cell.

Chromatin (DNA)

Genetic material found in cells that stores all the instructions needed for a cell's activities.

What is Cytosol?

The aqueous solution inside the cell where all the cell's organelles are suspended.

Nucleus

The control center of the cell, responsible for regulating cell activities.

Cytoplasm

The cytosol and all the cell organelles outside the nucleus but within the cell membrane.

Cell Wall

An additional outer covering found in plant cells that provides rigidity while allowing water and dissolved materials to pass through easily.

Unicellular Organisms

Organisms consisting of only one cell that must perform all functions of life for that cell.

Seven Functions of Life

1. Nutrition 2. Metabolism 3. Growth 4. Response 5. Excretion 6. Homeostasis 7. Reproduction

Surface Area to Volume Ratio

The ratio of surface area to volume in a cell, which affects the rate of chemical reactions, absorption of substances, and removal of waste products.

Multicellular Organisms

Organisms consisting of a single mass of cells that are fused together, accompanied by cellular specialization and division of labor.

Emergent Properties

The characteristics of a whole organism that arise from the interactions and cooperation of its cells.

Division of Labour

The concept that different cells in a multicellular organism perform different functions to allow the organism to carry out complex tasks.

Tissue

A group of cells that specialize in the same way to perform a specific function more efficiently than individual cells.

Differentiation

The process by which cells develop in different ways to carry out specific functions.

Cell Differentiation

When different sequences of genes are expressed in different cell types.

Gene expression

The process by which genes are activated and their instructions are used to create specific proteins or molecules.

Stem cell

An unspecialized cell that can divide and renew itself for long periods and has the potential to differentiate into specialized cell types.

Plasticity (transdifferentiation)

The ability of stem cells from one tissue to generate the differentiated cell types of another tissue.

Pluripotent

The ability of a single stem cell to give rise to all the various cell types in the body.

Adult stem cells

Undifferentiated cells found in differentiated tissues that can renew themselves and differentiate into specialized cell types.

Embryonic stem cells

Primitive cells derived from a 5-day preimplantation embryo that have the potential to become a wide variety of specialized cell types.

Umbilical cord blood stem cells

Stem cells obtained from the blood remaining in the placenta and umbilical cord after a baby is delivered.

Stromal Stem Cells

Stem cells derived from menstrual blood that exhibit stem cell properties such as self-renewal and multipotency.

Why embryos?

Stem cells derived from embryos that have the capacity to differentiate into all types of cells/tissues and are easier to grow in culture.

Therapeutic stem cells

Stem cells used for medical purposes, such as regenerating skin for burn victims or replacing damaged cells in Parkinson's patients.

Cell rejection

Concern that transplanted stem cells may be rejected by the recipient's immune system.

Insulation tissue

Tissue that surrounds and protects neurons.

Microenvironment

The immediate surroundings of a cell, including neighboring cells and molecules.

Nucleus

The control center of the cell that contains DNA and directs all cell activities.

Nuclear envelope

A double membrane that separates the nucleus from the cytoplasm and controls the passage of molecules.

Nucleoplasm

The fluid inside the nucleus that contains nucleic acids used in making RNA and DNA.

Nucleolus

A denser region inside the nucleus involved in ribosomal production.

Ribosomes

Organelles that produce proteins through protein synthesis.

Endoplasmic Reticulum (ER)

A system of channels attached to the nuclear envelope that manufactures proteins (rough ER) or synthesizes lipids (smooth ER).

Vesicles

Membrane-bound structures that transport molecules within the cell.

Golgi Apparatus

A stack of curved membrane sacs that chemically modifies fats and proteins produced in the ER and packages them in vesicles.

Lysosomes

Membrane-enclosed sacs containing enzymes that break down old or unnecessary parts of the cell and destroy microorganisms.

Peroxisomes

Membrane-enclosed sacs containing enzymes that catalyze redox reactions and break down fatty acids and alcohol molecules.

Vesicles ("Vacuoles")

Large membrane-bound sacs filled with a watery solution, responsible for storing sugars, minerals, and proteins.

Mitochondria

Membranous organelles responsible for cellular respiration and producing energy for the cell.

Plastids

Membranous organelles found only in plant cells, with the chloroplast being the most important, containing chemicals for photosynthesis.

Microtubules and Centrioles

Small cylindrical fibers responsible for moving chromosomes during cell division, with centrioles serving as an anchor point.

Cilia & Flagella

Whip-like structures made of microtubules, used for locomotion and creating currents in fluid.

Prokaryotic Cells

Cells without a defined nucleus, small in size, and found almost everywhere, with a cell wall made of peptidoglycan.

Nucleoid

A circular molecule containing DNA in prokaryotic cells.

Binary fission

A form of asexual reproduction in prokaryotic cells where the single circular DNA molecule is copied and each moves to opposite ends of the cell, followed by division of cytoplasm and cell.

Eukaryotic cells

Cells with compartmentalized structure, including a nucleus containing the cell's chromosomes and other organelles with distinctive structure and function.

Compartmentalization

The division of a cell into different compartments or organelles, allowing for concentration of enzymes and substrates, containment of harmful substances, different pH levels, and movement of organelles and their contents.

Cell membrane

A phospholipid bilayer that surrounds the cell and controls the movement of molecules in and out.

Amphipathic

Substances that have both hydrophilic and hydrophobic properties, such as phospholipids.

Phospholipid bilayer

The double layer of phospholipids in the cell membrane, with hydrophilic heads facing the water and hydrophobic tails facing each other.

Membrane proteins

Proteins embedded in the cell membrane that carry out various tasks, including hormone binding, enzyme activity, cell adhesion, cell-to-cell communication, and transport of molecules across the membrane.

Integral proteins

Membrane proteins that extend across the membrane, with hydrophobic parts embedded in the hydrocarbon chains of the cell membrane and hydrophilic ends projecting through the phosphate parts of the membrane.

Channel proteins

Integral proteins that transport water and ions across the cell membrane.

Carrier proteins

Integral proteins that transport small molecules across the cell membrane, such as glucose.

Surface proteins

Integral proteins used for binding and can attach movement structures like cilia and flagella, as well as serve as receptor sites for hormones.

Pumps

Carrier proteins that move molecules against the concentration gradient (requires energy - ATP)

Peripheral Proteins

Hydrophilic proteins on the surface of the membrane, not embedded in the membrane

Carbohydrate Chains

Carbohydrate chains attached to membrane proteins, involved in cell adhesion

Cholesterol

Present in animal cell membranes, helps control fluidity of cell membranes

Passive Transport

Processes that allow substances to move in and out of the cell without requiring energy (ATP)

Simple Diffusion

Movement of particles from an area of high concentration to an area of lower concentration until equilibrium is reached

Concentration Gradient

Difference in concentration between two areas

Dynamic Equilibrium

State of balance where particles move at equal rates in all directions

How does temperature affect the rate of diffusion?

Affects the rate of diffusion, higher temperatures result in faster diffusion

How does concentration affect the rate of diffusion?

More solute molecules in the solution lead to faster dynamic equilibrium

How does Molecule Size affect the rate of diffusion?

Larger molecules have more difficulty diffusing across the membrane

How does Molecule Polarity affect the rate of diffusion?

Small polar molecules have lower diffusion rates compared to non-polar molecules of the same size

Molecule or Ion Charge

Charged molecules and ions cannot diffuse across a cell membrane

Facilitated Diffusion

Diffusion of solutes across a membrane along its concentration gradient, assisted by transmembrane proteins

Channel Proteins

Transmembrane proteins that form a tunnel for ions or small polar molecules to pass through the cell membrane.

Carrier Proteins

Transmembrane proteins that bind to molecules, change shape, and transport them across the cell membrane.

Osmosis

The net movement of water across a selectively permeable membrane from an area of high concentration to an area of low concentration.

Aquaporins

Water channels in some cells that greatly increase the membrane's permeability to water.

Isotonic Solutions

Solutions that have equal solute concentrations.

Hypertonic solution

A solution with a higher concentration of solutes than another.

Hypotonic solution

A solution with a lower concentration of solutes than another.

Hemolysis

The swelling and bursting of red blood cells due to water diffusing into the cells in a hypotonic solution.

Crenation

The loss of water and shrinking of red blood cells in a hypertonic solution.

ATP (Adenosine Triphosphate)

A molecule that stores and releases energy for cellular processes.

Active Transport

The movement of substances through a membrane against a concentration gradient using trans-membrane carrier proteins and energy from ATP.

Sodium-potassium pump

An important type of active transport pump found in cell membranes, required for proper function of nerve and muscle cells.

Membrane-Assisted Transport

Movement of molecules that are too large to cross the cell membrane using vesicles.

Endocytosis

The process in which the cell membrane engulfs large amounts of material into the cell.

Phagocytosis

The transport of solids into the cell through the formation of a phagocytic vesicle.

Pinocytosis

The engulfing of extracellular fluid by the cell membrane to form a pinocytic vesicle.

Exocytosis

Cells moving large amounts of material out of the cell, essentially the reverse of endocytosis.

Secretory vesicle

A vesicle containing material destined to leave the cell, which fuses with the cell membrane during exocytosis.

Simple diffusion

The movement of substances from an area of higher concentration to an area of lower concentration, without the need for energy.

Facilitated diffusion

The movement of substances from an area of higher concentration to an area of lower concentration, facilitated by channel or carrier proteins.

Active transport

The movement of substances from an area of lower concentration to an area of higher concentration, requiring energy and carrier proteins.

Endocytosis

Cells moving material into the interior of the cell by forming vesicles from the cell membrane.

Biogenesis

The concept that all living things come from other living things.

Abiotic synthesis

The synthesis of small organic molecules from non-living components.

Polymers

Large molecules formed by the joining of smaller molecules (monomers).

Protobionts

Early "cells" that exhibit some properties of life, formed spontaneously from organic compounds.

RNA

The first genetic material discovered, capable of self-replication and acting as catalysts in cells.

DNA

More stable than RNA, possibly formed from RNA and serves as the template for protein synthesis.

Endosymbiosis

One species living permanently inside another, benefiting both organisms.