IB Biology - Unit 1: Intro to Cells

Metabolism

Living things undertake essential chemical reactions

Reproduction

Living things produce offspring, either sexually or asexually

Sensitivity

Living things are responsive to internal and external stimuli

Homeostasis

Living things maintain a stable internal environment

Excretion

Living things exhibit the removal of waste products

Nutrition

Living things exchange materials and gasses with the environment

Growth

Movement

Cell theory

The cell is the smallest unit of life, Cells only arise from pre-existing cells, All living things are composed of cells (or cell products)

Abiogenesis

Theory of cells having spontaneously arisen from non-living material. Has been hard to test due to conditions being difficult to replicate and there are no fossils of the first protocells to base off of.

Catalysis

Simple organic molecules were synthesized from primordial inorganic molecules (requirement for abiogenesis)

Self-Assembly

More complex polymers were constructed from simple organic molecules made during catalysis (requirement for abiogenesis)

Self-Replication

Certain polymers formed the capacity to be duplicated (enabling inheritance) (requirement for abiogenesis)

Compartmentalisation

These molecules became packaged into membranes with unique internal chemistry (requirement for abiogenesis)

Miller-Urey experiment

Recreated the postulated conditions of prebiotic Earth in order to demonstrate the non-living synthesis of organic materials (know the procedure of the experiment)

Organic compounds

Complex carbon-based macromolecules that make up all cells and organisms

Protocells

Self-organized and spherical collection of lipids proposed as a stepping stone toward the origin of life

LUCA

The last universal common ancestor is the most recent population from which all organisms on Earth share a common descent leading to the three domains (Bacteria, Archaea, Eukaryota)

Endosymbiosis

One cell was engulfed by another and became assimilated into its cellular structure. Mitochondria and chloroplasts are thought to have arisen from this process.

Multicellular

Organisms are composed of multiple cells operating in unison to support the total lifeforms. This includes all animal and plant cells, most fungi, and some eukaryotic algae.

Emergent properties

Collective actions of individual cells combining to create new synergistic effects arising from cell specialization.

Nucleus

Surrounded by a double membrane with pores. It stores genetic material.

Ribosomes

All living cells have them to be able to perform protein synthesis. They have 2 subunits and can be located either freely in the cytoplasm or on the Rough endoplasmic reticulum.

Mitochondria

Synthesizes large amounts of ATP and are thought to have been independent prokaryotic cells before endosymbiosis.

Chloroplast

Found within plant cells to perform photosynthesis by converting light to chemical energy. They are thought to have been independent prokaryotic cells before endosymbiosis.

Golgi apparatus

Sorts, stores, modifies and exports cellular materials using vesicles.

Vesicles

Transports materials between cellular compartments. Usually materials that are too large to be passed through the membrane without help.

Lipids

Fats made of carbon, hydrogen, and oxygen. Oils, waxes, phospholipids, triglycerides and steroids are examples.

Stem Cells

Cells in your body that can replicate themselves to make another identical cell, or differentiate into many different types of cells.

Self-renewal

The process by which a stem cell divides, making exact copies of itself and turning into more identical stem cells.

Differentiation

The process of which a stem cell can develop into many different types of specialized cells.

Embryonic stem cells

Cells that can be found within a blastocyst: the early stages of an embryo when the egg is fertilized by the sperm.

Pluripotent

Can differentiate all types of specialized cells in the body. As an example Embryonic stem cells are pluripotent.

Multipotent

Can differentiate multiple types of specialized cells but not all of them. As an example tissue cells are multipotent.

Totipotent

Can differentiate into all types of specialized cells but it also includes cells that are needed during embryonic development. Only: placenta, yolk sac, umbilical cord.

Induced pluripotent cells

The new stem cells that are made in the lab are called induced pluripotent cells. Just like the embryonic cells they can make all types of cells.

Phospholipid

The primary molecule of the cell membrane, synthesized by the smooth endoplasmic reticulum. They have amphipathic properties.

Phospholipid bilayer

Membrane structured by two layers of phospholipids due to its amphipathic properties.

Amphiphilic

The property of a molecule that one part is hydrophilic and another part is hydrophobic.

Hydrophobic

Molecules that are polar or ionic, and they attract water molecules.

Hydrophilic

Molecules that are non-polar and does not attract water molecules.

Integral proteins

A membrane protein embedded into the phospholipid bilayer

Peripheral proteins

Loosely attached to the surface of the membrane. Sometimes embedded lightly

Channel protein

Passive transport. Allows inorganic ions of certain size and charge to pass through

Carrier protein

Passive transport. Bind and changes specific solutes and transfers them across the membrane

Pump protein

A type of protein that uses energy (ATP) because of low to high concentration

Fluid-mosaic model

Represents and explains the structure of the cell membrane as a mosaic of components, in which includes phospholipids, cholesterol, carbohydrates and proteins.

Cholesterol

A steroid in charge of maintaining the integrity and regulating the fluidity of the cell membrane. Composed of a polar and hydrophilic head (hydroxyl group), carbon rings, and a non-polar and hydrophobic tail.

Glycosylation

A process of a modification of an organic cell, through the attachment of a carbohydrate chain (sugar). In the cell membrane, glycosylation in a phospholipid results in a glycolipid and glycosylation in a membrane protein results in a glycoprotein.

Glycoprotein

The result of a glycosylation of a membrane protein, its function is to maintain the stability of the cell membrane, the carbohydrate attached to it also serves as an attachment point for other cells.

Glycolipid

The result of a glycosylation of a phospholipid, its role is to maintain the stability of the cell membrane and facilitate cell recognition, judging a cell to be good or bad for the system

Passive Transport

Involves the movement of material along a concentration gradient (high concentration ⇒ low concentration). No ATP required.

Active Transport

Involves the movement of materials against a concentration gradient (low concentration ⇒ high concentration). ATP required.

Simple Diffusion

Occurs when small and lipophilic molecules pass between phospholipids to freely cross the bilayer.

Facilitated Diffusion

Occurs when molecules that are unable to freely pass the phospholipid bilayer need additional help from the channel or carrier protein.

Primary Active Transport

Uses an ATP from the surrounding area to change the shape of the protein and release the molecule against the gradient.

Secondary Active Transport

Requires two molecules moving across where one of them is going with the gradient (providing energy), and the other going against the gradient.

Osmosis

The net movement of water molecules across a semipermeable membrane from a region of low solute concentration to a region of high solute concentration (until equilibrium is reached)

Isotonic

Balanced concentrations inside and outside the cell.

Hypertonic

Higher solute concentration outside the cell

Hypotonic

Higher solute concentration inside the cell