BIO unit one

biology glossary terms

living things

anything that can move, respire, sense, grow, reproduce, maintain, equilibrium, excrete water and take up nutrients

homeostasis

The maintenance of a relatively stable 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 up 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 membrane

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

cytosol

The aqueous fluid that surrounds the organelles inside the cell

ribosomes

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

DNA

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

membrane-bound organelles

Structure within a cell that is enclosed by a phospholipid bilayer

chromosome

The structure made of protein and nucleic acids that carries genetic information

nucleus

Double membrane-bound organelle that protects and confides the genetic information (DNA) of a cell. 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

organelles

A cellular structure that performs specific functions

cytoplasm

The cytosol and organelles inside the plasma membrane excluding the nucleus

ribosomal RNA (rRNA)

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

mitochondria

The primary site of energy production from aerobic cellular respiration

cellular respiration

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

cristae

The fold of the inner membrane of the mitochondria

chloroplast

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

algae

A large diverse group of photosynthesis protists found in aquatic environments

grana

A stack of thylakoids

thylakoids

A flattened sac-like structure inside the chloroplast. Thylakoids stacked upon one another make up a grana

stroma

The fluid substance that makes up the interior of chloroplasts

photosynthesis

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

chlorophyll

A green pigment found in the thylakoids of chloroplasts it is responsible for absorbing light energy in photosynthesis

endosymbiosis

When one organism lives inside another in a mutually beneficial relationship

endosymbiosis theory

A theory suggesting that chloroplasts and mitochondria were once free-living organisms before being engulfed by a larger cell

volume

The amount of space inside an object measured in units of length 

surface area

The sum of the area of all exposed sides of a three dimensional shape

ratio

A comparison between two things to show proportions

SA:V

A comparison of the amount of surface area per unit of volume. In bio, SA:V influences temperature regulation 

intracellular

Inside a cell

extracellular

Outside a cell

selective permeability

A property of cell membranes that ensure only specific substances pass across them known as semi-permeable 

phospholipid

The main molecule of which membrane 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 subunit of a phospholipid 

hydrophillic

Having a tendency to be attracted to and dissolve in water

polar

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

hydrophobic

Having a tendency to repel and be insoluble in water 

non polar

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

amphipathic

Describes molecules with both hydrophilic and hydrophobic components 

protein

A class of biomacrmolecule 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 (known as saccharides or sugars)

cholesterol

A steroid-alcohol that regulates fluidity in plasma membranes 

integral protein

A protein that is permanently secured to the plasma membrane

transmembrane protein

A integral protein that spans the entire plasma membrane

peripheral protein

A protein that is temporarily attached to the plasma membrane

cytoskeleton

The microscope web of protein filaments in the cytoplasm. It provides structure and support and transports products around the cell

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

saturated

A fatty acid chain with only single bonds between carbon atoms

unsaturated

The fatty acid chain with at least one double triple bound between carbon atoms 

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 to the concentration gradient)

concentration gradient

The difference in solute concentration between two adjacent areas

solute

A substance dissolved in the solvent

solvent

A liquid in which a solute is dissolved forming a solution

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 the phospholipid bilayer that selectively enables transport of large or polar molecules

carrier protein

A membrane protein that undergoes conformational change to transport molecules across the membrane 

conformational change

A change in the 3D shape of macromolecules such as proteins

osmosis

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

tonicity

A measure of the relative concentration of solutes on either side of a semipermeable membrane, described as hypertonic, hypotonic or isotonic

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

plasmolyse

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

lyse

To cause a cell plasma membrane to burst or break 

protein-mediated active transport

A type of active transport which involves using membrane proteins to move molecules across a membrane against their concentration gradient. Also known as active transport 

bulk transport

A type of active transport that uses vesicles to move large molecules or groups of molecules into or out of the cell (known as cytosis)

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 of cellular processes 

vesicle

A small membrane-bound sac that transports or stores substances within a cell

exocytosis

A type of bulk transport that moves larges substances out of the cell 

endocytosis

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

rough endoplasmic reticulum (RER)

A membraneous chain of connected and flattened sacs which are coated with ribosomes on their outer surface that synthesise and modify proteins

golgi body

Stacked flattened sacs are the site of the protein sorting, packaging and modification. Also known as golgi apparatus or golgi complex

secretory products

The substances inside a vesicle that are being transported out of the cell

lysosome

A membrane-bound vesicle that contains digestive enzymes. They are responsible for breaking down cell waste 

phagocytosis

Endocytosis of solid material or food particles 

pinocytosis

Endocytosis of liquid or dissolved substances

binary fission

The method of cell replication used by prokaryotes 

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 

cytokenesis

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 cell growth and duplication of chromosomes, composed of three phases, G1, S and G2

mitosis

sister chromatids

The two identical halves of a replicated chromosome 

chromatin

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

quiescent

Dormant cells which can re-enter the cell

terminally differentiated

Cells that have fully specialised and no longer replicate 

chromatid

One half of a double-stranded chromosome

centromere

The structure which holds sister chromatids together