Science Unit 2

Prokaryotic

Cells that do not enclose their DNA in nuclei.

Eukaryotic

Cells that enclose their DNA in nuclei.

Organelles

Specialized structures within a cell, often referred to as little organs.

Cell Wall

The supporting layer around the cell membrane that provides support and protection for the cell.

Cell Membrane

A thin flexible barrier surrounding the cell that controls what comes in and out of the cell.

Nucleus

The control center of the cell that contains the DNA.

Nuclear Envelope

Surrounds the nucleus and allows material to move in and out through nuclear pores.

Chromatin

Thread-like complexes of DNA found inside the nucleus.

Nucleolus

A small dense region inside the nucleus where the assembly of ribosomes starts.

Cytoplasm

The gel-like fluid portion of the cell where many organelles are found.

Mitochondria

Organelles that are the powerhouse of the cell, converting chemical energy found in food into usable substances.

Endoplasmic Reticulum

Passageways that carry materials around the cell; rough when ribosomes are attached.

Ribosomes

Small particles of RNA and protein that assemble proteins following coded instructions from DNA.

Golgi Body

Modifies, sorts, and packages proteins and other materials; acts like the cell's UPS.

Chloroplast

Organelles that perform photosynthesis by converting sunlight into chemical energy, containing chlorophyll.

Vacuole

A large sac-like membrane enclosed structure that stores fluids like water, salt, and carbohydrates.

Lysosome

Cleanup crew of the cell, breaking down lipids, carbohydrates, and proteins into usable substances.

Centriole

Organizes cell division; found near the nucleus in animal cells, but not in plant cells.

Cytoskeleton

Network that helps maintain cell shape and is involved in movement, made of microtubules and microfilaments.

Macromolecules

Large molecules such as lipids, carbohydrates, nucleic acids, and proteins.

Carbohydrates

Organic compounds made of carbon, hydrogen, and oxygen; their monomers are monosaccharides used for energy.

Lipids

Organic compounds composed of carbon, hydrogen, and oxygen; their monomers are fatty acids and glycerol for energy storage.

Proteins

Made of carbon, hydrogen, oxygen, and nitrogen; their monomers are amino acids used for cell structure and reactions.

Enzyme

Biomolecules that speed up chemical reactions in cells.

Nucleic Acids

Made of carbon, hydrogen, oxygen, nitrogen, and phosphorus; their monomers are nucleotides that instruct cell functions.

Selective Permeability

Characteristic of membranes that allows some substances to pass through while others cannot.

Diffusion

The process of moving from an area of high concentration to low concentration.

Osmosis

The diffusion of water through a selectively permeable cell membrane.

Equilibrium

State when the concentration of a system is the same throughout.

Isotonic

A solution with the same concentration of water inside the cell as outside.

Hypertonic

A solution with a low water concentration and high solute concentration outside the cell.

Hypotonic

A solution with a high water concentration and low solute concentration outside the cell.

Passive Transport

Movement of dissolved materials through a membrane without using energy.

Active Transport

Movement of materials against a concentration difference that requires energy.

Endocytosis

The process of taking material into the cell.

Exocytosis

The process of releasing large amounts of material out of the cell.