U1T3 & U1T4 - Keywords Flashcards
What are cells?
Basic unit from which organisms are built up. They are the basic unit of life.
What is cell theory?
The theory of cells, their functions and how they work.
Unicellular organisms
Organisms which are made up of just one cell. e.g. Amoeba
Multicellular organisms
Organisms which are made up of millions of cells e.g. Humans
Organelles
Little organs
Prokaryotic cells
Found amongst bacteria + other members of the kingdom ‘prokaryotae’. They have no nucleus + very few organelles. No membrane bound organelles (mitochondria, chloroplasts, RER)
Eukaryotic cells
Found amongst organisms belonging to the other 4 kingdoms ‘plants, animal, fungi, protoctista’. They have nuclei + many organelles, some of which are bound by their own membranes (mitochondria), whilst others aren’t (ribosomes)
Membranes
A microscopic double layer of lipids + proteins forming the boundary of cells/organelles.
Naked DNA
When DNA isn’t incorporated into chromosomes around histone proteins.
Biotechnology
Exploitation of bio processes for industrial/other purposes.
Nutrient Cycles
Movement + exchange of organic/inorganic matter back into the production of matter.
Cell Wall
Strong rigid structure which gives cell shape + protection against swelling + bursting due to osmosis. Made from peptidoglycan. Permeable to water + other small molecules but not proteins + acids (same function as cellulose in cell walls of green plants)
Peptidoglycan
Polsaccharide + protein
Permeable
Allowing liquids or gases to pass through it.
Plasma Membrane
Fluid mosaic membrane made of lipids + proteins. Sometimes it’s invaginated to form mesosomes.
Fluid mosaic membrane
A flexible layer of lipid molecules interspersed with large protein molecules that act as channels where other molecules enter/leave cell. Some proteins are extrinsic and some are intrinsic. Proteins have hydrophobic regions in contact with lipid layer whilst hydrophilic regions face out.
Invaginated
Turned inside out/folded back on itself to form a cavity/ pouch.
Mesosomes
An organelle of bacteria that appears as an invagination of the plasma membrane + functions either in DNA replication + cell division/excretion of exoenzymes.
Aerobic respiration
The process of producing cellular energy involving oxygen.
Slime layer
Many bacteria that cause disease have this structure which gives it protection against host body’s defences.
Ring of DNA
This bacterial chromosome is a single stranded closed loop of DNA which doesn’t contain histone proteins as in eukaryotic chromosomes (naked DNA)
Cytoplasm
Contains few organelles except ribosomes which are smaller than the ribosomes in eukaryotic cells. (organelles outside nucleus)
Flagellum
To enable the bacteria to move, they’re anchored in the cell membrane.
Nuclear membrane
The lipid bilayer membrane which surrounds the genetic material + nucleolus in eukaryotic cells.
Chromatin
When DNA occurs as a helical structure, combined with histone proteins.
Mitotic spindle
Macromolecular machine that segregates chromosomes to two daughter cells during mitosis.
Cellulose
Insoluble substance which is main part of plant cell walls. Polysaccharide consisting of chains of glucose monomers.
Chitin
Fibrous substance consisting of polysaccharides, which is major part in exoskeleton of arthropods + cell walls of fungi.
Protoplasm
All of contents within cell surface membrane, including nucleus.
Cytosol
The part of the cell within the cell surface membrane but outside the nucleus + other membrane bound organelles (liquid)
Fluid Mosaic Model
The structure of the cell membrane.
Cell Membrane
Thin barrier which separates internal components of cell from external (extracellular) environment. Regulates passage of substances into and out of the cell.
Phospholipids
Lipids that contain phosphorous.
Cholesterol
Steroid
Glycolipids
Lipids with one or more sugars attached.
Phospholipid bilayer
When phospholipids line up In 2 parallel layers. The end with the phosphate group is hydrophilic (Polar/soluble) which point outwards and form H2 bonds with water molecules in cytosol or extracellular fluid whilst the other is hydrophobic (non-polar/insoluble) which are mutually attracting and point inwards.
Selective Barrier
A substance which only allows certain substances to leave and enter.