Bio U1 AOS 1

Living Things

Living Things

Anything that can move, respire, sense, grow, reproduce, maintain equilibrium, excrete waste, and take up nutrients.

Homeostasis

the maintenance of a relatively stable internal environment in the body despite changes in the external environment.

Organism

A living thing made up of one or more cells.

Cell Theory

The idea that all living things are made of cells, cells are the smallest functional unit of living things, and all cells come from pre-existing cells

Prokaryotes

A group of single-celled organisms with no nucleus and a circular loop of DNA. Bacteria and archaea are both prokaryotic.

Eukaryotes

A group of single and multi-celled organisms with a nucleus and linear strands of DNA. Animals, plants, fungi, and protists are eukaryotic.

Plasma/Cell membrane

The phospholipid bilayer and embedded proteins which separate the intracellular environment from the extracellular environment. Also known as the cell membrane.

Cytosol

The aqueous fluid that surrounds the organelles inside a cell.

Ribosomes

Small RNA-protein structures that are the site of protein synthesis. They either float freely in the cytoplasm or are attached to the RER.

DNA (deoxyribose nucleic acid)

A double-stranded nucleic acid chain made up of nucleotides. DNA carries the instructions for proteins which are required for cell and organism survival.

Membrane bound organelle

Structure within a cell that is enclosed by a phospholipid bilayer.

Chromosome

The structure made of protein and nucleic acids (DNA) that carries genetic information.

Nucleus

A double membrane-bound organelle that protects and confines the genetic information (DNA) of a cell.

Nucleolus

Inside the nucleus is a smaller structure known as the nucleolus which is the site of ribosome production.

Plasmid

A small, circular loop of DNA that is separate from a chromosome, typically found in bacteria

Somatic Cell

Any cell that is not a reproductive cell (such as sperm and egg cells). Somatic cells are diploid, meaning they contain two sets of chromosomes – one inherited from each parent.

Mitosis

The cell division phase which involves the complete separation of sister chromatids and nuclei.

Germline Cells

Cells that are involved in the generation of gametes in eukaryotes.

Gametes

Reproductive cells that arise from germline cells that contain half the genetic material of a somatic cell. In humans, gametes are sperm and eggs.

Meiosis

A specialised form of cell division used to produce gametes in sexually-reproducing organisms.

Binary Fission

The method of cell replication used by prokaryotes.

Micrometres (μm)

Unit of measurement where 1 mm = 1 000 μm.

Organelle

A cellular structure that performs specific functions.

Cytoplasm

The cytosol and organelles inside the plasma membrane, excluding the nucleus

Vacuole

A membrane-bound sac that is used for water and solute storage. Vacuoles can also play a role in maintaining plant cell structure.

Rough endoplasmic reticulum (RER)

A membranous chain of connected and flattened sacs which are coated with ribosomes. This allows the rough endoplasmic reticulum to synthesise and modify proteins. The rough endoplasmic reticulum typically surrounds, or is close to, the nucleus.

Smooth endoplasmic reticulum (SER)

A membranous chain of connected and flattened sacs which are not coated with ribosomes. The smooth endoplasmic reticulum is responsible for the production of lipids in a cell.

Golgi Apparatus

Stacked flattened sacs that are the sites of protein sorting, packaging, and modification for use in the cell or export. Protein-filled vesicles often fuse with or bud off from the Golgi apparatus. Also known as the Golgi body.

Lysosome

A membrane-bound vesicle that contains digestive enzymes. It is responsible for breaking down cell waste and toxins, acting like a garbage disposal.

Mitochondrion

An organelle with a highly folded inner membrane surrounded by a second outer membrane. Mitochondria are the site of aerobic cellular respiration, a chemical reaction that produces the ATP required to power cellular processes. They also contain their own DNA and ribosomes. They are the primary site of energy production from aerobic cellular respiration

Chloroplast

A double membrane-bound organelle that contains flattened, fluid-filled sacs that are the site of photosynthesis. Chloroplasts also contain their own DNA and ribosomes.

Cell wall

A sturdy border outside the plasma membrane that provides strength and structure to plant, bacterial, and fungal cells. (Eukaryotes)

Vesicle

A small, membrane-bound sac that transports substances into or out of a cell, or stores substances within a cell.

Cytoskeleton

A large network of protein filaments that start at the nucleus and reach out to the plasma membrane. The cytoskeleton is critical for maintaining shape and transporting vesicles around the cell. In the given fluorescence microscopy photo, the purple represents the cytoskeleton.

Ribosomal RNA (rRNA)

A type of nucleic acid that is a key structural component of ribosomes.

Cellular Respiration

The biochemical process in all living things that converts glucose into ATP. Can be aerobic or anaerobic respiration.

Crista

The fold of the inner membrane of the mitochondria.

Aerobic

Requiring oxygen.

Anaerobic

Requiring no oxygen.

Photosynthesis

The process of converting light energy, carbon dioxide, and water into glucose and oxygen.

Red blood cells

Cells that transport oxygen through the bloodstream and do not contain a nucleus.

Volume

The amount of space inside an object. Measured in (units of length)3 (i.e. mm3, cm3, m3).

Surface Area

The sum of the area of all exposed sides of a three-dimensional shape. Measured in (units of length)2 (i.e. mm2, cm2, m2).

Surface area : volume ratio (SA:V)

A comparison of the amount of surface area per unit of volume. In Biology, SA:V influences temperature regulation, and a high SA:V leads to more effective transport into and out of cells.

Intracellular

Inside a cell

Extracellular

outside a cell

Selective permeability

Property of cell membranes that ensures only specific substances pass across them. Also known as semipermeable.

Phospholipid

The main molecule of which membranes are composed. They have a phosphate head and two fatty acid tails.

Phospholipid bilayer

A double layer of amphiphilic molecules that forms the primary component of cell membranes.

Phosphate Head

The hydrophilic (water loving) subunit of a phospholipid

Fatty acid tail

The hydrophobic (water hating) lipid subunit of a phospholipid.

Polar

Describes a molecule with both a positive end and negative end. These tend to be hydrophilic.

Nonpolar

Describes a molecule without a clearly positive or negative end. These tend to be hydrophobic.

Amphipathic

Describes molecules with both hydrophilic and hydrophobic components. Also known as amphiphilic.

Protein

A class of biomacromolecule made of amino acid monomers folded into a 3D shape, consisting of carbon, hydrogen, oxygen, nitrogen, and sometimes sulphur.

Carbohydrate

A class of biomacromolecule made from monosaccharide monomers consisting of carbon, hydrogen, and oxygen. Also known as saccharides or sugars.

Cholesterol

A steroid-alcohol that regulates fluidity in plasma membranes.

Transmembrane protein

An integral protein that spans the entire plasma membrane.

Glycolipid

A phospholipid bound to a carbohydrate.

Glycoprotein

A protein bound to a carbohydrate.

Fluid mosaic model

The theory of how the plasma membrane is structured.

Passive transport

The movement of molecules through a semipermeable membrane and down the concentration gradient, without an input of energy.

Active Transport

Movement of molecules across a semipermeable membrane that requires energy.

Diffusion

The passive movement of molecules from areas of high concentration to areas of low concentration (down the concentration gradient).

Concentration Gradient

The difference in solute concentration between two adjacent areas.

Solute

A substance dissolved in the solvent.

Facilitated diffusion

A type of passive transport where molecules move through a phospholipid bilayer with the aid of a membrane protein.

Protein channel

A transmembrane protein pore in a phospholipid bilayer that selectively enables transport of large or polar molecules.

Carrier protein

A membrane protein that undergoes conformational change to transport molecules across a membrane.

Osmosis

The passive transport of a solvent (typically water) through a semipermeable membrane from a region of low solute (high solvent) to a region of high solute (low solvent).

Hypertonic

Describes a solution with a higher solute concentration when compared to another solution.

Isotonic

Describes a solution with the same solute concentration as another solution.

Hypotonic

Describes a solution with a lower solute concentration when compared to another solution

Turgid

Describes plant cells that are swollen and firm from water uptake.

Plasmolysed

Describes plant cells with weak and sagging plasma membranes from water loss.

Protein-mediated active transport

Describes plant cells with weak and sagging plasma membranes from water loss

Bulk transport/Cytosis

A type of active transport that uses vesicles to move large molecules or groups of molecules into or out of the cell.

Protein pump

A polypeptide that transports molecules across a membrane against its concentration gradient with the aid of ATP.

Adenosine triphosphate (ATP)

A high energy molecule that, when broken down, provides energy for cellular processes.

Carrier protein

A membrane based protein that undergoes conformational change to transport molecules across a membrane.

Exocytosis

A type of bulk transport that moves large substances out of the cell.

Endocytosis

A type of bulk transport that moves large substances into the cell.

Phagocytosis

Endocytosis of solid material or food particles.

Pinocytosis

Endocytosis of liquid or dissolved substances.

Asexual Reproduction

A method of reproduction that produces genetically identical cells without the fusion of gametes (sex cells).

Plasmid

A small, circular loop of DNA that is separate from a chromosome, typically found in bacteria.

Cytokinesis

The division of the cytoplasm and formation of two daughter cells.

Septum

A dividing wall formed during binary fission.

Interphase

The first stage of the eukaryotic cell cycle which involves cellular growth and duplication of chromosomes. Composed of three phases: G1, S, and G2.

Sister Chromatids

The two identical halves of a replicated chromosome.

Cytokinesis

The division of the cytoplasm and formation of two daughter cells.

Chromatin

Chromosomes (DNA and proteins) that have been unwound and loosely packed during interphase.

Terminally Differentiated

Cells that have fully specialised and no longer replicate.

Chromatid

One half of a double stranded chromosome.

Centromere

The structure that holds sister chromatid’s together.

Diploid

Cells or organisms that have two sets of chromosomes.

Daughter Cell

The formation of a new cell following cell replication.

Prophase

Prophase begins with the condensation of chromatin around histones into distinct chromosomes, so that they become visible under a microscope. Simultaneously, the centrioles migrate towards opposite ends (or poles) of the cell, and spindle fibres begin to form. The nuclear membrane breaks down and the nucleolus disappears.

Metaphase

In metaphase, the spindle fibres fully form and attach to the centromere of each chromosome. This allows the spindle fibres to guide the chromosomes towards the equator of the cell where they line up.

Anaphase

The spindle fibres contract, splitting the centromere and pulling sister chromatids to opposite ends of the cell.